Gurnell University Library
Ithaca, Nem York

Glumbia Maivessity
iii

‘ohn, ove2
COLUMBIA UNIVERSITY IN THE cry OF NEW YORK

PUBLICATION NUMBER NINE’ OF THE
ERNEST KEMPTON ADAMS FUND FOR PHYSICAL RESEARCH

EstTaBLISHED DEecEMBER 17TH, 1904

PARATLAXES OF 260 STARS

DERIVED FROM PHOTOGRAPHS MADE AT
THE LEANDER McCORMICK OBSERVATORY

 

 

 

BY

S. A. MITCHELL, Pu.D.

PROFESSOR OF ASTRONOMY IN THE UNIVERSITY OF VIRGINIA AND DIRECTOR OF THE MCCOR<
MICK OBSERVATORY, ADAMS RESEARCH FELLOW OF COLUMBIA UNIVERSITY, 1913-15;
SPECIAL ADAMS RESEARCH, FELLOW, 1915-

ASSISTED BY

C. P. OLIVIER, H. L. ALDEN AND OTHERS

 

NEW YORK
COLUMBIA UNIVERSITY PRESS
1920
“"RIUIBITA JO APISLOATU/] “AIOJVAINSGY YOMUUIONIIN Jopuvs'y otf,

 
COLUMBIA UNIVERSITY IN THE CITY OF NEW YORK

PUBLICATION NUMBER NINE OF THE
ERNEST KEMPTON ADAMS FUND FOR PHYSICAL RESEARCH

EstaBLIsHED DECEMBER 17TH, 1904

PARALLAXES OF 260 STARS

DERIVED FROM PHOTOGRAPHS MADE AT
THE LEANDER McCORMICK OBSERVATORY

 

 

BY

8. A. MITCHELL, Px.D.

PROFESSOR OF ASTRONOMY IN THE UNIVERSITY OF VIRGINIA AND DIRECTOR OF THE MCCOR-
MICK OBSERVATORY, ADAMS RESEARCH FELLOW OF COLUMBIA UNIVERSITY, 1913-15;
SPECIAL ADAMS RESEARCH FELLOW, I91S~

ASSISTED BY

C. P. OLIVIER, H. L. ALDEN AND OTHERS

 

NEW YORK
COLUMBIA UNIVERSITY PRESS

1920
mK
Copyright 1920 by Columbia University Press

PRESS OF
THE NEW ERA PRINTING COMPANY
LANCASTER, PA.
N the seventeenth day of December, nineteen hundred
and four, Edward Dean Adams, of New York, estab-
lished in Columbia University ‘‘The Ernest Kempton Adams
Fund for Physical Research’’ as a memorial to his son, Ernest
Kempton Adams, who received the degrees of Electrical Engi-
neering in 1897 and Master of Arts in 1898, and who devoted
his life to scientific research. The income of this fund is, by
the terms of the deed of gift, to be devoted to the maintenance
of a research fellowship and to the publication and distribution
of the results of scientific research on the part of the fellow.

(For list of Adams Fund Publications see back cover page)
CONTENTS

PAGE
The Leander McCormick Observatory...... ..... .... . 1
Parallax Methods. Sane: Lise GIS eee 3
The Meridian Circle... .... 0... 06. cee eee ee, 7
The Heliometer............. by ofits Patatis ad ited 8
Early Photographic Work.... .... .... 0... 0... 0... 10
Later Photographic Work. .... ........ .... «18
Photographic Apparatus. .... .... Mme. Sr cae 18
Photographic Methods. . LAREN. ashes .. 19
Elimination of Errors of ie Phatoeraphe. marae sng on 22
Guiding Error........ nay Chet cate. Rede Oe tate PQA
Choice of Comparison Stars. Pie. Ohh SR, nda2e! eg S28
Methods of Measurement. ...... ii, eee, “aes, see 9
Reductions of the Plates... ....  .... ... sues, eg AOR
Elimination of Systematic Errors... ....  .. tee sn 84
Proper Motions... ... ..... see. Sales iu Gus ong 386
Spectroscopic Parallaxes. .... ... ....0 1... 0 0... 38
The Detailed Results. Ss iced, LRG CRAY, Rega 39
Average Probable Errors Se crash ath teto io Otae 643
Comparisons with the Early Parallaxes. ee 643
Comparisons with the Yale Heliometer. ....... ee 646
Comparisons with Modern Photographic Parallaxes. ... 647
The Ursa Major Group. .......... .... tee. se. 649

Mean Parallaxes related to Proper Motions oun Magnitudes. 651
Mean Parallaxes Computed from McCormick Relative
Parallaxes::... ccc: cane oeeee Baee Faw aahesam edne 652
Constants for Mean Paral axes of F, G, K and M Stars.... 654
Comparisons with Mean Parallaxes from Van Rhijn’s Tables 655

Fifteen Exceptional Stars. Web NE ete ovewes 657
Comparisons with Spectroscopic Parallnges,. laa tea . 657
Masses..... a. eset, eR tien Gees, oa ore 659
Mass-Ratiossetacee ati BWP4 Lee OLADA Biba Sete 660
SUMMARY: io Stone GoahnGhaeienee wade asae .. 662
Table of Parallaxes and Proper Motions. Sede 665
~Part IT.
Measures of Double Stars on Parallax Plates............ 679

v
PARALLAXES OF 260 STARS

DERIVED FROM PHOTOGRAPHS MADE AT THE
LEANDER McCORMICK OBSERVATORY

BY

8. A. MITCHELL
ASSISTED BY

.C. P. OLIVIER, H. L. ALDEN, AND OTHERS

Tue Leander McCormick Observatory owes its existence to
the generosity of the late Leander J. McCormick of Chicago.
Born in Rockbridge County, Virginia, and desiring to do some-
thing to prove his affection for his native state, he contracted
with Alvan Clark and Sons for a mate of the telescope they were
then making for the U. S. Naval Observatory, and he offered,
on specified conditions, to present it to Washington and Lee
University, at Lexington, in the county where he was born.
As those conditions were not met, he next offered it to the Uni-
versity of Virginia, through Col. Venable, the professor of
mathematics in the latter institution, who immediately took
steps toward raising the necessary endowments. In answer to
an appeal to the state legislature, that body passed resolutions
recognizing the generosity of the donor and the importance of
securing such a telescope, but did not deem it wise in the con-
dition of the state finances at that time (1878), to make the
appropriation. An appeal was then made to the alumni of the
university, and a fund of over $50,000 was raised to pay the
salary of the director. To this sum, Mr. William H. Vanderbilt
of New York, added $25,000 as the beginning of a working fund.
The university provided ample grounds and built the director’s

2 1
2 S.A. MITCHELL

residence on the summit of Mt. Jefferson. It may be interesting
to note that this was the actual site chosen for an observatory
by the founder of the university, Thomas Jefferson, and a small
observatory in reality had been built there. Mr. McCormick
gave the telescope, the mounting, and the observatory building.
This building is not very large, consisting merely of a dome,
forty-five feet in diameter, constructed by Warner and Swazey,
to which are attached two rooms which serve as offices.

The telescope was mounted and work with it was begun in
1883, with the observatory under the directorship of Professor
Ormond Stone. The McCormick telescope is not an exact
duplicate of the U. S. Naval Observatory instrument. It has
an aperture slightly larger than the Washington telescope.
As a matter of fact, it was constructed with an aperture of
2614 inches so that it might be the largest of any refractor in
the United States, a proud position which it held for only a
short time.

In planning the work to be undertaken at the new observatory,
Professor Stone took advantage of the great light-gathering power
of the lens to make a photometric study of the nebula of Orion,
and to make a survey of the heavens to discover new and faint
nebulae, mainly in the southern skies. An account of these
researches is found in the Publications of the Leander McCormick
Observatory, volume 1. During the period from 1890 to 1902,
many micrometrical measures on the satellites of the planets were
made, as well as observations of many of the comets appearing
during that interval. From 1894 to 1902 Professor Stone and
several of the assistants made extended series of measures of the
fainter satellites of Saturn. The McCormick Observatory also
took a full part in the Eros campaign of 1900. The telescope was
also used for the measurement of doubles, this work being done
mainly by F. P. Leavenworth, C. P. Olivier, and R. E. Wilson.
These measures are found in the Publications, and also in the
Astronomical Journal and Astronomische Nachrichten. In 1901, in
coéperation with Harvard, Lick and Yerkes Observatories, work
was begun with the wedge photometer. The measures were
carried out mainly by H. D. Curtis, T. McN. Simpson and F. W.
Reed. Following this, in 1908, variable star observations were
PARALLAXES OF 260 STARS 3

taken up, visual estimates being made by the Argelander method.
No account of these photometric measures nor of the variable
star work has yet been published. Professor Stone resigned as
director of the observatory in 1912. Under his care, the in-
vestigations carried out had been entirely visual, no photographic
work of any sort having been attempted. with the refractor.

In September, 1913, S. A. Mitchell assumed the duties of
director. It seemed wise that photographic work with the
refractor should be started, and accordingly a photographic
dark-room was constructed, and arrangements were made with
the university for the installation of electric lights and running
water. But what photographic work should be attempted?
The choice seemed to lie between the determination of radial
velocities by the spectrograph and the investigation of stellar
parallax. So much excellent work has been accomplished in
the measurements of the motions of stars in the line of sight,
first by powerful refractors and then later by still more powerful
reflectors, that it did indeed seem that another large refractor
devoted to this line of work could add comparatively little in
constructive research.

In investigations of stellar distances the situation in 1913 was
very different. In the Silliman* lectures delivered at Yale
University in 1910, the director of the Lick Observatory spoke
as follows: “‘ Measures of stellar distances present difficulties so
great that even today we possess reliable knowledge of the ap-
proximate distances of not over a hundred stars. At no point
in astronomical science is fuller knowledge more desirable, more
pressingly urgent, than in the subject of stellar distances; or
speaking technically, of stellar parallaxes.”’

Schlesinger had recently published in the Astrophysical Journal
for 1910 and 1911 a remarkable series of papers in which were
given the methods and the measurements of the distances of
28 stars determined by photography with the 40-inch refractor
of the Yerkes Observatory. :

The photographic measures given by Schlesinger showed a
vast increase in accuracy over the older methods of determining
parallaxes visually, whether obtained by heliometer, by meridian

* “Stellar Motions,” Ww. W. Campbell, Yale University Press, 1913.
4 S. A. MITCHELL

circle or by micrometer. The work so admirably done by
Schlesinger was continued at Yerkes by Slocum and Mitchell
who published the parallaxes of 61 stars which showed an ac-
curacy as indicated by a probable error of + 07009. In addi-
tion to the Yerkes refractor, there were but three other tele-
scopes which had followed the example of Yerkes and were
engaging in determining stellar distances by photography, and
these were the 60-inch reflector at Mt. Wilson, the 26-inch re-
fractor at Greenwich, and the 24-inch refractor at Swarthmore.
With only four telescopes devoted to the determination of stellar
distances by photography, it seemed advisable that the 26-
inch McCormick refractor should also attempt this work, and
that the main energies of the observatory staff should be devoted
to carrying out these researches.

Since the present publication is not written for astronomers
only, it might not be out of place to recount briefly the history
of the determination of the distances of the stars. (For a fuller
account see Sir F. W. Dyson, ‘‘ Measurement of the Distances of
the Stars,’”’ Observatory, 249, 292, 1915.) The finding of the dis-
tances of the stars is a problem somewhat similar to that which
faces the surveyor in his attempt to measure the distance across
a river which it is impossible to cross. This latter problem is
readily accomplished by carefully measuring the length of a
base-line on the surveyor’s side of the river, and then measuring
the angles from each end of this line to some prominent point,
as a church spire or a tree, on the other side of the river. The
distance is found by elementary trigonometry. If the tree
across the river chosen by the surveyor for his measurements
had been a near-by tree located on the edge of a woods, then if
he walked from one end of his base-line to the other and had
kept his eyes on this tree, the surveyor would have seen it change
its position relative to the background of trees behind. If the
tree were fairly close to the surveyor, this angular displacement
would be comparatively large, while the farther and farther
distant the tree is from the surveyor, the smaller and smaller
would the displacement become. =

In quite a similar way, the distances to the stars are found.
Once a year the earth travels about the sun in an orbit which is
PARALLAXES OF 260 STARS 5

approximately a circle, and where the distance from sun to earth
is ninety-three millions of miles. Consequently, after a lapse of
six months, the earth finds itself at a position one hundred and
eighty-six millions of miles from wheré it had been earlier. Do
not the stars nearest to the earth and sun suffer a displacement
relative to the far-off stars, just as the near tree is displaced
as the surveyor walks the length of his base-line? This question
was asked of the followers of the Copernican system, and as
no such displacement was actually observed, the conclusions
were obvious,—either that the Copernican system was false
and the earth did not circle about the sun, or else the stellar
displacements were smaller than could be observed by the naked
eye. The displacements were too small even to be discovered
by the telescope invented by Galileo in 1609, and so one was
forced to assume that the universe was made on a much larger
scale than had once been thought.

With each increase in telescopic power, with each improve-
ment in measurement which added to the accuracy of stellar
measurements, the problem of finding the distance of the stars
was again attacked. Hooke, Flamsteed, Picard, Cassini,
Horrebow, and Halley each in turn attempted to find a dis-
placement of the stars, but each in turn failed, though Halley
found that three of the brightest stars, Aldebaran, Sirius and
Arcturus, were not in reality fixed, since each star had a slight,
but unmistakable motion of its own. Halley came to the con-
clusion that the stars were at least 20,000 or 30,000 times more
distant than the sun, though the exact distance of the sun was
then unknown.

In attempting to measure the distance of the stars, the astrono-
mer Bradley discovered the aberration of light, and also nutation,
and he recognized that one star y Draconis must be more than
200,000 times farther from the Earth than is the Sun.

Assuming that bright stars on the average must be closer to
us than faint stars, Sir William Herschel attempted an ingenious
method of detecting the displacement of the stars caused by
the earth’s annual journey about the sun by measuring accurately
the relative positions of stars near each other in the sky, one
being bright, the other faint. Although Herschel did not succeed
6 S. A. MITCHELL

in detecting the parallaxes of any stars, he did find an entirely
new class of stars, of which we now know many thousand,
namely, double or binary stars.

Following Herschel’s time, many attempts were made to
measure the distances to the stars, but these attempts ended
only in failure. It remained for the year 1838 to have the honor
of recording the first stellar distance, and singularly enough,
the distance of not only one star was measured but three, by
three different observers, using instruments of three different
types and employing three different methods. The greatest
honor probably belongs to Bessel in determining the distance of
61 Cygni, though Henderson found the distance of a Centauri,
and Struve gave that of a Lyrae. Each of the three sought
to measure the displacement of the star with respect to fainter
stars, but the method of measurement used by Bessel was the
best and led to the most accurate results.

The instrument used by Bessel was called the heliometer. Its
object-glass had the peculiarity that it was cut exactly in halves.
Since each half-objective forms a complete image of every star
in the field of view towards which the heliometer is pointed, it
is readily possible to measure the angular distance of one star
from the other by displacing the two halves of the objective by
a known and measurable amount; and by rotating the objective
on the end of the tube to determine the position of the two stars
relative to each other.

The method employed by Struve to measure the displacement
of a Lyra with respect to the neighboring stars was by using
the filar micrometer on the eye-end of the equatorial telescope.
This is the attachment usually employed in the measurement of
the position angle and distance of the components of a double
star. Where the angular distances are small, the micrometer
in skillful hands gives a wonderful degree of precision. In the
process of measurement, it is necessary to put the fixed wire of
the micrometer on one component of the double, and the movable
wire on the other component. The accuracy of the measure-
ment depends on the skill with which the observer can bisect
both stars of the double at the same time. The difficulty in
accomplishing this is great since most observers must first look
PARALLAXES OF 260 STARS 7

at one star to see whether the bisection is perfect and then to
the other star, and the difficulty becomes the greater as the
angular distance between the stars is increased. With the
heliometer, however, the measurement of a large angular distance
can be secured with as great a precision and with as great ease
as when the distance is small. The result has been that measures
with the equatorial telescope and micrometer have given stellar
parallaxes which may be very greatly in error. The main diffi-
culty lies in the fact that usually the only stars that ‘are avail-
able as comparison stars for the measurement of the displacement
of the parallax star are at such great angular distances that the
micrometer cannot be employed with sufficiently adequate
precision.

Henderson’s instrument used for discovering the distance of
the star a Centauri, which still holds the place of honor of being
the nearest fixed star that we know, was the meridian circle.
This instrument furnishes the right ascension and the declina-
tion of the stars in the sky, and gives therefore what is known
as their absolute positions. Two different methods may be
followed to determine the parallaxes of stars with the meridian
circle. The first method is to find the absolute position of the
star at times during the year when the earth is at opposite ends
of its orbit, and to obtain from a comparision of these absolute
positions the amount of change in position which is caused by
the motion of the earth. This change in position may be either
in right ascension, or in declination, or in both. The second
method is in comparing the right ascension or declination of a
star whose parallax is to be determined with the right ascension
or declination of a near-by star or stars, which shall serve as
comparison stars. The first procedure may be called the absolute
method, the second the differential one.

For obvious reasons, which it is not necessary to discuss here,
the differential method ‘gives the more accurate results. But
even the differential method may be subject to large systematic
errors since the parallax star and the comparison stars usually
are of quite different magnitudes. The average observer will
measure quite differently the exact time at which a bright
and a faint star will cross a wire, although gauze screens are
8 S. A. MITCHELL

placed before the telescopic objective to be rid of this systematic
effect. For a star on the equator one second of time is equal to
fifteen seconds of arc. A precision measured by a probable
error of + 0701 (one-hundredth of a second of arc) would require
of an equatorial star a precision measured by one fifteen-hun-
dredth of a second of time. If, therefore, one is to determine
stellar parallaxes by the meridian circle by means of observations
in right ascension, there will be required a remarkably perfect
instrument and an observer wonderfully skillful and careful,
if an accuracy is to be attained which is comparable with modern
photographic work.

According to Dyson (loc. cit.), the heliometer of Bessel which
was used to measure the distance of 61 Cygni with such accurate
results was later employed by Schliiter and Wickmann in measur-
ing the distance of Groombridge 1830, an interesting star with
a proper motion, the largest then known. With the same
instrument in the sixties, Auwers determined the parallax of
several stars, while with the heliometer at Bonn, Krueger and
Winnecke measured the distances of five stars. The third
heliometer to be employed, though only four inches in aperture,
in the capable hands of Gill, the director of the observatory at
the Cape of Good Hope, and Elkin, afterwards director of Yale
Observatory, gave the distances of nine stars in the Southern
Hemisphere with a high degree of accuracy. After such a
notable start, Gill and Elkin continued their measures separately.
Gill and his assistants at the Cape with a seven-inch heliometer,
determined the distances of no less than 17 stars between the
years 1888 and 1898. On being appointed director of the Yale
Observatory in 1884, Elkin with the assistance of Chase and
Smith carried out a most remarkable series of measurements,
which resulted in the determination of the distances of 238
stars. This work was published in 1912. Other observations
with the heliometer were carried out at Leipzig with a six-inch
instrument. Between the years 1890 and 1911, Peter deter-
mined the parallaxes of 20 stars.

As an example of the character of the work capable of being
done by the heliometer, the results are given below of the ex-
cellent measures by Elkin with the Yale heliometer on the bright
PARALLAXES OF 260 STARS 9

star « Canis Minoris, as given in the Transactions of the Yale
Observatory, 1, 287.. The star was measured with respect to
thirteen comparison stars in seven separate series, six of which
had two comparison stars, and the seventh of which had only
one. The parallax of a Canis Minoris as derived from each of
the seven series follows:

Beries: eee here tee aes ath w = +0257 + 0”018
Dx axe Aol ane ones Soe -461+ .085

ATID Sor cey shes ero haeeiispra ors ee .367 + .018

DV ie 8 ctpniscdih RSS he tsmliys ea eee .866 + .023

Wis irusiaawaadte soln nade -603 + .049

VD sth os a. tte perme oer aiaes .294+ .019

7 VL Gis ee a 0.228 + 07020
MIGRAINE oe. scacpiie faces Bash eee Bc tsra Sate mw = 07334 + 07015

Altogether 128 observations contributed to this result. The
measures, though most carefully made show results which have
a range in value from + 07228 to + 07503. Such a range in
values coming from the hands of a skillful observer after many
years of training shows the limitations of the heliometer.

Although the measures with the heliometer have given ex-
cellent results, the scope of astronomical work that may be ac-
complished by such an instrument is very limited, with the
consequent result that very few heliometers have ever been con-
structed. The case is far different with the meridian circle,
for there are in existence very many excellent instruments de-
voted to this department of astrometry. Kapteyn was the
first to show that satisfactory parallaxes might be determined
with the meridian circle, provided that sufficient care be taken
with the method of observation. Instead of obtaining the ab-
solute places of the stars, more satisfactory results could be
obtained if the parallax star were referred to one or more com-
parison stars, and if the differential displacements were secured
relative to these comparison stars. The results for parallax
secured by Kapteyn possess a high degree of accuracy. Here
then was a method that did not require a specially constructed
and highly intricate instrument like the heliometer, but the
many hundreds of meridian circles about the world could ap-
parently give valuable results in the field of this very difficult
10 S. A. MITCHELL

line of research, the determination of the distances of the stars.
Accordingly, many astronomers devoted themselves to observa-
tions with meridian circles with the greatest of zeal. Chief
among these indefatigable workers might be mentioned the
names of Flint of the Washburn Observatory of the University
of Wisconsin, Jost, Jewdokimov, Grossmann, G. Abetti, and
Vofite.

In the securing of stellar parallaxes, the meridian circle has
two advantages over the heliometer; first, that a special instru-
ment is not needed for parallax work, results being obtained with
existing apparatus, and, second, parallaxes can be determined
with an expenditure of labor that is less in the case of the meridian
circle than the heliometer. According to the estimdtion of
Dyson, however (loc. cit., p. 297), work with the meridian circle
on as many as 50 nights gives parallaxes ‘which are not nearly
as accurate as the best heliometer observations.”

Of all the methods of obtaining parallaxes by visual methods,
unquestionably the best results can be obtained with the helio-
meter. But even though the instrument be a most perfect
one, the observer highly trained, skillful, and careful, parallaxes
can be obtained by the heliometer only after a prodigious amount
of labor, and even then, the results from careful work may dis-
agree, as was plainly shown in the case of Elkin’s work on the
star a Canis Minoris (p. 9).

EARLY PHOTOGRAPHIC WORK.

On account of the very large role that photography has played
in the astronomy of precision, it is but natural that attempts
should have been made to determine parallaxes by photographic
processes. The first real attempt was the work of Pritchard at
Oxford who took a large number of photographs between the
years 1887 and 1889. Pritchard determined the parallaxes
of 28 stars, and if one should judge only by the size of the
probable errors derived, the parallaxes possessed a high degree
of precision. But compared with later and more accurate work,
Pritchard’s results show considerable systematic errors.

Photographs even older than Pritchard’s, those of Lewis
Morris Rutherfurd taken in New York in the sixties and seventies,
PARALLAXES OF 260 STARS 11

have been discussed for the determination of stellar parallax.
At Columbia University, Jacoby determined the parallaxes of
6 Cygni, of » and @ Cassiopeia, Davis found those of 61 Cygni
and 7 Cassiopeiz, while Bauer redetermined the parallax of »
Cassiopeiz. Judged by the criterion of the size of the probable
error, the Columbia measures seemed also to show a consider-
able degree of precision, but compared with later results these
parallaxes are evidently much in error. Nor is it difficult to
find the reasons for the discordances of the early photographic
parallaxes. The Columbia measures of the Rutherfurd photo-
graphs were very accurately carried out, as the results fully
show, but the plates were taken with no special reference to
parallax determination, often at very large hour angles, with
the result that large systematic errors crept into the work and
vitiated the value of the parallaxes determined.

The work of Kapteyn began a new era in the measurement of
parallaxes by photography. In the Publications of the Astronomi-
cal Laboratory at Groningen, 1, 1900, are given the parallaxes of
248 stars of the region around B. D. + 35°4013 contained on
photographs prepared by Prof. A. Donner. The method em-
ployed in taking the photographs was quite novel. This was
described by Donner as follows: “On each plate one and the
same region was to be photographed at three consecutive maxima
of parallax. At the first maximum, one to three images were
to be taken; in the case of more than one image, these were to
lie at small distances on the same circle of declination. The
images of the second maximum were to form two such rows, those
of the third maximum a single one like those of the first. The
first images of the four rows were to lie due east and west, similarly
the second and also the third images.” After exposing the
plate to the first set of three images, the plate was put away
without development until the time had arrived, six months
later for the second and the third sets of images, when again the
plate was put away undeveloped, and the development did not
take place until the fourth set of exposures were made, approxi-
mately one year after the initial set. Each plate of three images
exposed at four different times gave twelve images for each and
every star on the plate. The measurements of all the plates
12 S. A. MITCHELL

taken were carried out with the utmost care, and when the
calculations were completed a thorough discussion was made of
the results. Kapteyn’s conclusions were that very accurate
values of the parallax of large numbers of stars can thus be
obtained with great rapidity, and that the results are free from
systematic error, if certain reasonable precautions are taken.
A knowledge of these “reasonable precautions” has been of the
greatest help to all those who have since investigated parallaxes
by photography. The precautions were:

1. In photographing, the telescope should be used on one side

of the pier only.

2. Photographs should be taken when the star is as nearly

on the meridian as possible.

3. The greatest care must be taken in guiding.

4. Each plate should be measured direct and again when

reversed 180°.

Kapteyn’s method was intended to give the parallax of each
and every star on the photographs. When the results were
collected and the parallax values of the various stars on the
plates compared with one another, it was readily seen that
small parallaxes occurred with much greater frequency than
larger ones, and that positive and negative values were found
in equal numbers, though the total numbers of positive values
were slightly in excess. It therefore appeared as if the parallax
values were distributed according to the law of errors, or in
other words, the parallaxes were in most cases illusory.

The work of Kapteyn demonstrated very clearly that it was
possible by photography to obtain parallaxes with an accuracy
comparable with that attained by the heliometer, and with an
expenditure of energy far less than with the heliometer.

The photographs discussed by Kapteyn were taken by Donner
at Helsingfors with one of the so-called astrographic telescopes,
where the focal length of a little over eleven feet insured that
the scale on the photographic plate was one millimeter equal to
one minute, or sixty seconds of arc. It was easy to see that
telescopes of greater focal length would result in parallaxes of
a higher degree of precision. Although there are many “astro-
graphic telescopes” in existence, few of them have ever been
utilized in measurements of parallax.
PARALLAXES OF 260 STARS 13

Henry Norris Russell gives an excellent description of methods
of obtaining stellar distances by photography in the Determina-
tions of Stellar Parallax from photographs taken at the Cam-
bridge Observatory, England, by Russell and Hinks, published
by the Carnegie Institution of Washington in 1911. The
photographs were made in the years 1903 to 1907 with the
Sheepshanks Equatorial of the Coudé form. The object glass
of twelve-inch aperture had a focal length of 19.3 feet which
resulted in photographs where the scale was 1 mm = 35"2, ap-
proximately double the scale of the photographs employed by
Kapteyn. In 37 regions in the sky Russell determines the
parallax of 52 stars. The error in the determination of a star
resulting from the measure of a single plate of good quality
on which are impressed four separate images of the star was
found by Russell to be 07048. From an interesting table, he
finds that this is a higher degree of precision than had been
attained by any observer using visual observations whether the
instrument used is the heliometer, the equatorial, or the meridian
circle. Not only is the accuracy by photography much higher
than can be reached by visual methods, but the labor involved
is much less in the case of photography.

Russell’s work is an excellent contribution to the subject of
stellar distances. Sir David Gill, himself a great authority on
stellar parallaxes (Monthly Notices R. A. S., 62, 325, 1912)
says, “The Cambridge results give results of an accuracy which,
but for the wonderful precision of the Yerkes observations would
have been regarded as the highest class.”

LatTER PHoToGRAPHIC WORK.

The distances of the stars are enormous compared to the
diameter of the earth’s orbit—the only base-line available for
the measurement of these distances—and in consequence, the
parallactic shift is infinitesimally small. The guiding principle
that must underlie all advances in this difficult subject may be
found in the words of Gill (M. N. 62, 325, 1912). ‘“‘The most
careful previous consideration of every imaginable source of
systematic error, and the provision of means for its automatic
elimination alone renders progress possible in that extreme
14 S. A. MITCHELL

refinement of micrometric research which nowadays is necessary
for the extension of our knowledge of stellar parallax. It is
important to note that every preconceived source of possible
error has turned out to be a reality, and it has in every case
been found to be desirable to refine on the precautions for its
elimination in a degree not at first contemplated.”

It is hoped that the results in the present work will show that
the refinements in the refinements of precautions have all been
carefully looked after and that the parallaxes will be found to
be free from all systematic errors.

One great advantage that Russell had in his work over that of
the heliometer or meridian circle was the much greater focal
length of the instrument used by him. It is quite conceivable
that if one could use visually a heliometer of the great focal
length (62 feet) of the 40-inch Yerkes refractor, it would then
be possible to obtain parallaxes visually with as high a degree
of precision as is found in the best photographic work. But
there is not a heliometer of 62 feet focal length in existence, nor
would it pay to construct one! There are many obvious ad-
vantages of photography over visual methods. One of the most
striking is that by photography a record is obtained on a plate
which may be examined at once, or may be put away to be
examined later at one’s leisure. Apparently, a great gain in
accuracy in the determination of stellar distances would result
if the largest astronomical telescopes could be utilized for this
purpose in place of the shorter focal lengths of the heliometer
and meridian circle. The refracting telescope of greatest focal
length is the Yerkes lens of aperture 40 inches and focal length
of 62 feet. This superb object glass is from the hands of Alvan
Clark and Sons of Cambridge, Mass., and the mounting from the
shops of Warner and Swazey of Cleveland, Ohio. This lens,
however, is a visual one, and it was not manufactured by the
Clarks to be used for photographic work.

Making use of an artifice used by the landscape photographer
who obtained photographs exquisite in detail by the use of a
color filter and isochromatic plates, Ritchey* was able to obtain
astronomical photographs of great excellence. The principle

* Astrophysical Journal, 12, 352, 1900.
PARALLAXES OF 260 STARS 15

underlying this is very easy to understand. The Clarks made
the 40-inch objective so that two of the visual rays, those that
most strongly affect the eye, the yellow and the green, should
be brought to a sharp focus. The other rays of the spectrum,
the blue and violet at one end of the spectrum and the red at
the end of long wave-lengths are more or less out of focus. In
a visual telescope the blue and violet out-of-focus light combines
with the red light, also out of focus, to make a purple glow about
the visual (yellow and green) stellar nucleus. The larger the
telescope the more evident is the purple glow.

The ordinary photographic plate is most sensitive to the
violet and blue light, and less and less sensitive as the end of the
spectrum of longer wave-lengths is approached, being entirely
insensitive to red light. A photograph taken with an ordinary
plate at the visual focus of the 40-inch telescope would give
star images which would be quite large on account of the out-of-
focus light. If a plate of a different kind could be used which
would be highly sensitive to the yellow and green, and little
sensitive to the blue, violet, and red, then sharp star-images
would result. But no such plate has ever been invented, though
the Cramer Isochromatic plate approximates to it. This plate
is highly sensitive in the yellow, very little sensitive to the
red, but quite considerably sensitive to the blue and violet.
If one should interpose a ‘‘color filter” in the path of the light
in such a way that the light would be obliged to pass through the
color filter before falling on the photographic plate, then the
color filter would absorb some of the incident light. Color
filters vary in their absorbing powers. One can be made which
will absorb the violet, blue and blue-green, allowing only the
green, yellow, and red rays to pass through it unobstructed.
If such a filter were used in combination with a Cramer Isochro-
matic plate which is almost insensitive to red light, then a photo-
graph would result in which only the green and yellow rays have
any power to affect the plate, and those are exactly the rays for
which the visual telescope is corrected by the optician. Since
the Cramer plate is much more sensitive to the yellow than the
green, the photographs with a telescope like the 40-inch, ground
by the Clarks, are taken almost exclusively with the yellow
light.
16 S. A. MITCHELL

Consequently, Ritchey was able to obtain with the 40-inch
visual lens photographs of excellent definition where the star-
images are very small and clean-cut. Such photographs rendered
possible a new epoch in ‘exact stellar measurements. In the
years 1903 to 1905, Schlesinger secured photographs, the measures
of which are given in Photographic Determination of Stellar
Parallax made with the Yerkes Refractor, and published in the
Astrophysical Journal (vols. 32, 33 and 34) in the years 1910
and 1911. The parallaxes of 28 stars were determined with
an accuracy considerably greater than that attained by the very
best of the earlier work. Schlesinger gave a masterful discussion
of the subject of parallaxes, and those who have followed him are
deeply grateful to him for the magnificent service he rendered
to exact astronomy, particularly in the invention of the methods
of “dependences” used with such success in abbreviating the
work of reduction of stellar photographs.

Schlesinger’s work on stellar parallax at Yerkes was dis-
continued there when he was called to the Allegheny Observatory
as its director.

The photographs made by Schlesinger were obtained without
the use of a color filter, and the reasons for this procedure are
stated in the Astrophysical Journal, 32, 374, 1910. The parallax
work so excellently started at Yerkes by Schlesinger was con-
tinued by Slocum and Mitchell, who, in the years 1913 and 1914,
published the parallaxes of 61 stars. The photographs dis-
cussed by them, and all subsequent photographs with this large
refractor, were obtained with the use of a color filter. The
work at Yerkes has been continued by Lee, Joy, Van Biesbroeck
and others. A complete account of all the parallax results
accumulated up to the year 1917 and including 131 stars will
be found with bibliography in Publications of the Yerkes Observa-
tory, volume IV, part 1.

Consequently, as the present writer realized from his work at
Yerkes the importance of a refractor of great focal length in the
accurate determination of stellar distances, it was but natural
that he should desire to continue the work with the McCormick
telescope. This refractor had an aperture of 26 inches instead
of the 40 inches of the Yerkes instrument, and moreover its
 

The 26-inch Clark Refractor.
PARALLAXES OF 260 STARS 17

focal length was only about one half that of Yerkes, 32.5 feet
against 62.5 of the larger instrument. However, in discussing
with my co-worker and friend Slocum the possibility of ob-
taining parallaxes comparable in accuracy with those of the
40-inch, we came to the conclusion that the accuracy of the
two instruments might be nearly the same, in spite of the much
greater focal length of the larger instrument. The reasons for
this belief are readily stated. In photographing with any
telescope under average conditions of seeing, the image of a
star is not a point but an area of greater or less extent depending
on the focal length of the telescope, the quality of the objective
and the character of the seeing. If the “seeing” is bad, the star
images are discs of appreciable size; if the quality of the seeing is
“good,” the star images are smaller; and if the seeing is ‘‘ex-
cellent,” the star images may be quite small. With object
glasses of the finest excellence, the star images under constant
conditions of seeing, are smaller in diameter with the instrument
of shorter focal length. Consequently, under average conditions
of seeing, the star images with the 26-inch McCormick tele-
scope are much smaller than those with the 40-inch Yerkes,
being as a matter of fact about one half the diameter, or in fact
roughly approximating to the ratio of their focal lengths. Under
average conditions of seeing therefore, since the light from the
larger object glass is spread out into a larger circle, the time
necessary to obtain a star of certain magnitude (say the 12th)
is approximately the same with the 26-inch as it is with the
40-inch. When the photograph under average conditions is
measured in order to obtain the position of the stars, it is possible
to set a micrometer wire a little more accurately on the smaller
image, and consequently this increase in accuracy of setting
may almost compensate for the difference in focal length of the
two instruments.

All that is said above refers only to average conditions of seeing.
When the seeing is extraordinarily good the time of necessary
exposure is shorter with the larger refractor and the accuracy
of results is greater, but under average conditions this does not
seem to be the case, and as a rule the series of plates necessary

3
18 S. A. MITCHELL

for the complete discussion of most of the parallax regions are
taken under average conditions of seeing.

The methods followed in the determination of stellar parallax
at the McCormick Observatory are those of Schlesinger with
some slight modifications in the matter of detail.

PHOTOGRAPHIC APPARATUS.

The McCormick object glass has an aperture of 2614 inches
with a focal length of 32.5 feet, a ratio of aperture to focal
length 1:15. A Hartmann test has never been applied, though
in 1913 a diaphragm was made in order to obtain the necessary
photographs. The photographs, however, have never been
taken, for it seemed wiser to spend the limited time of the rather
small staff of the observatory in measuring parallax plates rather
than in measuring photographs to test an objective which both
visual observations and photographs show to be a lens probably
unsurpassed in excellence. The writer was fortunate in the fact
that Professor John A. Miller, the director of the Sproul Observa-
tory, had recently had constructed by the John A. Brashear Co.,
a plate-holder attachment for his 24-inch refractor. A descrip-
tion of this plate-holder is found in Popular Astronomy, 21,
252, 1913. Accordingly, a contract was entered into with the
Brashear- Co. to make an exact duplicate of the Swarthmore
plate-holder with modifications in detail occasioned by the
difference in focal length, etc. This plate-holder was delivered
in May, 1914.

The writer was again fortunate in finding a steel tube on the
Clark mounting, now rather old, so that it was a comparatively
simple matter to attach the plate-holder to the telescope tube.
To carry the other apparatus that is used with a refractor, the
filar micrometer, the photometer, the visual eyepieces, etc.,
another attachment was constructed. The change from the
photographic plate-holder to the tail piece used in other lines of
work is a matter of about ten minutes. Although made of
aluminum, the plate-holder weighs about 80 pounds, so that a
carriage is used to hold this when not attached to the telescope.
To make the change, the telescope is pointed to the zenith, the
McCormick Observatory not being provided with an elevator
PARALLAXES OF 260 STARS 19

floor as is found in many observatories with refractors of similar
size.

The writer here wishes to express his appreciation of the care
exercised by Professor Miller in designing his plate-holder and
to the Brashear Co. for making such an excellent attachment.
Four metallic plate-holders are provided, though in practice
only one is used.

The plate-holder is of the double slide variety devised by
Ritchey for the Yerkes refractor, and described in Astrophysical
Journal, 12, 355, 1900. It will, therefore not be necessary to
describe it in detail here.

Although this photographic attachment was delivered in
May, 1914, and was then thoroughly tested and slight imperfec-
tions rectified, few plates were secured during the summer and
it was not till the fall of 1914 that parallax work was begun with
any energy. The result of five year’s work in this field of
investigation is the parallaxes of 260 stars.

It might be interesting to remark that although the McCormick
telescope is practically a duplicate of the 26-inch refractor of
the U. 8. Naval Observatory the lens is still in its original Clark
mounting. The Washington glass, however, was many years
ago placed in a modern mounting by Warner and Swazey. The
McCormick mounting is very light in weight compared with a
Warner and Swazey mounting, so that it is indeed fortunate that
in Virginia there is at night very little wind.

PuHotToGRAPHic METHODS.

In order that as few distortions as possible be introduced into
the photographs to be measured to determine the parallax of
a certain star, it is necessary that the telescope be used in nearly
the same position for each of the plates taken. Consequently,
Kapteyn, Russell and Schlesinger each in turn give certain
rules to be observed in photographing, which rules will be found
on page 12.

The McCormick plates have always been taken with the tele-
scope west of the pier, not a single parallax plate being taken
with the telescope east. South of declination + 20°, the tele-
scope will swing past the pier, but north of this declination it
20 S.A. MITCHELL

will go only five or ten minutes beyond the. meridian. An
attempt has always been made to photograph the star when as
near the meridian as possible, and in the first table connected
with the detailed measures of each star, is given the hour angle
at the middle of the exposures for each plate. By reference to
these tables, it will be seen that the majority of the plates were
taken within half an hour of the meridian, while it is only in
comparatively rare cases that the telescope was ever used as
far from the meridian as one hour.

Instead of taking four images of the star on each plate as
Russell has done, or three images as Schlesinger did at Yerkes
Observatory and later at Allegheny Observatory, the McCormick
plates in nearly every case had only two images impressed on
them. Occasionally, but very rarely, three images were made,
and more frequently but still quite rarely, there was only one
exposure, the-second being stopped by clouds, etc. Ordinarily,
two separate plates were taken of the same region in succession,
this being done in order to save the time lost in shifting the
telescope from one region to the next. Since 1915, two separate
regions have been photographed on the same plate. Thus the
number of plates necessary to handle and develop was cut in
two. The only drawback to this method is the possibility of the
image of a star from one region being superimposed on an image
in another region. The chance of this happening, however, is
small. As a matter of fact such a superposition of images has
not happened even once in the more than 8,000 photographs
taken to date. It should be unnecessary to remark that the
cost of plates is likewise cut in two.

The procedure at the telescope is practically identical with that
followed at the Yerkes Observatory. The observing program
is kept on a series of cards. On each card appears the star’s
name, its right ascension and declination for 1920, the magnitude,
the spectral type, the proper motion, the number in the B. D.,
Boss’s Preliminary General Catalogue, etc. In brief, the card
gives the reasons why this particular star was placed on the
observing list. On the lower right hand corner is copied from
the B. D. charts for purposes of ready identification, a drawing
on the same scale as the charts, and this drawing shows the field
PARALLAXES OF 260 STARS 21

as it appears in the finder of five inches aperture. Also on the
card is given the setting of the guiding eyepiece,:the opening of
the sector, the position of the parallax star behind the sector,
and the length of exposure. On each card is kept likewise a
record of the plates taken on each region, the number of each
plate and the quality of each plate being recorded, in black ink
if the plate was taken before midnight and in red ink if after
midnight. After a little practice, it is a comparatively simple
matter to set the telescope on the star and begin the exposure. —

The McCormick Observatory does not have a rising floor, but
this does not seem a serious handicap with which to contend.
On account of the small size of the observatory staff, only one
observer at a time works with the telescope, and not two as at
Yerkes Observatory. As already stated, two plates are taken
in succession on each region, and two separate regions on each
plate, a matter which can be readily accomplished by changing
the plate in between the two separate sets of exposures to the
same region. Occasionally, one region only is put on a plate,
but at other times three separate regions or even four appear on
a plate.

The McCormick dome has the peculiarity of having three
separate slits all on the same vertical circle, instead of a single
slit, as is the case with most domes. At times this is a handicap,
but on the other hand by making out the night’s observing pro-
gram beforehand, stars both north and south of the zenith can
be observed with a minimum of motion to the dome.

Photographic work is started each evening as svon as it is
sufficiently dark. By the use of a color filter and isochromatic
plates, it is possible to begin considerably earlier than if the
telescope were a photographic one and ordinary plates were
used. Work is started ordinarily thirty minutes after sunset,
and stopped thirty minutes before sunrise. Near the mid-
night hours when the parallax factor is less than 0.5, the telescope
is available for other lines of research. Practically, as many
plates must be taken after midnight as before midnight, or in
other words, the number of plates available for a parallax mea-
surement amounts approximately to twice the number that are
taken after midnight; the plates just after sunset and just be-
22 S. A. MITCHELL

fore sunrise being the most important since their parallax factors
are the largest. As a matter of fact, parallax work costs a great
many hours loss of sleep, and it is therefore a difficult research
for one to carry on who in addition to this work must engage in
university teaching. As mentioned above, an attempt was made
to photograph only when the parallax factor was greater than
0.5, but occasionally, on account of cloudy weather, etc., es-
pecially during the short summer nights, plates were taken with
a smaller parallax factor.

ELIMINATION OF ERRORS OF THE PHOTOGRAPHS.

The size of plate used is 5x7 inches. Since the scale of the
photographs is 1 mm = 20"8, the plate covers an area in the
sky approximately one degree by three quarters of a degree,
the longer side of the plate being placed parallel to the equator.
In photographing the sky there is projected on a surface more or
less plane a portion of the celestial sphere. In this projection
there are certain distortions, some being caused after the ray
of light from the star reaches the objective, the instrumental
distortions, and others which happened beyond the objective.

The super-refinement referred to by Gill which is required in
parallax work demands a careful survey of the errors brought into
the photographs by these distortions, and the provision of
methods for the automatic elimination of as many errors as
possible.

Among the distortions beyond the telescope are the following,
caused by:

1. Refraction.
2. Aberration.
3. Precession.
4. Nutation.

These above cause changes in the apparent places of the stars.

After the ray reaches the objective there may be errors caused
by:

1. Optical distortions by the objective.
2. Lack of perfect collimation of the objective.
3. Change in centering.

4. Change in scale-value.
PARALLAXES OF 260 STARS 23

5. Change in orientation of plate.

In addition to the above two classes of distortions must be
added those of the photographic plate, caused by:

1. Photographic plate not being perpendicular to the
collimation axis.

2. Plate being not exactly plane.

3. Slipping and distortion of the photographic film.

After the photographic plate is developed, it is placed under
a microscope and the positions of the stars are measured, usually
in two directions at right angles which we call x and y coérdinates.
If the z-coérdinate is measured parallel to-the celestial equator
we must be able to transfer from measures in x and y to right
ascension and declination.

To obtain parallaxes as near perfect as possible it is necessary
to eliminate all errors of measurement of the plate and also all
errors caused by distortion both instrumental and non-instru-
mental.

Turner was the first to show that except at great zenith dis-
tances all non-instrumental errors, refraction, aberration, pre-
cession, and nutation, can be represented by functions of the
measured coérdinates which are practically linear.

Turner also showed how to allow for errors of centering,
orientation, and scale of plate. If a is the correction to the
scale value,-then the correction in the measured codérdinate
X is aX, while the correction for orientation b is bY, and the
correction for center is the constant c applied to all the measures,
X and Y being the measured rectangular coérdinates. Con-
sequently, the measured coérdinate X for each star needs a
correction aX +bY +c. Similarly, measured codrdinates in
Y demand a correction dX + eY +f, where d is the correction
for orientation, e that for scale-value, and f the zero-point
correction.

Since the corrections for refraction, etc., are linear, they are
also of the form aX + bY +c. As Turner pointed out, the
corrections for refraction, etc., are automatically applied when we
determine the quantities a, b and c from the measures themselves.
If the area of the sky covered by the plate is sufficiently large,
it would be necessary to take into account terms in X?, Y? and
24 S, A. MITCHELL

XY, and possibly also terms of higher order. The X-coérdinates
in the present plates are less than a half-degree from the center
of the plate. On account of the limited area covered by these
plates, it has not been thought necessary to take account of the
very small corrections brought in by second and higher order
terms.

In the McCormick plates, the X-codrdinate was always placed
parallel to the equator, so that X is in the direction of right
ascension, and Y in declination. The parallactic shifts in right
ascension only were measured, or, in other words, the shifts in
the X-codrdinate. It was unnecessary, therefore, to decide
whether the scale-value and orientation in the directions X and Y
were the same or different.

The quantities a, b and c are constants for each plate, and from
each plate these quantities must be derived from the measured
coérdinates, and these coérdinates must be corrected accordingly.
There is no interest attached to the plate-constants a, b and c,
and their computation entails considerable time. Parallax
workers are under a great obligation to Schlesinger for showing
that it is unnecessary to determine these constants since the
same results can be derived from reducing the plates by the
method of ‘“‘dependences.” For a complete description of this
method, see Astrophysical Journal, 33, 161, 1911. See also
Sproul Observatory Publications, 4, 23.

GuIDING ERROR.

Kapteyn was the first to call attention to the importance of
eliminating as fully as possible the effects of ‘guiding error.”
While the exposure of the plate is being made, it is impossible
to keep the guiding star always perfectly bisected, imperfections
of the clock-work, the rate of the-clock, etc., causing small
excursions of the star from the center of the cross-wires of the
guiding microscope. This will cause the image of each and
every star on the plate to make small excursions from the mean
position. If the star being photographed is faint, and the
guiding good, then the impressions on the plate caused by the
departure of the star from the mean position will be so com-
paratively faint that no evidence will be visible on the photo-
PARALLAXES OF 260 STARS 25

graphed plate. The question is entirely different with a bright
star, for even a small drift will leave a visible impression on the
plate, and if the telescope has a tendency to drift caused by the
clock not being exactly rated, then the center of brightness of
the bright star may be shifted by a small amount due to imper-
fections in guiding. If, therefore, the stars to be measured on
the photograph differ in brightness, the measured coérdinates
may be affected by errors in guiding. If, on the other hand,
the measured stars are all of the same brightness, then guiding
error will affect each alike and there will be no relative shift.
These considerations point the way to the method of practically
eliminating the effects of guiding error.

In the photographic method the position of the parallax star
is referred to several stars, which shall be called “comparison
stars,’ usually fainter. The shift of the parallax star with re-
spect to the comparison stars is measured, and thus is found the
parallax of the star under consideration relative to the average
of the set of comparison stars chosen. The photographic method,
therefore, gives the ‘relative parallax.” To eliminate guiding
error as fully as possible the comparison stars should be each of
nearly, the same brightness, and consequently the size of the
image of each on the photographic plate will be nearly the same.
The image of the parallax star must be of the same size as that
of the average comparison star if the guiding error is to be
eliminated, and the more nearly this equality in the size of the
measured star images is approximated the more nearly will
the ill effects of errors of guiding be eliminated from the results.

Although Russell used a small piece of dyed gelatine to cut
down the brightness of the parallax star, Schlesinger was the
first to realize the importance of making the image of the paral-
lax star on the photographic plate the same size as the average
comparison stars. To accomplish this result, a small disk was
made to rotate as close to the photographic plate as possible.
The disk was made in two halves so that any angular opening up
to 180° could be secured. The disk is rotated by means of a
small electric motor. On-the edge of the disk is graduated a
scale, either in degrees, or in hundredths of the circumference.
If the image of the parallax star is placed behind the rotating
26 S. A. MITCHELL

disk and this disk is rotated, then the light from this star reaches
the photographic plate only when it passes through the opening
in the sector. By regulating the size of the sector opening, the
brightness of the parallax star can be reduced at will. Thus,
if the opening in the disk is one-hundredth part of the circum-
ference, the brightness of the parallax star is reduced 100 times,
or 5 magnitudes. Since the jaws of the sector are radial, it is
obvious that the opening of one-hundredth will reduce the
brightness of the star by the same amount no matter what the
position of the image of the star behind the sector, or the speed
at which the sector is driven. It was at first feared by Schlesinger
that if the sector opening were made quite small, the image of-
the star might be altered from its position by diffraction through
the small aperture. These fears have since been found to be
utterly unfounded. By the use of such a rotating disk it has
been found possible to reduce the brightness of the parallax
star as much as 7 magnitudes.

The McCormick telescope is provided with a rotating disk with
the scale graduated to hundredths of the sector opening. The
average brightness of the McCormick comparison stars is ap-
proximately the tenth magnitude on the B. D. scale. Conse-
quently, it was possible with the rotating sector to make the
image of the parallax stars of third magnitude or fainter to be
equal in size to the average comparison star. For first and
second magnitude stars, the equality in size of image could
only be approximated with the rotating sector, and accordingly,
for the brightest stars some mechanical device must be employed
to still further reduce. Various methods may be employed.
The simplest perhaps is to have the rotating sector to consist of
two separate disks so geared that they will rotate on the same
hub at different speeds. When such a double sector is employed
the light from the star can reach the photographic plate only
when the two sector openings come together. In other words,
instead of the light from the star reaching the plate at each
rotation of the single disk, the light from the star reaches the
plate much less frequently, and as a result, the photographed
image of the parallax star will consist of much fewer impressions
when the double disk is utilized than when the single disk is
PARALLAXES OF 260 STARS 27

used. Herein, however, may lie a possible source of guiding
error in photographing the brightest stars with the double sector.
Even though the guiding may be as perfect as possible, the
comparatively few impressions of the bright star permitted by
the double sector may be made at instants when the guiding
may be sensibly different from the average of the guiding from
which results the impressions of the comparison stars.

The McCormick Observatory is provided with a double
rotating sector designed and constructed by Dr. L. G. Hoxton,
of the University of Virginia. It was used to obtain photographs
of Sirius. Although the images of Sirius were round, small,
and equal in size to the comparison stars, the measures of the
different plates were not in satisfactory enough agreement to
warrant the continuation of the series of plates for the deter-
mination of the parallax of Sirius. The double sector was used
to obtain some of the plates of Aldebaran, Altair and Procyon.
All other regions of the present series were secured by the single
sector, whenever a sector was necessary. The experience with
the double sector shows the necessity of rotating the single
sector at as high a rate as possible in order to have the image of
the parallax star consist of as many impressions as possible.
Similar conclusions have been reached by Schlesinger, Publi-
cations of the Allegheny Observatory, 4, 12.

At Allegheny Observatory a diffraction grating has been placed
over the objective for the purpose of obtaining the parallaxes of
the brightest stars. For the results secured, see Publications,
4, 15. Kapteyn’s ingenious device of securing an out-of-
focus photograph of a region, and then utilizing this nega-
tive as an absorbing medium has not been tried at the
McCormick Observatory. Experiments with other methods are
in progress.

On beginning a series of plates for parallax the first plate
secured is carefully examined to see whether a proper system of
comparison stars can be secured, and whether the sector opening
used has resulted in the equality of images of the parallax and
comparison stars. Unless these conditions can be satisfied,
the region is abandoned and the star removed from the parallax
program.
28 S. A. MITCHELL

CHOICE OF COMPARISON STARS.

In the reduction of the measures of the plates in X-coérdi-
nates, there are three plate-constants, a,b andc. Consequently,
three comparison stars at least must be used. What is the best
number? It is obvious that with an increase in the number of
comparison stars there will be a consequent reduction in the size
of the accidental errors, and also a reduction resulting from the
fact that one of the comparison stars may have a parallax of
appreciable size. The time and labor consumed in the measure-
ment of the plates increases with the number of stars measured.
When will the accuracy accruing from the additional comparison
stars no longer warrant the extra time spent in measurement?
In the measurement of the Cambridge plates, Russell adopted
wherever possible eight comparison stars. A similar selection
is followed by Van Maanen in the work with the 60-inch reflector
at Mt. Wilson. On the other hand, at the Allegheny Observa-
tory sixty per cent. of the plates in the first series of fifty paral-
laxes had four comparison stars, while forty per cent. had only
three.

The practice at the McCormick Observatory has been to
select five comparison stars when possible. If a suitable five
could not be found, then either four or six were chosen. Oc-
casionally a satisfactory grouping could be found only with a
selection of three stars. In a few cases seven or eight stars were
chosen for comparison stars. The average number of com-
parison stars for all the regions under investigation has been
4.5.

The conditions for the selection of the comparison stars are:

1. That they shall each be of the same magnitude and also
equal in brightness to the parallax star reduced by the rotating
sector. The more nearly this condition is fulfilled the more
nearly will the results be free from systematic errors.

2. That the center of position, or centroid, of the system of
comparison stars shall coincide as nearly as pon with the
position of the parallax star.

How nearly these two conditions are fulfilled may be seen from
the tables attached to each star, where under the head “Com-
PARALLAXES OF 260 STARS 29

parison Stars’ are given the diameters in millimeters of the
star images measured on the plates, and alsc the X and Y coérdi-
nates of the parallax star and each comparison star referred to
the center of position of the comparison stars.

MetHops oF MEASUREMENT.

In order to eliminate personal errors as much as possible, all
plates were measured direct, and reversed 180°.

Measuring engines of two types were used. Through the
kindness of Dr. Harold Jacoby, Rutherfurd Professor of Astron-
omy at Columbia University a measuring machine was loaned to
the McCormick Observatory as soon as the first photographic
plates were taken. At the beginning of the work, this was
the only machine used. In 1916, a machine was purchased from
Wm. Gaertner and Son, an engine exactly similar to those pur-
chased at the same time by Allegheny, Yerkes and other observa-
tories. In 1917, a second ‘Repsold machine was loaned by
Professor Jacoby.

The McCormick Observatory is under a great debt to Pro-
fessor Jacoby and to Columbia University for their kindness in
lending these measuring machines, and due acknowledgement
is accordingly made. Likewise our thanks are to be expressed
to Dr. Frank Schlesinger, who more than anyone else was
responsible for the excellent design of the Gaertner machine.

The instruments obtained from Columbia University were
made by Repsold. They were used at Columbia in the measure-
ment of the Rutherfurd photographs. Their construction and
method of use are fully described in the Contributions from the
Observatory of Columbia Uuiversity. A description need not be
given here. The method of measurement consists in bringing
the star to be measured in the center of the field of view of the
measuring microscope and close to and just above the hori-
zontal wire. The star is now bisected by the vertical wire, and
the head of the micrometer read. By turning a lever, the mi-
croscope is rotated so as to point at a scale graduated on silver
to millimeters. The microscope is again pointed at the star,
and its image is again bisected. In bisecting the star, a single
vertical wire is used, but in reading the millimeter scale a double
30 8. A. MITCHELL

wire is employed. Two turns of the micrometer head are equal
to a millimeter. The micrometer was read by estimation to
tenths of a division. In each reading of the position of a star,
two bisections were first made on the star, then two on the milli-
meter scale, and again two on the star. The reading, therefore,
consisted of four readings on the star and two on the scale.
An objection might be made to this method of measurement
that there was a possible chance of shift in position of the micro-
scope in turning it from star to scale. In making many thousands
of measures, the writer has found no indication of any motion of
this sort. The writer always used both eyes in measurement,
the right to bisect the star, and the left to bisect the scale.
This relieved the strain on the eyes caused partially by difference
in illumination of the photographic plate and scale.

The Gaertner machine has been fully described in the publica-
tions of the Yerkes and Allegheny Observatories. This machine
consists essentially in a long screw which moves a microscope.
The position of the microscope can be read directly to the thous-
andth of a millimeter, and by estimation to tenths, or to the
tenth of a micron.

Each type of machine has its advantage, each has its dis-
advantage. Since there is no scale to read, the Gaertner machine
is a faster machine, though the difference in speed is not so great
as might first appear. If the same number of bisections of the
star are made with both instruments, then the readings of the
scale in the Columbia machine would apparently entail this
much additional time. Since however, there is much less weight
to move, each bisection with the Columbia machine can be made
more quickly than is possible with the Gaertner machine; and,
in addition, the microscope can be moved from star to star
more readily with the Columbia type of machine.

The accuracy in the measurements with the Gaertner machine
depends on the accuracy of the screw, its freedom from periodic
and non-periodic errors. The errors of the McCormick machine
have been investigated by Mr. Alden, and the errors of the screw
have been found to be negligible. But no matter how carefully
the machine is handled, the screw is liable to wear. Conse-
quently, though a screw may be perfect, errors may gradually
PARALLAXES OF 260 STARS 3l

appear. The only part of the Columbia machine that can wear
is the very short micrometer screw, and the wear in this will
cause errors in the measurements very much smaller in size than
those in the long screw of the Gaertner machine. With the
Columbia machine the measures are referred to a millimeter
scale, and after-the errors of this scale have been once investi-
gated there is little chance for any change in the scale. On
the whole, therefore, the Columbia machine will stay in adjust-
ment more constantly than the Gaertner machine. In the
measurement of the plates taken for parallax with the 60-
inch Mt. Wilson reflector, Van Maanen uses a blink microscope.
The McCormick Observatory does not possess this form of meas-
uring machine nor any funds with which to buy one.

On one plate of the series to be measured for parallax there is
always impressed a trail of a bright star, obtained by stopping
the telescope. This trail gives a line on the plate parallel to
the celestial equator. On each of the other plates of the series
a trail is drawn with ink on the glass side of the plate, the star
images of the two plates being superposed. By means of these
trails the plates can be readily oriented in the measuring machine.
As above stated, the parallactic shifts in right ascension only
were measured, so that X-codrdinates correspond to right
ascension. On one plate of the series, the Y-codérdinates were
measured in order to obtain the dependences.

At the telescope care was taken to have the parallax star and
comparison stars always photographed in as nearly the same
position on the plate as possible. This could be readily accom-
plished by following the directions on the cards, 7. e., by using
the same guiding star and placing the parallax star under the
sector at the same relative position.

In placing each plate of the series in the machine for measure-
ment, after properly orienting the plate, the plate was shifted
laterally in the jaws so that the reading of each star should fall
always on the same division of the scale, if one of the Columbia
machines were used, or at the same reading of the screw for the
Gaertner machine. As before stated, two images of each star
were usually photographed and measured on each plate, so that it
would be possible to make the adjustments just specified for
32 S. A. MITCHELL

one set of images only. In taking the photographs, however,
the guiding eyepiece was always shifted by approximately the
same amount, since it was moved from one notch to the next,
so that ordinarily always the same part of the scale or screw
was used in the measurement of the parallax star and of each of
the comparison stars. After measuring the plate direct, it
was reversed 180°, and the complete measurement consisted of
those made direct and reversed. In the reversed position, the
measures for the stars all come at a different part of the scale or
screw from the measures direct. Consequently, by using the
same divisions of the scale or the same part of the screw always
for the measurement for each plate of the series there was thus
eliminated all departures from the errors of division of the scale
used, or almost equally completely any errors of the screw. It
is felt, therefore, that all errors of the machines have been elimi-
nated, and that all personal errors have been largely eliminated
except the purely accidental errors of measurement.

After what has been said above, it should be unnecessary to
add that in measuring a series of plates to determine the parallax
of a star one machine only was used. Under no circumstances
can part of the series be measured on one machine and part on
another. Since the Columbia machine, No. 1, was for a time
the only machine we possessed, more than half of the present
parallaxes have been determined from measures with it. Most of
the balance of the measures were carried out with the Gaertner
engine.

The writer has always felt more confidence in his ability to
accurately bisect a star image if this image were well blackened
and had a clean crisp edge. Consequently, the exposures at
the telescope were lengthened until the star images were satis-
factorily blackened.

REDUCTIONS OF THE PLATEs.

In order to make the thousandths of a millimeter more certain,
the measures and reductions were carried out to 0.0001 mm.
The measures and reductions of the two sets of images on the
plate, images A and B as we called them, were carried out en-
tirely independently, until the “solution” (m) by the method
 

 

ute-Holder.

Pl

Double-Stide
PARALLAXES OF 260 STARS 33

of dependences was obtained for image A and image B separ-
ately. The solution for the plate was then found by combining
those for A and B. If the images of the A exposure were better
than those of B, then it was given a higher weight when com-
bining, the relative weights of A and B and the weight of the
plate being assigned at the time of measurement. In nearly
all cases A and B were given equal weight.

In combining the measures direct and reversed, certain checks
were devised so as to eliminate any chance of errors in computa-
tion. In computing the solutions from the measures, a multi-
plying machine was used. The McCormick Observatory is
under a great obligation to Mr. John Neilson of New York for
his gift of one computing machine and his loan for a considerable
time of a second machine.

The reductions were always carried out in millimeters, and the
results were not converted into seconds of arc until the final
values of the parallax and proper motion were obtained.

The solution of each plate (m) is made up of three quantities
represented by the equation:

cttut+Pr=m (1)

where 7 is the value of the annual parallax of the star to be found
and P is the parallax factor. In order to eliminate the possi-
bility of errors in the parallax factors their values were found
by two different methods. y is the proper motion in right as-
cension, or is equal to u, Cosd. For the sake of simplicity in
reductions u is the value of the proper motion for one hundred
days, and not per year as is ordinarily the case. ¢ is the time in
days from any arbitrarily assumed time, usually taken as some
date in the middle of the series of plates. cis a plate constant
depending on the zero-point, and has no meaning in the sky.

Each plate, therefore, gives an equation in the form (1), in
which c, » and w are unknown quantities, and t, P and m are
known. Since the plates have different weights, they are com-
bined into a least-square solution by multiplying each equation
by Vp, p being the weight.

Using the usual notation of least-squares, the normal equa-
tions take the following form:

4
34 S. A. MITCHELL

[ple + [pt]u + [pP]x = [pm]
+ [p?]u + [ptP]x = [ptm] (2)
+ [pP?]x = [pPm|]

The formation of the normal equations was performed partially
by the use of Crelle’s tables and partially by the multiplying
machine. Each of the coefficients such as [pé], [ptm], and [pP?]
were found by two different methods of computation. For
instance, the product pim is found either by multiplying pt by
mor pm by t. Similarly pP? can be found by a table of squares
in Crelle, or by multiplying pP by P by means of the machine.

The normal equations were solved by the multiplying machine.
When the values c, » and = are found, their values are substi-
tuted in the original equations, and the residuals (v) are found.
A final check on the accuracy of the computation is found when
[pv], [ptv] and [pPv] must each equal zero. This part of the
computation was carried out to 0.00001 mm.

The reductions of the first parallaxes were carried out by Mrs.
Alfred L. Hall-Quest. Miss Eudora Magill has carried out
most of the least-square reductions. The writer wishes to ex-
press to her his appreciation of her faithful and efficient services.
She was associated with the writer in all of his parallax work at
the Yerkes Observatory and with nearly all of it at the McCor-
mick Observatory. It is felt that with the system of checks
in the progress of the reductions and with the great care with
which the calculations were performed there is little chance of
any errors in the work resulting from the computation.

ELIMINATION OF SysTEMATIC ERRORS.

The average probable error of the parallaxes of the McCormick
series of 260 stars is 07009, which expressed in millimeters is
0.00048. To obtain + with as high a degree of accuracy as
possible, its weight in the least-square solution must be as great
as possible. By using the Gaussian method of elimination with
the above normal equations (2) it will readily be seen that the
maximum weight of 7 is obtained under the following conditions:

(1) p the weight of each plate should be as large as possible.
(2) [pP?] should be as large as possible.
PARALLAXES OF 260 STARS 385

(3) [pP] should be as small as possible.

(4) [pt] should be as small as possible.

(5) [pt?] should be as large as possible.

These conditions will be fulfilled under the following cir-
cumstances:

(a) Each plate should be of as good quality as possible.

(b) Each plate should be taken when the parallax factor is a
maximum, thus giving a maximum base-line with
which to determine the distance.

(c) The plates taken after midnight should be as well de-
termined as those before midnight.

(d) The series of plates should be as symmetrical as possible
with regard to the time.

(e) The series of plates should be spread over as much time
as possible.

Most of the above are self-evident. Ifthe star’s proper motion
is to be regarded as an unknown, then the three unknown quanti-
ties c, » and + may be determined from plates taken at three
seasons, or after the lapse of one year. In the measurement of
the plates it is conceivable that all of the plates taken in any one
season might possibly give quantities which are all too large or
all too small. Where quantities are to be measured which
are such minute fractions of a millimeter as are the stellar paral-
lactic displacements, it is quite possible that the accidental
errors of measurement might cause all the values of the measures
in one season to be either too large or too small. There is thus
the possibility of systematic errors creeping into the parallaxes
which for lack of a better name might be called ‘‘seasonal errors.”
If, therefore, the series of plates are allowed to run to a fourth
or a fifth season, there will be every chance that the seasonal
errors will have much less effect on the final value of the parallax.

In the early part of the work at the McCormick Observatory,
an attempt was made to finish the work on a given region in
three seasons wherever possible. Most of the parallax results
published in Popular Astronomy, 25, 23, 1917, were completed
in three seasons. In conference with the other members of the
Parallax Committee of the American Astronomical Society,
it seemed advisable that the plates should cover five seasons,
36 S. A. MITCHELL

and accordingly most of the stars in the list of 83 published in
Popular Astronomy were again put on the observing program;
and new determinations of the parallaxes were made. Con-
sequently, these values already published should be regarded
as preliminary values only, and the results should be superceded
with these herewith published.

As Schlesinger has already pointed out, the method of allowing
the photographs to cover five seasons instead of three does not
necessarily entail a greater number of photographs. If 15 plates
are to be used in a parallax determination, then if the work were
finished in three seasons the plates would probably be taken in
number, 4, 7, and 4, in the three successive seasons. Three
plates in each of five seasons will give a more reliable value
of the parallax.

An additional advantage of allowing the plates to cover five
seasons, or two years, instead of concluding them in three seasons,
or one year, is that the proper motion is more accurately de-
termined.

Most of the McCormick parallaxes, therefore, result from the
measures of photographs which cover five seasons. It is be-
lieved that systematic errors of all kinds have been pretty
thoroughly eliminated. How fully this elimination has been
accomplished will be seen later.

Proper Motions.

A valuable by-product resulting from the measures of the
plates is the determination of the proper motions. These proper
motions are relative and furnish the difference in proper motion
between the parallax star and the average proper motion of
the comparison stars. On the other hand, the meridian circle
gives proper motions which are absolute, or which are referred
to the system of the stars as a whole. The proper motions de-
termined from the plates may differ from those derived by meri-
dian circle for three reasons: (a) On account of errors in the
photographic measurements; (b) on account of errors in the
meridian circle positions; (c) on account of motions of the com-
parison stars with respect to the stellar system. _
PAWwALLAXES OF 260 STARS 37

As already stated, in most of the regions the plates have been
allowed to cover a period of two years, and for such a series the
proper motions are determined with a probable error 0"01.
For the stars under investigation visible to the naked eye com-
parisons are made with the Preliminary General Catalogue
of Boss. Most of the fainter stars are found in Porter. The
results will be found in Table.

The meridian circle results are not infallible, the position of a
star can be known only within a certain limit of error. For the
early catalogues, these errors may be quite large. In the cata-
logue of Boss the probable errors of the determination of the
proper motions are given. Porter furnishes the original observa-
tions and the positions brought up to the epoch 1900, from which
the probable error can be readily determined. The earliest
accurate star catalogue is that of Bradley for the epoch 1755.
A comparison of the accuracy of visual work by means of the
best meridian circles of the present day with photographic work
by telescopes of great focal length may be gained when one
realizes that proper motions can be determined from photo-
graphs stretching over an interval of two years with quite as
high a degree of accuracy as from meridian circle observations
from the earliest times of exact measurements up to the present,
1.¢., 165 years. After a lapse of a few years, say ten years, ad-
ditional photographs may be taken to determine the proper
motions with a higher degree of precision, if such is necessary.
A few photographs of each region will be entirely ample for the
purpose and a probable error 0”002 will result. If such photo-
graphs are made, then, on account of the errors in the early
catalogue positions it will be impossible to attain an equal de-
gree of accuracy with the meridian circle until after the lapse of
at least another century.

On account of the solar drift, the stars of tenth magnitude used
as comparison stars may have a parallactic drift. As Schlesinger
has pointed out, Publications. of the Allegheny Observatory, 4, 1,
a comparison of photographic and meridian circle proper motions
will give valuable material regarding the relation of proper
motion to brightness and to star streaming.
38 S. A. MITCHELL

A fourth cause of difference between photographic and meridian
circle proper motions will result from orbital motion of stars
forming a physical system. As will be shown later, this will
afford a means of determining the relative masses of the stars
forming a physical system. In the Table such differences of
proper motion are found in the stars  Cassiopeie#, 70 Ophiuchi,
Krueger 60, etc.

Other large differences in this table between proper motions
from catalogue and from photographs can be explained by errors
in the positions of the early catalogues. For instance, in the
star Lalande 1799, there is apparently an error in right ascension
in the catalogue by Lalande.

SPECTROSCOPIC PARALLAXES.

One of the most important investigations that have taken
place in recent years is the determination by Adams of the dis-
tances of the stars by means of the spectroscope, Proceedings of
the National Academy of Sciences, 2, 147, 152, 1916. By com-
paring the relative intensities of certain lines in the spectra of
stars, Adams is able to determine their absolute magnitude
or, in other words, the magnitude that the stars would have if
placed at a distance where the parallax would be equal to 071.
By means of the formula 5 log = M + m — 5, where M is the
absolute magnitude, m the apparent magnitude and 7 the
parallax in seconds of arc, Adams has been able to derive paral-
laxes. These values are absolute in value and are not relative
to a particular system of comparison stars. It should be pointed
out that the spectroscopic results of Mt. Wilson are based on the
measured or trigonometric parallaxes, and that the accuracy of
the spectroscopic parallaxes is increased as the measured paral-
laxes are increased in number and accuracy. The Luminosities
and Parallaxes of Five Hundred Stars published by Adams and
Joy, 1917 (Contributions from the Mt. Wilson Observatory, 142)
were founded on the system of parallaxes then published. Since
then many parallaxes have been determined by photography
and their results have been communicated to Adams and Joy
in advance of publication. These recent parallaxes have been
furnished chiefly by Mt. Wilson, Yerkes, Allegheny, Sproul, and
McCormick Observatories. Dr. Adams has kindly informed the
PARALLAXES OF 260 STARS 39

writer that.at Mt. Wilson there are about 1800 parallaxes spec-
troscopically determined. These parallaxes, in advance of
publication are given for all of the stars on the McCormick list
except those of early spectral type, for which as yet Mt. Wilson
can furnish no values. As will be shown later, the early
trigonometric parallaxes, those due mostly to heliometer and
meridian circle, are subject to large errors. On the whole these
early parallaxes are too large in size. As a result, the Mt. Wil-
son “500” parallaxes are based on a system different from the
more recent results. A comparison of the ‘‘500” with the recent
results shows considerable differences in some of the individual
stars. The recent spectroscopic parallaxes are on the average
0”005 smaller than those in ‘'500” stars.

The average magnitude of the comparison stars used in the
McCormick measures is about 10 on the B. D. scale. It has
been assumed that the average parallax of the comparison stars
is 07005. To compare the absolute para)laxes of Mt. Wilson
with the relative values in the Table, 0005 has been subtracted
from the Mt. Wilson results.

THE DETAILED RESULTS.

In the early years of parallax work, stars were ordinarily
observed only when it was expected they would show an appreci-
able parallax. Thus there were specially investigated stars
with large proper motions. The observing program of the
McCormick Observatory has attempted a more representative
selection of stars. The main part of the program consists of
all stars of F, G, K and M types brighter than 4.50 magnitude,
and all stars of the earlier types brighter than magnitude 4.00
and north of declination — 20° These stars formed the back-
bone of the program. To these were added stars whose paral-
laxes by meridian circle or heliometer gave discordant results,
and also some interesting visual binaries, stars of the 61 Cygni
type, etc. Our observing program was sent on cards to the Alle-
gheny, Dearborn, Sproul and Yerkes Observatories, and in turn
their lists were sent to the McCormick Observatory. In this
manner each was kept advised of the program of the other
so that sufficient duplication could be made, but excessive dupli-
cation avoided.
40 S. A. MITCHELL

Below, under the details for each star, are given the reasons
why the star was observed and anything of particular interest
concerning the star. Following a brief description, there are
added in Table I, the details of the plates taken, their serial
number, date, hour angle at the middle of exposure, observers,
and quality or weight. In nearly all cases, two images were
exposed on each plate. A good plate was given a weight 1.0,
a fair plate 0.7, and a poor plate 0.4. A plate of one good image
received a weight 0.7.

The observers taking part in the work at the telescope were:

M =S. A. Mitchell.

1 = C. P. Olivier.

L. Alden.

. H. Graham.

R. C. Lamb.

. B. Briggs.

. A. Dales.

= Marguerite D. Darkow.
H = M. Alberta Hawes.
F = Jennie V. France.

Under the table of ‘Comparison Stars” there is given for com-
parison stars and parallax star their diameters in millimeters, the
X and Y coérdinates measured from the center of position of the
comparison stars, and the dependences of the comparison stars.

In Table II are given the residuals in millimeters, and the
weighted residual in seconds of arc. The scale value of the
photographs is 208 per millimeter.

The value of u given by the least-square solution is the proper
motion in right ascension, or u,Cosé. These values are given in
the following units: (a) in millimeters per one hundred days, (6)
in seconds of arc per one hundred days, and (c) in seconds of arc
per year.

O
A
L
B

H
G
P

ll

G
Ds
D

B CASSIOPELZ (0° 3"; +58° 35’)

This star is interesting on account of the proper motion of
0755. This large proper motion has caused the star to be
many times investigated for parallax. The star is of magnitude
2.42, and of F5 type. The rotating sector was used to reduce
the brightness on the photographic plate. Twenty-eight plates
were measured by Mr. Mitchell.
PARALLAXES OF 260 STARS

TABLE 1

PLATES OF 6 CaASSIOPELE

41

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
152 1914 July 21 —oh1 M 1.0
512 Nov. 5 —0.2 M 1.0
522 Nov. 6 —0.4 A 0.8
553 Nov. 11 ~0.1 M,G 0.8
602 Nov. 21 0.0 M,A 1.0
659 Dec. 12 —0.4 M, Ol 0.7
1554 | 1915 Aug. 15 -0.2 Ol 0.7
"1559 Aug. 18 —1.0 ol 0.6
1560 Aug. 18 -0.4 Ol 0.5*
2096 Nov. 30 —0.3 A 0.7
2131 Dec. 9 -0.6 M 0.9
2132 Dec. 9 —0.2 M, A 0.8
2868 1916 Aug. 13 —0.3 Ol 0.9
2869 Aug. 13 +0.1 Ol 0.6
2954. Sept. 3 —0.1 A 1.0+
2965 Sept. 4 +0.1 L 0.8
3421 Nov. 21 —0.4 L 1.0
3422 Nov. 21 —0.1 M 1.0
3440 Nov. 26 —0.3 M 0.7
3496 Dee. 7 —0.6 M 0.9
3497 Dec. 7 —0.3 M 0.7
4282 1917 Aug. 18 —0.5 Ol 1.0
4307 Aug. 20 —0.2° B 1.0
4308 Aug. 20 +0.1 B 1.0
4795 Nov. 19 —0.2. A 1.0
4838 Dec. 2 —0.6 M 0.9
4839 Dec. 2 —0.3 M 0.9
4846 Dec. 5 -0.1 A 0.9
* One exposure. { Three exposures.
42

S. A. MITCHELL

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR 8 CASSIOPEL®
Pies | Stason | Mf" | macart). | Beye. | ei | al
mm. mm.
152 +0.0046 1.0 +0.828 | —676 —0.0010 | —0%02
512 + .0056 1.0 — .602 | —569 + .0014 | + .03
522 + .0083 0.8 — .614 | —568 — .0012 | — .02
553 + .0066 0.8 — .669 | —563 + .0007 | + .01
602 + .0072 1.0 — .764 | —553 + .0005 | + .01
659 + .0140 0.7 — .886 | —532 — .0052 | — .09
1554 + .0304 0.7 + .585 | —286 — .0005 | — .01
1559 + .0314 0.6 + .548 | —283 — .0014 | — .02
1560 + .0325 0.5 + .548 | —283 — .0025 | — .04
2096 + .0342 0.7 — .829 | —179 — .0009 | — .O1
2131 + .0350 0.9 — .875 | —170 — .0012 | — .02
2132 + .0343 0.8 — .875 | —170 — .0005 | — .O1
2868 + .0552 0.9 + .599 | + 78 — .0002 -00
2869 + .0509 0.6 + .599 | + 78 + .0042 | + .07
2954 + .0535 1.0 + .316 | + 99 + .0022 | + .05
2965 + .0541 0.8 + .301 | +100 + .0016 | + .03
3421 + .0582 1.0 | — .769 | +178 — .0049 | + .10
3422 + .0584 1.0 — .769 | +178 + .0003 | — .O1
3440 + .0547 0.7 — .807 | +183 + .0087 | + .06
3496 + .0578 0.9 — .870 | +194 + .0012 ) + .02
3497 + .0530 0.7 — .870 |~+194 + .0060 | + .10
4282 + .0824 1.0 + .541 | +448 — .0020 | — .04
4307 + .0832 1.0 + .515 | +450 — .0027 | — .06
4308 + .0781 1.0 + .515 | +450 + .0024 | + .05
4795 + .0843 1.0 — .750 | +541 — .0010 | — .02
4838 + .0866 0.9 — .844 | +554 — .0027 | — .05
4839 + .0848 0.9 — .844 | +554 — .0009 | — .02
4846 +0.08386 0.9 —0.859 | +557 —0.0046 | —0.09

 

The normal equations are:
23.8¢ + 4.770u — 6.75107 = + 1.1564 mm.

391.7264, — 3.09277 = + 2.9247 mm.
12.0855 = — 0.3116 mm.
PARALLAXES OF 260 STARS \ 48

from which:

c = + 0.04800 mm.
# = + 0.00690 mm. = + 071436, or + 0"524 per year.
a = + 0.00279 mm. = + 07058 + 0’011
Probable error of plate of unit weight
+ 0.00166 mm. = + 07034.

ComPaRISON STARS

 

 

 

 

 

 

No. Diameter. X (Right Ascen-) y (Declination). Dependence.
sion).
mm. mm. | mm. |
1 0.14 —A7.9 +25.4 +0. 223
2 11 +10.2 —38.2 . 269
3 .09 +13.8 —43.2 .273
4 .09 +23 .9 +56.0 +0. 235
Parallax star 0.20 + 1.46 — 3.27

 

 

The following values of the parallax have been found:

 

 

 

 

Parallax. | Authority. Method.
+0°154+07085 | Pritchard Photography
+ .161+ .028 Kostinsky Prime Vertical
+ .10 + .029 Flint Meridian Circle
+ .082+ .009 Russell Photography
+ .0514 .015 Smith Heliometer
+ .0654+ .081 Jewdokimov Meridian Circle
+ 074+ .011 Allegheny Photography
+0.060 Adams Spectrograph

 

The McCormick value for the annual proper motion in right
ascension, or za cos 6 is + 07524, while that due to Boss’s Pre-
liminary General Catalogue is + 07529.

PIAZZI 0° 130 (0% 32"; —25° 19’)

This star is called also 82 Ceti, and it is a double 6 395. Ac-
cording to Burnham, ‘“‘this interesting system was discovered
with the 6-inch, and it was evident from the first that it was a
44 S. A. MITCHELL

TABLE 1

Puates oF Prazzi 08 130

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
2183 1915 Dee. 21 —053 M io
2184 Dec. 21 +0.1 M 1.0
2195 Dec. 22 —0.7 M 0.9
2228 Dec. 26 0.0 M 0.9
2920 1916 Aug. 25 —0.1 A 1.0
2921 Aug. 25 +0.2 A 1.0
2955 Sept. 3 0.0 A 1.0
2956 Sept. 3 +0.6 A 1.0
2969 Sept. 5 —0.4 M 0.5*
2983 Sept. 9» —0.3 M 1.0
3387 Nov. 16 —0.2 L 1.0
3388- Nov. 16 +0.2 L 0.8
3475 Dec. 2 —0.3 A 1.0
3476 Dec. 2 +0.1 A 1.0
4248 1917 Aug. 5 —0.5 A 0.9
4297 Aug. 19 +0.1 Ol 0.8
4298 Aug. 19 +0.5 ol 0.9
4328 Aug. 24 -—0.8 B 0.9
4329 Aug. 24 —0.4 B 1.0
4842 Dec. 2 +0.6 M 1.0
4843 Dec. 2 | +1.0 M 0.8
4852 Dec. 6 —0.3 A 1.0

 

 

* One exposure.

physical pair from the large proper motion of the components.”’
The total proper motion is 1740 per year. The radial velocity
is + 17.2 km. per second, and the type G5. The only tri-
gonometric parallax is that of Flint who, by the meridian circle
finds the value + 0734 + 07060. Recently, Adams by means
of the spectroscope derives the parallax + 0”095. In Lick
Observatory Bulletin, 3, 88, 1905, Aitken derives the orbit, and
finds a period of 24.0 years. Since the distance separating the
pair is always less than 078, and the magnitudes very nearly
PARALLAXES OF 260 STARS 45

TABLE 2

Repvuctions For Prazzi 0® 130

 

 

 

 

 

 

 

 

 

“Pie | SE | MEE | eeeae). | Dare. | ee | ines
mm. mm.
2183 +0.0028 1.0 —0.890 ~367 +0.0010. | +0702
2184 + .0023 1.0 — .890 —367 + .0015 + .03
2195 + .0028 0.9 — .893 — 366 + .0012 | + .02
2228 + .0066 0.9 | — .901 —362 — .0019 — .04
2920 + .0562 1.0 + .550 —119 — .0009 — .02
2921 + .0524 1.0 + .550 —119 + .0029 + .06
2955 + .0570 1.0 + .480 —110 — .0005 — .O1
2956 + .0568 1.0 + .480 —110 — .0003 — .01
2969 + .0626 0.5 + .402 —108 — .0059 — .09
2983 + .0602 1.0 + .844 — 104 — .0030 — .06
3387 + .0640 1.0 — .646 — 36 + .0016 + .03
3388 + .0666 0.8 — .646 — 36 — .0010 — .02
3475 | + .0696 1.0 — .796 — 20 — .0017 — .04
3476 + .0659 1.0 — .796 — 20 + .0020 | + .04
4248 + .1190 0.9 + .771 +226 + .0006 | + .01
4297 + .1195 0.8 + .629 +240 + .0021 + .04
4298 + .1167 0.9 + .629 +240 + .0049 + .10
4328 + .1231 0.9 + .566 +245 — .0008 — .02
4329 + .1246 1.0 + .566 +245 — .0024 — .05
4842 + .13852 1.0 — .795 +345 — .0002 .00
4843 + .1362 0.8 — .795 +345 — .0012 | — .02
4852 +0.1361 1.0 —0.823 +349 —0.0005 —0.01

 

equal, being 6.6 and 6.7, respectively, the values for 7 and u
below will be the same as those for the center of gravity of the
system. Using Flint’s value of the parallax, the mass of the
system (Popular Astronomy, 18, 483, 1910), is 0.01. With
the McCormick value of the parallax, the mass of the system
is 0.68 times that of the sun. The annual proper motion in
right ascension from the present series of plates is + 17394,
while the value from Boss is + 17384. The plates were measured
by Mr. Alden. ~~
46 S. A. MITCHELL

ComPaRIsON STARS

 

 

 

 

 

 

No. Diameter. |< Ss Naat Y (Declination). Dependence.
mm. mm. mm.

1 0.21 —49.5 —16.4 +0.1297

2 17 —42.0 +29.5 . 1570

3 .19 “ — 9.4 +50.6 . 1865

4 .10 +3.4 | —45.2 .1461

5 :09 445.4 ~39.2 1735

6 .18 +52.1 +20.7 +0.2072
Parallax star 0.13 + 4.41 + 2.83

 

The normal equations are:

20.4c — 0.631p — 3.05987 = + 1.5036 mm.
117.4163 + 9.27687 = +.2.1480 mm.
9.85617 = ~— 0.0179 mm.

from which:

c = + 0.07490 mm.
pw = + 0.01837 mm. = + 073820, or + 17394 per year.
a = + 0.00414 mm. = + 07086 + 0010.
Probable error of plate of unit weight
+ 0.00144 mm. = + 070300.

. a CASSIOPELZ (0° 34™; +55° 59’)

There is nothing specially worthy of note regarding the
brightest star in the constellation of Cassiopeia except that it is a
variable with a magnitude range from 2.2 to 2.8, it is of type K,
and of small proper motion 0706. A small parallax would be
expected. Twenty-two plates of this region were measured by
Mr. Mitchell.
 

 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 47
TABLE 1
Puates of a CAssioPElZ
No. Date. Hour Angle. Observers. Weight.
179 1914 Aug. 16 —10 Ol 0.4*
495 Nov. 4 —0.3 G 0.5*
513 Nov. 5 —0.1 M 0.9
565 Nov. 12 —0.4 Ol 0.7
603 Nov. 21 0.0 M,A 0.9
615 Nov. 22 —0.5 M 0.8
627 Nov. 23 —0.1 Ol, G 0.8
643 Nov. 25 —0.1 M,A 0.7
1533 1915 Aug. 6 —0.3 G 0.7%
1534 Aug. 6 0.0 G 0.6*
1581 Aug. 25 —1.3 A 0.8
1582 Aug. 25 —0.9 A 0.8
2054 Nov, 24 —0.6 G, Ol 0.7
2076 Nov. 27 —0.7 G 0.5
2177 Dec. 19 —0.6 M 0.8
2178 Dec. 19 —0.2 M 0.8
2856 1916 Aug. 1 —0.6 A 0.7
2857 Aug.- 1 —0.2 A 0.7
2864 Aug. 12 —0.5 A 1.0
2865 Aug. 12 —0.1 A 1.0
3441 Nov. 26 —0.4 M 1.0
3442 Nov. 26 0.0 M 1.0
* One exposure.
Comparison Stars
No. Diameter. |* a lat Y (Declination). Dependence.
mm. mm. mm.
1 0.10 —46.7 —28.6 +0.201
2 .10 —32.0 —33.0 .194
3 .14 —29.6 +52.1 236
4 .16 +47.3 — 3.7 182
5 .10 +61.0 +13.2 +0.187
Parallax star 0.22 — 2.6 + 1.9

 

 

 

 

 
S. A. MITCHELL

 

 

 

 

 

 

 

 

 

48
TABLE 2
REDUCTIONS FOR a CASSIOPELE
rie, | Same | mae | eee | esis | get | tase
mm. mm.
179 +0.0110 0.4 +0.672 —439 +0.0005 | +0701
495 + .0079 0.5 — .484 —359 + .0026 | + .04
518 + .0094 0.9 — .497 —358 + .0011 + .02
565 + .0093 0.7 — .586 —351 + .0011 | + .02
603 + .0114 0.9 — .687 —342 — .0010 — .02
615 + .0109 0.8 — .697 —341 — .0005 — .01
627 + .0112 0.8 — .707 —340 — .0008 | — .02
643 + .0101 0.7 — .726 | —38388 + .0002 -00
1533 + .01389 0.7 + .773 — 84 — .0004 ) — .01
1534 + .0135 0.6 + .773 — 84 -0000 -00
1581 + .0147 0.8 + .570 — 65 — .0013 — .02
1582 + .0149 0.8 + .570 — 65 | — .0015 — .08
2054 + .0138 0.7 — .714 + 26 — .0015 — .02
2076 + .0130 0.5 — .742 + 29 — .0007 — .01
2177 + .0129 0.8 — .882 | + 51 — .0006 | — .01
2178 + .0106 | ° 0.8 — .882 } + 51 + .0017 | + .03
2856 + .0147 0.7 + .809 +277 + .0008 + .01
2857 + .0141 0.7 + .809 +277 + .0014 | + .02
2864 + .0156 1.0 + .708 +288 — .0002 -00
2865 + .0150 1.0 + .708 +288 + .0004 | + .01
3441 + .0151 1.0 — .740 +894 — .0008 | — .02
3442 +0.0136 1.0 —0.740 | +894 +0.0007 | +0.01

 

The normal equations are:

16.8¢ — 3.5934 — 2.37697 = + 0.2143 mm.

+ 181.8629n + 9.37672

from which:

c

M
T

+ 0.01304 mm.

+ 8.53017

= + 0.0348 mm.
= — 0.0159 mm.

+ 0.00054 mm. = + 070111, or + 0041 per year
+ 0.00119 mm. = + 07025 + 07005.
Probable error of plate of unit weight

+ 0.00066 mm. = + 07014.
PARALLAXES OF 260 STARS 49

The only values of the parallax so far published are an early
one by photography by Pritchard, the mean of four values giving
+ 07038 + 0%023, and a determination by Flint with the
meridian circle with the result — 07014 + 07034. By the
spectroscopic method, Mt. Wilson finds a parallax ranging from
+ 0022 to + 0028 depending on the visual magnitude of this var-
iable star. As already noted, the method of Adams gives absolute
values of the parallax, while the McCormick results are relative
to the particular system of comparison stars used. To reduce
the relative parallax of a Cassiopeiz to an absolute value, 07005
should be added to the McCormick value. The proper motion
in right ascension from the present series of plates is + 07040
per year. Boss gives + 07051.

54 PISCIUM (05 34™; +20° 42’)
This star of magnitude 6.08 and of spectral type K has a
total proper motion 0761. The parallax was first determined at

TABLE 1
Puates or 54 Piscrum

 

 

 

No. Date, Hour Angle. Observers. Weight.
3480 1916 Dec. 5 —O*1 L, M 0.6
3517 Dec. 10 —1.2 M 1.0
4330 1917 Aug. 24 +0.3 B 0.7
.
4331 Aug. 24 +0.9 B 0.7
4380 Sept. 1 —0.6 B 0.9
4381 Sept. 1 —0.2 B 1.0
4814 Nov. 26 —0.2 B 1.0
4815 Nov. 26 © +0.4 B 1.0
5572 1918 July 20 —0.7 A 0.5*
5588 Aug. 2 +0.1 A 0.8
5589 Aug. 2 +0.5 A 0.5*
5628 Aug. 14 0.0 A 0.7
5636 Aug. 19 —0.2 A 0.9
5899 Nov. 6 —0.5 F 0.8
5900 Nov. 6 +0.1 F 0.6
5990 Nov. 23 —0.2 D,H 0.8
5991 Nov. 23 +0.5 D, H 0.7

 

 

 

 

 

5 * One exposure.
50 §. A. MITCHELL

Yale by Chase with the relative value + 07140 + 07019. The
absolute value from the spectrograph is 07120. Miss Darkow
measured the McCormick plates, and found the relative parallax
+ 07101 + 0"012, with a proper motion in right ascension
— 0"477 where the corresponding value from Boss is — 07463.

Comparison STARS

 

 

 

 

 

 

No. Diameter. x Soca Y (Declination). Dependence.
1 0.09 —28.9 +14.9 +0.278
2 .09 — 8.5 —25.0 .261
3 -10 +18.2 —20.9 234
4 .14 +19.2 +31.0 +0.227
Parallax star 0.12 — 1.6 — 0.2
TABLE 2

‘Repucrtions For 54 Piscrum

 

 

 

Solution Weight | Parallax erin - Residual Vp-v
Plate. (m). (p). Factor (P). | Days (t). (v). in Are.

mm. mm.
3480 —0.0064 0.6 —0.814 —451 +0.0022 +0704
3517 — .0004 1.0 — .845 —446 — .0043 — .09
4330 — .0156 0.7 + .572 —189 + .0016 + .03
4331 | — .o1e2 | 0.7 | + .572 | —189 | + .o022 | + .04
4380 — .0151 0.9 + .469 —181 + .0001 -00
4381 — .0130 1.0 + .469 —181 — .0020 — .04
4814 — .0278 1.0 — .740 — 95 + .0016 + .03
4815 — .0296 1.0 — .740 — 95 + .0084 + .07
5572 — .0309 0.5 + .887 +141 — .0023 — .08
5588 — .0346 6.8 + .803 +154 + .0002 .00
5589 — .0375 0.5 + .803 +154 + .0031 + .05
5628 — .0362 0.7 + .691 +166 + .0005 + .01
5636 — .0336 0.9 + .636 +171 — .0027 — .05
5899 — .0484 0.8 — .513 +250 + .0016 + .03
5900 — .0471 0.6 — .513 +250 + .0003 -00
5990 — .0466 0.8 — .709 +267 — .0022 — .04
5991 —0.0472 0.7 —0.709 +267 —0.0016 —0.08

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS 51

The normal equations are:

13.2¢ — 2.238 — 0.35977 = — 0.3652 mm.
+ 73.2073u + 3.63067 = — 0.3784 mm.

‘+ 6.13517 = + 0.0172 mm.
from which:
c = — 0.02860 mm.
# = — 0.00628 mm. = — 071307, or — 0477 per year.
a = + 0.00485 mm. =-+ 07101 + 07012.

Probable error of plate of unit weight
+ 0.00147 mm. = + 07081.

LALANDE 1198 (0° 39"; +1° 15’)

This star of magnitude 8.14, of type Ko has a total proper
motion of 0763. With the Yale heliometer, Chase has found the
relative parallax + 07069 + 07088, and with the spectrograph,
Adams found the absolute parallax + 07037. Mr. Olivier
measured the McCormick plates and found a relative parallax
of + 07039 + 07008, and a proper motion in right ascension
— 07058 where the corresponding value by Porter is — 07063.
52 S. A. MITCHELL

 

 

 

TABLE 1
Puates oF LALANDE 1198
No. Date. Hour Angle. Observers. ; Weight.
3485 1916 Dec. 6 +0*1 M, Ol 1.0
3486 Dec. 6 +0.3 Ol 0.9
3547 1917 Jan. 1 —0.2 ol 0.8
3548 Jan. 1 +0.2 Ol 0.8
3549 Jan. 1 +0.8 Ol 0.7
4255 Aug. 11 -0.1 B 0.7
4256 Aug. 11 +0.2 B 0.8
4318 Aug. 21 +0.1 ol 0.9
4319 Aug. 21 +0.5 Ol 0.9
5614 1918 Aug. 6 0.0 A 0.9
5615 Aug. 6 +0.4 A 1.0
5637 Aug. 19 +0.4 A 0.9
5638 Aug. 19 +0.8 A 0.7*
6029 Nov. 30 +0.2 D 0.8
6030 Nov. 30 +0.6 Cc 0.5*
6084 Dec. 17 —0.4 H 1.0
6085 Dec. 17 +0.1 H 0.9
6126 Dec. 26 +0.6 F 0.7
7400 1919 July 30 +0.2 H 0.5*
7407 Aug. 2 —0.5 Ol 0.7
7408 Aug. 2 0.0 ol 0.7
7510 Aug. 19 —0.5 F 0.9
7511 Aug. 19 —0.1 F 0.9

 

 

 

 

 

* One exposure.

CoMPARISON STARS

 

 

 

 

 

No. | Diameter. fe eae Y (Deélination). Dependence.
mim. mm. mm.

1 0.10 —100.2 —12.4 +0.2779

2 19 + 16:0 —21.9 .3565

3 12 + 42.1 + 6.0 2346

4 08 + 42.1 +28.3- +0.1310
Parallax star 0.12 — 6.75 — 6.14

 
PARALLAXES OF 260 STARS

TABLE 2

-Repuctions ror LALANDE 1198

 

 

 

 

 

 

 

 

 

 

Plate. Solution Weight | Parallax Time in Residual vp+o
(m). (p). Factor (P). | Days (d). OF in Arc.
mm. mm.
8485 —0.0048 1.0 —0.811 —526 —0.0020 —004
3486 — .0098 0.9 — .811 —526 + .0030 + .06
3547 — .0074 0.8 — .905 —500 + .0003 .00
3548 — .0088 0.8 — .905 —500 + .0017 + .03
3549 — .0088 0.7 -— .905 —500 + .0017 + .03
4255 — .0077: 0.7 + .736 —278 + .0019 + .03
4256 — .0036 0.8 + .736 —278 — .0022 — .04
4318 — .0053 0.9 + .629 —268 — .0007 — .01
4319 — .0043 0.9 + .629 —268 — .0017 — .03
5614 — .0081 0.9 | + .783 + 82 — .0003 — .01
5615 — .0072 1.0 + .783 + 82 — .0012 — .02
5637 — .0065 0.9 + .654 + 95 — .0022 — .04
5638 — .0108 0.7 + .654 + 95 a -0021 + .04
6029 — .0124 0.8 — .760 +198 + .0002 .00
6030 — .0131 0.5 — .760 +198 + .0010 + .01
6084 — .0091 1.0.) — .871 +215 — .0034 — .07
6085 -| — .0138 0.9 — .871 +215 + .0013 + .02
6126 — .0100 0.7 — .899 +224 — .0026 — .05
7400 — .0101 0.5 + .840 +440 — .0009 — .01
7407 — .0124 0.7 + .820 +443 + .0013 + .02
7408 — .0132 0.7 + .820 +443 + .0021 + .04
7510 — .0108 0.9 + .659 +460 — .0007 — .01
7511 —0.0150 0.9 +0.659 +460 +0.0035 +0.07
The normal equations are:
18.6¢ — 2.501u + 0.62997 = — 0.1687 mm.
+ 229.9454u + 20.0895r = — 0.1142 mm.
+ 11.34127 = 0.0000 mm.
from which:
c = — 0.00924 mm.
uw = — 0.00076 mm. = — 070158, or — 07058 per year.

Tv

+ 0.00186 mm. = + 07039 + 07008.
Probable error of plate of unit weight

+ 0.00126 mm. =

+ 07026.
54 S. A. MITCHELL

n CASSIOPELZ (05 43™; +57° 17’)

This star is well known to all users of small telescopes on
account of it being an easy double and with a large difference of
magnitude, the magnitudes being 3.6 and 7.6, and of types F8
and Ko respectively. The star has been very frequently meas-
ured both with small and with large telescopes. Since its
measurement by Y in the year 1832, it has completed only 90°
of its orbit. As a consequence, there is a large range in the
values of the periods published in Burnham’s General Catalogue,
a variation all the way from 181 to 500 years.

The star has a large proper motion of 1”21, and its parallax
has been frequently determined. The present series of plates
was specially for the purpose of seeing how good an agreement
there would be between the parallax values of the principal
star and the companion. The results below show a difference
of only 07002. In photographing this region, the rotating sector
was used. When the opening in the sector was adjusted so that
the companion was well visible and measurable on the photo-
graphic plates, the principal star was larger than one would
wish in parallax work of the best quality. There remained
always the possibility of further reducing the sector opening so
as to make the principal star equal in size to the average com-
parison star. This would have made the companion too faint
to be seen. On account of the exquisite definition of the 26-inch
telescope, it was possible under good conditions of seeing and
with perfect guiding to procure plates with both components
measurable on the same plate. A reference to the plate numbers
below in Tables 2 and 3 will readily show the frequency with
which the plates were taken with the smaller sector opening.
The diameter of the principal star below gives the value with
the reduced sector. With sector opened to show the companion,
the principal star had a diameter of 0.22 mm. The plates were
measured by Mr. Mitchell.
PARALLAXES OF 260 STARS

TABLE 1

PLATES OF 7 CASSIOPEIE

55

 

 

 

No. Date. Hour Angle. Observers. Weight.
473 1914 Nov. 2 —043 M 0.9
554 Nov. 11 0.0 G 0.8
585 Nov. 17 —0.2 M,A 0.8 ;
660 Dec. 12 —0.3 A 0.5*
1605 1915 Sept. 6 —0.5. M 0.8
2065 Noy. 25 —0.3 A 0.9
2107 Dec. 4 —0.3 M 0.5*
2108 Dec. 4 0.0 M 0.5*
2845 1916 Aug. 4 —0.5 A 0.8
2846 Aug. 4 —0.1 A 0.8
2903 Aug. 19 —0.3 A 0.9
2942 Aug. 30 —0.5 A 0.9
2943 Aug. 30 —0.2 A 0.9
3498 Dec. 7 —0.5 L 1.0
3499 Dec. 7 —0.2 L 1.0
3511 Dec. 8 —0.6 L 1.0
3512 Dec. 8 —0.2 L 0.7*
4348 1917 Aug. 26 —0.5 A 1.0
4349 Aug. 26 —0.2 A 1.0
4357 Aug. 27 -1.1 Ol 1.0
4358 Aug. 27 —0.7 Ol 1.0
4364 Aug. 28 —0.8 B 1.0
4373 Aug. 29 —0.5 B 1.0
4374 Aug. 29 —0.1 B 1.0
4789 Nov. 18 —0.3 B 1.0
4790 Nov. 18 +0.1 B 1.0
4796 Nov. 19 —0.2 A 1.0
4840 Dec. 2 —0.4 M 0.8
4841 Dec. 2 0.0 M 0.8
4847 Dec. 5 —0.1 A 1.0

 

 

 

 

 

* One exposure.
56 S. A. MITCHELL

Comparison STARS

 

 

 

 

 

 

No. Diameter. = ae aaa Y (Declination). Dependence.
mm. mm, mm.

1 0.09 —46.4 +35.8 +0.230

2 .08 —21.7 —25.5 -206

3 11 + 6.0 — 3.6 -196

4 | .13 +18.1 —36.8 .184

5 .10 +44.0 +30.1 +0.184
Principal star .10 — 2.2 go edd
Companion 0.05 — 2.5 + 1.0

 
PARALLAXES OF 260 STARS

TABLE 2

REDUCTIONS FOR 7 CASSIOPEI®, PRINCIPAL STAR

57

 

 

 

Soluti Weigh Parall: ime i i .
ee et PA renal pean nar fina
mm. mm.

473 +0.0606 0.9 —0.426 —693 0.0000 0700
554 + .0621 0.8 — .546 — 684 — .0011 — .02
585 + .0604 0.8 — .619 —678 + .0009 | + .02
660 + .0667 0.5 — .841 — 663 — .0050 | — .07
1605 + .1144 0.8 + .443 —385 + .0013 | + .02
2065 + .1174 0.9 — .702 —305 + .0007 ; + .01
2107 + .1224 0.5 — .784 —296 — .0036 | — .05
2108 + .1211 0.5 — .784 —296 — .0023 | — .03
2845 + .1713 0.8 + .804 — 52 — .0012 | — .02
2846 + .1698 0.8 + .804 — 52 + .0004 | + .O1
2903 + .1716 0.9 + .660 — 37 — .0004 | — .01
2942 + .1708 0.9 + .527 — 26 + .0010 | + .02
2943 + .1685 0.9 + .527 — 26 + .0033 | + .06
3498 + .1712 1.0 — .812 + 73 + .0042 | + .09
3499 + .1726 1.0 — .812 + 73 + .0028 | + .06
3511 + .1752 1.0 — .819 + 74 + .0003 | + .01
3512 + .1747 0.7 — .819 + 74 + .0008 | + .01
4348 + .2295 1.0 + .581 +335 — .0016 — .03
4349 + .2278 1.0 + .581 +335 + .0001 00
4357 + .2292 1.0 + .568 +336 — .0012 — .02
4358 + .2284 1.0 + .568 +336 — .0004 | — .0O1
4789 + .2316 1.0 — .633 +419 — .0012 — .02
4790 + .2307 1.0 — .633 +419 — .0004 ; — .O1
4796 + .2304 1.0 — .645 +420 -0000 00
4840 + .2327 0.8 — .772 +433 — .0014 | — .03
4841 + .28385 0.8 — .772 +433 — .0022 | — .04
4847 +0.2307 1.0 —0.795 +436 +0.0009 | +0.02

 

 

 

 

 

 

 

The normal equations are:

23.3c + 9.140u — 4.62787 = + 4.0901 mm.
+ 6.4862 mm.
— 0.6649 mm.

317 .8544py + 2.20367
10.78577
58

from which:
c = + 0.17121 mm.
w= + 0.01542 mm.
a7 = + 0.00866 mm.
Probable error of plate of unit weight
+ 0.00120 mm. = + 070250.

. MITCHELL

+ 03208, or + 17171 per year.
+ 07180 + 07008.

 

 

 

 

 

 

 

 

 

 

TABLE 3
REDUCTIONS FOR 7 CASSIOPEIL®, COMPANION

Solution Weight Parallax Time in Residual. . vp-o
Plate. (m). (p). | Factor (P). | Days (2). (v). in Are.

mm. mm.
554 —0.2405 0.8 —0.546 —684 +0.0005 | +0°01
585 — .2418 0.8 — .619 —678 + .0020 | + .04
660 — .2402 0.5 — .841 —663 + .0005 | + .01
1605 — .1917 0.8 + .443 —385 — .0004 — .01
2065 — .1924 0.9 — .702 —3805 + .0010 | + .02
2107 — .1922 0.5 — .784 —296 + .0012 | + .02
2108 — .1898 0.5 — .784 —296 — .0012 | — .02
2845 — .1483 0.8 + .804 — 52 — .0019 — .04
2846 — .1455 0.8 + .804 — 52 + .0003 -00
2903 — .1444 0.9 + .660 — 87 — .0001 -00
2942 — .1441 0.9 + .527 — 26 — .0001 .00
2943 — .1446 0.9 + .527 — 26 + .0004 | + .01
3498 — .1414 1.0 — .812 + 73 — .0012 — .02
3499 — .1446 1.0 — .812 + 73 + .0020 + .04
3511 — .1378 1.0 — .819 + 74 — .0048 | — .10
3512, — .1885 0.7 — .812 + 74 — .0041 — .07
4364 — .0953 1.0 + .555 +337 — .0009 | — .02
4373 — .0976 1.0 + .543 +338 + .0014 |} + .03
4374 — .0968 1.0 + 543 +338 + .0006 | + .01
4840 — .0964 1.0 — .772 +433 + .0015 | + .08
4841 — .0980 1.0 — .772 +433 + .00381 | + .06
4847 —0.0942 1.0 —0.795 +436 —0.0005 | —0.01
The normal equations are:

18.8¢ + 1.2394 — 3.29927 = — 2.7433 mm.
218.5608u + 4.05447 = + 2.7303 mm.

9.22087

= + 0.6117 mm.
PARALLAXES OF 260 STARS 5S

from which:
ce = — 0.14528 mm.
# = + 0.01315 mm. = + 02737, or + 07999 per year.

a = + 0.00857 mm. = + 07178 + 0°009.
Probable error of plate of unit weight
+ 0.00123 mm. = + 070256.

The parallax of the principal star is + 07180 + 0"009.
and that of the companion + 07178 + 07008.
Hence, the parallax of the system is -+ 07179 + 07006.

Other values of the parallax are:

 

 

 

 

 

Parallax. Authority. : Method.
+07154+-07045 O. Struve Equatorial
+ .2754 .055 Schweiger and Socoloff Equatorial
+ .180+ .015 Peter Heliometer
+ .4654 .044 Davis Photography
+ .84 4+ .044 Flint Meridian Circle
+ .188+ .021 Russell Photography
+ .096+ .067 Jewdokimov Meridian Circle
+, .18240.009 Steele Photography
+0.173+ .006 Allegheny Photography

 

The present measures give the first trigonometric determina-
tion of the parallax of the fainter star. The spectroscopic method
of Adams furnishes the values for principal star and component,
+ 07166 and + 07166 respectively.

In spite of the fact that the orbital motion is very slow,
nevertheless, it makes itself manifest in the above measures.
Boss in the Preliminary General Catalogue finds the proper
motion of the center of gravity of the system along a great circle,
or ua cos 6 = +1127. The amounts that the proper motions
of the two components of 7 Cassiopeie differ from this furnish a
measure of the orbital motion, and consequently, present a ready
means of determining the relative masses. It is easy to find
that the ratio of the masses B/A is 0.34, where A is the principal
star, and B the companion.
60 S. A. MITCHELL

The first determination of this ratio was found in 1881 by
L. Struve (Melanges Math. et Astr., Vol. V) who gave a value
B/A = 0.268. A later discussion by T. Lewis (Mem. R. A. S.,
Vol. LVI) gives B/A = 0.5. The Preliminary General Cata-
logue of Boss (p. 264) furnishes the values:

From right ascensions, B/A = 1.63 (Weight 60).
From declinations = 0.41 (Weight 85).

Boss assumes the value of B/A = 0.76, but adds that this
result is ‘uncertain owing to the interdependence of the ex-
pressions for orbital and proper motions respectively.”

In Astronomical Journal, 29, 173, 1916, Van Biesbroeck gives
the best values so far obtained. From the measures of two
photographs taken with the 40-inch telescope, and separated
by an interval of eleven years, there results from measures in
right ascension, the value B/A = 0.23, and from declination
measures, the value B/A = 0.31, with a mean value of 0.27.

The McCormick photographs cover a period of three years.
The agreement between the photographic values at Yerkes ‘and
at McCormick, and the wide disagreement between the two
values due to Boss show the advantages of photography for
investigations of this kind.

LALANDE 1799 (05 57"; +4° 31’)

This star of 8.4 magnitude, of K2 type, and of total proper
motion 0748 has been found by Chase to have a relative parallax
of + 0%046 + 07056 and by Mt. Wilson to have a spectroscopic
parallax + 07046. Miss Hawes measured the McCormick plates
and found the relative parallax of + 07022 + 0007, with a
proper motion in right ascension amounting to + 07268 per
year. The value of the proper motion in right ascension given
by Porter is + 07354, but his results seem to show that there
is a considerable error in the position given by Lalande.
PARALLAXES OF 260 STARS

TABLE 1

Puates or LaLanpE 1799

61

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
4340 1917 Aug. 25 +051 ol 1.0
4341 Aug. 25 +0.5 ol 1.0
4366 Aug. 28 +0.2 B 0.8
4367 Aug. 28 +0.7 B 0.9
4885 Dec. 20 —0.2 B 1.0
4886 Dec. 20 +0.2 B 1.0
5652 | 1918 Aug. 23 =0.4- A 0.8
5653 Aug. 23 +0.1 A 1.0
5663 Aug. 29 —0.2 A 0.7*
5879 Nov. 5 —0.1 H 0.9
5880 Nov. 5 +0.4 D. 1.0
5908 Nov. 7 —0.5 H 1.0
5909 Nov. 7 +0.1 D 1.0
6076 Dec. 6 +0.9 H 1.0
7362 1919 July 26 -1.0 H 0.9
7363 July 26 —0.6 H 0.7*
7378 July 27 —0.7 D 1.0
7379 July 27 —0.3 _D 1.0
7398 July 30 —0.9 H 1.0
7399 July 30 —0.5 H 1.0
* One exposure.
CoMPARISON STARS
No. Diameter. = eee Y (Declination). Dependence.
mm. mm. mm. o
1 0.15 —40.0 +19.9 +0.373
2 .10 —32.1 —47.9 .161
3 12 +20.9 + 6.0 - 2384
4 14 +51.2 +22.0 0.232
Parallax star | 0.14 — 3.34 + 6.20

 

 

 

 

 
 

 

 

 

 

 

 

 

 

 

62 S. A. MITCHELL
TABLE 2
Repuctions ror LALANpE 1799
i i Time i Residual vp
Plate: Puree | MEP aac (| Dare G. | Ge” | an are
mm. mm.
4340 —0.0350 1.0 +0.639 —388 —0.0006 —0%01
4341 — .0370 1.0 + .639 —388 + .0014 + .03
4366 — .0352 0.8 + .604 —385 — .0003 — .01
4367 — .0347 0.9 + .604 —385 — .0008 — .02
4885 — .0326 1.0 — .867 —271 — .0004 — .01
4886 — .0350 1.0 — .867 —271 + .0020 + .04
5652 — .0214 0.8 + .665 — 25 — .0013 — .03
5653 — .0228 1.0 + .665 | -— 25 + .0001 .00
5663 — .0215 0.7 + .595 — 19 — .0011 — .02
5879 — .0227 0.9 — .417 + 49 + .0014 + .03
5880 — .0197 1.0 — .417 + 49 — .0016 | — .03
5908 — .0210 1.0 — .445 + 61 — .0002 -00
5909 — .0219 1.0 — .445 + 51 + .0007 + .01
6076 — .0190 1.0 — .774 + 80 — .0015 — .03
7362 — .0098 0.9 + .894 +3812 — .0008 — .02
7363 — .0126 0.7 + .894 +312 + .0020 + .04
7378 — .0119 1.0 + :889 +3813 + .0013 + .03
7379 — .0130 1.0 + .889 +3813 + .0024 + .05
7398 — .0092 1.0 + .873 +316 — .0013 — .03
7399 —0.0088 1.0 +0.873 +316 —0.0017 —0.04
The normal equations are:
18.7c + 0.0154 + 4.68247 = — 0.4165 mm.
+ 126.8894u + 9.49307 = + 0.4575 mm.
+ 9.69327 = — 0.0619 mm.
from which:
“¢ = — 0.02254 mm. \
# = + 0.00353 mm. = + 070734, or + 0"268 per year.
a = + 0.00105 mm. = + 07022 + 0”007.

Probable error of plate of unit weight

= 0.00092 mm. = + 0’019.
PARALLAXES OF 260 STARS 638

e PISCIUM (0° 57"; +7° 27’)

This star is of G5 type, of magnitude 4.45, and of compara-
tively small proper motion, 0”08, so that a small value of the
parallax would be expected. The value below agrees closely
with that obtained at Allegheny Observatory by photography,
+ 07023 + 07008. (Publ. Allegheny Observatory, 4, 1, 1917.)
-By the spectrographic method, Adams derives the absolute
parallax + 07014. The McCormick value of the proper motion
in right ascension is — 0"066, while that due to Boss is
— 07080. Twenty-one plates were measured by Mr. Alden.

 

 

 

TABLE 1
Puates oF ¢ Piscrum
No. Date. Hour Angle. Observers. : Weight.
2114 1915 Dee. 6 —054 G 1.0
2115 Dec. 6 0.0 G 0.9
2282 1916 Jan. 4 —0.5 ol 0.7
2922 Aug. 25 +0.3 A 0.9
2923 Aug. 25 +0.6 A 1.0
2929 Aug. 26 —0.3 Ol 0.6
2930 Aug. 26 0.0 Ol 0.7
2944 Aug. 30 0.0 A 0.8
2945 Aug. 30 +0.3 A 0.9
3464 Dec. 1 —0.1 Ol 1.0
3543 Dec. 31 —0.1 A 1.0
3544 Dec. 31 +0.2 A 1.0
4249 1917 Aug. 5 —0.4 A 0.9
4250 Aug. 5 0.0 A 1.0
4257 Aug. 11 +0.6 B 0.9
4269 Aug. 13 —0.9 A 1.0
4270 . Aug. 13 —0.5 A 1.0
4816 Nov. 26 —0.2 B 1.0
4817 Nov. 26 +0.2 B 1.0
4823 Nov. 28 —0.1 A 1.0
4824 Nov. 28 +0.3 A 1.0

 

 

 

 

 
S. A. MITCHELL

ComPaARISON STARS

 

 

 

 

 

 

 

 

 

 

No. Diameter. = banal Y (Declination). Dependence.
mm. mm. mm.
gd 0.27 —39.5 + 9.9 +0.2903
2 11 —20.0 — 9.7 . 2649
3 .10 +26.7 —40.8 -2100
4 .09 +32.8 +40.6 +0.2348
Parallax star 0.14 | — 8.46 + 1.27
TABLE 2
REDUCTIONS FOR e Piscium
Solution Weight Parallax Time in Residual . vp-o
Plate. (m). (y). Factor (P). | Days (é). (). in Are.
mm. mm.
2114 —0.0084 1.0 —0.770 —415 —0.0001 0700
2115 — .0052 0.9 — .770 —415 — .0033 — .06
2282 — .0100 0.7 — .906 —386 + .0011 + .02
2922 — .0066 0.9 + .638 —152 — .0027 — .05
2923 — .0084 1.0 + .638 —152 — .0009 — .02
2929 — .0111 0.6 + .627 —151 + .0018 + .03
2930 — .0100 0.7 + .627 —151 + .0007 | + .01
2944 — .0138 0.8 + .578 —147 + .0044 | + .08
2945 — .0132 0.9 + .578 —147 +. .0038 + .07
3464 — .0118 1.0 — .732 — 54 + .0002 -00
8543 — .0109 1.0 — .902 — 24 — .0011 — .02
3544 — .0122 1.0 — .902 — 24 + .0002 .00
4249 — .0106 0.9 + .831 +193 — .0015 — .03
4250 — .0124 1.0 + .831 +193 + .0003 + .01
4257 — .0122 0.9 + .783 +199 .0000 .00
4269 — .0104 1.0 + .766 +201 — .0018 — .04
4270 — .0106 1.0 + .766 +201 — .0016 — .03
4816 — .0161 1.0 — .680 +303 + .0014 + .03
4817 — .0152 1.0 — .680 +303 + .0006 + .01
4823 — .0155 1.0 — .701 +308 + .0008 + .02
4824 —0.0143 1.0 —0.701 +308 —0.0004 —0.01

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS 65

The normal equations are:

19.3¢c + 2.741p — 0.56977 = — 0.2209 mm.
+ 110.6429u + 3.91997 = — 0.1237 mm.
+ 10.66157 = + 0.0142 mm.
from which:
c = — 0.01129 mm.
pw = — 0.00088 mm. = — 070182, or — 07066 per year.

+ 0.00105 mm. = + 07022 + 07008.
Probable error of plate of unit weight
+ 0.00125 mm. = + 07026.

vi

8B ANDROMEDZ (1 4™; +35° 5’)

Three trigonometric values of the parallax of this star have
been found: Pritchard by photography, + 07073 + 07023,
Flint by meridian circle, + 07036 + 07031, and Allegheny Ob-
servatory by photography, + 0033 +0°007. The star is of Ma
type, and of magnitude 2.37. The total proper motion is 0"22,
that in right ascension, as determined by Boss, is + 07181 per
year. Adams finds the spectroscopic parallax of + 07048.
The series of seventeen plates were measured by Mr. Olivier.

~
 

 

 

 

 

 

 

 

 

 

 

66 S. A. MITCHELL
TABLE 1.
PLATES oF 6 ANDROMEDZ
No. Date. Hour Angle. Observers. Weight.
686 1914 Dec. 17 —O0r G 0.5*
705 Dec. 23 —0.5 A 0.5
743 1915 Jan. 7 —0.2 Ol 0.8
763 Jan. 9 —0.1 M 0.8
775 Jan. 10 —0.1 M 0.9
1540 Aug. 9 —0.5 ol 0.8
1541 Aug. 9 0.0 ol 0.5*
1557 Aug. 15 —0.3 Ol 0.7
1561 Aug. 18 —0.7 Ol 0.5
1562 Aug. 18 —0.4 Ol 0.8
1594 Aug. 31 —1.2 Ol 0.9
1595 Aug. 31 —0.6 Ol 0.7
2147 Dec. 10 —0.8 01, G 0.8
2148 Dec. 10 —0.3 G 0.6*
2196 Dec. 22 —0.8 Ol 0.7
2197 Dec. 22 —0.3 G 0.7
2264 1916 Jan. 3 —0.3 Ol 1.0
* One exposure.
ComPaARISON STARS
No. Diameter. « ee Y (Declination). Dependence.
mm. mm. mm.
1 0.10 —35.3 —26.0 +0.201
2 .21 —29.7 +21.6 .278
3 .12 +10.4 +16.1 .278
4 -12 +54.6 —-11.7 +0.243
Parallax star 0.24 + 0.8 + 2.4

 

 

 

 
PARALLAXES OF 260 STARS

TABLE 2

ReEpDvucTIONS FoR 8 ANDROMED

 

 

 

Soluti Wei ll ime i id ‘
nae A lean nee || eae | ae
mm. mm.

686 | —0.0044 | 0.5 | —0.840 | —221 | —0.0016 | —o%02
705 | ~— .0053 | 0.5 | ~— .872 | —205 | — .0002 .00
743 | — .0075 | 0.8 | — .909 | —190 | + .0024 | + .04
763 | — .0046 | 0.8 | — .909 | —188 | — .0005 | — .O1
775 | — .0044 | 0.9 | ~— .908 | —187 | — .0006 | — .O1
1540 | + .0079 | 0.8 | + .820] +24 | — .0012 | — .02
1541 | + .0075 | 0.5 | + .820 | +24 | — .0008 | — .o1
1557 | + .0083 | 0.7 | + .770 | +30 | — .0015 | — .03
1561 | + .0083 | 0.5 | + .741 | +33 | — .0015 | — .02
1562 | + .0042 | 0.8 | + .741 | +33 | + .0026 | + .05
1594 | + .0050 | 0.9 | + .599 | +36 | + .0015 | + .03
1595 | + .0065 | 0.7 | + .599 | + 36 .0000 .00
2147 | + .0076 | 0.8 | — .789 | +147 | — .0014 | — .02
2148 | + .0044 | 0.6 | — .789 | +147 | + .0018 | + .03
2196 | + .0095 | 0.7 | — .866 | +159 | — .0031 | — .05
2197 | + .0035 | 0.7 | — .866 | +159 | + .0029 | + .05
2264 | +0.0068 | 1.0 | —0.905 | +171 | —0.0001 | 0.00

 

 

 

 

 

 

 

The normal equations are:

from which:

c = + 0.00363 mm.
uw = + 0.00327 mm.

12.2¢ + 0.684 — 2.82297 = + 0.0386 mm.
+ 23.3815u + 2.08047
+ 8.11467

= + 0.0848 mm.
= + 0.0194 mm.

x = + 0.00281 mm. = + 07058 + 07008.

Probable error of plate of unit weight

+ 0.00100 mm. = + 07121.

= + 0"0680, or + 07248 per year.
68 S. A. MITCHELL

6 CASSIOPEIZ (1" 5"; +54° 37’)

The present results give the second determination of the
parallax of 6 Cassiopeiz under the auspices of Columbia Uni-
versity. In 1893, Professor Harold Jacoby, from a discussion
of Rutherfurd photographs found a parallax of + 07232 + 07067.
Two later values have been found: — 07018 + 07091 with the
meridian circle by Jewdokimov, and — 07003 + 07003 by
photography at Swarthmore. The star is of A5 type, and of
magnitude 4.52, with a, proper motion in right ascension, as
determined by Boss, of + 07229 per year. Nineteen plates were
measured by Mr. Alden.

 

 

 

TABLE 1
a
Puates oF 6 CassIOPELe
No. Date. Hour Angle. Observers. Weight.
496 1914 Nov. 4 —O1 G 0.9
514 Nov. 5 —0.2 M 0.6*
566 Noy. 12 —0.1 Ol 1.0
628 Nov. 23 —0.1 G, Ol 0.9
644 Nov. 25 0.0 M,A 1.0
1606 1915 Sept. 6 —0.3 M 0.8
1626 Sept. 8. —0.2 M 1.1f
2020, Nov. 16 —0.4 A 1.0
2246 1916 Jan. 2 —0.7 M 0.9
2247 Jan. 2 —0.3 M 1.0
2838 July 29 —0.6 A 1.0
2839 ‘July 29 —0.3 A 0.7*
2858 Aug. 7 —0.1 A 0.7*
2870 Aug. 13 —0.3 Ol 0.7
2871 Aug. 13 0.0 Ol 0.6*
2885 Aug. 17 0.0 Ol 0.6*
3554 1917 Jan. 3 —0.5 M 1.0
3555 Jan. 3 —0.2 M 0.9
3560 Jan. 6 —0.4 M 1.0

 

 

 

 

 

* One exposure. t Three exposures.
PARALLAXES OF 260 STARS

Comparison STARS

 

 

| Diameter.

X (Right Ascen-
sion).

 

 

 

 

 

 

 

No. Y (Declination). Dependence.
mm. mm. mm.

1 0.16 —44.1 —28.3 +0.1944

2 .18 —16.3 +21.5 - 1639

3 .12 —13.9 —12.7 . 2023

4 .16 +28.9 —27.1 - 2523

5 .16 +45.4 +46.6 +0.1871

Parallax star 0.17 + 1.7 — 2.7 =
TABLE 2
REDUCTIONS FOR 0 CASSIOPELE
Solution Weight Parallax Time in Residual Vp+o
Plate. (m). (p). | Factor (P). | Days ({). (). in Arc,
mm. mm.

496 —0.0134 0.9 —0.371 —427 +0.0003 +0°01
514 — .0107 0.6 — .386 —426 — .0024 — .04
566 — .0178 1.0 — .484 —419 + .0046 + .10
628 — .0078 0.9 — .622 < —408 — .0054 — .il
644 — .0156 1.0 — .645 —406 + .0024 + .05
1606 — .0009 0.8 + .526 —121 — .0030 — .06
1626 — .0059 1.1 + .500 —119 + .0020 + .04
2020 — .0032 1.0 — .533 — 50 — .0014 — .03
2246 — .0040 0.9 — .903 —- 8 — .0004 — .01
2247 — .0044 1.0 — .903 -— 3 .0000 .00
2838 + .0059 1.0 + .888 +206 — .0013 — .03
2839 + .0033 0.7 + .888 +206 + .0013 + .02
2858 + .0068 0.7 + .831 +215 — .0021 — .04
2870 + .0054 0.7 + .783 +221 — .0007 — .01
2871 — .0008 0.6 + .783 +221 + .0055 + .09
2885 + .0060 0.6 + .746 +225 — .0013 — .02
3554 + .0068 1.0 | — .906 +364 — .0026 — .05
3555 + .0012 0.9 — .906 +364 + .0030 | + .06
3560 +0.0038 1.0 —0.908 +367 +0.0005 +0.01

 

 

 

 

 

 

 
70 S. A. MITCHELL

The normal equations are:

16.4c¢ — 1.3394 — 2.60487 = — 0.0458 mm.
+ 137.7802u + 6.51627 = + 0.3410 mm.
+ 8.88047 = + 0.0412 mm.

ll

from which:

c = — 0.00224 mm.
w= +.0.00235 mm. = + 070488, or + 07178 per year.
x = + 0.00226 mm. = + 07047 + 0°013.

Probable error of plate of unit weight

+ 0.00178 mm. = + 07037.

w ANDROMEDZ (1" 22; +44° 53’)

This is a double star, 8 999, with a 12th magnitude companion
at a distance 2"5. The principal star is of 4.96 magnitude, and
of type F5, and the system has a considerable proper motion
of 0"35. The proper motion in right ascension determined by
Boss is + 0344. Two measured values of the parallax have
been published, both from observations with meridian circle:
+ 0708 + 07042 by Flint, and + 07097 + 0"087 by Jew-
dokimov. By the spectroscopic method, Adams finds the
parallax + 0"030. By photography the recent value at Yerkes
is + 0”001 + 07016. The plates of this series were measured
by Mr. Alden.
PARALLAXES OF 260 STARS

TABLE 1

PLATES OF w ANDROMEDZ

71

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
661 1914 Dec. 12 040 M,A 1.0
706 Dec. 23 —0.2 A 0.8
709 Dec. 26 —0.4 G 1.0
719 Dec. 27 —0.1 A 1.0
732 1915 Jan. 2 —0.2 A 0.7*
1535 Aug. 6 0.0 G 0.6*
1573 Aug. 23 —-1.1 A 1.0
1574 Aug. 23 —0.7 _A 1.0
1583 Aug. 25 —1.2 A 0.8
1584 Aug. 25 —0.8 A 1.0
2066 Nov. 25 —0.4 A 1.0
2067 Nov. 25 0.0 A 0.8
2133 Dec. 9 —1.0 A 0.8
2134 Dec. 9 —0.6 A,M 0.9
2179 Dec. 19 —0.6 M 1.0
2180 Dec. 19 —0.2 M 1.0

* One exposure.
ComPaRIsoN STARS

No. Diameter. |* a Y (Declination). Dependence.

1 0.18 —44.0 —38.2 +0.2437

2 25 —22.6 +45.2 2355

3 21 +33.9 +38.3 . 2533

4 -20 +32.7 —45.3 +0.2675

Parallax star 0.18 + 1.3 -— 1.1

 

 

 

 

 
72 S. A. MITCHELL

TABLE 2

REDUCTIONS FOR w ANDROMED

 

 

 

 

 

 

 

 

 

pits | Be” | "Ge |waneee.| Deco. | oe | alee
mm. mm.
661 +0.0028 1.0 —0.774 —218 —0.0023 | —0%05
706 — .0028 0.8 — .853 —207 + .0037 | + .07
709 — .0007 1.0 — .869 —204 + .0018 | + .04
719 + .0032 1.0 — .874 —203 — ,0021 — .04
732 + .0019 0.7 — .896 —197 — .0005 | — .O1
1535 + .0131 0.6 + .875 + 19 + .0009 | + .01
1573. + .0146 1.0 + .741 + 36 -0000 -00
1574 + .0146 1.0 + .741 + 36 -0000 -00
1583 + .0155 0.8 + .721 + 38 — .0008 | — .O1
1584 + .0146 1.0 + .721 + 38 + .0001 .00
2066 + .0184 1.0 — .595 +130 — .0007 | — .O1
2067 + .0158 0.8 — .595 +130 + .0019 | + .02
2133 + .0229 0.8 — .745 +144 — .0046 | — .08
2134 + .0178 0.9 — .745 +144 + .0005 | + .01
2179 + .0170 1.0 — .826 +154 + .0017 | + .02
2180 +0.0180 1.0 —0.826 +154 +0.0007 | +0:01

 

The normal equations are:
14.4¢ + 0.101p — 4.511387 = + 0.1688 mm.
+ 31.0306u + 3.24877 = + 0.1568 mm.
+ 8.70087 = — 0.0286 mm.

~

from which:
c = + 0.01204 mm. -
w= + 0.00490 mm. = + 071018, or + 0372 per year.
a = + 0.00113 mm. = + 0"023 + 0°010.
Probable error of plate of unit weight
+ 0.00131 mm. = + 0”027.

n PISCIUM (1" 26"; +14° 49’)

By photography Allegheny Observatory derives the relative
parallax — 07015 + 07005, while Adams furnishes the spectro-
PARALLAXES OF 260 STARS

73

scopic value of + 0"015. The star is of G5 type, of magnitude
3.72, and of small proper motion 0703, that in right ascension,

 

 

 

 

 

 

 

 

 

 

 

according to Boss, amounting to + 0029 per year. Mr. Olivier
measured the series of plates.
TABLE 1
Puates oF 7 Piscium

No. Date. Hour Angle. Observers. Weight.
181 1914 es Aug. 16 —02 Ol 0.8
182 Aug. 16 +0.4 Ol 0.5*
515 Nov. 5 +0.1 M 1.0
555 Nov. 11 0.0 G 0.9
567 Nov. 12 +0.3 Ol 0.8
568 Nov. 12 +0.8 Ol 1.0
578 Nov. 13 -0.6 G 0.9
708 Dec. 26 —1.0 G 1.0
734 1915 Jan. 4 —0.3 Ol 0.5
1546 Aug. 12 —0.2 G 0.8
1547 Aug. 12 +0.2 Ol 0.7
1558 Aug. 15 +0.1 G 0.7
1563 Aug. 18 —0.1 ol 0.9
1564 Aug. 18 +0.3 Ol 0.9
2089 Nov. 27 —0.2 G 0.7
2199 Dec. 22 +0.5 Ol 0.7
2236 Dec. 27 —0.2 Ol 0.5*
2237 Dec. 27 +0.4 G 1.0
2316 1916 Jan. 14 +0.2 Ol 0.5*
2317 Jan. 14 +0.6 Ol 0.9

* One exposure.
Comparison STARS
No. Diameter. x | Y (Declination). Dependence.
mm. m. mm.

1 0.22 —26.8 +45.8 +0.233

2 19 — 0.1 —52.7 238

3 .24 +12.2 —42.6 -253

4 .28° +14.7 +49.5 +0.276

Parallax star 0.28 + 0.9 + 1.0

 

 

 

 

 
74 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR 7 PisciuM

Solution Weight Parallax Time in Residual iv peo
Plate. (m). (p). | Factor (P). | Days (t). (). in Are.

mm. mm.
181 +0.0124 0.8 +0.814 —286 +0.0026 +0705
182 + .0154 0.5 + .814 —286 — .0004 — .01
515 + .0125 1.0 — .306 —205 — .0002 | — .00
555 | + .0167 | 0.9 | — .395 | —199 | — .0046 | — .o9
567 + .0113 0.8 — .410 —198 + .0008 + .01
568 | + .0124 | 1.0 | — .410 | —198 | — .0003 | — .O1
578 + .0089 0.9 — .423 —197 + .0032 + .06
708 + .0108 1.0 — .863 —154 + .0002 -00
734 + .0128 0.5 — .879 —145 — .0019 — .03
1546 + .0135 0.8 + .846 + 75 + .0007 + .01
1547 + .0132 0.7 + .846 + 75 + .0010 + .02
1558 + .0158 0.7 + .824 + 78 — .0017 — .03
1563 + .0168 0.9 + .799 + 79 — .0027 — .05
1564 + .0135 0.9 + .799 + 79 + .0006 + .01
2089 + .0084 0.7 — .605 +182 + .0023 + .04
2199 + .0084 0.7 _— .839 +207 | + .0017 + .03
2236 + .0138 0.5 — .868 +212 — .0038 — .05
2237 + .0092 1.0 — .868 +212 + .0008 + .02
2316 + .0143 0.5 — .914 +230 — .0044 — .06
2317 +0.0074 0.9 —0.914 +230 +0.0025 +0.05

 

The normal equations are:

15.7¢ — 2.9454 — 2.33297 = + 0.1918 mm.
+ 54.23124 — 2.66627 = — 0.0561 mm.
+ 8.48687 = — 0.0098 mm.
from which:
ec = + 0.01250 mm.
» = — 0.00024 mm. = — 070051, or — 0019 per year.
a = + 0.00243 mm. = + 0”046 + 0010.

Probable error of plate of unit weight
+ 0.00142 mm. = + 0029.
PARALLAXES OF 260 STARS 76

v ANDROMED& (1* 31"; +40° 54’)

The only value of the parallax of this star so far published is
the spectroscopic result of Adams of + 07091. The star is of
G type, of magnitude 4.18, and of fairly large proper motion of
0°42, of which, according to Boss — 0”179 is in right ascension.
Of the seventeen plates of the series, eleven were measured by
Mr. Graham and the balance by Mr. Mitchell.

TABLE 1
PLATES OF v ANDROMEDZ

 

 

 

No. Date. Hour Angle. Observers. Weight.
779 1915 Jan. 13 —041 M 0.8
790s} Jan. 14 —0.2 Ol 0.8
806 Jan. 16 —0.1 M 0.5
1644 Sept. 10 1:3 Ol 0.8
1645 Sept. 10 -0.8 Ol 0.8
1658 Sept. 11 —0.5 M 0.8
1659 Sept. 11 —0.1 M 0.9
1666 Sept. 12 —0.4 Ol 1.0
2049 Nov. 19 —0.4 G 1.0
2185 Dee. 21 —0.5 G 0.7
2248 1916 Jan. 2 —0.2 M 0.8
2970 Sept. 5 —0.5 M 0.5*
3005 Sept. 16 —0.7 M 1.0
3006 Sept. 16 -0.3 M ~ 1.0
3034 Sept. 19 —0.2 A 0.8
3561 1917 Jan. 6 —0.4 M 1.0
3562 Jan. 6 —0.1 M 1.0

 

 

 

 

 

* One exposure.

Comparison STARS

 

 

 

No. Diameter. ms eal Y (Declination). Dependence.
mm. mm. mm.
1 0.14 —39.7 +19.1 +0.211
2 .15 —40.6 —14.0 . 230
3 .10 +33.8 +38.4 -251
4 21 +46.5 —43.5 +0.308
Parallax star 0.14 + 5.1 — 3.0

 

 

 

 

 
76 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR v ANDROMED

Solution Weight Parallax Timein |. Residual Vp+o
Plate. (m). (p). | Factor (P). | Days (t). (). in Are.

mm. mm.
779 +0.0480 0.8 —0.915 —339 —0.0025 —0705
790 + .0524 0.8 — .915 —338 + .0019 + .04
806 + .0503 0.5 — .915 —336 — .0001 .00
1644 + .0513 0.8 + .569 — 99 + .0031 + .06
1645 + .0481 0.8 + .569 — 99 — .0001 -00
1658 + .0472 0.8 + .556 — 98 — .0010 — .02
1659 + .0486 0.9 + .556 — 98 + .0004 + .01
1666 + .0478 1.0 + .543 — 97 — .0003 — .01
2049 + .0444 1.0 — .485 — 29 + .0006 + .01
2185 + .0402 0.7 — .824 + 3 — .0019 — .03
2248 + .0417 0.8 — .889 + 15 -0000 .00
2970 + .0413 0.5 + .621 +262 + .0020 + .03
3005 + .0368 1.0 + .479 +273 — .0018 — .04
3006 + .0384 1.0 + .479 +273 — .0002 .00
3034 + .0371 0.8 + .487 +276 — .0014 — .02
3561 + .0340 1.0 — .902 +885 + .0016 + .03
3562 +0.0323 1.0 —0.902 +385 —0.0001 0.00

 

The normal equations are:
14.2¢ + 5.2134 — 1.48184 = + 0.6120 mm.

+ 82.2996u + 1.60367 = + 0.0282 mm.
+ 6.87107 = — 0.0524 mm.
from which:
c = + 0.04429 mm.
B= — 0,00251 mm. = — 070522, or — 0”190 per year.

+ 0.00252 mm. = + 07052 + 0”008.
Probable error of plate of unit weight
+ 0.00098 mm. = + 07020.

Tv
+

; PARALLAXES OF 260 STARS 17

2

41 H ANDROMEDZ (15 35"; +42° 6’)

This star of magnitude 4.97, and of type F has a considerable
proper motion of 0782 per year. Its parallax has been twice
determined with the following results: Smith with the Yale

TABLE 1

Puates or 41 H ANDROMED

 

 

 

No. Date. Hour Angle. Observers. Weight.
2265 1916 Jan. 3 —042 Ol 0.7
2859 Aug. 7 —0.2 A 1.0
2904 Aug. 19 -0.8 A 0.7
2905 Aug. 19 —0.5 A 1.0
2994 Sept. 11 —1.2 Ol 1.0
2995 Sept. 11 —0.9 Ol 1.0
3583 1917 Jan. 16 —0.1 M 1.0
3594 Jan. 19 0.0 Ol 0.5*
4271 Aug. 18 —0.6 A 1.0
4272 Aug. 18 —0.2 A 1.0
4284 © Aug. 18 —1.1 Ol 1.0
4285 Aug. 18 —0.8 ‘ Ol 0.9
{
4848 Dec. 5 —0.5 A 1.0
4895 Dec, 22 —0.4 B 1.0
4896 Dec. 22 —0.1 B 0.9

 

 

 

 

 

* One exposure.

Comparison STARS

 

 

 

 

 

 

 

No. Sansa, | sree eee ¥ Weclinatien). Dependence.
mm. mm. mm.
1 0.15 —49.3 +21.9 +0.1710
2 -08 —21.4 +11.9 . 1689
3 12 —18.1 —45.2 - 1604
4 -08 — 9.3 +40.9 1728
5 -10 -+38.7 + 9.8 1674
6 -07 +59.4 —39.3 +0.1595
Parallax star 0.17 — 0.6 + 1.0

 
78

S. A. MITCHELL

heliometer obtained the value + 07103 + 07037;
dokimov with the meridian circle secured the result + 07166
+ 0”094. Adams obtains the absolute parallax + 07095 by the
spectroscopic method. Mr. Alden measured the present series
of plates and obtained for the proper motion the value in right
ascension of + 0”854, while Boss derived the value + 07807.

and Jew-

 

 

 

 

 

 

 

 

 

TABLE 2
Repuctions ror 41 H ANDROMEDZ

Solution Weight Parallax Time in Residual P Vp+v
Plate. (m). (p). Factor (P). | Days (¢). (v). in Are.

mm. mm.
2265 —0.0298 0.7 —0.890 —429 —0.0023 | ‘—0"04
2859 + .0009 1.0 + .891 —212 — .0007 — .01
2904 — .0020 0.7 + .809 —200 + .0032 + .06
2905 + .0031 1.0 + .809 —200 — .0019 — .04
2994 — .0022 1.0 + .564 —177 |. + .0049 + .10
2995 + .0041 1.0 + .564 —-177 — .0014 — .03
3583 + .0115 1.0 — .917 — 50 — .0011 — .02
3594 + .0085 0.5 — .916 — 47 + .0023 + .03
4271 + .0410 1.0 + .856 +159 + .0008 + .02
4272 + .0442 1.0 + .856 +159 — .0024 — .05
4284 + .0440 1.0 + .820 +164 — .0018 — .04
4285 + .0412 0.9 + .820 +164 + .0010 + .02
4848 + .0484 1.0 — .674 +273 — .0006 — .01
4895 + .0451 1.0 — .827 +290 + .0040 + .08
4896 +0.0518 0.9 —0.827 +290 —0.0027 —0.05

 

The normal equations are:
13.7¢ + 1.7388y + 2.42107 = + 0.3058 mm.

+ 64.4019 — 4.40927 = + 0.7396 mm.
+ 8.85447 = + 0.0383 mm.

from which:

c = + 0.02011 mm.
uw = +0.01126 mm.
az = + 0.00443 mm.

+ 0.00172 mm. = + 07036.

+ 072339, or + 07854 per year.
+ 07092 + 0°013.
Probable error of plate of unit weight
PARALLAXES OF 260 STARS 79

7 CETI (15 39"; —16° 27’)

This star is of more than usual interest due to the fact that it
is one of the ten nearest stars to the solar system. It has a
parallax less than that of Sirius, but slightly greater than 61
Cygni. Two trigonometric parallaxes have been found: + 07310
+ 07012 with the heliometer by de Sitter, and + 07268 + 0029

 

 

 

 

TABLE 1
Puates or 7+ Cett
No. Date. | Hour Angle. Observers. Weight.
1
720 1914 Dec. 27 +07 A 0.6
764 1915 Jan. 9 0.0 M 0.4*
1685 Sept. 14 —0.5 A 0.6
1707 Sept. 16 +0.1 Ol 1.0
2050 Nov. 23 +0.1 G 0.5
2109 Dec. 4 —0.3 M 0.9
2110 Dec. 4 +0.2 A 0.9
2181 Dec. 19 +0.3 M 0.7
2957 | 1916 Sept. 3 +0.1 A 0.8
2958 Sept. 3 +0.6 A 0.7
3007 Sept. 16 +0.4 M 0.6
3015 Sept. 17 —0.3 A 0.8
8033 Sept. 19 —0.9 M,A 0.9
3500 Dec. 7 —0.5 L 0.7
8501 Dec. 7 0.0 L 0.7
3550 1917 Jan. 2 +0.2 L 1.0
3563 Jan. 6 +0.4 A 1.0

 

 

 

 

 

* One exposure.

with the meridian circle by Flint. Adams gives the spectroscopic
value of + 07257. The star is of K type, of magnitude 3.65,
and with a total proper motion of 1792. The proper motion in
right ascension determined by Boss is — 17717 per year, while
that from the McCormick photographs is — 17711. The seven-
teen plates of the series were measured by Mr. Mitchell.
80

S. A. MITCHELL

CoMPARISON STARS

 

 

X (Right Ascen-

 

 

 

 

 

 

 

 

No. Diameter. sion); Y (Declination). Dependence.
mm. mm. ° mm.

1 0.10 —67.3 +388 .2 +0.211

2 .10 —15.9 +41.7 -229

3 .12 +15.8 —14.6 .193

4 .08 +15.8 —650.4 .164

5 ; -10 +61.6 —14.9 +0.203

Parallax star 0.16 — 1.7 + 3.4
TABLE 2
Repuctions For 7 CETI
Solution Weight Parallax Time in Residual Vv pry
Plate. (m). (p). | Factor (P). | Days (2). ). in Are.
mm. mm.

720 +0.0778 0.6 —0.853 —406 —0.0045 —0"07
764 + .0667 0.4 — .908 —393 + .0028 + .04
1685 + .0414 0.6 + .547 —145 — .0060 — .10
1707 + .0334 1.0 + .520 — 143 + .0012 + .02
2050 + .0040 0.5 — .511 — 75 — .0002 -00
2109 — .0017 0.9 — .648 — 64 + .0010 + .02
2110 — .0036 0.9 — .648 — 64 + .0028 + .06
2181 — .0095 0.7 — .795 — 49 + .0032 + .05
2957 — .0439 0.8 + .672 +210 + .0012 + .02
2958 — .0433 0.7 + .672 +210 + .0006 + .01
8007 — .0533 0.6 + 510 +223 + .0052 + .08
8015 — .0466 0.8 + .497 +224 — .0019 — .03
3033 — .0483 0.9 + .470 +226 — .0010 — .02
3500 — .0850 0.7 — .689 +3805 + .0004 + .01
3501 — .0798 0.7 — .689 +805 — .0048 — .08
3550 — .0910 1.0 — .886 +331 — .0024 — .05
3563 —0.0962 1.0 +0.901 +335 |. +0.0017 +0.04

 

 

 

 

 

 

 

The normal equations are:

12.8¢ + 11.0664 — 2.62227 = — 0.3585 mm.
+ 73.9729u — 0.75077 = — 1.7391 mm.
+ 6.08637 = + 0.1218 mm.
PARALLAXES OF 260 STARS 81

from which: =
c = — 0.00545 mm. fe
w= — 0.02254 mm. = — 074689, or — 17711 per year.
z= + 0.01501 mm. = + 07312 + 0°016.

Probable error of plate of unit weight
+ 0.00179 mm. = + 07087.

8 TRIANGULI (25 3™; +34° 30’)

This is a star of magnitude 3.08, of type A5, and according to
Mitchell (Astrophysical Journal, 30, 240, 1909), is a spectroscopic
binary. The plates of the series were measured by Mr. Briggs
with the exception of the last four plates which were measured

by Mr. Mitchell.

The proper motion in right ascension found

 

 

 

 

 

TABLE 1
PLATES OF 8 TRIANGULI
No. Date. Hour Angle. Observers. Weight.
3069 1916 Sept. 23 —011 M 0.7
3096 Sept. 26 —0.4 L 0.9
3097 Sept. 26 0.0 L 0.7
3576 1917 Jan. 14 —0.1 M 0.7
3584 Jan. 16 —0.1 M 1.0
3601 Jan. 20 —0.1 M 1.0
3604 . Jan. 25 0.0 M 1.0
4350 Aug. 26 —0.6 A 1.0
4351 Aug. 26 —0.4 A 0.9
4359 Aug. 27 —1.2 Ol 0.7
4360 Aug. 27 —1.0 Ol 0.7
4375 Aug. 29 —0.9 B 1.0
4376 Aug. 29 —0.7 B 1.0
4377 Aug. 29 —0.5 B 1.0
4887 Dec. 20- —0.4 B 1.0
4888 Dec. 20 —0.2 B 1.0
4904 Dec. 26 —0.7 B 1.0
4905 _ Dec. 26 —0.4 B 1.0

 

 

 

 
82 8S. A. MITCHELL

from the plates is + 0156 per year, while the value from Boss is
+0”’152. The value of the parallax determined at Allegheny
Observatory by photography is + 0”006 + 07006.

CoMPaRISON STARS

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. 6 i ae Y (Declination). Dependence.
mm. mm. mm.
1 0.09 —22.2 —18.8 +0.2452
2 12 —17.5 + 3.5 -3227
3 14 +13.3 —23.5 .1079
4 .10 +26.4 +38.8 +0.3242
Parallax star 0.14 -— 1.1 + 6.6
TABLE 2
REDUCTIONS FOR 8 TRIANGULI
Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p). Factor (P). | Days (é). (). in Are.
mm. mm.
3069 —0.0057 0.7 +0.507 —260 +0.0034 +0706
38096 — .0029 0.9 + .466 —257 + .0006 + .01
8097 — .0018 0.7 + .466 —257 — .0005 — .01
8576 — .0035 0.7 — .913 —147 + .0024 + .04
3584 — .0018 1.0 — .918 —145 + .0007 + .01
3601 + .0022 1.0 — .921 —141 — .0032 — .07
3604 + .0010 1.0 — .925 —136 — .0019 — .04
4350 + .0057 1.0 + .822 + 77 — .0009 — .02
4351 + .0068 0.9 + .822 + 77 — .0020 — .04
4359 + .0028 0.7 + .814 + 78 + .0020 + .04
4360 + .0012 0.7 + .814 + 78 + .0036 + .06
4375 + .0072 1.0 + .796 + 80 — .0023 — .05
4376 + .0055 1.0 + .796 + 80 — .0006 — .01
4377 + .0054 1.0 + .796 + 80 — .0005 — .01
4887 “+ .0042 1.0 — .759 +193 + .0018 + .04
4888 + .0074 1.0 — .759 +193 — .0014 — .03
4904 + .0048 1.0 — .811 +199 + .0013 + .03
4905 +0.0053 1.0 —0.811 +199 +0.0008 +0.02

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS 83

The normal equations are:
16.3¢ + 1.614y — 0.35327 = + 0.0455 mm.
+ 42.0209n — 0.16747 = + 0.0903 mm.
+ 10.28747 = + 0.0065 mm.
from which:
c = + 0.00261 mm.
uw = + 0.00205 mm. = + 070427, or + 0"156 per year.
~ = + 0.00076 mm. = + 0016 + 07008.

Probable error of plate of unit weight
+ 0.00131 mm. = + 07027.

LALANDE 4141 (25 9™; +23° 49’)

This star of magnitude 6.9 and of type G has a total proper
motion 0°60. With the Yale heliometer the relative parallax
+ 07018 + 07041 was determined, and with the spectroscope
the absolute value + 0025. Miss Hawes measured the McCor-
mick plates with the exception of six plates measured by Mr.
Mitchell, and derived the relative parallax + 07034 + 0"007
and the proper motion in right ascension + 07450 while the
corresponding value from Porter is + 07452 per year.

CoMPARISON STARS

 

 

 

 

 

 

No. Diameter. o en Y (Declination). Dependence.
mm. mm. mm.
1 0.08 —46.7 — 2.6 +0.485
2 10 +12.8 —42.6 -390
3 10 +33.9 +45 .2 +0.125
Parallax star 0.10 —13.4 |

 
 

 

 

84 S. A. MITCHELL
TABLE 1
Puates oF LauanpE 4141
No. Date. Hour Angle. Observers. Weight.
4954 1918 Jan. 20 040 M 1.0
4979 Jan, 22 0.0 M 1.0
5685 Sept. 14 —0.5 M 1.0
5686 Sept. 14 -—0.3 M 1.0
5698 Sept. 21 —0.1 M 1.0
6032 Nov. 30 +0.3 D 1.0
6087 Dec. 17 0.0 H 1.0
6088 Dec. 17 +0.3 H 1.0
6241 1919 Jan. 13 +0.1 H 1.0
6242 Jan. 13 +0.3 H 1.0
7466 Aug. 10 —0.5 H 1.0
7467 Aug. 10 —0.4 H 0.8
7468 Aug. 10 —0.2 H 0.6*
7494 Aug. 15 0.0 D 1.0
7495 Aug. 15 +0.1 D 1.0
8238 Dec. 14 —0.4 M 0.9
8288 Dec. 17 —0.2 M 0.8
8289 Dec. 17 +0.2 A 0.8
8424 1920 Jan. 10 +0.5 A 1.0

 

 

 

 

 

* One exposure.
PARALLAXES OF 260 STARS

ReEpuctTions FoR LALANDE 4141

TABLE 2

 

 

 

 

 

 

 

 

 

 

ee kc eee
mm. mm.
4954 —0.0132 1.0 —0.924 —424 —0.0003 —0"01
4979 — .0114 1.0 — .926 —422 — .0020 — .04
5685 + .0036 j 1.0 + .650 —187 — .0005 — .01
5686 + .0009 1.0 + .650 —187 + .0022 | + .05
5698 + .0037 1.0 + .563 —180 — .0004 — .01
6032 + .0069 1.0 — .508 —110 — .0011 — .02
6087 + .0042 1.0 — .714 — 93 + .0022 | + .05
6088 + .0068 1.0 — .714 — 93 — .0004 — .o1
6241 + .0072 1.0 — .906 — 66 + .0005 | + .01
6242 + .0058 1.0 — .906 — 66 + .0019 + .04
7466 + .0212 1.0 + .932 +143 + .0019 | + .04
7467 + .0246 0.8 + .932 +143 — .0015 — .03
7468 + .0218 0.6 + .9382 +1438 + .0013 + .02
7494 + .0260 1.0 + .910 +148 — .0026 — .05
7495 + .0232 1.0 + .910 +148 + .0002 .00
8238 + .0292 0.9 — .679 +269 — .0012 | — .02
8288 + .0298 0.8 — .712 +272 — .0017 — .03
8289 + .0258 0.8 — .712 +272 + .0023 | + .04
8424 +0.0298 1.0 —0.893 +296 —0.0006 —0.01
The normal equations are:
17.9¢ — 2.1554 — 2.82157 = + 0.2182 mm.
+ 86.2309 + 5.97037 = + 0.4925 mm.
+ 11.55697 = + 0.0236 mm.
from which:
c = + 0.01311 mm.
w= + 0.00593 mm. = + 071233, or + 07450 per year.
x = + 0.00161 mm. = + 07034 + 07007.

Probable error of plate of unit weight

+ 0.00109 mm. = + 07023.
86 S. A. MITCHELL

6 TRIANGULI (2) 10"; +33° 46’)

This star has a fairly large proper motion of 1715 per year.
It is of G type, and of magnitude 5.07. The parallax has been
determined with the Yale heliometer by Smith giving the value,
+ 07115 + 07038; and three times with the meridian circle as
follows: Flint, + 07070 + 07030, Flint, + 07151 + 07024, and
Jewdokimov, + 07053 + 07085. Adams by the spectrograph
determines the parallax + 07115. Mr. Alden measured the
twenty plates of the series. The proper motion in right ascen-
sion from this series of plates is + 17183 per year, while the value
determined by Boss is + 17153.

 

 

 

TABLE 1
PLATES OF 5 TRIANGULI
No. Date. Hour Angle. Observers. Weight.
1676 1915 Sept. 13 —155 A 0.9
1677 Sept. 13 —1.2 A 0.8
1686 Sept. 14 —0.3 A 0.9
1725 Sept. 21 -0.6 G 0.8
2078 Nov. 27 —0.6 G 0.6
2079 Nov. 27 —0.3 G 0.9
2228 Dec. 26 0.0 M 0.6*
2322 1916 Jan. 17 —0.6 Ol 0.9
2323 Jan. 17 —0.2 Ol 0.9
2342 Jan. 23 —0.2 M 1.0
2906 Aug. 19 —0.5 A 0.6*
2907 Aug. 19 -0.4 A 0.8
2946 Aug. 30 —0.4 A 1.0
2947 Aug. 30 =U, A 1.0
8035 Sept. 19 —0.3 A 1.0
3036 Sept. 19 0.0 A 1.0
3545 Dec. 31 —0.3 A 0.9
3546 Dec. 31 0.0 A 1.0
3556 1917 Jan. 3 —0.6 M,A 1.0
3557 Jan. 3 0.3 0.8

 

 

 

 

 

* One exposure.
PARALLAXES OF 260 STARS

CoMPARISON STARS

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. x ae Vaal Y (Declination). Dependence.
mm. mm. mm.

1 0.11 —56.7 / +22.2 +0.3404

2 .12 —25.7 —47.0 -2194

3 215: +36.2 +37.2 - 2568

4 .10 +46 .2 —12.4 ; +0.1834
Parallax star 0.17 — 7.2 + 4.5

TABLE 2
REDUCTIONS FOR 5 TRIANGULI
ina, |) Maen: | eet | eae gee | ea | tase
mm. mm.

1676 +0.0034 0.9 +0.670 —235 +0.0010 +0702
1677 + .0003 0.8 + .670 —235 — .0022 — .04
1686 — .0010 0.9 + .658 —234 — .0035 — .07
1725 + .0046 0.8 + .571 —227 + .0015 + .03
2078 + .0068 0.6 — .451 —160 — .0005 — .01
2079 + .0078 0.9 — .451 —160 + .0005 + .01
2228 + .0117 0.6 — .877 —119 + .0006 + .01
2322 + .0168 0.9 — .917 —109 + .0044 + .09
2323 + .0120 0.9 — .917 —109 — .0004 — .01
2342 + .0123 1.0 — .927 —103 — .0010 — .02
2906 + .0577 0.6 + .886 +106 + .0007 + .01
2907 + .0577 0.8 + .886 +106 + .0007 + .01
2946 + .0574 1.0 + .804 +117 — .0008 — .02
2947 + .0624 1.0 + .804 +117 + .0042 + .09
3035 + .0595 1.0 + .587 +137 — .0005 — .01
3oze | + .0583 | 1.0 | + .587 | +137-| — .0017 | — .04
3545 + .0685 0.9 — .838 +240 + .0011 + .02
3546 + .0690 1.0 — .838 +240 + .0016 + .03
3556 + .0656 1.0 — .861 +243 — .0021 — .04
3557 +0.0638 0.8 —0.861 +243 —0.0039 —0.07

 

 

 

 

 

 
88 S A, MITCHELL

The normal equations are:

17.4c + 1.475u — 0.71197 = + 0.6281 mm.
+ 55.9652u — 3.4195¢ = + 0.9031 mm.
+ 10.30277 = — 0.0155 mm.

from which:
c = + 0.03503 mm.
yw = + 0.01559 mm. = + 073242, or + 17153 per year.
a = + 0.00609 mm. = + 07127 + 07010.

Probable error of plate of unit weight
+ 0.00145 mm. = + 07030.

LALANDE 4268 (2% 12"; +1° 17’)

The only parallax published for this star is the spectroscopic
one of Adams with the absolute value + 07052. It is of mag-
nitude, 5.8, of spectral type F5, and of total proper motion
0"527. Mr. Olivier measured the McCormick plates, and found
a proper motion in right ascension + 07407 while the corre-
sponding value from Boss is + 07367.

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. |~ ie een Y¥ (Declination). Dependence.
mm. mm. mm.

1 0.08 —55.8 —23.1 +0.1829

2 20 —30.6 +22.0 2128

3 16 —31.6 —39.1 1738

4 10 +387.9 +40.8 2276

5 08 +80.1 — 0.6 +0.2029
Parallax star 0.14 4 O.7 + 2.8

 
PARALLAXES OF 260 STARS

TABLE 1

Puates or LALANDE 4268

89

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
3068 1916 Sept. 23 —048 M 0.7
3125 Oct. 1 —0.9 L 0.6
3605 1917 Jan. 25 +0.3 M 0.9
3606 Jan. 25 +0.6 M 0.9
3616 Jan. 26 0.0 ol 0.8
3617 Jan. 26 +0.4 Ol 0.9
4333 Aug. 24 +0.4 B 0.7
4342 Aug. 25 ~ 0.0 Ol 1.0
4343 Aug. 25 +0.4 Ol 0.7*
4400 Sept. 10 0.0 B 1.0
4401 Sept. 10 +0.4 B 0.9
4906 Dec. 26 —0.1 B 0.9
4907 Dec. 26 +0.3 B 0.9
5664 1918 Aug. 29 ° -0.1 A 1.0
5665 Aug. 29 +0.3 A 1.0
5709 Sept. 22 0.0 M 0.8
6012 Nov. 26 +0.3 H 0.8
6013 Nov. 26 +0.8 H 1.0
6280 1919 Jan. 20 —0.2 F 0.7
6281 Jan. 20 +0.2 F 1.0

 

* One exposure.
90

S, A. MITCHELL

TABLE 2

RepuctTions FoR LALANDE 4268

 

 

 

 

. . i . id ] rae
sas. | Seta | vigia| eae ee | eae | ee
mm. % mm.

3068 —0.0193 0.7 +0.541 —428 —0.0005 —0°"01
3125 — .0195 0.6 + .429 —420 -0000 -00
3605 — .0157 0.9 — .929 —304 + .0012 + .02
3606 — .0147 0.9 — .929 —304 + .0002 -00
3616 — .0137 0.8 — .929 —303 — .0008 — .01
3617 — .0142 0.9 — .929 |. —3803 — .0002 .00
4333 — .0025 0.7 + .858 — 93 + .0009 + .02
4342 — .0037 1.0 + .851 — 92 + .0021 + .04
4343 + .0005 0.7 + .851 — 92 — .0021 — .04
4400 — .0002 1.0 + .703 — 76 — .0006 — .01
4401 — .0020 0.9 + .703 + 76 + .0012 + .02
4906 + .0051 0.9 — .795 + 31 — .0015 — .03
4907 + .0040 0.9 — .795 + 31 — .0004 — .01
5664 + .0209 1.0 + .822 +277 — .0027 — .06
5665 + .0179 1.0 + .822 +277 + .0003 + .01
5709 + .0174 0.8 + .560 +301 + .0018 + .03
6012 + .0217 0.8 — .441 +366 + .0001 .00
6013 + .0224 1.0 — .441 +366 — .0006 — .01
6280 + .0227 0.7 — .923 +421 + .0016 + .03
6281 +0.0241 1.0 —0.923 +421 +0.0002 0.00

 

 

 

 

 

 

The normal equations are:

17.2¢ + 2.453 — 0.93437
+ 1385.8010u + 0.20977
+ 10.55967

from which:
c = + 0.00261 mm.
uw = + 0.00536 mm.
7 = + 0.00089 mm.

= + 0.0572 mm.
+ 0.7341 mm.
+ 0.0081 mm.

+ 0.00084 mm. = + 07017.

+ 071114, or + 0407 per year.
= + 07019 + 0°005.
Probable error of plate of unit weight
PARALLAXES OF 260 STARS 91

o CETI (25 14"; —3° 25’).

Mira, the Wonderful, in the constellation of Cetus is thoroughly
well known. The first plates of the present series were taken in
September 1914, when the variable was near a minimum, and
when the magnitude was approximately 9.0. No rotating
sector was then used. The last plates of the series in December
and January, 1915-16, ‘were obtained when the star was near
maximum with the magnitude 3.0, and the rotating sector
necessarily was used. The diameters of the images of Mira on
the photographic plates were kept as nearly constant as possible.
The star is of Md type, and with a total proper motion of 0724.
The only trigonometric value of the parallax so far found is that
of Russell, whose parallax by means of photography is + 07136

TABLE 1
PuatTes oF o CETI

 

 

 

No. Date. Hour Angle. Observers. Weight.
233 1914 Sept. 13 —04 M, A 0.7
244 Sept. 14 —1.4 M,G 0.7
264 Sept. 19 —1.1 G, Ol 0.7
663 Dec. 14 +0.3 Ol 0.8
707 Dee. 23 +1.1 A 0.8
744 1915 Jan. 7 —0.6 Ol 0.7*
766 Jan. 9 +0.4 A 0.7
780 Jan. 13 —0.2 M 0.8
791 Jan. 14 —0.3 Ol 1.0
1575 * Aug. 23 —0.9 A 0.9
. 1576 Aug. 23 —0.4 A 1.0
1633 Sept. 9 —1.3 M 0.9
1634 Sept. 9 —0.8 M 0.9
1712 Sept. 17 —0.7 M 1.0
1713 Sept. 17 —0.2 M 1.0
2231 Dec. 26 —0.2 M 0.9
2249 1916 Jan. 2 —0.3 M 1.0
2343 Jan. 23 +0.3 M 1.0
2344 Jan. 23 +0.8 M 1.0

 

 

 

 

 

* One exposure.
92

S. A. MITCHELL

+ 0’035. <A result by Kostinsky gives the value of the absolute

parallax -+ 0702 + 0702.

The plates of the present series,
nineteen in number, were measured by Mr. Mitchell. The

Comparison STARS

 

 

 

 

 

 

 

 

 

 

t

‘No. Diameter. |* | Y (Declination). Dependence.

1 0.13 —58.3 +382.4 +0.208

2 13 + 5.3 —52.1 237

3 16 +10.0 + 1.3 .260

4 -10 +43.0 +18.4 +0.295

Parallax star 0.16 + 4.4 + 0.2
TABLE 2
REDUCTIONS FOR o CETI

Solution Weight Parallax Time in Residual Vp-o

Plate. (m). (p). | Factor (P). | Days (). (). in Are.
mm. mm.
233 —0.0092 0.7 +0.677 —211 +0.0011 | +0702
244 — .0069 0.7 + .666 —210 — .0012 — .02
264 — .0072 0.7 + .605 —205 — .0011 — .02
663 — .0140 0.8 — .670 —119 + .0019 | + .03
707 — .0099 0.8 — .763 —110 — .0024 | — .04
744 — .0148 0.7 — .875 — 95 + .0016 | + .03
766 — .0114 0.7 — .885 — 93 — .0013 — .02
780 — .0157 0.8 — .903 — 89 + .0029 + .05
791 — .0114 1.0 — .907 — 88 — .0014 | — .03
e

1575 — .0088 0.9 + .872 +133 + .0012 + .02
1576 — .0088 1.0 + .872 +133 + .0012 + .02
1633 — .0062 0.9 + .724 +150 — .0018 | — .03
1634 — .0075 0.9 + .724 +150 — .0015 — .01
1712 — .0070 1.0 + .633 +158 — .0013 — .03
1713 — .0098 1.0 + .633 +158 + .0015 | + .03
2231 — .0136 0.9 — .787 +258 + .0011 | + .02
2249 — .0112 1.0 — .842 +265 — .0015 — .03
2343 ‘— .0116 1.0 — .927 | +286 — .0013 | — .03
2344 —0.0143 1.0 —0.927 +286 +0.0014 +0.03

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS 93

proper motion in right ascension from the photographs is — 07001
per year, which agrees exactly with the value from Boss.

The normal equations are:

16.5¢ + 9.957 — 1.82257 = — 0.1726 mm.
+ 55.6675 — 2.141397 = — 0.1084 mm.
+ 10.44627 = + 0.0494 mm.
from which:
c = — 0.01012 mm.
w= — 0.00002 mm. = — 070005, or — 0%001 per year.

a = + 0.00295 mm. = + 07061 + 0'007.
Probable error of plate of unit weight
+ 0.00106 mm. = + 07022.

PIAZZI 2" 123 (2 30™; +6° 24’)

This is a G5 type star of 5.92 magnitude, and with a very large
proper motion which amounts to 234 per year. Van Maanen
finds that a star of 11.5 magnitude 13 seconds following has
almost the same proper motion. For the companion, the proper
motion amounts to 2763. Though widely separated, the two
stars must form a physical system. Mr. Olivier measured the
McCormick series of plates, and found a parallax of + 07137
+ 07005, and a proper motion in right ascension of + 17791
per year, while the value due to Boss is + 17802.

The parallax has been determined as follows:

 

 

 

Parallax. | Authority. Method.
|
+0711 +07043 Flint Meridian Circle
+ .188+4 .031 i Elkin-Smith Heliometer
— .092+ .101 Jewdokimov Meridian Circle
+ .1454 .008 | Allegheny Photography
+ .144 Mt. Wilson Spectrograph

 
 

 

 

94 S. A. MITCHELL
TABLE 1
Puates oF Prazzr 2% 123

No. Date. Hour Angle. Observers. Weight.
1698 |. 1915 Sept. 15 —143 M 0.7
1737 Sept. 22 +0.2 Ol 1.0
2116 Dec. 6 +0.1 G 0.6
2117 Dec. 6 +0.6 G 0.9
2324 1916 Jan. 17 +0.4 G 0.5
2325 Jan. 17 +0.8 G 0.5*
2871 Aug. 13 —0.8 Ol 0.6
2885 Aug. 17 —0.8 Ol 0.8
2886 Aug. 17 —0.2 Ol 0.8
2986 Sept. 9 —0.5 M 0.8
2987 Sept. 9 0.0 M 1.0
3551 1917 Jan. 2 -—0.1 L 0.9
3552 Jan. 2 +0.3 M 1.0
3595 Jan. 19 —0.3 Ol 1.0
3596 Jan. 19 +0.1 Ol, M 0.9
4299 \ Aug. 19 —0.8 Ol 0.8
4300 / Aug. 19 —0.3 Ol 1.0
4320 Aug. 21 —0.6 Ol 0.8
4321 Aug. 21 —0.2 Ol 1.1f
4867 Dec. 14 —0.4 Ol 0.7*
5093 1918 Feb. 17 +1.9 M 0.9
5110 Feb. 18 +1.9 A 0.6

 

 

 

 

 

* One exposure.

t Three exposures.

CoMPARISON STARS

 

 

X (Right Ascen-

 

No. Diameter. | sion). Y (Declination). Dependence.

1 0.17 —655.7 + 2.1 +0.1978

2 13 -—11.9 +39.2 .0373

3 .14 -— 1.9 —54.1 . 53800

4 .16 +69.5 +12.8 +0.2349
Parallax star 0.13 + 3.9 —23.8

 

 

 

 
PARALLAXES OF 260 STARS

 

 

 

 

 

 

 

 

 

 

TABLE 2
RepuctTions FOR Piazzi 25 123
Solution Weight Parallax Time in Residual Vp-o
Plate. ‘m). (Pp Factor (P). | Days (1). (0). in Are.
mm. mm.
1698 —0.0311 0.7 +0.709 —441 —0.0015 —0"03
-1737 — .0297 1.0 + .626 —424 + .0006 + .01
2116 — .0171 0.6 — .517 —349 — .0019 — .03
2117 — .0206 0.9 — .517 —349 + .0016 + .03
2324 — .0129 |. 0.5 — .907 —307 + .0012 + .02
2325 — .0104 0.5 — .907 —307 — .0012 — .02
2871 + .0499 0.6 + .944 — 98 — .0001 -00
2885 + .0528 0.8 + .929 — 94 — .0021 — .04
2886 + .0488 0.8 + .929 — 94 + .0019 -04
2986 + .0550 0.8 + .764 — 71 -0000 .00
2987 + .0546 1.0 + .764 — 71 + .0004 + .01
3551 + .0736 0.9 — .823 + 44 — .0019 — .04
3552 + .0206 1.0 — .823 + 44 + .0011 + .02
3595 + .0739 1.0 — .917 + 61 + .0012 + .02
3596 + .0755 0.9 — .917 + 61 — .0004 — .01
4299 + .1386 0.8 + .921 +273 — .0014 — .08
4300 + .1379 1.0 + .921 +273 — .0007 — .01
4320 + .1362 0.8 + .911 +275 + .0014 + .03
4321 + .1366 1.1 + .911 +275 + .0010 + .02
4867 + .1563 0.7 — .623 +390 — .0017 — .03
5093 + .1667 0.9 — .901 +453 + .0009 + .02
5110 +0.1691 0.6 —0.886 +456 —0.0006 | —0.01
The normal equations are:
17.9¢ + 2.6754 + 1.17197 = + 1.2655 mm.
+ 132.6345u — 2.54392 = + 3.2902 mm.
+ 12.39517 = + 0.0999 mm.
from which:
c = + 0.06674 mm.
pw = + 0.02359 mm. = + 074906, or + 17791 per year.
xr = + 0.00659 mm. = + 07137 + 07005

Probable error of plate of unit weight
+ 0.00082 mm. = + 07017.
96 S. A. MITCHELL

y CETI (25 38"; 4+2° 49’)

This is a double star = 299, but according to Burnham, ‘‘the
angles are very discordant for so easy a pair.’ The principal
star is of 3.6 magnitude, and of type A, while the companion
is of magnitude 6.8, and is at a distance of 3’, at position
angle 290°. The orbital motion is very slow. The parallax
published by the Yale heliometer is + 07119 + 07017. The
Allegheny value by photography is + 07014 + 07008. The
present series of plates were measured by Mr. Mitchell, who
finds a parallax of + 07037 +: 07008. Boss gives the proper
motion in right ascension to be — 0147. The least square
solution from the photographs gives — 07059. In order to
check up this photographic value, two extra plates were taken
in February, 1918. Their solution compared with plates 729
to 847 inclusive, taken three years previously, give a proper
motion of — 0”%060, in close agreement with the least square
solution. The reason for the disagreement with Boss is difficult
to explain. On account of the slow orbital motion, it cannot be
due to this cause. Four comparison stars were used for the
photographic solution, and it possible that there might be a
proper motion of one or more of these stars. The plates were
compared with this idea in view, and no trace was found of any
appreciable proper motion of any of the comparison stars.

CoMPaARISON STARS

 

 

 

 

 

No. Diameter. % sr eas Y (Declination). Dependence.

1 0.11 —32.7 +24.0 +0.246

2 .16 — 1.8 —58.2 247

3 14 +11.3 + 4.5 252

4 -13 +23 .2 +29.7 +0.255
Parallax star 0.15 + 0.3 + 0.3 =

 

 

 
PARALLAXES OF 260 STARS

97

 

 

 

TABLE 1
PLatEes oF y CETI
No. Date. Hour Angle. Observers. Weight.
221 1914 Sept. 9 —046 M 0.5
222 Sept. 9 —0.1 M 0.7*
579 Nov. 13 —0.6 G 0.7
646 Nov. 25 —0.2 A 1.0
710 Dec. 26 —0.8 G 0.5
729 Dec. 30 —0.2 Ol 0.7
825 1915 Jan. 28 +0.8 A 1.0
837 Feb. 4 +0.8 Ol 0.7
847 Feb. 7 +0.7 M 0.7
1585 Aug. 25 —1.2 A 0.7
1586 Aug. 25 —0.8 A 0.7*
1635 Sept. 9 —0.6 M 0.7
1636 Sept. 9 —0.2 M 0.5*
1699 Sept. 15 —0.6 M 0.7
2136 Dec. 9 —0.3 M 0.7
2137 Dec. 9 +0.2 M 0.7
2233 Dec. 26 +0.3 M 0.9
2345 1916 Jan. 23 +0.8 M 0.9

 

 

 

 

 

* One exposure:
98 S. A. MITCHELL

TABLE 2

REDUCTIONS FOR y CETI

 

 

 

 

 

 

 

 

 

 

Solution | Weight | Parallax | Timein | Residual | vp-2
Plate. (m). (p). | Factor (P). | Days (1). (0). in Are.
mm. . mm.
221 +0.0158 0.5 +0.790 —265 —0.0028 —0"04
222 + .0154 0.7 + .790 —265 — .0024 — .04
579 + .0091 0.7 — .142 —200 + .0017, | + .03
646 + .0106 1.0 — .334 —188 — .0002 .00
710 + .0110 0.5 — .740 —157 — .0016 — .02
729 + .0080 0.7 — .779 —153 + .0013 + .02
825 + .0082 1.0 — .935 ~—124 + .0006 + .01
837 + .0099 0.7 — .938 —117 — .0011 — .02
847 + .0056 0.7 — .934 —114 + .0032 + .05
1585 + .0097 0.7 + .905 + 85 + .0008 + .01
1586 + .0116 0.7 + .905 + 85 — .0011 — .02
1635 + .0090 0.7 + .792 +100 + .0012 | + .02
1636 + .0082 0.5 + .792 +100 + .0020 ,; + .03
1699 + .0080 0.7 + .732 +106 + .0020 + .03
2136 + .0066 0.7 — .534 +191 + .0005 + .01
2137 + .0096 0.7 — .534 +191 — .0025 — .04
» 2233 + .0072 0.9 — .738 +208 — .0006 — .01
2345 +0.0074 0.9 —0.924 +236 —0.0013 —0.02
The normal equations are:
13.0c — 1.371y — 2.15977 = + 0.1212 mm.
+ 38.0498u + 0.20117 = — 0.0423 mm.
ann wee + 7.60627 = — 0.0071 mm.
~¢ = + 0.00954 mm.
w= — 0.00078 mm. = — 070161, or — 07059 per year.

a = + 0.00179 mm. = + 0°037 + 0008.
Probable error of plate of unit weight
+ 0.00102 mm. = + 07021.

a CETI (25 57™; +3° 41’)

The only values of the parallax of this star so far published are
the spectroscopic one of Adams who gives the result + 0”023,
and the Allegheny value by photography of 07000 + 07005.

PARALLAXES OF 260 STARS

The star is of Ma type, of magnitude 2.82, and of small proper
motion 0708 per year.

measured by Mr. Alden.

The sixteen plates of the series were
Boss finds the proper motion in right

ascension to be — 07018 per year.

TABLE 1

-PLATES OF @ CETI

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
234 1914 Sept. 13 —Of M,A 0.5*
257 Sept. 15 —1.5 Ol, A 0.9
265 Sept. 19 —1.3 G, Ol 1.0
319 Sept. 26 —1.4 M 0.7*
664 Dec. 14 +0.6 Ol 0.8
674 Dec. 15 +0.2 A 0.9
711 Dec. 26 —0.5 G 0.5*
767 1915 Jan. 9 +0.4 A 1.0
849 Feb. 8 +0.6 Ol 0.7*
859 Feb. 9 +0.6 M 1.0
874 Feb. 10 +0.7 M 0.8

1577 Aug. 23 —0.4 A 0.9

1587 Aug. 25 —0.6 A 0.8

1588 Aug. 25 —0.1 A 1.0

1680 Sept. 13 +0.5 A 1.0

1681 Sept. 13 +1.0 A 0.9

* One exposure.
CoMPARISON STARS ~
No. Diameter. x Pe ee Y (Declination). Dependence.
1 0.12 » —40.4 —11.0 +0.1149
2 15 -17.7 + 1.2 .1724
3 .16 + 9.5 +50.9 - 2983
4 .20 * 410.5 —18.8 .1870
5 .23 +38.1 —22.3 +0.2274
Parallax star 0.28 + 5.8 + 5.5

 

 

 

 

 
100 S. A. MITCHELL

TABLE 2
REDUCTIONS FOR a CETI

 

 

 

 

 

 

 

 

 

. : . : id al ee
Pinte, | Sefation | Weight | pParales, | Base. | Mei | an kee.
mm. mm.
234 0.0000 0.5 +0.802 —165 +0.0019 +0703
257 + .0016 0.9 + .784 —163 + .0003 + .01
265 + .0034 1.0 + .743 —159 — .0015 — .03
319 + .0028 0.7 + .664 —152 — .0010 — .02
664 + .0006 0.8 — .546 — 73 + .0004 + .01
674 — .0013 0.9 — .559 — 72 + .0024 + .04
711 + .0008 | 0.5 | — .695 | — 61 | + .0002 | + .03
767 — .0020 1.0 — .831 — 47 + .0029 + .06
849 + .0027 0.7 — .945 — 17 — .0018 — .03
859 + .0039 1.0 — .945 — 16 — .0030 — .06
874 + .0015 0.8 — .944 — 15 — .0006 — .01
1577 + .0068 0.9 + .944 +179 — .0040 — .06
1587 + .0028 0.8 + .936 +181 .0000 -00
1588 + .0018 1.0 + .936 +181 + .0010 + .02
1680 + .0011 1.0 + .804 +200 + .0017 + .03
1681 +0.0016 0.9 +0.804 +200 +0.0012 +0.02

 

The normal equations are:
13.4c + 1.3174 + 1.89637 = + 0.0242 mm.
+ 25.6422u + 5.58647 = + 0.0127 mm.
+ 9.02557 = + 0.0117 mm.
from which:
c = + 0.00167 mm.
w= +.0.00023 mm. = + 070048, or + 07018 per year.
a = + 0.00080 mm. = + 07017 + 07010.
Probable error of plate of unit weight

+ 0.00132 mm. = + 07027.

y PERSEI (25 57™; +53° 6’)

This star is a long period spectroscopic binary of Gp type, of
magnitude 3.08, and of very small proper motion 0”01 per year.
Mt. Wilson finds the spectroscopic parallax + 0”025 while Alle-
PARALLAXES OF 260 STARS

101

gheny by photography derives the relative value + 07010 + 07006.
The series of plates were measured by Mr. Alden.
motion in right ascension determined by Boss is + 0004 per year.

The proper

 

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
PLates oF y PERSEI

No. Date. Hour Angle. Observers. Weight.
341 1914 Sept. 28 —048 G 1.0
392 Oct. 11 —0.6 A 0.6*
759 1915 Jan. 8 —0.5 G 0.7*
776 Jan. 10 —0.3 M 1.0
781 Jan. 13 —0.2 A 0.8
1679 Sept. 13 —0.1 A 0.9
1687 Sept. 14 —0.4 A 0.7
2250 1916 Jan. 2 —0.6 M 0.8
2251 Jan. 2 —0.3 M 0.7
2285 Jan. 4 —0.7 A 1.0
2286 Jan. 4 —0.2 A, Ol 1.0
2360 Feb. 3 +0.1 M 0.6*
2971 Sept. 15 —0.8 M 0.8
3037 Sept. 19 —0.4 A 0.8
3126 Oct. 1 —0.9 L 0.7
3127 Oct. 1 —0.5 L 0.8
3564 1917 Jan. 6 —0.4 A 1.0
3565 Jan. 6 0.0 A 1.0
3591 Jan. 17 -—0.9 Ol 0.6*
3602 Jan. 20 —0.5 M 0.9

* One exposure. .
Comparison Stars
No. Diameter. os ae Y (Declination). Dependence.
mm. mm. mm.

1 0.18 —78.5 +52.9 +0.3446

2 17 —43.9 —21.2 -0316

3 .12 +29.6 — 3.0 . 2288

4 .12 +44.9 —18.8 .1732

5 14 +47.9 -— 9.9 +0.2218

Parallax star 0.18 — 3.2 +11.4

 

 

 

 
102

S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR Y PERSEI
Solution Weight Parallax Time in Residual Vp v
Plate. (m). (p). Factor (P). | Days (é). (2). in Are.
mm. mm.
341 +0.0099 1.0 +0.642 —484 +0.0013 +003
392 + .0043 0.6 + .466 —467 + .0068 + .11
759 - + .0110 0.7 | — .821 —378 — .0005 — .01
776 + .0110 1.0 — .837 —376 — .0005 — .01
781 + .0112 0.8 — .859 —373 — .0007 — .01
1679 + .0122 0.9 + .807 —130 — .0028 — .06
1687 + .0155 0.7 + .798 —129 — .0061 — .ill
2250 + .0105 0.8 — .764 — 19 — .0018 — .03
2251 + .0091 0.7 — .764 — 19 — .0004 — .01
2285 + .0084 1.0 — .783 — 17 + .0003 + .01
2286 + .0108 1.0 — .783 — 17 — .0021 — .04
2360 + .0046 0.6 — .944 + 13 + .0039 + .06
2971 + .0038 0.8 + .867 4228 + .0038 + .07
3037 + .0070 0.8 + .740 +242 + .0005 + .01
3126 + .0085 0.7 + .597 +254 — .0011 | — .02
3127 + .0078 0.8 + .597 +254 — .0004 — .01
3564 + .0042 1.0 — .808 +351 + .0026 -05
3565 + .0070 1.0 — .808 +351 — .0002 -00
3591 + .0107 0.6 — .888 +362 — .0039 — .06
3602 +0.0052 0.9 —0.904 +365 +0.0016 +0.03
The normal equations are:
16.4¢ + 0.3954 — 3.95217 = + 0.1418 mm.
+ 137.6030u — 3.06667 = — 0.0668 mm.
+ 10.06187 = — 0.0320 mm.
from which:
-- ¢ = + 0.00868 mm.
& = — 0.00051 mm. = — 070106, or — 0039 per year.

a = + 0.00007 mm. =

Probable error of plate of unit weight
+ 0.00172 mm. = + 07036.

+ 07002 + 07012.
PARALLAXES OF 260 STARS 103

p PERSEI (25 58"; +38° 27’)

Russell, by photography finds the parallax of this variable to
be + 07083 + 07040. Adams by the spectroscopic method,
gives the parallax between + 0”011 and + 0%017, depending
on the apparent magnitude assumed for the variable, which
has a range from 3.4 to 4.2 magnitude. The star is of Mb type,
and of total proper motion 0"17 per year. The twenty plates of
the series were measured by Mr. Lamb. The proper motion in
right ascension from the present photographs is + 07105 per
year, while the value of Boss is + 07135.

 

 

 

TABLE 1
PLATES OF p PERSEI
No. Date. Hour Angle. Observers. Weight.
792 | 1915 Jan. 14 —0n2 A 1.0
822 Jan. 25 —0.6 ol 0.6*
823 Jan. 25 —0.3 Ol, M 1.0
824 Jan. 28 |  —0.5 Ol 1.0
834 Jan. 29 —0.4 Ol 0.8
1646 Sept. 10 -1.5 Ol 0.7
1647 Sept. 10 —0.8 Ol 0.5
1667 Sept. 12 —1.2 Ol 0.8
1668 Sept. 12 —0.7 Ol 0.9
1726 Sept. 21 —0.8 G 0.7
2245 Dec. 31 —0.5 Ol 1.0
2266 1916 Jan. 3 —0.9 G* 1.0
2318 Jan, 14 —0.2 G 0.8
2968 Sept. 4 —0.2 L 1.0
3027 Sept. 18 —0.2 L 0.9
3047 |. Sept. 20 —0.5 L 0.9
3048 Sept. 20 —0.9 L 0.6*
3083 Sept. 24 —0.6 L 0.7*
3084 | Sept. 24 —-0.2 L 0.8
3098 Sept. 28 —0.4 L 1.0

 

 

 

 

 

* One exposure.
104 S. A. MITCHELL

Comparison Stars

 

 

 

 

 

 

 

 

No. Diameter. - car aaa Y (Declination). Dependence.
mm. mm. mm. -
1 0.08 —53.9 — 9.4 +0.1604
2 I —31.0 —23.6 1710
3 -10 —22.9 +17.9 1544
4 10 +10.8 —18.3 - 1769
5 -08 +47.8 — 7.0 -1790
6 18 +49.2 +40.4 -+0.1583
Parallax star 0.18 + 0.77 — 0.88
TABLE 2

REDUCTIONS FOR p PERSEI

 

 

 

 

 

 

 

 

 

Solution Weight | Parallax Time in Residual vp-o
Plate. (m). (p). | Factor (P). | Days (#). (). in Are.

mm. Tam.
792 +0.0051 1.0 —0.864 —288 —0.0012 | —0%02
822 + .0035 0.6 — .922 —277 + .0003 | + .01
823 + .0022 1.0 — .922 —277 + .0018 + .04
824 + .0071 1.0 — .932 —274 — .0031 — .06
834 + .0028 0.8 — .985 —273 + .0010 | + .02
1646 + .0124 0.7 + .837 — 49 — .0020 | — .05
1647 + .0129 0.5 + .837 — 49 — .0016 — .05
1667 + .0060 0.8 + .819 — 47 + .0029 + .06
1668 + .0083 0.9 + .819 — 47 + .0012 + .02
1726 + .0073 0.7 + .730 — 38 + .0016 | + .04
2245 + .0056 1.0 — .741 + 63 + .0033 | + .07
2266 + .0116 1.0 — .762 + 65 — .0027 — .05
2318 + .0084 0.8 — .863 + 77 + .0004 | + .01
2968 + .0156 1.0 + .877 +311 — .0010 — .02
3027 + .0150 0.9 + .754 +325 — .00038 — .01
3047 + .0145 0.9 + .733 +327 + .0001 -00
3048 + .0186 0.6 + .733 +327 — .0023 | — .06
3083 + .0155 0.7 + .688 +331 — .0006 | — .O1
3084 + .0134 0.8 + .688 +3831 + .0010 + .02
3098 +0.0136 1.0 +0.664 +333 +0.0010 +0.02

 
PARALLAXES OF 260 STARS 105

The normal equations are:

16.7¢c + 7.242u + 1.04627 = + 0.1636 mm.
+ 98.8402 + 22.49127 = + 0.2342 mm.
+ 10.99187 = + 0.0560 mm.

from which:

c = + 0.00911 mm.
w= +.:0.001388 mm. = + 070288, or + 07105 per year.
ax = + 0.00140 mm. = + 07029 + 07012.

Probable error of plate of unit weight

+ 0.00140 mm. = + 07030.

a PERSEI (3" 17"; +49° 30’)

The measured values of the parallax of this star of magnitude
1.90, of spectral type F5, and of small proper motion and radial
velocity are discordant. The méasures are:

 

 

 

 

 

Authority. Method. Parallax.
Pritchard Photography +0"087+0"021'
Flint Meridian circle + .109+ .025
Slocum and Mitchell Photography — .008+ .011
Mt. Wilson Spectrograph + .023

 

The McCormick plates were measured by Mr. Alden except

the four last measured by Mr. Mitchell.

CoMPARISON STARS

The relative parallax

 

 

 

 

 

 

No. Diameter. x a all Y (Declination). | Dependence.
mm. mm. mm.

1 0.12 —36.2 —25.9 +0.1722

2 -10 —32.5 +26.1 0.1680

3 .14 —14.4 + 3.1 0.1679

4 17 +20.6 —11.4 0.1654

5 15 +23.8 —18.2 0.1656

6 .12 +38.7 +26.3 +0.1610
Parallax star 0.15 — 0.5 — 0.2

 
106 S. A. MITCHELL

+ 07013 + 07010 resulted, with a proper motion in right
ascension + 0"032, while the corresponding value from Boss is
+ 0027.

 

 

 

 

 

 

 

 

TABLE 1
PLavTes OF a PERSEI
No. Date. Hour Angle. Observers. Weight.
8195 1916 Oct. 14 —045 M 1.0
3196 Oct. 14 —0.1 M 1.0
3206 Oct. 17 —0.4 L 1.0
3207 Oct. 17 —0.1 L 1.0
3578 1917 Jan. 14 —0.4 M 0.8
3602 Jan. 20 —0.3 A 1.0
3603 Jan. 20 0.0 A 0.8
3624 Jan. 28 —0.9 M 0.9
3625 Jan. 28 —0.6 M 0.9
3635 Jan. 30 —0.8 M 0.8
3636 Jan. 30 —0.5 M 0.8
4352 Aug. 26 —1.1 A 1.0
4353 . Aug. 26 —0.8 A 1.0
4368 Aug. 28 —0.7 B 0.9
4369 Aug. 28 —0.4 B 0.8
4426 Sept. 12 —0.7 A 1.0
4427 Sept. 12 —0.3 A 1.0
4923 1918 Jan. 10 —0.2 A 1.0
4924 Jan. 10 —0.1 A 0.6*
4955 Jan. 20 —0.7 M 0.7
4956 Jan. 20 —0.3 M 1.0
5656 Aug. 23 —1.0 A 1.0
5657 Aug. 23 —0.6 A 1.0
5666 Aug. 29 —0.3 A 1.0
5667 Aug. 29 0.0 A 0.7*
* One exposure. ‘

The normal equations are:

22.7¢ — 0.4874 + 2.44030 + 0.0248 mm.
+ 120.9072u + 15.65847 = + 0.0599 mm.
+ 16.3595r = + 0.0196 mm.
PARALLAXES OF 260 STARS 10

 

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR a PERSEI
Solution Weight Parallax Time in Residual Vp-0
Plate. (m). (p). | Factor (P). | (Days t). (0). in Arc.
mm. mm.
3195 +0.0006 1.0 +0.489 —288 —0.0004 —0"01
3196 — .0038 1.0 + .489 —288 + .0040 + .08
3206 + .0030 1.0 + .444 —285 — .0029 — .06
3207 — .0014 1.0 + .444 —285 + .0015 + .03
3578 — .0045 0.8 — .841 —196 + .0042 + .08
3602 — .0022 1.0 — .884 —190 + .0019 + .04
3603 + .0026 0.8 — .884 —190 — .0029 — .05
3624 + .0040 0.9 — .925 —182 — .0043 — .09
3625 — .0022 0.9 — .925 —182 + .0019 + .04
3635 — .0013 0.8 — 933 —180 + .0010 + .02
3636 + .0010 0.8 — .933 —180 — .0013 — .02
4352 + .0014 1.0 + .956 + 28 + .0004 + .01
4353 + .0008 1.0 + .956 + 28 + .0010 + .02
4368 — .0008 0.9 + .949 + 30 + .0026 + .05
4369 + .0044 0.8 + .949 + 30 — .0026 — .05
4426 + .0043 1.0 + .859 + 45 — .0025 — .05
4427 + .0054 1.0 + .859 + 45 — .0036 — .07
4923 + .0018 1.0 — .805 +165 — .0006 — .01
4924 |.+ .0053 0.6 — .805 +165 — .0041 — .07
4955 — .0044 0.7 — .882 +175 + .0056 + .10
4956 + .0026 1.0 — .882 +175 — .0014 — .03
5656 + .0014 1.0 + .966 +390 + .0019 + .04
5657 + .0038 1.0 + .966°} +390 — .0005 — .01
5666 + .0008 1.0 + .946 +396 + .0025 + .05
5667 +0.0050 0.7 +0.946 +396 —0.0017 —0.03
from which:

c = + 0.00103 mm.

uw = + 0.00042 mm. = + 070087, or + 07032 per year.

xe = + 0.00065 mm. = + 07013 + 07010.

Probable error of plate of unit weight
+ 0.00177 mm. = + 07037.
108 S. A. MITCHELL

LALANDE 6320 (3> 20"; —5° 42")

This star of fairly large proper motion 0°82 pér year, is of
magnitude 7.9, and of K5 type. Two trigonometric determina-
tions of its parallax have been made: the Yale heliometer in
the hands of Chase giving the result + 07061 + 07016, and the

TABLE 1

Puates oF LALANDE 6320

 

 

No. Date. Hour Angle. Observers. Weight.

 

 

 

 

 

1748 1915 Sept. 23 —048 M 1.0
1786 Oct. 8 —0.4 G 0.5*
2189 Dec. 21 —0.2 G 0.8
2190 Dec. 21 +0.2 G 0.5*
2304 1916 Jan. 13 0.0 A 0.9
2305 Jan. 13 +0.5 A 0.9
2959 Sept. 3 —0.6 A 0.9
2960 Sept. 3 —0.2 A 1.0
2961 Sept. 3 +0.2 A 1.0
3018 Sept. 17 —0.4 A 0.9
3019 Sept. 17 0.0 A 0.9
3566 1917 Jan. 6 +0.1 A 1.0
3567 Jan. 6 +0.3 A 1.0
3607 Jan. 25 +0.1 L * 1.0
3608 Jan. 25 +0.5 L 1.0

 

* One exposure.

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. x ne as Y (Declination). Dependence.
mm. mm. mm. |
1 0.10 —47.1 — 3.6 +0.2511
2 -11 + 4.2 +55.7 .1714
3 -11 + 5.3 —20.9 . 20385
4 .09 +14.7 — 6.5 . 1873
5 .09 +22.9 —24.7 +0.1867
Parallax star 0.17 — 3.0 — 1.4

 
PARALLAXES OF 260 STARS

109

meridian circle by Jewdokimov giving the parallax + 07074
+ 07099. Adams finds the spectroscopic value of + 07058.
Mr. Alden measured the fifteen plates of the series, and found
the proper motion in right ascension to be — 0"266 per year, a
value which agrees with that determined by Porter.

TABLE 2

RepuctTions FOR LALANDE 6320

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p). | Factor (P). | Days (t). (0). in Arc.
mm. ‘ mm.
1748 —0.0044 1.0 +0.770 —273 —0.0025 —0°05
1786 — .0020 0.5 + .592 —258 + .0009 + .01
2189 — .0073 0.8 — .566 —184 + .0016 + .03
2190 — .0085 0.5 — .566 —184 + .0004 + .01
2304 — .0096 0.9 — .823 —161 + .0008 + .02
2305 — .0107 0.9 — .823 —161 — .0002 -00
2959 — .0102 0.9 + .923 + 73 + .00384 + .06
2960 — .0151 1.0 + .923 + 73 — .0015 — .03
2961 — .0136 1.0 + .923 + 73 -0000 .00
3018 — .0114 0.9 + .820 + 87 .0030 + .06
3019 — .0171 0.9 + .820 + 87 — .0027 — .05
3566 — .0260 1.0 — .765 +198 — .00381 — .06
3567 — .0226 1.0 — .765 +198 + .0003 + .01
3607 — .0224 1.0 — .910 +217 + .0016 + .03
3608 —0.0247 1.0 —0.910 +217 —0.0007 —0.01
The normal equations are:
13.3c + 2.673u — 0.34857 = — 0.1930 mm.
+ 40.0146u — 2.86757 = — 0.1858 mm.
+ 8.91147 = + 0.0408 mm.
from which:
c = — 0.01373 mm.
w = — 0.00352 mm. = — 070730, or — 07266 per year.
a+ = + 0.00291 mm. = + 07060 + 0’010.

Probable error of plate of unit weight

+ 0.00137 mm. = + 07028.
110 S, A. MITCHELL

e ERIDANI (3 28"; —9° 47’)

This star is of exceptional interest on account of its com-
paratively large parallax which is about equal to that of 61 Cygni.
Two trigonometric parallaxes have already been found: that of
Flint with meridian circle giving a value of + 07379 + 07025,
and that with the Yale heliometer by Smith with the value
+ 0307 + 07014. Adams further gives the parallax by the
spectroscopic method of + 07331. The star has a total proper
motion of 0“97 per year, it is of type K, and of magnitude 3.81.
It is interesting to note that both « and 6 Eridani (see below),

 

 

 

TABLE 1
Puates oF ¢ ERIDANI
No. Date. Hour Angle. Observers. Weight.
223 1914 Sept. 9 —01 M 0.5*
247 Sept. 14 —0.6 M,G 0.7
393 Oct. 11 0.0 0.7
410 Oct. 19 —0.3 G 0.9
439 Oct. 30 +0.4 A 1.0
675 Dec. 15 +0.7 M 0.7
730 Dec. 30 0.0 Ol 0.8
848 1915 Feb. 7 +0.4 M 0.7*
884 Feb. 11 +0.5 Ol 0.7
891 Feb. 18 +0.9 M 1.0
1637 Sept. 9 —0.4 M 0.8
1638 Sept. 9 +0.1 M 0.8
1701 Sept. 15 0.0 M 1.0
1702 Sept. 15 +0.4 M 0.7*
1714 Sept. 17 —0.8 M 1.0
1715 Sept. 17 —0.5 M 1.0
3597 1917 Jan. 19 —0.3 M 0.9
3598 Jan. 19 0.0 ol 0.8
3628 Jan. 28 +0.5 M 0.8
3629 Jan. 28 +0.8 M 0.8

 

 

 

 

 

* One exposure.
PARALLAXES OF 260 STARS 111

are of type K, of large proper motion, and of large parallax,
though the parallax of « Eridani is much greater than that of
6 Eridani. The twenty plates of the series were measured by
Mr. Mitchell, who finds the proper motion in right ascension to
be — 0986 per year, while Boss gives the value — 07971.

TABLE 2

REDUcTIONS FoR € ERIDANI

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual vVp+o
Plate, (m). (p). Factor (P). | Days (t). (v). in Are.

mm. mm.
223 —0.0380 0.5 +0.904 —325 —0.0018 —0°03
247 — .0345 0.7 + .869 —320 + .0028 + .05
393 — .0460 0.7 + .576 —293 — .0009 — .01
410 — .0466 0.9 + .463 —285 + .0012 + .02
439 — .0504 1.0 + .292 —274 + .0013 + .03
675 — .0669 0.7 — .458 —228 + .0016 + .03
730 — .0767 0.8 — .661 —213 — .0033 — .06
848 — .0841 0.7 °| — .951 —174 — .0014 — .02
884 — .0834 0.7 — .957 —170 — .0001 -00
891 — .0834 1.0 — .956 —163 + .0008 + .02
1637 — .0850 0.8 + .906 + 40 — .0014 — .02
1638 — .0856 0.8 + .906 + 40 — .0020 — .03
1701 — .0860 1.0 + .863 + 46 — .0010 — .02
1702 — .0864 0.7 + .863 + 46 — .0014 — .02
1714 — .0850 1.0 + .847 + 48 + .0005 + .01
1715 — .0836 1.0 + .847 + 48 + .0019 + .04
3597 — .1742 0.9 — .863 +538 — .0002 -00
8598 — .1716 0.8 — .863 +538 + .0024 + .04
3628 — .1776 0.8 — .918 +547 — .0016 — .03
3629 —0.1752 0.8 —0.918 +547 +0.0008 +0.01

 

The normal equations are:

16.3¢ + 1.721u + 0.70607 = — 1.5044 mm.
+ 145.4996u — 14.73147 = — 2.2627 mm.
+ 10.76097 = + 0.2828 mm.
112 S. A. MITCHELL
from which:
c = — 0.09155 mm.
p = — 0.01300 mm. = — 072704, or — 07986 per year.

a = + 0.01448 mm. = + 07302 + 07007.
Probable error of plate of unit weight
+ 0.00105 mm. = + 07022.

Comparison STaRs

 

 

 

 

No. Diameter. ee (Right oe Y (Declination). Dependence.
mm. mm. mm.
1 0.14 —44.6 +53 .2 +0.184
2 .14 —45.4 +14.4 .174
3 14 + 9.5 —39.1 -156
4 .12 +22.9 —20.0 -160
5 .16 +23.1 | 421.0 -170
6 14 +384.5 . —29.5 +0.156
Parallax star +0.16 — 1.7 + 1.9

 

 

10 TAURI (35 31™; +0° 5’)

This star of magnitude 4.40, of type G5, and of total proper
motion 07536. Its parallax has been three times published;
the Yale heliometer by Chase gave + 07057 + 07039, the mer-
idian circle by Jewdokimov gave + 07095 + 07104, and the
spectrographic value of Adams is + 07100. Mr. Mitchell
measured the McCormick plates, and found a relative of + 07043
+ 07006, with a proper motion in right ascension — 0”260
while the corresponding value from Boss is — 0"234. The same

series of plates was used for the star D 422.

Comparison Stars

 

 

 

 

No. Diameter. 26 ae aa Y (Declination). Dependence.
mm. mm. mm.

1 0.10 —54.0 +34.6 +0.189

2 -10 —16.6 —17.5 - 232

3 -10 + 0.4 —14.6 .218

4 15 +30.3 —19.8 .207

5 -12 +39.9 +17.3 +0.154
Parallax star 0.18 — 1.6 — 2.1

 

 

 

 
PARALLAXES OF 260 STARS

118

 

 

 

 

 

 

 

TABLE 1
Puates or 10 Tauri
No. Date. Hour Angle. Observers. Weight.
1749 1915 Sept. 23 —04 M 0.7
1770 Oct. 2 —0.3 M 0.7
1771 Oct. 2 +0.1 M. 0.7
2252 1916 Jan. 2 —0.3 M 0.4*
2319 Jan. 14 +0.2 Ol 0.6
2320 Jan. 14 +0.7 Ol 0.6
2359 Feb. 3 —0.1 M,A 0.6
2988 Sept. 9 —0.5 M 0.7
3146 Oct. 7 —1.2 M 0.8
3642 1917 Feb. 6 —0.3 M 0.8
3643 Feb. 6 +0.2 M, L 0.8
8665 Feb. 14 +0.6 M 0.7
3668 Feb. 16 +0.7 Ol 0.6
4384 Sept. 1 —1.2 B 0.7
4477 Sept. 26 +0.8 B 0.6
4524 Oct. 6 —0.9 M 1.0
4525 Oct. 6 —0.6 M 0.7
5113 1918 Feb. 21 +1.3 A 0.9
5157 Mar. 3 +2.1 M 0.7
5701 Sept. 21 —0.1 M 0.7
5702 Sept. 21 +0.3 M 1.0
5713 Sept. 22 +0.2 M 1.0
5714 Sept. 22 +0.6 M 1.0
6103 Dec. 18 —0.3 M 1.0
6104 Dec. 18 +0.1 M 0.9
6230 1919 Jan. 12 —0.4 M 0.9
6231 Jan. 12 +0.1 M 1.0

 

* One exposure.

The normal equations are:

20.8¢ + 15.156n — 0.58817
+ 371.2914 — 1.49597

+ 13.3964r

— 0.8857 mm.
— 1.8805 mm.
+ 0.0564 mm.
114

S, A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 2
Repvuctions ror 10 Tauri
Pinte, | Sefagon | MGR | aciorte. | Dae. | GO | sake
mm. mm.
1749 —0.0141 0.7 +0.801 —624 —0.0029 —0"%05
1770 — .0165 0.7 + .705 —615 — .0010 — .02
1771 — .0204 0.7 + .705 —615 + .0029 + .05
2252 — .0236 0.4 — .685 —523 0000 -00
2319 — .0263 0.6 — .811 —511 .0021 + .03
2320 — .0274 0.6 — .811 —511 + .0032 + .05
2359 — .0222 0.6 — .988 —491 — .0030 — .05
2988 — .0282 0.7 + .908 —272 — .0006 — .01
3146 — .0286 0.8 + .635 —244 — .0018 — .03
3642 — .0408 0.8 — .949 —122 + .0030 + .06
3643 — .0376 0.8 — .949 —122 — .0002 .00
3665 — .0888 0.7 — .959 —114 + .0007 + .01
3668 — .0379 0.6 — .959 —112 — .0003 -00
4384 — .0418 0.7 + .952 + 85 + .0008 + .01
4477 — .0390 0.6 + .765 +110 — .0032 — .05
4524 — .0425 1.0 + .651 +120 — .0003 ie .01
4525 — .0431 0.7 + .651 +120 + .0003 + .01
5113 — .0505 0.9 — .953 +258 — .0003 — .01
5157 — .0486 0.7 — .920 +268 — .0025 — .04
5701 — .0526 0.7 + .817 +470 — .0018 — .038
5702 — .0562 1.0 + .817 +470 + .0018 + .04
5713 — .0558 1.0 + .808 +471 + .0013 + .03
5714 — .0566 1.0 + .808 +471 + .0021 + .04
6103 — .0588 1.0 — .490 +558 — .0013 — .08
6104 — .0610 0.9 — .490 +558 + .0009 + .02
6230 — .0592 0.9 — .794 +583 — .0024 — .05
6231 —0.0626 1.0 —0.794 +583 +0.0010 +0.02
from which:

c = — 0.04003 mm.

B= — 0.00342 mm. = — 070712 or — 0"260 per year.

x = + 0.00207 mm. = + 0043 + 0”006.

Probable error of plate of unit weight

+ 0.00114 mm. = + 07024.
PARALLAXES OF 260. STARS 115

z 422 (35 31™; +0° 15’)

This double star of magnitudes 6.0 and 8.2 is a system of
the 61 Cygni type of common proper motion amounting to
07151 per year. The only determination of its parallax is the

TABLE 1

Puates or 2 422

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1749 1915 Sept. 23 —04 M 0.7
1770 Oct. 2 —0.3 M 0.7
1771 Oct. 2 +0.1 M 0.7
2252 1916 Jan. 2 —-0.3 M 0.4*
2319 Jan. 14 +0.2 Ol 0.6
2359 Feb. 3 =0,1 M,A 0.6
2988 Sept. 9 —0.5 M 0.7
3070 Sept. 23 —0.9 M 0.4*
3146 Oct. 7 —1.2 M 0.8
3642 1917 Feb. 6 —0.3 M 0.8
8643 Feb. 6 +0.2 M, L 0.8
3665 Feb. 14 +0.6 M 0.7
3668 Feb. 16 +0.7 Ol 0.6
4384 Sept. 1 —1.2 B 0.7
4477 Sept. 26 +0.8 B 0.6
4524 Oct. 6 —0.9 M 1.0
4525 Oct. 6 —0.6 M 0.7
5157 1918 Mar. 3 +2.1 M 0.7
5701 Sept. 21 = 0.1 M 0.7
5702 Sept. 21 +0.3 M 1.0
5713 Sept. 22 +0.2 M 1.0
5714 Sept. 22 +0.6 M 1.0
6103 Dec. 18 —0.3 M 1.0
6104 Dec. 18 +0.1 M 0.9
6230 1919 Jan. 12 —0.4 M 0.9
6231 Jan. 12 +0.1 M 1.0

 

 

 

 

* One exposure.
116 S. A. MITCHELL

spectroscopic value + 07052. The rotating sector was used, and
as a consequence the fainter star did not appear. Mr. Mitchell
measured the plates and found a relative parallax of + 07007
+ 07007 with a proper motion in right ascension — 07077
while the corresponding value from Boss is — 07021. The same
plates were used for the star 10 Tauri.

TABLE 2
REDUCTIONS FOR 2 -422

 

 

 

 

 

 

 

 

 

. : . : . id ; a
Bisley. | SAGON | NaN allan nae Meidaal | See
mm. mm.
1749 +0.0535 0.7 +0.801 —624 —0.0017 —0°03
1770 + .0521 0.7 + .705 —615 — .0004 — .O1
1771 + .0502 0.7 + .705 —615 + .0015 + .03
2252 + .0537 0.4 — .685 —523 — .0034 — .05
2319 + .0502 0.6 — .811 —511 — .0001 .00
2359 + .0520 0.6 — .938 —491 — .0021 — .03
2988 + .0472 0.7 + .908 —272 + .0011 + .02
3070 + .0499 0.4 + .794 —259 — .0018 — .02
3146 + .0450 0.8 + .635 —244 + .0029 + .05
3642 + .0432 0.8 — .949 —122 + .0029 + .05
3643 + .0438 0.8 — .949 —122 + .0023 + .04
3665 + .0483 0.7 — .959 —114 — .0023 — .04
3668 + .0472 0.6 — .959 —112 — .0012 — .02
4384 + .0448 0.7 + .952 + 85 — .0002 -00
4477 + .0456 0.6 + .765 +110 — .0013 — .02
4524 + .0440 1.0 + .651 +120 + .0002 -00
4525 + .0449 0.7 + .651 +120 — .0007 | — .01
5157 + .0390 0.7 — .920 +268 + .0032 + .05
5701 + .0399 0.7 + .817 +470 + .0008 + .01
5702 + .0412 1.0 + .817 +470 — .0005 — .01
5713 + .0403 1.0 + .808 +471 + .0004 + .01
5714 + .0410 1.0 + .808 +471 — .0003 — .01
6103 + .0421 1.0 — .490 +558 — .0027 — .06
6104 + .0382 0.9 — .490 +558 + .0012 + .02
6230 + .0414 0.9 — .794 +583 — .0024 — .05
- 6231 +0.0374 1.0 —0.794 +583 +0.0016 +0.03

 
PARALLAXES OF 260 STARS 117

CoMPARISON STARS

 

 

X (Right Ascen-

 

 

 

No. | Diameter. | sion). Y (Declination).° Dependence.
mm, mm. mm.
1 0.10 —47.8 + 8.1 +0.349
3 -10 + 6.6 —41.1 -296
6 .12 +41.2 +33.0 +0.355
Parallax star 0.14 -— 0.1 + 2.3

 

The normal equations are:

19.7¢ + 14.864y + 1.0738¢ = + 0.8756 mm.
+ 352.31664 — 2.59227 = + 0.3122 mm.
+ 12.43667 = + 0.0553 mm.

from which:
c = + 0.04520 mm.
w= — 0.00102 mm. = — 070212, or — 0077 per year.
wr = + 0.00034 mm. = + 0007 + 0’007.

Probable error of plate of unit weight
+ 0.00110 mm. = + 07023.

W. B. 35 617 (3 35"; —3° 32’)

This is a star of 7.2 magnitude, and F8 type, with a consider-
able proper motion of 0”79, and also a large radial velocity of
+114 km. per second, (Adams, Astrophysical Journal, 42,
172, 1915.) Two values of the parallax have been found, Smith
with the Yale heliometer deriving the value — 07080 + 0°015,
and Adams by the spectrograph the result + 0”035. Mr. Alden
measured the McCormick series of plates, and found the parallax
+ 07021 - 07008, and the proper motion in right ascension of
+ 07682 per year, the corresponding value derived by Porter
is + 07713.
118

S. A. MITCHELL

TABLE 1

Puates or W. B. 34 617

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1793 1915 Oct. 9 —09 M 0.6
3028 1916 Sept. 18 0.0 L 0.8
3085 Sept. 24 +0.1 L 0.9
3646 1917 Feb. 7 —0.1 Ol 1.0
3653 Feb. 12 +0.4 Ol 0.9
3654 Feb. 12 +1.1 A 1.0
4428 Sept. 12 0.0 A 1.0
4429 Sept. 12 +0.5 A 1.0
4506 Oct. 2 +0.6 A 0.9
4517 Oct. 5 —0.7 A 1.0
4518 Oct. 5 —0.2 A 1.0
4925 1918 Jan. 10 +0.4 A 0.9
5091 Feb. 14 +0.6 A 0.9
5133 Feb. 26 +1.7 Ol 0.8
5152 Mar. 2 +1.9 M 0.8

®
ComPaRISON STARS
No. Diameter. - ight een Y (Declination). Dependence.
mm. mm. mm.
1 0.14 —81.4 —13.9 +0.2274
2 .14 +14.9 +34.0 - 2433
3 .12 +16.0 +12.9 . 2509
4 -13 +50.5 —33.0 +0.2784
Parallax star 0.16 + 3.2 — 0.8

 

 

 

 

 
PARALLAXES OF 260 STARS 119

 

 

 

 

 

 

 

 

 

 

TABLE 2
Repuctions ror W. B. 34 617
lat. | ee | ae | reales | pee | Pe | ae
mm. mm.
1793 +0.0038 0.6 +0.631 —612 —0.0011 —0%02
8028 + .0332 0.8 + .848 —267 + .0007 + .01
3085 + .0352 0.9 + .793 —261 — .0008 —..02
3646 + .0464 1.0 — .950 —125 — .0016 — .03
3653 + .0424 0.9 — .959 —120 + .0028 + .06
3654 + .0447 1.0 — .959 —120 + .0006 + .01
4428 + .0669 | 1.0 + .896 | + 92 — .0007 — .01
4429 + .0661 1.0 + .896 + 92 + .0001 .00
4506 + .0656 0.9 + .709 +112 + .0022 + .04
4517 + .0710 1.0 + .674 +115 — .0030 — .06
4518 + .0656 1.0- | + .674 +115 + .0024 + .05
4925 + .0757 0.9 — .770 +212 — .0004 — .01
5091 + .0790 0.9 — .960 | +247 — .0008 — .01
5133 + .0793 0.8 — .945 +259 .0000 .00
5152 +0.0804 0.8 —0.930 +263 —0.0007 —0.01
The normal equations are:

13.5¢ + 1.768% — 0.2803¢ = + 0.7854 mm.

+ 64.5077n — 6.22167 = + 0.6741 mm.

+ 9.76607 = — 0.0618 mm.

from which:
c = + 0.05702 mm.
p = + 0.00899 mm. = + 071869, or + 07682 per year.
a = + 0.00103 mm. = + 07021 + 07008.
Probable error of plate of unit weight
+ 0.00111 mm. = + 07023.

ll

v PERSEI (3 38™; +42° 16’)

This star of 3.93 magnitude and of type F5 has a small proper
motion 0”009. The only parallax so far published is the spectro-
scopic result of Adams who finds the absolute parallax + 07016.
Mr. Olivier measured the McCormick plates, and derived a
relative parallax of + 07028 + 07012, with a proper motion in
120 S. A. MITCHELL

right ascension of + 0%029, while the corresponding value from
Boss is — 0”009.
TABLE 1
PuLatTes OF v PERSEI

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1618 1915 Sept. 7 —O11 Ol 0.8
1832 Oct. 22 —0.6 G 0.9
1859 Oct. 25 —0.2 Ol 0.8
2267 1916 Jan. 3 —1.1 G 0.7
2287 Jan. 4 —0.4 Ol 0.8
3059 Sept. 22 -0.5 Ol 0.4*
8060 Sept. 22 -1.1 Ol 0.4*
3184 Oct. 12 —0.8 L 0.7
3220 Oct. 20 —0.4 L 0.7
3309 Oct. 30 0.0 Ol 0.7
3552 1917 Jan. 2 —0.3 M 0.9
3553 Jan. 2 0.0 M 0.7
3618 Jan. 26 0.4 L, Ol 1.0
3619 Jan. 26 —0.1 L 0.8
4402 Sept. 10 —0.2 B 0.7
4414 Sept. 11 —1.2 Ol 0.5*
4415 Sept. 11 —0.4 Ol 0.9
4467 Sept. 24 =0.3 B 0.9
4476 Sept. 26 —0.1 B 0.9
4908 Dec. 26 —0.5 B 0.9
4909 Dec. 26 —0.1 B 0.9

 

* One exposure.

Comparison Stars

 

 

 

 

 

 

No. Diameter. x ee Y (Declination). Dependence.
mm. mm. mm.

1 0.12 —45.1 — 8.6 +0.1735

2 .12 —26.0 + 1.1 .1922

3 .08 —25.2 +31.9 .2311

4 .10 +49.1 —36.7 -1713

5 -1l +47.2 +12.3 +0.2319
Parallax star 0.12 + 0.7 + 2.6

 
PARALLAXES OF 260 STARS 12

TABLE 2

REDUCTIONS FOR v PERSEI

 

 

 

 

 

 

 

1: : . h ri . * : ia
Pini, | Paion: | Miaeet | Eaten, | Baie | Beat | ee
mm. mm.
1618 —0.0032 0.8 +0.935 —461 +0.0021 +0704
1832 + .0034 0.9 + .461 —416 — .0049 — .10
1859 — .0044 0.8 + .415 —413 + .0028 + .05
2267 — .0038 0.7 — .679 —343 + .0011 + .02
2287 — .0021 0.8 — .691 —842 — .0006 — .01
3059 + .0014 0.4 + .821 — 80 — .0012 — .01
3060 — .0021 0.4 + .821 — 80 + .0024 | + .03
3184 + .0026 0.7 + .592 — 60 — .0026 — .05
3220 — .0058 0.7 + .479 — 52 + .0057 + .10
8309 + .0045 0.7 + .825 — 42 — .0048 — .08
3552 — .0022 0.9 — .677 + 22 + .0009 + .02
3553 — .0014 0.7 — .677 + 22 + .0001 -00
3618 ans - 0002 1.0 — .897 + 46 — .0013 — .03
3619 — .0034 0.8 — .897 + 46 + .0019 | + .04
4402 + .0028 0.7 + .915 +273 -=— .0011 — .02
4414 + .0045 0.5 + .909 +274 — .0028 — .04
4415 + .0006 0.9 + .909 +274 + .0011 + .02
4467 — .0007 0.9 + .804 +287 + .0024 + .05
4476 + .0026 0.9 + .784 +289 — .0010 — .02
4908 — .0018 0.9 — .584 +380 + .0020 | + .04
4909 +0.0025 0.9 —0.584 +380 —0.0023 —0.05

 

 

 

The normal equations are:
16.0c + 1.360u + 1.69417 = — 0.0055 mm.
+ 121.9996u + 0.30737 =.+ 0.0467 mm.
+ 8.42567 = + 0.0104 mm.
from which:
c = — 0.00052 mm.
zw = + 0.00039 mm. = + 070080, or - 07029 per year.
x = + 0.00132 mm. = + 07028 + 07012.
Probable error of plate of unit weight
+ 0.00162 mm. = + 07034.
122

5 ERIDANI (3 38";

S. A. MITCHELL

—10° 6’)

Like ¢ Eridani, this star has a large proper motion amounting

to 0°75 per year, and it is of type K.
Two trigonometric parallaxes have been found:

Its magnitude is 3.72.

+ 07086

+ 0"034 by Flint with the meridian circle, and + 07181 + 07015

by Smith with the heliometer.

The spectroscopic parallax of

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Piates or 6 ERmant
No. Date. Hour Angle. Observers. Weight.
275 1914 Sept. 20 —055 M,A 0.7
307 Sept. 23 +0.6 A 0.7
453 Oct. 31 +0.4 M 0.8
482 Nov. 3 +0.2 G 0.7
746 1915 Jan. 7 —0.6 G, Ol 0.7
817 Jan, 21 —0.5 G 0.9
818 Jan, 21 +0.1 G 0.9
850 Feb. 8 —0.6 G 0.8
1708 Sept. 16 —1.0 Ol 0.5*
1709 Sept. 16 —0.3 Ol 0.8
1727 Sept. 21 —0.7 G 0.4*
1728 Sept. 21 —0.1 G 0.5
1794 Oct. 9 —0.1 M 0.8
1831 Oct. 15 —0.4 M 0.9
3581 1917 Jan. 14 +0.7 M 0.8
3582 Jan. 14 +1.1 M 0.8
3599 Jan. 19 +0.3 Ol 1.0
3600 Jan. 19 +0.8 Ol 1.0
* One exposure.
CompPaRIsONn STARS

No. Diameter. = Cee sera Y (Declination): Dependence.

1 0.20 47. 0 — 8.8 | +0.2129

2 13 —44.5 | + 7.1 - 2053

3 .29 +21.1 +27.9 . 1833

4 14 433.5 | 429.5 .1802

5 .16 +36.9 —55.7 +0.2183

Parallax star 0.18 — 1.2 — 2.1

 

 
PARALLAXES OF 260 STARS 123

Adams is + 07082. The eighteen plates of the series were
measured by Mr. Mitchell, who finds the proper motion in right
ascension to be — 0%083 per year, while Boss gives the value
— 07098.
TABLE 2
RepvctTIons FoR 6 ERIDANI

 

 

 

 

 

 

 

 

 

Bins) | Pe | ae | aaceete| Dama | me | aes
mm. mm.
275 +0.0188 | 0.7 | +0.843 | —347 | +0.0023 | +0704
307 + .0215 | 0.7 | + .816 | —344 | — .0006 | — .01
453 + .0212 | 0.8 | + .317 | -—306 | — .0039 | — .07
482 + .0156 | 0.7 |°+ .269 | —303 | + .0013 | + .02
746 + .0099 | 0.7 | — .728 | —238 | — .0001 .00
817 + .0077 | 0.9 — .859 | —224 | + .0011 | + .02
818 + .0064 | 0.9 | — .859 | —224 | + .0024 | + .05
850 + .0105 | 0.8 | — .951 | —206 | — .0025 | — .04
1708 + .0161 | 0.5 | + .877 | +14 | 4+ .00138 | + .02
1709 + .0173 | 0.8 | + .877 | +14 | + .0001 .00
1727 + .0157 | 0.4 | + .836 | +19 | + .0014 | + .02
1728 + 01385 | 0.5 | + .8836 | +19 | + .0036 | + .05
1794 + .0160 | 0.8 | + .641 | +37 | — .0004 | — .O1
1831 + .0184 | 0.9 | + .561 |) +53 | — .0035 | — .07
3581 + .0034 | 0.8 | — .805 | +500 | — .0022 | — .04
3582 — .0025 | 0.8 | — .805 | +500 | + .0038 | + .07
3599 + .0022 | 1.0 | — .848 | +505 | ~ .0013 | — .03
3600 +0.0006 | 1.0 | —0.848 | +505 | +0.0003 | +0.01

 

The normal equations are:

13.7¢c + 2.474u — 1.28727 = + 0.1519 mm.
+ 138.4466y — 13.3605¢ = — 0.2079 mm.
+ 8.23327 = + 0.0524 mm.
from which:
c = + 0.01189 mm.
zn = — 0.00109 mm. = — 070227, or — 07083 per year.

aw = + 0.00645 mm. = + 07134 + 07011.
Probable error of plate of unit weight

+ 0.00140 mm. = + 07029.
124 S. A. MITCHELL

LALANDE 6888-6889 (38 407; +41° 9’)

These stars form the double = 443. They are of unusual in-
terest due to their very large common proper motion of 1738
per year. The magnitudes are 8.2 and 8.8. These stars were
placed on the McCormick observing program for the reason
that the early parallax determinations show large discordances,
the parallax values ranging all the way from — 0714 to + 0723.
The individual measures are as follows:

 

 

 

 

 

 

Lal. 6888. Lal. 6889. Authority. Method.
—0'14 +07040 Flint Meridian Circle
+0.085+ .034 Chase Heliometer
+0.068+ .020 | +0”7046+0"020 | Kostinsky and Photography

von Zeipel
+0.228+ .090 Jewdokimov Meridian Circle
+0.029+ .033 | +0.020+ .034 | Russell Photography
—0.016+0.011 | +0.010+0.008 | Slocum and Photography
Mitchell

 

In order that the McCormick results might be directly com-
parable with the results from the use of the 40-inch refractor,
the same set of comparison stars were utilized as were employed
by Slocum and Mitchell (Publications of Yerkes Observatory,
4, 9, 1917). The comparison of the two results is especially
interesting as giving a ready means of deriving a more accurate
value of the proper motion than could be obtained from the
measures already made at either telescope alone. The deter-
mination of the proper motion increases in accuracy as the time
is increased, and the combination of Yerkes and McCormick is
separated by a greater interval than is found in either the Yerkes
or the McCormick measures. In spite of the difference in scale
of the Yerkes and McCormick photographs, it is readily possible
to compare their results by employing for the McCormick
measures the same dependences as were utilized at Yerkes.
When this is done, both sets of measures may be turned into
seconds of arc by multiplying by their respective scale values.
If the first six plates taken at Yerkes (loc. cit.), are compared
PARALLAXES OF 260 STARS 125

with the last eight McCormick plates, it is readily seen that
the parallax is eliminated. The interval separating the Yerkes
and McCormick plates is 2625 days. In this interval, the proper
motion of Lalande 6888 is + 4341, and of Lalande 6889,
+ 47384, respectively, corresponding to annual proper motions
of + 07603 and + 07609, respectively. The mean of these
results gives a proper motion in right ascension of + 0”606 per
year. This, however, is the motion referred to the mean of the
four comparison stars which were used. If any of the four has
motion of its own, this motion will, of course, show its effect.
Since also these comparison stars are at a finite distance away
from us, they must show the results of the solar drift. This
drift will amount approximately to + 07009 in right ascension
per year. The proper motion of Lalande 6888 is given by Boss
as amounting to + 07599 per year. If we correct the value of
the proper motion found from the comparison of the Yerkes and
McCormick photographs by the amount depending on the
solar drift, then there results a proper motion in right ascension
of + 0°615 per year, which is greater than Boss’s value by
+ 07016. The proper motions found from the Yerkes and
McCormick plates separately are:

 

 

 

 

 

 

Lalande 6888. Lalande 6889.
VOEIKG8y dsc cvcdw sawn cae tiiewares +0°580 +07598
McCormick... ............00 000s +0.629 +0.631
Nica nanads aammneareueuey +0"604 +0"614

 

The McCormick photographs which were measured by Mr.
Mitchell give the parallax of the system Lalande 6888-9 to be
+ 07025 + 07007.
126

S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Puates oF LALANDE 6888-9
No. Date. Hour Angle. Observers. Weight.
3232 1916 Oct. 21 —055 M 0.8
3259 Oct. 24 —0.4 M 0.9
3260 Oct. 24 —0.1 M 0.8
3579 1917 Jan. 14 0.8 M 1.0
3626 Jan. 28 —0.5 M 0.9
3627 Jan. 28 —0.3 M 1.0
4354 Aug. 26 —0.9 A 1.0
4450 Sept. 19 —0.7 A 1.0
4451 Sept. 19 —0.4 A 1.0
4504 Oct. 2 —0.4 A 1.0
4505 Oct. 2 0.0 A 1.0
4957 1918 Jan. 20 —0.4 M 0.8
4958 Jan. 20 —0.1 M 0.8
5009 Jan. 31 —0.2 A 1.0
5033 Feb. 9 —0.2 M 0.8
5689 Sept. 14 —0.6 M 0.8
5690 Sept. 14 —0.2 M 0.8
5710 Sept. 22 —1.0 M 1.0
5712 Sept. 22 —0.6 M 1.0
ComPaRIson STARS
No. Diameter. X (Right Y (Declina- cee
agestignon)s fon) Lat. 6888. | Lat. 6889.

1 0.13 —44.9 + 6.5 +0.276 | +0.272

2 -1l —18.0 +13.0 -199 - 208

3 10 +12.2 —16.4 -329 .316

4 wt +50.7 — 3.1 +0.196 | +0.204
Lal. 6888 122 — 2.1 — 1.6
Lal. 6889 0.18 ; — 1.8 — 1.4

 

 

 

 
PARALLAXES OF 260 STARS

REDUCTIONS FOR LALANDE 6888

TABLE 2

12'

 

 

Weight

 

 

 

 

 

 

 

 

Ss 1 ois . . . ae
Eins. oe | gh | Restor Cri: | Daye ©. om aoe
mm. 1 mm.

3232 —0.0344 0.8 +0.469 —347 +0.0006 +0°%01
8259 — .0327 0.9 + .424 —344 — .0010 — .02
3260 — .0360 0.8 + .424 —344 + .0023 + .04
3579 — .0274 1.0 — .802 —262 — .0007 — .01
3626 — .0250 0.9 — .907 —248 — .0021 — .04
3627 — .0304 1.0 — .907 —248 + .0033 + .07
4354 — .0083 1.0 + .978 — 388 + .0006 - 01
4450 — .0031 1.0 + .853 — 14 — .0028 — .06
4451 — .0039 1.0 + .853 — 14 — .0020 — .04
4504 — .0082 1.0 + .723 - ij + .0033 + .07
4505 — .0026 1.0 + .723 - il — .0023 — .05
4957 + .0022 0.8 — .852 +109 + .0004 + .01
4958 + .0024 0.8 — .852 +109 + .0002 -00
5009 + .0041 1.0 — .922 +120 — .0007 — .01
5033 + .0052 0.8 — .954 +129 — .0011 — .02
5689 + .0272 0.8 + .893 +346 — .0032 — .06
5690 + .0229 | 0.8 + .893 +346 + 0011 + .02
5710 + .0219 1.0 + .829 +354 + .0027 + .06
5712 | +0.0236 1.0 +0.829 +354 +0.0010 +0.02
The normal equations are:
17.4c + 0.044u + 2.73917 = — 0.0946 mm.
+ 97.3738y + 9.20477 = + 0.8171 mm.
+ 11.53507 = + 0.0731 mm.
from which:
c = — 0.00558 mm.
nw = + 0.00829 mm. = + 071724, or + 07629 per year.
x = + 0.00105 mm. = + 07022 + 07009.

Probable error of plate of unit weight
+ 0.00139 mm. = + 07029.
128 S. A. MITCHELL

TABLE 3

REDUCTIONS FOR LALANDE 6889

 

 

 

 

 

 

 

 

ce ‘eal
iste | on | ae ee | | ae
mm. mm.
3232 | +0.0029 | 0.8 | +0.469 | —347 | —0.0002 | 0700
3259 | + .0040 | 0.9 | + .424 | —344 | — .0011 | — .02
3260 | + .0025 | 0.8 | + .424 | —344 | + .0004 | + .01
3579 | + .0103 | 1.0 | — .802 | —262 | — .0022 | — .05
3626 | + .0084 | 0.9 | — .907 | —248 | + .0007 | + .01
3627 | + .0095 | 1.0 | — .907 | —248 | — .0004 | — .o1
"4354 | + .0260 | 1.0 | + .978 | — 38 | + .0031 | + .06
4450 | + .0310 | 1.0 | + .853 | — 14 | — .0001 00
4451 | + .0276 | 1.0 | + .853 | — 14 | + .0033 | 4 .07
4504 | + .0820.| 1.0 | + .723 | ~ 1) — .oo11 | — .02
4505. | + .0339 | 1.0 | + .723 | ~ 1 | — .o0a1 | — .04
4957 | + .0372 | 0.8 | — .852 | +109 | + .0016 | + .03
4958 | + .0410 | 0.8 | — .852 | +109 | — .0022 | — .04
5009 | + .0389 | 1.0 | — .922 | +120 | + .0008 | + .02
5033 | + .0378 | 0.8 | — .954 | +129 | + .0026 | + .05
5689 | + .0666 | 0.8 | + .893 | +346 | — .0057 | — .11
5690 | + .0573 | 0.8 | + .893 | +346 | + .0036 | + .07
5710 | + .0627 | 1.0 | + .829 | +354 | — .0013 | — .08
5712 | +0.0612 | 1.0 | +0.829 | +354 ! +0.0002 | 0.00

 

 

The normal equations are:

17.4¢ — 0.044y + 2.73917 = + 0.5414 mm.
+ 97.3738u + 9.20477 = + 0.8201 mm.
+ 11.53507 = + 0.1767 mm.

from which:
c = + 0.03092 mm.
# = + 0.00831 mm. = + 01728, or 07631 per year.

x = + 0.00134 mm. = + 0028 + 0010.
Probable error of plate of unit weight

+ 0.00153 mm. = + 07032.
PARALLAXES OF 260 STARS 129

7’ ERIDANI (35 42™; —23° 32’)

This is a star of magnitude 4.33, of spectral type F8 and of
total proper motion 07548. Mr. Mitchell measured fifteen
plates of the present series, the earlier plates being measured
by Mr. Briggs and partially by Mr. Lamb. A relative parallax
+ 07068 + 07010 resulted and a proper motion in right ascension
— 07162 per year whereas the corresponding value from Boss is
— 07163.

TABLE 1

PLATES OF +° ERIDANI

 

 

 

No. Date. Hour Angle. Observers. Weight.
8099 1916 Sept.26 |- —043 L 0.6
3128 Oct. 1 —0.6 L 1.0

~ 8129 Oct. 1 —0.2 L 1.0
3288 Oct. 27 —0.2 M 1.0
8637 1917 Jan. 30 —0.4 L 0.8
3638 Jan. 30 0.0 L 1.0
4452 Sept. 19 +0.2 A 1.0
4492 Oct. 1 —0.2 B 0.9
4493 Oct. 1 +0.2 B 0.9
4910 Dec. 26 +0.4 B 0.6*
4911 Dec. 26 +0.8 B 0.8
5826 1918 Oct. 21 +0.2 M 0.7
5827 Oct. 21 +0.6 M 0.6
6449 1919 Feb. 2 +0.7 M 0.8
6450 Feb. 2 +1.1 M 1.0
6471 Feb. 5 —0.4 D 1.0
6472 Feb. 5 +0.1 D 1.0
7653 Sept. 6 —0.9 M 0.7
7654 Sept. 6 0.4 M 1.0
7705 Sept. 13 -0.9 M 1.0
7706 Sept. 13 —0.4 M 1.0

 

 

 

 

 

* One exposure.

10
130

REDUCTIONS FOR 7° ERIDANI

S. A. MITCHELL

TABLE 2

 

 

 

 

 

Solution Weight Parallax Time in Residual 4 Vp+»
Plate. (m). (p). Factor (P). | Days (t). (v). in Are.
3099 +0.0218 0.6 +0.792 —551 +0.0015 +0702
3128 + .0189 1.0 + .740 —546 + .0042 + .09
3129 + .0237 1.0 + .740 —546 — .0006 — .01
3288 + .0229 1.0 + .387 —520 — .0016 — .03
3637 + .01383: 0.8 — .916 —425 + .0017 + .03
3638 + .0154 1.0 — .916 —425 — .0004 — .G1
4452 + .0178 1.0 + .858 —193 — .0019 — .04
4492 + .0182 0.9 + .742 —181 — .0029 — .06
4493 + .0180 0.9 + .742 —181 — .0027 — .05
4910 + .0067 0.6 — .573 — 95 + .0024 + .04
4911 + .0108 0.8 — .573 — 95 — .0017 — .03
5826 + .0052 0.7 + .485 +204 + .0010 + .02
5827 + .0018 0.6 + .485 +204 + .0044 + .07
6449 — .0028 0.8 — .928 +308 + .0022 + .04
6450 + .00C2 1.0 — .928 +308 — .0008 — .02
6471 — .0022 1.0 — .940 +311 + .0015 + .03
6472 + .0028 1.0 — .940 +311 — .0085 — .07
7653 — .0039 0.7 + .946 +524 + .0048 + .08
7654 + .0003 1.0 + .946 +524 |, + .0006 + .01
7705 + .0036 1.0 + .906 +531 — .0030 — .06
7706 +0.0008 1.0 +0.906 +531 —0.0002 0.00

 

 

 

 

 
PARALLAXES OF 260 STARS 131

Comparison STARS

 

 

 

 

 

 

No. | Diameter. x ee Y (Declination). -Dependence.
| mm. mm. mm.
1 0.13 —42.9 —14.2 +0.343
2 24 —27.7 +22.9 .153
3 .10 — 0.5 + 2.8 .237
4 .10 +71.1 —11.5 +0.267
Parallax star 0.16 — 0.06 — 3.76

 

The normal equations are:

18.4¢c + 0.3504 + 2.58517 = + 0.1729 mm.
+ 293.1771 — 0.67227 = — 0.6239 mm.
+ 12.10467 = + 0.0644 mm.
from which:
c = + 0.00898 mm.
w = — 0.002138 mm. = — 070443, or — 07162 per.year.

wr = + 0.00328 mm. = + 07068 + 07010.
Probable error of plate of unit weight
+ 0.00163 mm. = + 07034.

32 ERIDANI (3 49"; —3° 15’)

The brighter star of this double = 470 is of magnitude 4.95
and spectral type Gp, and the fainter of magnitude 6.33 and A.
They have a common proper motion 07035, and show no orbital
motion. The distance separating them is 677. Miss France
measured the plates finding the proper motions for the brighter
and fainter stars to be +0031 and + 0%032, respectively,
where the corresponding value from Boss is + 07034. Small
relative parallaxes + 0”008 + 07010 and — 07009 + 07009 for
brighter and fainter stars resulted.
132 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
PuatEes oF 32 ERIDANI
, No. Date. Hour Angle. Observers. Weight.
3147 1916 Oct. 7 —049 M 1.0.
4519 1917 Oct. 5 +0.3 A 1.0
4520 Oct. 5 +0.7 A 1.0
4542 Oct. 7 —0.7 Ol 0.8
4543 Oct. 7 —0.3 Ol 0.9
6171 1919 Jan. 4 0.0 M 1.0
6197 Jan. 8 —0.7 F 1.0
6360 Jan. 27 —0.3 D 1.0
6361 Jan. 27 +0.2 D 0.9
7614 Sept. 2 —0.7 F 0.9
7615 Sept. 2 —0.3 F 1.0
7629 Sept. 3 —0.2 H 1.0
7714 Sept. 14 0.0 OL 0.9
7715 Sept. 14 +0.2 Ol 0.7*
8361 Dec. 30 —0.7 F 0.9
8362 Dec. 30 —0.3 F 0.7*
8633 1920 Feb. 26 +1.0 A 0.7
* One exposure.
Comparison: STARS
: . Dependence.
No. Diameter. X (Right Y (Declina-
Ascension). tion). Bt. Ft.
1 0.08 —60.2 +11.3 +0.325 +0.320
2 .12 — 0.6 + 4.8 -221 224
3 -10 + 3.5 +16.3 .140 .149
4 13 +57.3 —32.4 +0.314 +0.307
Brighter star .18 — 1.3 — 3.1
Fainter star | 0.11 as es = 2.9 |

 

 

 

 

 
PARALLAXES OF 260 STARS

TABLE 2

Repvuctions ror 32 Eripani, BricHTER StTaR

13

 

 

 

 

 

 

 

 

 

 

1 . . . . : ane
Bike, | Site, | PE ee | ee ee
mm. mm.
3147 —0.0153 1.0 +0.691 —806 —0.0008 —0"02
4519 — .0160 1.0 + .717 —443 + .0013 + .03
4520 — .0146 1.0 + .717 —443 — .0001 -00
4542 — .0160 0.8 + .694 —441 + .0013 + .02
4543 — .0128 0.9 + .694 —441 — .0019 — .04
6171 — .0082 1.0 — .666 + 13 — .0051 -— 11
6197 — .0150 1.0 — .714 + 17 + .0017 + .04
6360 — .0166 1.0 — .887 + 36 + .0033 + .07
6361 — .0148 0.9 — .887. + 36 + .0015 | + .03
7614 — .0118 0.9 + .970 +254 .0000 -00
7615 — .0136 1.0 + .970 +254 + .0018 + .04
7629 — .0117 1.0 + .967°| +255 -0000 -00
7714 — .0111 0.9 + .912 +266 — .0006 — .01
7715 — .0111 0.7 + .912 +266 — .0006 — .01
8361 — .0118 0.9 — .600 +373 — .0001 -00
8362 — .0088 0.7 — .600 +373 — .0031 — .05
8633 —0.0122 0.7 —0.959 +431 +0.0004 | +0.01
The normal equations are:

15.4c — 2.816y + 2.877497 = — 0.2023 mm.

+ 202.9126u — 13.38527 = + 0.1137 mm.

+ 10.04607 = — 0.0394 mm.

from which:
c = — 0.01314 mm.
uw = + 0.00040 mm. = + 00084, or + 07031 per year.

wT

+ 0.00037 mm. = + 07008 + 07010.
Probable error of plate of unit weight

+ 0.00139 mm. = + 07029.
134 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 3
Repuctions ror 32 Eripant, Fainrer Star
ae | ea Be teeta cae | a Nee
mm. mm.
3147 —0.0170 1.0 +0.691 —806 —0.0003 —0’01
4519 — .0162 1.0 + .717 —443 + .0004 + .01
4520 — .0158 1.0 + .717 —443 .0000 .00
4542 — .0155 0.8 + .694 —441 — .0003 — .01
4543 — .0148 0.9 + .694 —441 — .0010 — .02
6171 — .0158 1.0 — .666 + 13 + .0025 +..05
6197 | — .o104 | 1.0 | — .714| +17 | — .0029 | — .06
6360 — .0159 1.0 — .887 + 36 + .0028 + .06
6361 — .0133 0.9 — .887 + 36 | -+ .0002 -00
7614 — .0144 0.9 + .970 +254 + .0014 + .03
7615 — .0112 1.0 + .970 +254 — .0018 — .04
7629 — .0122 1.0 + .967 +255 — .0008 — .02
7714 — .0153 0.9 + .912 +266 + .0024 + .05
7715 — .0135 0.7 + .912 +266 + .0006 + .01
8361 — .01380 0.9 — .600 +373 + .0012 + .02
8362 — .0069 ‘0.7 — .600 +373 — .0049 — .09
8633 —0:0107 0.7 —0.959 +431 .} —0:0007 —0.01
The normal equations are:
15.4¢ — 2.816 + 2.87742 = — 0.2124 mm.
+ 202.9126u — 13.38527 = + 0.1302 mm.
+ 10.04607 = — 0.0492 mm.
from which:
c = — 0.01363 mm.
uw = + 0.00042 mm. = + 070088, or + 07032 per year.
a = — 0.00042 mm. = — 07009 + 0009.

Probable error of plate of unit weight
+ 0.00132 mm. = + 07027.

y ERIDANI (3" 53"; —13° 47’)

This is a star of magnitude 3.19, and of K5 type, with a total
proper motion of 07130. The only value of the parallax is the
PARALLAXES OF 260 STARS 135

spectroscopic result of Adams who finds this to be: + 07019.
Mr. Alden measured the McCormick series of plates and found a
proper motion of + 07045 while the result from Boss is + 07067.

 

 

 

TABLE 1
PuLates oF y ERIDANI

No. Date. Hour Angle. Observers. Weight.
259 1914 Sept.15 —049 Ol, A 0.9
498 Nov. 4 +0.3 M 0.9
523 Nov. 6 +0.8 G 1.0
783 1915 Jan. 13 —0.1 A 1.0
860 “Feb. 9 +0.3 M,A 0.9
861 Feb. 9 +0.7 A 1.0
906 Feb. 19 +0.5 M 1.0
1688 Sept. 14 -0.8 A 1.0
1689 Sept. 14 —0.4 A 1.0
1779 Oct. 3 —0.6 A 1.0
1780 Oct. 3 —0.1 A 0.9
3639 1917 Jan. 30 +0.4 L 1.0
3640 Jan. 30 +0.7 M 0.8
3676 Feb. 20 +0.5 M 0.9
3677 Feb.: 20 _ +0.8 L 0.7*
4404 Sept. 10 +0.3 B 0.7
4438 Sept. 18 +0.3 B 0.8
4439 A Sept, 18 +0.5 B 0.7
4569 Oct. 13 +0.2 B 0.7

 

 

 

 

 

* One exposure.

ComPaRISON STARS

 

 

 

 

 

No. | Diameter. [* Right Ascen-’ y (Declination). | Dependence.
mm. mm. mm.

1 | 0.18 —46.1 +29.7 +0.3088

2 .20 —$2.2 —22.6 .3031

3 .16 +78.3 — 7.1 +0.3881
Parallax star 0.20 + 6.4 — 0.4

 

 
136

S. A. MITCHELL

ReEDvUcTIONS FoR y ERIDANI

TABLE 2

 

 

 

 

 

 

 

 

 

 

. %. . . id 1 ts
Fiat, || Sea | ee poe. | ee | ae,
mm. mm.
259 +0.0005 0.9 +0.912 —531 —0.0047 —0709
498 — .0002 0.9 + .311 —481 — .0041 — .08
523 — .0003 1.0 + .279 —479 — .0040 — .08
783 — .0080 1.0 — .759 —411 + .0034 + .07
860 — .0065 0.9 — .949 —384 + .0019 + .04
861 — .0042 1.0 — .949 —384 — .0004 — .01
906 — .0059 1.0 — .967 —374 ; + .0014 + .03
1688 — .0052 1.0 + .920 —167 + .0082 + .07
1689 — .0049 1.0 + .920 —167 + .0028 + .06
1779 — .0039 1.0 + .757 —148 + .0018 | + .04
1780 — .0049 0.9 + .757 —148 + .0028 + .06
3639 + .0014 1.0 — .905 +337 — .0016 — .03
3640 + .0034 0.8 — .905 +337 — .0036 — .07
3676 + .0008 0.9 — .967 +358 — .0010 — .02
3677 — .0030 0.7 — .967 +358 + .0028 + .05
4404 + .0012 0.7 + .940 +560 + .0011 + .02
4438 + .0002 0.8 + .889 +568 + .0021 + .04
4439 + .0048 0.7 + .889 +568 — .0025 — .04
4569 +0.0049 0.7 +0.631 +593 —0.0026 —0.05
The normal equations are:
16.9¢ — 6.811 + 0.38597 = — 0.0319 mm.
+ 273.6887» + 4.26707 = + 0:1766 mm.

from which:
c = — 0.00166 mm.
vw = + 0.00059 mm.
a = + 0.00065 mm. =

+ 11.97057 = + 0.0097 mm.

Probable error of plate of unit weight

+ 0.00193 mm. = + 07040.

'

+ 070124, or + 07045 per year.
+ 07014 + 07012.
Grossman with the meridian circle finds a parallax of + 07108
+ 07041 for this star, while Adams derives the spectroscopic
13. It is of G type, of magnitude 5.67, and
The plates were measured by Mr.
Alden, who finds the proper motion in right ascension to be
+ 0076 while the value given by Boss is + 0075.

parallax + 0°0

of small proper motion.

PARALLAXES OF 260 STARS

43 TAURI (4° 3™; +19° 20’)

137

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Puates or 43 Tauri
No. Date. Hour Angle. Observers. Weight.
321 1914 Sept. 26 —0*6 M 0.7
343 Sept. 28 +0.1 . G 0.8
361 Sept. 30 —0.6 A 1.0
531 Nov. 9 +0.4 G 1.0
_ 762 1915 Jan. 8 +0.8 G 1.0
885 Feb. 11 +1.1 Ol 0.5*
886 Feb. 17 +0.9 G 0.9
1757 Sept. 24 +0.2 G 0.7*
1758 Sept. 24 +0.5 G 0.8
1806 Oct. 10 —0.7 A 0.7
1807 Oct. 10 —0.1 A , 0.6
2360 1916 Feb. 3 0.0 A 0.9
2361 Feb. 3 +0.6 M 0.7
2402 Feb. 14 +0.8 G 0.7
* One exposure.
ComPaRIson STARS
No. Diameter. |* ie veal Y (Declination). Dependence.
mm. mm. mm.
1 0.12 —52.1 — 5.4 +0.1917
2 .14 »—-13.2 +27.2 -1731
3 .14 + 6.1 —54.6 - 2489
4 -12 +12.7 +17.7 -1878
5 -13 *+46.5 +15.1 +0.1985
Parallax star 0.17 + 0.9 — 3.6

 

 

 

 

 
138 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

TABLE 2
Repvuctions ror 43 Tauri

Solution Weight Parallax Time in Residual Vp+o
EIB! (m). (p). | Factor (P). | Days (). (). in Are.
: mm. .: mm.
321 +0.0020 0.7 +0.870 —244 —0.0004 —0/01
343 — .0025 0.8 + .831 —242 + .0040 + .07
361 + .0035 1.0 + .823 —240 — .0019 — .04
531 + .0033 1.0 + .270 —200 —. .0018 — .04
762 + .0015 1.0 — .678 —140 — .0003 — .01
885 — .0014 0.5 — .951 —106 + .0027 + .04
886 + .0016 0.9 — .966 —100 — .0002 -00
1757 + .0043 0.7 + .868 +119 + .0009 + .01
1758 + .0033 0.8 + .868 +119 + .0019 + .03
1806 | + .0081 | 0.7 | + .708 | +135 | — .0029 | — .05
1807 + .0051 0.6 + .708 +1385 + .0001 -00
2360 + .0085 0.9 — .913 +251 — .0036 — .07
2361 + .0016 0.7 — .913 +251 + .0083 + .05
2402 +0.0039 0.7 —0.959 +262 +0.0011 +0.02

 

The normal equations are:

11.0¢ — 1.484 + 0.43427 = + 0.0343 mm.
+ 41.4131 — 5.92087 = + 0.0313 mm.
+ 7.3485¢ = + 0.0020 mm.
from which:

c = + 0.00322 mm.
B= + 0.00100 mm. = + 070208, or + 07076 per year.
az = + 0.00089 mm. = + 07019 + 0012.

Probable error of plate of unit weight
+ 0.00149 mm. = + 07031.

o? 40 ERIDANI (4" 10™; —7° 48’)

This is an interesting triple system. The brightest star of the
system is of G5 type, and of magnitude 4.48. At a distance of
82”, there is a binary system BC of magnitudes 9.4 and 10.8
PARALLAXES OF 260 STARS 139

respectively. According to Burnham, “only four stars in the
northern hemisphere have a larger proper motion, and this is
common to the principal star and to the binary companion.”
This proper motion amounts to 4708 per year. The. large
common proper motion. signifies a physical system. There is
little change in the position angle and distance of BC with
respect to A. According to Doolittle (Publications of Flower
Observatory, 2, 44, 1905), it is probable that the small pair is
pursuing a closed orbit about the principal star, but the period
must be reckoned in thousands of years. Lewis (Memoires
Royal Astronomical Society, 56, 114, 1906) finds a period in the
neighborhood of 9000 years. The best orbit for the small pair
is that of Doolittle who finds a period of 180 years. The photo-
graphs for the present measures were taken in two separate
series, one set of plates without rotating sector in order to obtain
the brighter star of smaller pair, and the other set with the sector
for the principal star. The plates were measured by Mr. Mitchell.
The parallaxes obtained were for the star A, m = + 07194
+ 07009, and for B of the binary system BC, the value of r
is + 07214 + 0"008. Thence the parallax of the triple system
is
+ 07204 + 07006.

For the star A, Boss obtains the proper motion in right ascen-
sion of — 2220 per year. The plates give the proper motion
of A equal to — 27224, which is in good agreement with the value
of Boss, but for the star B, the plates give a proper motion
which is considerably different, and which amounts to — 17767
per year. The difference in proper motion is due mainly to
orbital motion.

The photographic plates were taken at four different seasons
when the position angles and distances of C with respect to B,
obtained by using Doolittle’s orbit were as follows:

1914.72 18°8 2°90
15.12 17:4 2.95
15.77 15.3 2.99

16.77 12.0 3.04
140 S. A. MITCHELL

In order to obtain the ratios of the mass of B with respect to C
it is necessary to know the proper motion of the center of gravity
of the system BC. This is unknown, but if we adopt the value
of the proper motion of — 2720 in right ascension, obtained by
combining Boss’s value with that by Lewis, and utilize the
measures of plates at the first and fourth seasons, which are
separated by only 2.05 years, then the masses of B and C appear
about equal. It should be needless to add that little confidence
should be placed in this result, both for the reason that the
motion of the center of gravity of the system is not known with
sufficient accuracy, and also for the reason that the orbital
motion in two years for such.a slow moving system is very small.
This star will be kept on the observing program, and after a
lapse of a few years, other plates will be taken in order to obtain
the proper and orbital motions with greater accuracy. The
only other determination of the mass-ratios of B and C is by
Lewis, who finds C of greater mass than B, and the masses of
B and C in the ratios of 6 to 6.5. The McCormick value of the
parallax gives the mass of the system BC 3.72 times that of the
sun; B and C are separated by 22.9 astronomical units, while A
is distant from BC by 415 times the distance of earth from sun,
or 14 times the distance of Neptune from the sun.

Other values of the parallax of the bright star A have been
published:

 

 

 

 

Parallax. Authority. Method.
+0%223 +04020 Hall Equatorial

-1664 .018 Gill Heliometer

21 + .042 Flint; Meridian Circle

-11 + .039 Flint, Meridian Circle

.060+ .127 Jewdokimov Meridian Circle
+0.240 Adams Spectrograph

 

The present measures furnish the first value of the parallax
of B to be published.
PARALLAXES OF 260 STARS 141

TABLE 1

Puates oF o% 40 Eripani, Princrpau Star A

 

 

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Ghesmras Weight.
1750 1915 Sept. 23 —043 M 1.0
1751 Sept. 23 +0.1 M 1.0
1907 Oct. 29 —0.6 G 0.9
1921 Oct. 30 —0.6 M 1.0
2306 1916 Jan. 13 +0.3 A 0.8
2307 Jan. 13 +0.7 A 0.8
2346 Jan. 23 —0.1 M 0.7
2347 Jan. 23 +0.3 M 0.7
2387 Feb. 9 —0.3 — M 0.8
3020 Sept. 17 —0.3 A 1.0
3021 Sept. 17 +0.1 A 1.0
3039 Sept. 19 —0.8 A 1.0
3040 Sept. 19 —0.6 A 1.0
8049 Sept. 20 —1.3 L 0.8
3050 Sept. 20 —0.9 L 0.8

ComPaRISON STARS
No. | Diameter. f ee Y (Declination). Dependence.
1 0.15 —43.8 +31.0 +0.309
2 .14 —24.0 —54.1 -438
3 14 +67.8 +23.1 +0.253
Principal star 0.16 — 6.9 — 8.3

 
142

S. A. MITCHELL

TABLE 2

Repvuctions ror o? 40 Eripani, Principan Star A

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in _ Residual Np
Plate. (m). (p). Factor (P). | Days (t). (v). in Arc.
1750 | —0.0668 | 1.0 | +0.891 | —151 | 0.0017 | —0%03
1751 — .0693 1.0 + .891 —151 + .0008 + -02
1907 — .0838 0.9 + .475 —115 + .0009 + .02
1921 — .0838 1.0 + .460 —114 + .0005 + .01
2306 — .1151 0.8 — .716 — 39 — .0012 — .02
2307 — .1187 0.8 — .716 — 39 + .0024 + .04
2346 — .1189 0.7 — .820 — 29 — .00138 — .02
2347 — .1183 0.7 — .820 — 29 — .0019 — .03
2387 — .1274 0.8 — .9388 — 12 + .0011 + .02
3020 — .1731 1.0 + .926 +209 — .0005 — .01
3021 — .1719 1.0 + .926 +209 — .0017 — .03
3039 — .1728 1.0 + .914 +211 — .0015 — .03
3040 — .1741 1.0 + .914 +211 — .0002 .00
3049 — .1768 0.8 + .907 +212 + .0022 + .04
3050 —0.1771 0.8 +0.907 +212 +0.0025 +0.04
The normal equations are:

13.3¢ + 5.471p + 4.75677 = — 1.7253 mm.

+ 32.2541y + 7.96727 = — 1.5321 mm.

+ 9.16997 = — 0.7233 mm.

from which:
c = — 0.12102 mm.

w= — 0.02928 mm. = — 076094, or — 27224 per year. :

T

Probable error of plate of unit weight
+ 0.00104 mm. = + 0"022.

+ 0.00934 mm. = + 07194 + 07009.
PARALLAXES OF 260 STARS 143

TABLE 1

Puates oF o? 40 Eripani, Companion, B

 

 

 

No. Date. Hour Angle. Observers. Weight.
276 1914 Sept. 20 —052 : M,A 1.0
289 Sept. 21 -0.1 G, Ol 0.8
290 Sept. 21 +0.5 G, Ol 0.7
308 Sept. 23 +0.9 A 1.0
793 1915 Jan. 14 —0.6 Ol , 0.6
875 Feb. 10 +0.2 G 1.0
876 Feb. 10 +0.8 G 1.0
934 Feb. 21 +0.8 A 1.0
935 Feb. 22 +0.6 M,G 1.0
936 Feb. 22 +1.1 G 1.0
1661 Sept. 11 -0.9 M 1.0
1662 Sept. 11 -0.3 M 0.4
1833 Oct. 22 —0.5 G 0.7*
1841 Oct. 24 —1.1 G 0.7
1842 Oct. 24 —0.7 G 0.4
1871 Oct. 27 —0.4 A 0.4
3148 1916 Oct. 7 —0.8 M 0.8
3149 Oct. 7 —0.5 M 0.8
3150 Oct. 7 —0.1 M 0.8

 

 

 

 

 

* One exposure.

Comparison STaRs

 

 

 

 

 

No. | Diameter. ii ca uae Y (Declination). Dependence.
mm. mm. mm.

1 0.15 —43.8 +31.0 +0.267

2 14 —24.0 —54.1 -448

3 14 +67.8 +23.1 +0.285

Companion, B 0.14 — 3.1 — 9.4

 
144

S. A. MITCHELL

TABLE 2

Repuctions For o? 40 Eripani, Companion, B

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp+o
Plate. (m). (p). | Factor (P). | Days (t). (). in Are.

mm. mm.
276 +0.1006 1.0 +0.911 —155 0.0000 0700
289 + .1004 0.8 + 904 —154 — .0001 .00
290 + .0980 0.7 + .904 —154 .0023 + .04
308 + .1006 1.0 + .889 —152 — .0010 — .02
793 + .0538 0.6. — .730 — 39 — .0026 — .04
875 + .0390 1.0 — .943 — 12 + .0024 + .05
876 + .0410 1.0 — .943 — 12 +. .0004 + .01
934 + .0342 1.0 — .972 - 1 + .0038 + .08
935 + .0408 1.0 — .973 0 — .0030 — .06
936 + .0396 1.0 — .973 0 — .0018 — .04
1661 — .0015 1.0 + .962 +201 + .0027 + .03
1662 + .0018 0.4 + .962 +201 — .0005 — .01
1833 — .0140 0.7 + .577 +242 — .0002 .00
1841 — .0188 0.7 + .548 +244 — .0013 — .02
1842 — .0112 0.4 + .548 +244 — .0039 — .05
1871 — .0161 0.4 + .504 +247 — .0003 .00
3148 — .1112 0.8 + .754 +593 + .0003 .00
3149 — .1116 0.8 + .754 +593 + .0007 + .01
3150 +0.1110 0.8 +0.754 +593 +0.0001 0.00

 

The normal equations are:

14.8¢ + 15.9544 + 1.97697 = + 0.2796 mm.
+ 110.3633y + 11.33187
+ 10.81617

from which:

Cc
be

+ 0.04777 mm.
— 0.02807 mm.
a = + 0.01029 mm.

Probable error of plate of unit weight
+ 0.00121 mm. = + 07025.

= — 2.2189 mm.
= — 0.1123 mm.

= — 075838, or — 1767 per year.

+ 07214 + 07008.
PARALLAXES OF 260 STARS 145

& ERIDANI (45 18"; —3° 58’)

According to Holteschek (Astronomische Nachrichten, 4738),
this star forms one of the Ursa Major group, and on this assump-
tion, it should have a theoretical parallax of + 0019. It is
A2 type, of magnitude 5.23, and of small proper motion 0°07.
The nineteen plates of the series were measured by Mr. Alden
and furnish a parallax + 07010 + 07009. The value of the
proper motion in right ascension given by Boss is — 0”050 per
year.

 

 

 

 

TABLE 1
PLATES OF £ ERIDANI
No. Date. Hour Angle. Observers. Weight.
202 -| 1914 Sept. 4 —017 M 0.8
224 Sept. 9 —0.3 M 1.0
236 Sept. 13 —0.1 M,A 1.0
277 Sept. 20 +0.4 M,A 0.9
426 Oct. 27 0.0 Ol 1.0
713 Dec. 26 +0.2 G 0.7*
820 1915 Jan. 21 +0.8 Ol 0.9
862 Feb. 9 +1.0. M 1.0
920 Feb. 20 +0.2 A 1.0
921 Feb. 20 +0.6: A 1.0
947 Feb. 25 +1.1. M 0.8
1650 Sept. 10 —0.2 Ol 0.8
1670 Sept. 12 —0.9 Ol 0.6
1690 Sept. 14 -0.3 A 0.9
1691 Sept. 14 +0.1 A 1.0
2321 1916 Jan. 14 +0.8 Ol 0.9
2378 Feb. 4 +0.2 G 1.0
2396 Feb. 10 —0.6 ol 0.8
2401. Feb. 14 | —0.2 Ol 0.9

 

 

 

 

* One exposure.

11
L46

S: A. MITCHELL

ComPaRISON STARS

 

 

 

 

 

 

 

 

 

 

No. Diameter. i (iene AacaD ¥ (Declination). || Dependence.

1 0.16 —32.7 —25.8 +0.2078

2 .16 —29.1 — 6.1 .1971

3 .19 —16.4 +39.7 . 1678

4 +138 +18.0 —13.5 1543

5 .13 +24.9 —35.8 . 1559

6 -12 +35.3 +41.5 +0.1171

Parallax star 0.20 — 4.5 — 2.7
TABLE 2
RepucTIONS FoR £ ERIDANI
Plate. Solution Weight Parallax Time in Residual J Vp
(m). (p). Factor (P). | Days (é). (v). in Are.
mm. mm.-~-

202 —0.0084 0.8 +0.990 —240 +0.0041 +0°07
224 — .0044 1.0 + .977 —235 -0000 -00
236 — .0061 1.0 + .962 —231 + .0016 + .03
277 — .0036 0.9 + .924 —224 — .0010 — .02
426 — .0020 1.0 + .838 —187 — .0030 — .06
713 — .0068 0.7 — .453 —127 + .0005 + .01
820 — .0100 0.9 — .788 —101 + .0033 + .06
862 — .0039 1.0 — .933 — 82 — .0031 — .06
920 — .0046 1.0 — .970 — 71 — .0025 — .05
921 — .0068 1.0 — .970 — 71 — .0003 — .01
947 — .0086 0.8 — .976 — 66 + .0014 + .03
1650 — .0063 0.8 + .976 +131 — .0021 — .04
1670 — .0113 0.6 + .967 +133 + .0029 + .04
1690 — .0100 0.9 + .958 +135 + .0016 + .03
1691 — .0054 1.0 + .958 +135 — .0030 — .06
2321 — .0108 0.9 — .708 +257 + .0002 .00
2378 — .0118 1.0 — .902 +278 + .0009 + .02
2396 — .0108 0.8 — .936 +284 + .0002 -00
2401 —0.0122 0.9 —0.953 +288 —0.0012 —0.02

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS 147

The normal equations are:

17.0c — 0.664 — 0.24407 = — 0.1258 mm.
+ 61.0428n — 10.56227 = — 0.0665 mm.
+ 14.20147 = + 0.0200 mm.
from which:
c = — 0.00743 mm.
w= — 0.00109 mm. = — 070226, or — 07083 per year.

+ 0.00047 mm. = + 07010 + 07009.
Probable error of plate of unit weight
+ 0.00146 mm. = + 07030.

Tv

a TAURI (4» 30"; +16° 19’)

The first magnitude star, Aldebaran, has been many times
investigated for parallax with values which are quite discordant.
Its magnitude is 1.06, and it is a K5 star, of proper motion 0”20
per year. The following values of the parallax have been found:

 

 

 

Parallax. | Authority. Method.
+07516 £07057 O. Struve Equatorial
+ .102+ .030 Hall Equatorial
+ .02 + .058 Flint Meridian Circle
+ .109+ .014 Elkin Heliometer
+ .079+ .029 Donner-Kapteyn Photography
— .005+ .020 Kiistner-Kapteyn Photography
+ .082+ .084 Jewdokimov . Meridian Circle
+ .047+ .010 Van Biesbroeck Photography
+0.051 Adams Spectrograph

 

It was very difficult to obtain a satisfactory series of plates on
account of the great brightness of the parallax star. The
difficulty was increased from the fact that the only available
guiding star was faint, with the consequent trouble that perfect
guiding was almost impossible. The plates of the series were
measured by Mr. Mitchell who finds a proper motion in right
ascension of + 0°072 per year, while the value due to Boss is
+ 07069.
148 S. A. MITCHELL

TABLE 1

PLATES OF a TAURI

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
454 1914 Oct. 31 040 M 0.6*
556 Nov. 11 —0.2 A 0.6*
892 1915 Feb. 18 +0.5 M 0.7
988 Mar. 3 +0.9 M 0.6*
1772 Oct. 2 -0.1 M 0.8
1773 Oct. 2 +0.2 M 0.5*
1873 Oct. 27 +0.3 A 1.0
2348 1916 Jan. 23 +0.7 M 0.5*
2428 Feb. 29 +1.2 A 0.8
2429 Feb. 29 +1.7 A 0.5*
2438 Mar. 4 +1.1 A 0.5*
3022 Sept. 17 +0.4 A 0.6
3041 Sept. 19 —0.4 A 0.6
3042 Sept. 19 0.0 A 0.5
3151 Oct. 7 +0.1 M 0.5*
3152 Oct. 7 +0.5 M 0.6
3197 Oct. 14 —0.7 M 0.7
3262 Oct. 24 -—0.1 M 1.0
3289 Oct. 27 —0.4 M 0.7
3290 Oct. 27 0.0 M 0.8
3333 Nov. 2 —0.8 M 0.8
3687 1917 Feb. 22 +0.1 M 0.8
3688 Feb. 22 +0.4 L 0.6*
3713 Mar. 6 +1.0 M 1.0
3728 Mar. 8 +1.2 L 0.6
4526 Oct. 6 -1.0 M 0.5*
4550 Oct. 9 +0.6 A 0.8
4551 Oct. 9 +0.1 A 0.9

 

 

* One exposure.
PARALLAXES OF 260 STARS

TABLE 2

ReEDvucTIONS FOR a TAURI

149

 

 

 

 

 

 

 

Plate. Solution Weight | Parallax Time in Residual Vp-o

‘m). (p). Factor (P). | Days (t). (v). in Arc.

mm. mm.
454 +0.0278 0.6 +0.512 —604 —0.0012 | —0*%02
556 + .0298 0.6 + .342 —593 — .0034 | — .05
892 + .0252 0.7 — .962 —494 — .0001 .00
988 + .0265 0.6 — .979 —481 — .0013 | — .02
1772 + .0254 0.8 + .877°| =268 + .0050 | + .09
1773 + .0312 0.5 + .877 —268 — .0008 — .01
1873 + .0304 1.0 + .573 —243 — .0003 — .01
2348 | + .0271 0.5 — .781 —155 + .0015 | + .02
2428 + .0275 0.8 — .980 —118 + .0012 | + .02
2429 + - 0292 0.5 — .980 —118 — .0006 | — .01
2438 + .0315 0.5 — .978 —114 — .0028 — .04
3022 .| + .0352 0.6 + .956 + 83 — .0014 | — .02
3041 + .0377 0.6 + .946 + 85 — .0088 | — .06
3042 + .0340 0.5 + .946 + 85 — .0002 .00
3151 + .0318 0.5 + .806 +103 + .0020 | + .03
3152 + .0303 0.6 + .806 +103 + .00385 | + .06
3197 + .0307 0.7 + .731 +110 + .0030 | + .05
3262 + .0294 1.0 + .604 +120 + .0042 | + .09
3289 + .0350 0.7 + .563 +123 — .0014 — .02
3290 + .0343 0.8 + .563 +123 — .0007 | — .01
3333 + .0361 0.8 + .475 +129 — .0026 | — .05
3687 + .0281 0.8 — .974 +241 + .0040 | + .07
3688 + .0340 0.6 — .974 +241 — .0019 — .03
3713 + .0823 1.0 — .972 +253 — .0001 -00
3728 + .0328 0.6 — .971 +255 — .0006 | — .O1
4526 + .0396 0.5 + .819 +467 — .0024 | — .04
4550 + .0387 0.8 + .788 +470 — .0015 | — .08
4551 +0.0388 0.9 +0.788 +470 —0.0016 —0.03

 

 

 
150 S. A. MITCHELL

ComPaRISON STARS

 

 

 

 

 

 

 

No. Diameter. |* eae | Y (Declination). Dependence.
mm. m. mm. |
1 0.10 —56.4 — 0.2 +0.222
2 13 — 0.6 *—16.5 -250
3 18 +27.7 —31.1 -265
4 -16 +29.3 +47.8 +0.263
Parallax star 0.25 + 2.4 + 0.2
The normal equations are:
19.1e + 2.858u + 2.48317 = + 0.6074 mm.

+ 168.0092u + 7.36577 = + 0.2610 mm.
+ 12.68217 = + 0.1066 mm.

from which:

c = + 0.03144 mm.
w= + 0.00095 mm. = + 070197, or 0”072 per year.
a = + 0.00170 mm. = + 07035 + 0°008.

Probable error of plate of unit weight
+ 0.00140 mm. = + 0”029.

BOSS 1128 (47 42"; +63° 20’)

This star is of 5.81 magnitude, of Mb type, and with a total
proper motion 0711 per year. With the exception of two plates
measured by Mr. Mitchell, the series of plates were measured
by Miss Hawes. A relative parallax — 0”003 + 0”011 resulted,
and a proper motion in right ascension + 0027 where the
corresponding value from Boss is + 07056. The spectroscopic
parallax of Mt. Wilson is + 0010.
PARALLAXES OF 260 STARS

151

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Puates or Boss 1128
No. Date. Hour Angle. Observers. Weight.
8061 1916 Sept. 23 —145 Ol 0.7*
3130 Oct. 1 —0.3 L 1.0
3222 Oct. 20 —0.4 *L 0.8
3223 Oct. 20 —0.1 L 0.7*
4668 1917 Nov. 1 —0.3 Ds 1.0
5797 1918 Oct. 12 —0.7 M 0.7
5854 Nov. 2 —0.8 M 1.0
5855 Nov. 2 —0.5 M 1.0
6243 1919 Jan. 13 —1.2 H ‘ 1.0
6244 Jan. 13 —0.8 H 1.0
6370 Jan. 28 —0.4 D 1.0
6371 Jan. 28 0.0 D 1.0
6399 Jan. 30 —0.5 H 1.0
6400 Jan. 30 0.0 H 1.0
7670 Sept. 8 —-1.0 H 0.8
7671 Sept. 8 —0.7 H 0.8
7693 Sept. 12 —0.3 H 1.0
7723 Sept. 15 —0.9 D 1.0
* One exposure.
ComPaARISON STARS

No. | Diameter. P Se Y (Declination). Dependence.

1 0.14 —39.3 +32.5 +0.136

2 .10 —20.2 —24.4 .172

3 .07 — 9.5 — 6.8 . 167

4 .12 — 3.6 —25.9 .179

5 .16 +12.4 —15.5 .179

6 .14 +60.2 +40.0 +0.167

- Parallax star 0.13 + 1.2 — 1.6

 

 

 
152

S. A. MITCHELL

TABLE 2

RepDuctTions ror Boss 1128

 

 

 

 

 

 

 

 

 

 

On . . - « idt al é
Piste, | Sefation | Wai lace te). | Doe. | es | aan.
mm. mm.
3061 —0.0064 0.7 +0.946 —678 +0.0034 +0706
3130 — .0024 1.0 + .890 —670 — .0006 — .01
8222 — .0049 0.8 + .698 —651 + .0020 |; + .04
3223 + .0016 0.7 + .698 —651 — .0045 — .08
4668 — .0028 1.0 + .541 —274 + .0013 + .03
5797 — .0004 0.7 + -795 + 71 + .0001 .00
5854 + .0029 1.0 + .5380 + 92 — .0031 — .06
5855 + .C015 1.0 + .530 + 92 — .0017 — .04
6243 — .0016 1.0 — .630 +164 + .0018 04
6244 + .0042 1.0 — .630 +164 — .0040 — .08
6370 + .0010 1.0 — .805 +179 — .0007 — .01
6371 — .0004 1.0 — .805 +179 + .0007 + .01
6399 — .0007 1.0 — .824 +181 + .0010 + .02
6400 — .0019 1.0 — .824 +181 + .0022 + .05
7670 + .0001 0.8 + .997 +402 + .0007 + .01
7671 — .0022 0.8 + .997 +402 + .0030 | + .06
7693 .0000 1.0 + .990 +406 + .0008 + .02
7723 +0.0025 1.0 +0.982 +409 —0-0016 —0.03
The normal equations are:
16.5¢ + 3.448u + 3.80597 = — 0.0069 mm.
+ 227.5992u — 10.86347 = + 0.0831 mm.
+ 10.42897 = — 0.0069 mm.
from which:
c = — 0.00047 mm.
w= + 0.00085 mm. = + 070074, or + 0027 per year.
a = — 0.00013 mm. = — 07003 + 0011.

Probable error of plate of unit weight
= 0.00153 mm. = - 0032.
Adams finds the spectroscopic parallax of this star to be
+ 07151. It has a total proper motion of 0747 per year, it is
of magnitude 3.31, and of type F8. The fifteen plates of the
series were measured by Mr. Mitchell, who found a proper
motion in right ascension of + 07497 per year, while the value

PARALLAXES OF 260 STARS

m ORIONIS (4% 44"; +6° 47’)

of Boss is + 0471.

153

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
PLATES OF 7? ORIONIS

No. Date. Hour Angle. Observers. Weight.
394 1914 Oct. 11 +051 A 1.0
440 Oct. 30 —0.2 A 0.7
~ 516 Nov. 5 —0.2 A 1.0
524 Nov. 6 +0.6 G 0.9
750 1915 Jan. 7 +1.0 Ol 0.8
1013 Mar. 9 +1.5 A 0.7
1026 | Mar. 10 +1.7 M 0.7
1710 | Sept. 16 —0.8 Ol 0.7
1788 Oct. 8 —0.5 G 0.7
1795 Oct. 9 —0.5 M 0.7
1968 Nov. 5 —0.2 Ol 0.7
2388 1916 Feb. 9 —0.3 G 1.0
2389 Feb. 9 +0.1 G 0.9
2455 Mar. 11 +1.3 M 0.7
2471 Mar. 12 +1.4 M 0.7

CoMPaRISON STARS

No. Diameter. @ cae oe aaa Y (Declination). Dependence.

1 0.15 —48.4 + 9.5 +0.255

2 -15 —15.6 +11.7 -278

3 -15 +18.7 + 4.8 .274

4 -15 +45.3 —26.0 +0.192

Parallax star 0.20 — 2.8 + 2.0

 

 

 

 
154 S. A. MITCHELL

TABLE 2

REDUCTIONS FOR 7* ORIONIS

 

 

 

 

 

 

 

 

 

Plate. Solution Weight Parallax Time in Residual z Vp-o
(m). (p). Factor (P). | Days (t). (v). in Are.
mm. mm. .
394 —0.0208 1.0 +0.811 —253 +0.0014 +0703
440 — .0194 0.7 + .581 —234 — .0004 — .01
516 — .0202 1.0 + .494 —228 + .0001 .00
524 — .0174 0.9 + .478 —227 — .0027 — .05
750 — .0256 0.8 — .540 —165 + .0022 + .04
1013 — .0233 0.7 — .981 —104 + .0007 + .01
1026 — .0209 0.7 — .980 —103 — .0017 — .03
1710 + .0005 0.7 + .984 + 87 + .0036 + .06
1788 + .0047 0.7 + 842 +109 — .0002 -00
1795 + .0058 0.7 + .833 +110 — .0013 — .02
1968 + .0064 0.7 + .497 +137 — .0025 — .04
2388 + .0014 1.0 — .900 +233 — .0014 — .03
2389 — .0006 0.9 — .900 +233 + .0006 + .01
2455 + .0004 0.7 — .978 +264 + .0011 + .02
2471 +0.0010 0.7 —0.974 +265 +0.0006 +0.01

 

The normal equations are:

11.9¢ — 0.0294 — 0.53007 = — 0.1076 mm.
+ 47.3793u — 8.21157 = + 0.2509 mm.
+ 7.62827 = + 0.0062 mm.
from which:
c = — 0.00871 mm.

w= + 0.00655 mm. = + 071362, or + 07497 per year.
a = + 0.00725 mm. = + 07151 + 0”009.

Probable error of plate of unit weight
+ 0.00111 mm. = + 07023.

_ A. G. LEIPZIG 1819 (4 44™; +6° 46’)

This star was on the series of plates that were taken for 7°
Orionis, and its parallax, therefore, was determined with little
extra labor. Its magnitude is 7.02 and spectral type A2.
PARALLAXES OF 260 STARS ]

The proper motion is small, and a small parallax would be |
pected. The series of plates were measured by Mr. Mitchell

TABLE 1
Puates or A. G. Lerpzia 1819

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
394 1914 Oct. 11 +051 A 1.0
440 Oct. 30 —0.2 A 0.7
516 Nov. 5 —0.2 A 1.0
524 Nov. 6 +0.6 . G 0.9
750 1915 Jan. 7 +1.0 Ol 0.7
1013 Mar. 9 +1.5 A 0.7
1026 Mar. 10 +1.7 M 0.7
1710 Sept. 16 —0.8 ‘Ol 0.7
1788 Oct. 8 -0.5 G 0.5
1795 Oct. 9 -0.5 M 0.7
1968 Nov. 5 —0.2 Ol 0.5
2388 1916 Feb. 9 —0.3 G 0.7
2389 Feb. 9 +0.1 G 0.9
2455 Mar. 11 +1.3 M 0.7
2471 Mar. 12 +1.4 M 0.5

ComPaRISON STARS

 

 

 

 

 

 

No. | Diameter. F ee Annet Y (Declination). Dependence

2 0. 15 | oi 1.7 +14.9 +0.151

3 + 2.6 + 8.0 -666

4 +29.1 —22.9 +0.183

Parallax star 0. e + 2.3 + 3.4
The normal equations are:

10.9¢ — 1.5854 — 0.27907 = + 0.0069 mm.
+ 43.4609n — 7.47507 = — 0.0152 mm.
+ 6.97517 = + 0.0018 mm.
156

S. A. MITCHELL

TABLE 2

Repvuctions ror A. G. Lerpzie 1819

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual 3 Vp-0
Plate. (m). (p). Factor (P). | Days (t). v). in Arc.
mm. mm.
394 +0.0045 1.0 +0.811 —253 —0.0031 —0"06
440 + .0031 0.7 + .581 —234 — .0018 — .03
516 + .0028 1.0 + .494 —228 — .0015 — .03
524 | + .0005 0.9 + .478 —227 + .0008 + .02
750 — .0025 0.7 — .540 —165 + .0037 + .06
1013 + .0006 0.7 — .981 —104 + .0004 + .01
1026 | — .0022 | 0.7 | — .980 | —103 | + .0032 | + .06
1710 + .0017 0.7 + .984 + 87 — .0015 — .03
1788 — .0046 0.5 + .842 +109 + .0047 + .07
1795 — .0015 0.7 + .833 +110 + .0016 + .03
1968 — .0047 0.5 + .497 +137 + .0047 + .07
2388 + .0026 0.7 = -900 +233 — .0027 — .05
2389 + .0022 0.9 — .900 +233 — .0023 — .04
2455 — .0023 0.7 — .978 +264 + .0021 + .03
2471 +0.0044 0.5 —0.974 +265 —0.0046 —0.07
from which:

c = + 0.00058 mm.

w= — 0.00035 mm. = — 070072, or — 07026 per year.

aw = — 0.00010 mm. = — 0”002 + 0”015.

Probable error of plate of unit weight
+ 0.00176 mm. = + 0”037..

W. B. 4" 1189 (4 56™; —5° 52’)

This star of 6.5 magnitude, and K9 type has a considerable
proper motion of 1725. Two values of the parallax have been
found visually: Flint with the meridian circle obtaining the
result + 0729 + 07042, and Smith with the Yale heliometer
deriving the value + 0”104 + 0015. There are two photo-
graphic values: + 07111 + 07019 from Swarthmore, and + 0”107
+ 0°006 from Allegheny. Mt. Wilson obtains the spectroscopic

!
PARALLAXES OF 260 STARS 157

parallax + 07115. Mr. Olivier measured the McCormick series
of plates, and obtained the parallax of + 0”124 + 0”007, with
a proper motion in right ascension of + 07562 per year, while
the value given by Porter is + 0”550.

TABLE 1
Puates or W. B. 45 1189

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
3029 1916 Sept. 18 —057 L 0.9
3030 Sept. 18 —0.4 L 0.9
3086 Sept. 24 —0.6 L 0.8
3087 Sept. 24 —0.2 L 0.8
3620 1917 Jan. 26 —0.6 Ol 0.9
3621 Jan, 26 —0.3 Ol 0.9
3645 Feb. 6 0.0 M 1.0
3655 Feb. 12 +0.5 A 0.9
3656 Feb. 12 +0.8 A 1.0
4570 Oct. 13 —0.2 B 0.8
4571 Oct. 13 +0.2 B 0.8
4615 Oct. 21 —0.2 B 0.9
4616 Oct. 21 +0.2 B 0.9
5080 1918 Feb. 13 +0.7 M 0.7
5115 Feb. 22 +0.7 Ol 0.7
5170 Mar. 5 +0.8 Ol 0.9
5171 Mar. 5 +1.2 Ol 1.0

ComPaRISON STARS
No. Diameter. |~ ae oe saad Y (Declination). Dependence.
i
mm. mm. mm.

1 0.16 —52.7 -19.9 +0.1756

2 .14 —10.7 +42.4 .1754

3 .19 — 6.1 —45.7 -2155

4 .27 +33.2 +32.9 - 2068

5 .19 +36.3 — 9.7 +0. 2267

Parallax star 0.21 + 2.7 — 1.3

 

 

 

 

 
158 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

TABLE 2
Repuctions ror W. B. 4 1189

Solution Weight Parallax Time in Residual : Vp-o
Plate. (m). (p). | Factor (P). | Days (f). (). in Are.

mm. mm.
3029 +0.0053 0.9 +0.981 —258 —0.0009 —0"02
3030 + .0035 0.9 + .981 —258 + .0009 | + .02
3086 + .0051 0.8 + .955 —252 — .0004 | — .O1
3087 + .0040 0.8 + .955 —252 + .0007 + .01
3620 + .0088 0.9 — .762 —128 — .0002 - .00
3621 + .0026 0.9 "| — .762 —128 + .0010 + .02
3645 + .0034 1.0 — .868 —117 + .0004 | + .01
3655 + .0054 0.9 — .912 —111 — .0014 — .03
3656 + .0088 1.0 — .912 —111 + .0002 .00
4570 + .0332 0.8 + .812 +132 — .0010 — .02
4571 + .0336 0.8 + .812 +132 — .0014 — .02
4615 + .0317 0.9 + .724 +140 + .0006 | + .01
4616 + .0310 0.9 + .724 +140 + .0013 + .02
5080 + .0342 0.7 — .917 +255 — .0032 — .06
5115 + .0338 0.7 — .963 +264 — .0024 | — .04
5170 + .0287 0.9 — .986 +275 + .0034 | + .07
5171 +0.0312 1.0 —0.986 +275 +0 .0009 +0.02

 

The normal equations are:

14.8¢ — 0.769% — 1.26567 = + 0.2475 mm.
+ 58.9162u — 8.74067 = + 0.3701 mm.
+ 11.6588¢ = — 0.0172 mm.

from which:

¢ = + 0.01762 mm.
w= + 0.00740 mm. = + 071539, or + 0"562 per year.
a = + 0.00598 mm. = + 07124 + 0”007.

Probable error of plate of unit weight
+ 0.00101 mm. = + 07021.

e LEPORIS (55 1™; —22° 30’)

The only value of the parallax is the spectroscopic result of
Adams who finds the parallax + 07018. The star is of K5 type,
PARALLAXES OF 260 STARS

159

of magnitude 3.95, and of 0°07 total annual proper motion.
Mr. Briggs measured the seventeen plates of the series, and
found the proper motion in right ascension to be + 0”026 per
year, while the value due to Boss is + 07026.

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Puates or e LEPORIS
No. Date. Hour Angle. Observers. Weight.
368 1914 Oct. 1 —017 M 0.9
1808 1915 Oct. 10 —0.4 A 0.9
1809 Oct. 10 0.0 A 1.0
1908 Oct. 29 —0.9 G 0.8
1909 Oct. 29 —0.4 G 0.8
2271 1916 Jan. 3 —0.2 G 0.9
2272 Jan. 3 +0.2 G 0.8
2327 Jan. 17 +0.2 G 0.7
3100 Sept. 26 —0.8 L 0.5*
3131 Oct. 1 —0.3 L 0.9
3610 1917 Jan. 25 —0.1 L 1.0
8735 Mar. 9 +0.9 Ol, L 0.9
4440 Sept. 18 —0.1 B 0.8
4454 Sept. 19 —0.2 A 0.9
4479 Sept. 26 +0.4 B 0.9
4494 Oct. 1 —0.4 B 1.0
4495 Oct. 1 0.0 B 1.0.
* One exposure.
Comparison Stars

No. Diameter. ms (Right Ascen- Y (Declination). Dependence.

1 0.15 —48.5 —24.5 +0.1575

2 .14 + 4.0 +29.3 - 2622

3 .23 +12.3 +26.5 - 2769

4 : -18 +32.2 —31.3 +0.3034

Parallax star 0.23 + 6.59 + 1.67

 

 

 

 

 
160 S, A. MITCHELL

TABLE 2
REDUCTIONS FOR « LEPORIS

 

 

 

 

 

Solution Weight Parallax Time in Residual * iv Dev
Plate. (m). (p). | Factor (P). | Days (2). @). in Are,
mm. mm.

368 +0.0049 0.9 +0.925 —681 +0.0001 +0700
1808 + .0070 0.9 + .858 —307 — .0007 — .01
1809 + .0076 1.0 + .858 —307 | ee 0013 — .03
1908 + .0085 0.8 + .647 — 288 + .0027 + .05
1909 + .0061 0.8 + .647 —288 + .0001 -00
2271 + .0068 0.9 — .426 —222 — .0013 — .02
2272 + .0033 0.8 — .426 —222 + .0022 + .04
2327 + .0050 0.7 — .630 —208 + .0004 + .01
3100 + .0122 0.5 + .952 + 45 — .0046 — .07
3131 + .0064 0.9 + .922 + 50 + .0012 + .02
3610 + .0086 1.0 — .738 +166 — .0020 — .04
3735 + .0055 0.9 — .988 +209 + .0011 + .02
4440 + .0088 0.8 + .986 +402 .0000 .00
4454 + .0039 0.9 + .983 +403 + .0049 + .10
4479 + .0090 0.9 + .953 +410 — .0002 -00
4494 + .0124 1.0 “+ 923 +415 — .0036 — .07
4495 +0.0083 1.0 +0 .923 +415 +0.0005 +0.01

 

 

 

 

 

The normal equations are:
14.7c + 1.249y + 6.38857 = + 0.1030 mm.
168.4559u + 4.32907 = + 0.0703 mm.
10.238507 = + 0.0521 mm.
from which:
c = + 0.00663 mm.
w= + 0.00035 mm. = + 070072, or + 07026 per year.
a= = + 0.00081 mm. = + 07017 + 0'011.
Probable error of plate of unit weight
+ 0.00146 mm. = + 07030.

» AURIGZA (55 12"; +40° 0’)

This star of magnitude 4.85 and of Go type has a considerable
total proper motion 0”846. Its parallax has been several times
PARALLAXES OF 260 STARS 161

determined as follows: Chase with the heliometer derived the
value + 07112 + 07041, Kostinsky by photography + 0710
+ 0702, Flint by meridian circle + 0”077 + 0”028, and Abetti
by meridian circle + 07111 + 07030, Swarthmore Observatory
by photography + 07069 + 07008, and Mt. Wilson by the

 

 

 

TABLE 1
PuatTes oF \ AURIGE
No. Date. Hour Angle. Observers. Weight.
4528 1917 Oct. 6 —017 M 1.0
4585 : Oct. 15 —1.1 B 0.9
4586 Oct. 15 —0.8 B 0.9
4719 Nov. 16 —0.9 Ds 0.9
4720 Nov. 16 —0.5 Ds 0.9
5126 1918 Feb. 23 —0.2 M 0.9
5856 Nov. 2 —0.6 M 0.9
5857 Nov. 2 —0.3 M 1.0
6199 1919 Jan. 8 —0.3 F 1.0
6284 Jan. 20 —1.2 F 0.9
6285 Jan. 20 —0.9 F 0.7
6306 Jan. 21 —0.3 D 1.0
‘7785 Sept. 24 —0.8 D 1.0
7786 Sept. 24 —0.3 D 1.0
7953 Oct. 19 —0.5 A 1.0
7954 Oct. 19 —0.1 A 1.0
8548 1920 Feb. 8 —0.5 M 0.6
8549 Feb. 8 —0.1 M 0.9

 

 

 

 

 

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. |* or Y (Declination). Dependence.
mm. mm. mm.
1 0.07 —37.2 — 5.0 +0.236
2 .09 —16.6 + 2.0 -195
3 .12 — 0.7 +11.8 .142
4 -08 +21.9 + 4.6 -171
5 .10 +32.6 j —13.4 +0.256
Parallax star 0.13 - 0.1 — 1.7

 

12
162 S, A. MITCHELL

spectrograph + 07066. Miss France measured the McCormick
plates and found the parallax + 07064 + 07009 with a proper
motion in right ascension + 0”534 where the corresponding
value from Boss is + 0”529.

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR \ AURIGZ
Plate Solution Weight Parallax Time in Residual 7 Vp-0
' (m). (p). Factor (P). | Days (é). (v). in Are.
mm. mm.

4528 —0.0826 1.0 +0.908 —418 +0.0036 +007
4585 — .0296 0.9 + .832 —409 + .0010 + .02
4586 — .0278 0.9 + .832 —409 — .0008 — .01
4719 — .0251 0.9 + .416 —377 — .0025 — .05
4720 — .0282 0.9 + .416 —377 + .0006 + .01
5126 — .0229 0.9 — .954 —278 — .0020 — .04
5856 — .0010 0.9 + .626 — 26 — .0013 — .02
5857 — .0008 1.0 + .626 — 26 — .0015 — .03
6199 + .0014 1.0 — .468 + 41 — .0024 — .05
6284 — .0013 0.9 — .639 + 53 + .0007 + .01
6285 — .0014 0.7 — .639 + 53 + .0008 + .01
6306 — .0035 1.0 — .652 . + 54 + .0029 + .06
7785 + .0219 1.0 + .978 +300 — .0002 -00
7786 + .0194 1.0 + .978 +300 + .0023 + .05
7953 + .0244 1.0 + .797 +3825 — .0015 — .03
7954 + .0243 1.0 + .797 +325 — .0014 — .03
8548 + .0229 0.6 — .849 +4387 + .0028 + .05
8549 +0.0261 0.9 —0.849 +4387 —0.0004 —0.01

 

The normal equations are:
16.5¢ — 0.471p + 3.619387 = — 0.0316 mm.

+ 148.9297 — 6.26857 = + 1.0286 mm.
+ 9.50777 = — 0.0233 mm.
from which:
c = — 0.00239 mm.
uw = +.0.00703 mm. = + 071462, or + 07534 per year.

a = + 0.00309 mm. = + 07064 + 07009.
Probable error of plate of unit weight
+ 0.00132 mm. = + 0"027.
PARALLAXES OF 260 STARS 163

6B LEPORIS (5° 24"; —20° 50’)

Like the star a Leporis, the only parallax published is that
by Adams, who gives the result + 07038. The star is of G
type, of magnitude 2.96, and of small proper motion, 0”09
per year. The plates were measured by Mr. Olivier, who found
the proper motion in right ascension to be + 0007 while the
value from Boss is + 07006.

TABLE 1

PLates oF 6 LEPORIS

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
570 1914 Nov. 12 +051 M 0.9
805 1915 Jan. 15 —0.1 G 0.4*
1892 Oct. 28 —0.6 Ol 0.8
1969 Nov. 5 +0.1 Ol 0.8
2022 Nov. 16 +0.3 G 0.9
2055 Nov. 24 +0.1 G 0.5
2379 1916 Feb. 4 0.0 G 0.5*
2403 Feb. 14 0.0 G 0.8
2404 Feb. 14 +0.5 G 0.9
2426 Feb. 27 +0.2 M 1.0
2427 Feb. 27 +0.6 M 0.8
3088 Sept. 24 0.0 L 0.9
3102 Sept. 26 —0.3 L 0.9
3103 Sept. 26 +0.1 L 0.7*
8245 Oct. 22 —0.1 L 0.9
3246 Oct. 22 +0.4 L 1.0
8593 1917 Jan. 17 +0.5 Ol 0.6*
3641 Jan. 30 —0.3 M 1.0
3642 Jan. 30 0.0 M 0.9
3671 Feb. 16 —0.4 Ol 0.9
3672 Feb. 16 +0.1 Ol 0.9

 

* One exposure.
164

S. A. MITCHELL

REDUCTIONS FOR #8 LEPoris

TABLE 2

 

 

 

 

 

 

 

 

. . = . id aye
pias: | Oe || ee cies eee) | alee
mm. mm.

570 +0.0007 0.9 +0.521 —541 +0.0011 | +0702
805 + .0020 0.4 — .6385 —477 — .0001 00
1892 + .0039 0.8 + .721 —191 — .0018 — .03
1969 + .0035 0.8 + .624 —183 — .0014 — .02
2022 + .0014 0.9 + .465 —172 + .0007 | + .01
2055 + .0006 0.5 + ..337 —164 + .0016 + .02
2379 + .0046 0.5 — .786 — 92 — .0023 — .03
2403 + .0038 0.8 — .879 — 82 — .0015 — .03
2404 + .0007 0.9 — .879 — 82 + .0016 | + .03
2426 + .0020 1.0 — .960 — 69 + .0003 | + .01
2427 + .0027 0.8 — .960 — 69 — .0004 — .01
3088 + .0017 0.9 + .985 +141 + .0007 | + .01
3102 + .0024 0.9 + .978 +143 .0000 .00
3103 + .0013 0.7 + .978 +143 + .0011 + .02
8245 + .0025 0.9 + .785 +169 — .0001 -00
3246 + .0036 1.0 + .785 +169 — .0012 — .02
3593 + .0005 0.6 — .571 +256 + .0021° -03
3641 + .0036 1.0 — .739 +269 — .0010 |; — .02
3642 + .0016 0.9 — .739 +269 + .0010 + .02
3671 + .0032 0.9 — .901 +286 — .0006 | — .O1
3672 +0.0023 0.9 —0.901 +286 +0.0003 | +0.01

 

 
PARALLAXES OF 260 STARS 165

ComPaRISON STARS

 

 

 

 

 

 

No. Diameter. * aor ies Y (Declination). Dependence.
~ mm. 7 mm. mm.
1 0.24 — 23.5 —36.5 +0.2239
2 25 —13.7. —17.5 2034
3 18 — 5.5 —27.9 2598
4 -20 - 1.1 +53.5 -0465
5 14 +43.8 +28 .4 +0. 2664
Parallax star 0.21 | + 2.1 — 8.9

 

The normal equations are:

17.0c + 3.3304 — 1.12317 = + 0.0398 mm.
+ 90.8624n — 5.03237 = + 0.0160 mm.
+ 10.88777 = — 0.0037 mm.
from which:
c = + 0.00232 mm.
Bw = + 0.00009 mm. = + 0”0018, or + 0"007 per year.

a = — 0.00006 mm. = — 07001 + 07005.
Probable error of plate of unit weight
ef + 0.00074 mm. = + 0"015.

W.. B. 55592 (55 26"; —3° 42’)

This star of 8.9 magnitude, of type Ma has a considerable
proper motion 2722 per year. Miss Darkow measured the
McCormick plates and derived a relative parallax + 07163
+ 07009, with a proper motion in right ascension + 07811 where
the corresponding value from Porter is + 07744.

The parallax has been several times determined as follows:

 

 

 

 

 

Parallax. Authority. Method.
+0706 +07036 Flint Meridian circle
+ .189+ .010 Schlesinger Photography
+ .1386+ .065 Kimberg Photography
+ .208+ .118 Jewdokimov Meridian circle
+0.166 Mt. Wilson Spectrograph

 
166 8. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Piates or W. B. 55592
No. Date. Hour Angle. Observers. Weight.
4683 1917 Nov. 2 —0h7 - M 0.5
4691 Nov. 3 0.1 Ds 0.5
4692 Nov. 3 +0.3 Ds 0.9
4729 Nov. 7 —1.2 B 0.9
4730 Nov. 7 —0.8 B 0.9
4802 Nov. 22 +0.2 B 0.9
5094 1918 Feb. 17 —0.6 M 0.6*
5095 Feb. 17 —0.2 M 0.6*
5715 Sept. 22 —0.8 M 0.8
5716 Sept. 22 —~0.4 M 1.0
5883 Nov. 5 —0.6 M 1.0
5884 Nov. 5 —0.2 M 1.0
6256 1919 Jan. 15 +0.3 D 0.8
6257 Jan. 15 +0.8 D 0.9
6362 Jan. 27 —0.5 D 1.0
6363 Jan. 27 -—0.1 D 0.9
6600 Mar. 3 +0.1 D 1.0
6601 Mar. 3 +0.4 D 1.0
7724 Sept. 15 —1.0 D 1.0
7725 Sept. 15 —0.7 D 0.8
7744 Sept. 16 -1.1 D 1.0
7745 Sept. 16 —0.7 D 1.0
* One exposure.
Comparison STARS
No. Diameter. F a nea Y (Declination). Dependence.
mm. mm. mm.

1 0.14 —37.5 — 5.4 +0.164

2 11 -—13.9 — 9.7 .192

3 13 + 4.0 +48.8 -169

4 -11 + 5.3 3 —19.5 .220

5 15 +42.1 —14.2 +0.255

Parallax star 0.15 + 3.7 — 2.4

 

 
PARALLAXES OF 260 STARS

16

 

 

 

 

 

 

 

 

TABLE 2
Repvuctions ror W. B. 55592

Solution Weight | Parallax Time in Residual: Vp-o
Plate. (m). (p) Factor (P). | Days (é). (). in Are

mm. mm.
4683 —0.0506 0.5 +0.665 —323 —0.0024 —0°04
4691 — .0586 0.5 + .652 —322 + .0056 + .08
4692 — .0542 0.9 + .652 —322 + .0012 + .02
4729 — .0534 0.9 + .598 —318 + .0004 + .01
4730 — .0516 0.9 + .598 —318 — .0014 — .03
4802 — .0534 0.9 + .371 —303 + .0002 -00
5094 — .0498 0.6 — .902 —216 — .0041 — .07
5095 — .0483 0.6 — .902 —216 — .0056 — .09
5715 — .0148 0.8 + .994 + 1 — .0010 — .02
5716 — .0166 1.0 + .994 + i + .0008 + .02
5883 — .0134 1.0 + .629 + 45 — .0006 — .01
5884 — .0165 1.0 + .629 + 45 + .0025 + .05
6256 — .0165 0.8 — .527 +116 + .0010 + .02
6257 — .0179 0.9 — .527 +116 + .0024 + .05
6362 — .0180 1.0 — .690 +128 + .0025 + .05
6363 — .0154 0.9 — .690 +128 — .0001 .00
6600 — .0134 1.0 — .975 +163 — .0006 — .01
6601 — .0150 1.0 — .975 +163 + .0010 + .02
7724 + .0228 1.0 +1.004 +359 — .0003 — .01
7725 + .0262 0.8 +1.004 +359 — .0037 — .07
7744 + .0228 1.0 +1.003 +360 — .0002 .00
7745 +0.0232 1.0 +1.003 +360 —0.0006 —0.01

 

 

The normal equations are:

19.0c + 5.0784 + 4.27677 = — 0.3630 mm.
+ 112.0341u + 2.28777 = + 1.0943 mm.
+ 12.23437 = + 0.0191 mm.
from which:
c = — 0.02373 mm.
w= +.0.01068 mm. = + 072222, or + 07811 per year.

ax = + 0.00786 mm. = + 07164 + 07009.
Probable error of plate of unit weight is

+ 0.00142 mm. = + 07030.
168 S. A. MITCHELL

a LEPORIS (5' 28"; —17° 53’)

The only parallax so far published -of this star is the spectro-
scopic value of Adams, + 0019. The star is of F type, and of
magnitude 2.69, and with a total proper motion less than 0701
per year. The twenty-three plates of the series were measured
by Mr. Mitchell, who found the proper motion in right as-
cension to be + 0%023 per year while the value due to Boss
is + 07001.

TABLE 1

PLATES OF a@ LEPORIS

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
455 1914 Oct. 31 —043 M 0.7
483 Nov. 3 —0.8 G 0.7
532 Nov. 9 —0.2 G 0.6
616 | ~~ Nov. 22 0.0 A 0.7
821 1915 Jan. 21 +0.7 Ol 0.7
836 Jan. 29 —0.4 G 0.7
853 Feb. 8 +1.2 Ol 0.6
989 Mar. 3 +0.6 G 0.7
1729 Sept. 21 -1.2 G 0.7
1730 Sept. 21 —0.6 G 0.7
1759 Sept. 24 —0.2 G 0.7
1789 Oct. 8 —0.6 G 0.8
3153 1916 Oct. 7 +0.1 M 0.9
3154 Oct. 7 +0.4 M 0.8
8155 Oct. 7 +0.8 M 0.8
3264 Oct. 24 0.0 M 0.8
3265 Oct. 24 +0.4 M 0.8
3630 1917 Jan. 28 —0.3 M 1.0
3631 Jan. 28 +0.2 M 0.8
3666 Feb. 14 —0.5 A 1.0
3667 Feb. 14 —0.2 A 1.0
3689 Feb. 22 +0.3 L 1.0
3690 Feb. 22 +0.7 L 1.0

 

 

 

 
PARALLAXES OF 260 STARS, 169

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR a LEPORIS
Pies | SR | Mee) eee | ene | ae | ae.
mm. . mm.
455 +0.0034 0.7 +0.699 —453 —0.0040 |- —0%07
483 — .0032 0.7 + .662 —450 + .0026 ; + .04
532 — .0016 0.6 + .580 —444 + .0009 | + .01
616 — .0028 0.7 + .382 —431 + .0021 + .04
821 — .0011 0.7 — .607 —371 + .0001 .00
836 — .0001 0.7 — .710 —363 — .0009 — .01
853 — .0012 0.6 — .820 —353 + .0002 .00
989 — .0018 0.7 — .973 —330 + .0008 | + .01
1729 + .0012 0.7 + .998 —128 — .0007 — .01
1730 -0000 0.7 + .998 —128 + .0005 | + .01
1759 + .0012 0.7 + .991 —125 — .0007 | — .Ol
1789 + .0022 0.8 + .924 —111 — .0017 — .03
3153 — .0021 0.9 + .926 +253 + .0037 | + .07
3154 + .0022 0.8 + .926 +253 — .0006 | + .O1
3155 + .0018 0.8 + .926 +253 — .0002 -00
3264 + .0003 | 0.8 + .775 +270 + .0013 | + .02
3265 + .0038 0.8 + .775 +270 — .0022 |.— .04
3630 + .0030 1.0 — .704 +367 — .0018 — .04
3631 + .0019 0.8 — .704 +867 — .0007 — .01
3666 — .0028 1.0 — .878 +884 + .0040 | + .08
3667 + .0034 1.0 — .878 +384 — .0022 | — .05
3689 + .0028 1.0 — .934 +892 — .0016 | — .03
3690 —0.0002 1.0 —0.934 +392 +0.0014 —0.03

 

 

 
170 S. A. MITCHELL

CoMPARISON STARS

 

 

 

 

 

 

 

No. Diameter. “ ae ne Y (Declination). Dependence.
mm. mm, mm. Ns
1 0.10 —40.8 —44.3 +0.0951
2 18 —25.6 +14.5 .1545
3 .10 —22.4 +49.3 . 1844
4 -10 — 0.7 +27.9 .1877
5 .20 +43.0 +11.9 .2151
6 3 14 +46.5 —59.3 +0.1632--
Parallax star 0.15 + 4.8 + 5.2
The normal equations are:
18.2c + 7.648 + 0.96707 = + 0.0102 mm.
+ 203.83868n — 12.62197 = + 0.0590 mm.
+ 12.67797 = + 0.0021 mm.

from which:

c = + 0.00041 mm.
pw = + 0.00030 mm.

ax = + 0.00044 mm. =

Probable error of plate of unit weight

+ 070063, or + 07023 per year.
+ 07009 + 0”008.

+ 0.00127 mm. = + 0"026.

GROOMBRIDGE 990 (55 30"; +51° 23’)

Three parallax values have been published for this star, the
heliometer result of Chase with the value + 07015 + 07037,
the Allegheny photographie result + 07035 + 07006, and the
The star is of

spectroscopic value of Mt. Wilson, + 0"048.

magnitude 8.1, of spectral type K, and of total proper motion,
0756. Miss France measured the plates, and derived the relative
parallax of + 07024 + 0007, while the proper motion in right
ascension amounted to — 0567 while the corresponding result

of Porter is — 0"552.
PARALLAXES OF 260 STARS

171

 

 

 

 

 

 

 

 

 

 

 

&
TABLE 1
PLatTEes OF GROOMBRIDGE 990
: N 0. Date. Hour Angle. Observers. Weight.
3224 1916 Oct. 20 —043 L 0.7
3225 Oct. 20 0.0 L 0.7
3335 Nov. 2 —0.2 M 0.7
3358 Nov. 7 —0.5 L 1.0
3359 Nov. 7 —0.1 L 1.0
3669 1917 Feb. 16 —0.4 L 1.0
3670 Feb. 16 —0.1 L, Ol 0.9
4546 Oct. 7 —0.2 Ol 1.0
4547 Oct. 7 +0.1 Ol 0.7
4706 _ Nov. 5 —0.6 B 1.0
4707 ~ Nov. 5 —0.2 B 1.0
5064 1918 Feb. 12 —0.8 Ol 1.0
5065 Feb. 12 —0.3 Ds 1.0
5691 Sept. 14 -1.3 M 1.0
5703 Sept. 21 —1.1 M 1.0
5704 Sept. 21 —0.7 M 1.0
5828 Oct. 21 —0.6 M 1.0
6269 1919 Jan. 19 —0.6 M 1.0
6270 Jan. 19 —0.2 M 1.0
6334 Jan. 24 —0.5 D 1.0
6335 Jan. 24 —0.1 D 1.0
6581 Feb. 27 -0.5 M 1.0
6582 Feb. 27 —0.1 M 1.0
ComPaRIsON STARS

No. Diameter. x aught Ascen-| y (Declination). Dependence.

1 0.15 —21.7 —15.4 +0.129

2 .16 —18.8 — 1.0 232

3 .10 + 5.0 +27.0 443

4 ll +35.5 —10.6 +0.196

Parallax star 0.14 + 2.0 + 7.7

 

 

 

 

 
172

S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR GROOMBRIDGE 990
Solution Weight Parallax Time in Residual : vp-»
Plate. (m). (p). | Factor (P). | Days @). . (). in Are.
mm. mm.
3224 +0.0184 0.7 +0.823 —459 —0.0010 —0'02
3225 + .0141 0.7 + .823 —459 + .0033 + .06
3335 + .0138 0.7 + .675 —446 + .0024 | + .04
3358 + .0170 1.6 + .609 —441 — .0012 | — .02
3359 + .0199 1.0 + .609 —441 — .0041 — .08
3669 + .0057 1.0 — .889 —340 + .0008 | + .02
3670 + .0070 0.9 — .889 —340 — .0005 — .01
4546 — .0114 1.0 + .981 —107 + .0026 | + .05
4547 — .0097 0.7 + .931 —107 + .0009 | + .02
4706 — .0124 1.0 + .639 — 78 + .0011 |. + .02
4707 — .0122 1.0 + .639 — 78 + .0009 + .02
5064 — .0188 1.0 — .853 + 21 — .0016 — .03
5065 — .0204 1.0 — .853 + 21 .0000 .00
5691 — .0326 1.0 +1.003 +235 — .0017 — .04
5703 — .0354 1.0 + .998 +242 + .0006 + .01
5704 — .0319 1.0 + .998 +242 — .0029 — .06
5828 — .0376 1.0 + .818 +272 + .0003 | + .01
6269 — .0451 1.0 — .569 +362 — .0005 | — .O1
6270 — .0461 1.0 — .569 +362 + .0005 | + .01
6334 — .0472 1.0 — .638 +367 + .0012 + .02
6335 — .0476 1.0 — .638 +367 + .0016 | + .03
6581 — .0502 1.0 — .954 +401 + .0012 | + .02
6582 —0.0468 1.0 —0.954 +401 —0.0022 —0.04
The normal equations are:
21.7¢ + 4.7234 + 1.803387 = — 0.4212 mm.
+ 217.47154 — 17.11427 = — 1.7294 mm.
fase + 14.20497 = + 0.1121 mm.
c = — 0.01788 mm.
w= — 0.00747 mm. = — 071554, or — 07567 per year.
«= + 0.00116 mm. = + 0024 + 0”007.

Probable error of plate of unit weight

+ 0.00122 mm. = + 0”025.
PARALLAXES OF 260 STARS 173

y LEPORIS (5' 40"; —22° 28’)

According to Burnham’s General Catalogue, ‘‘this is a remark-
able system from the large proper motion of the stars.’ This
proper motion amounts to 0"47 per year. The principal star
is of magnitude 3.80 and of type F8. The companion is Lalande
10931, and is of magnitude 6.4 and type K. The only deter-
mination of the parallax is due to Adams, who finds for the
brighter star the value + 0”158, and for the fainter the parallax
+0%115. On account of the common parallax and common
proper motion, these two stars undoubtedly form a physical sys-
tem. ‘The present series of plates were measured by Mr. Mitchell.

TABLE 1

Puates oF y Leporis, AND LALANDE 10931

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
369 1914 Oct. 1 —017 M 0.8
411 Oct. 19 —0.3 G 0.7
863 1915 Feb. 9 +0.2 M 0.8
864 Feb. 9 +0.8 M 0.7
975 Mar. 2 +0.4 A 0.8
1845 Oct. 24 —0.5 G 0.8
1846 Oct. 24 —0.2 G 0.7
1924 Oct. 30 —0.8 M 0.8
1925 Oct. 30 —0.5 M 0.6
2364 1916 Feb. 3 +0.5 M 0.5*
2418 Feb. 20 0.0 M 0.7
2419 Feb. 20 +0.4 M 0.5*
2451 Mar. 9 +0.6 A 1.0
2452 Mar. 9 +0.9 A 1.0
8714 1917 Mar. 6 +0.3 L 1.0
8715 Mar. 6 +0.6 L 1.0
3729 Mar. 8 +0.5 L 1.0
3730 Mar. 8 +0.9 L 1.0

 

 

 

* One exposure.
174

S. A. MITCHELL

Combining the parallaxes of the two stars, we have the parallax

of the system to be:

+ 07143 + 07006.

ComPARISON STARS

 

 

 

 

 

 

 

 

 

 

 

Dependence.
: ¢ (Righ Y (Declina-

No: Diameter. Ketan . (es i: a Principal :

Star. Companion.
mm. mm. mm.

1 0.11 —66.3 + 0.3 +0.258 +0.275

2 .16 +12.3 -17.1 -346 - 264

3 -12 +24.4 +25.1 .108 .213

4 .08 +29.6 — 8.3 +0.293 +0.248

Principal star 18 — 1.7 — 5.7
Companion 0.08 — 2.5 — 1.2
TABLE 2
RepuctTions For y Leroris, BRIGHTER STAR
Solution Weight Parallax Time in Residual Vp-v
Plate. (m). (p). Factor (P). | Days (t). v). in Arc.
mm. mm.

369 —0.0018 0.8 +0.976 —474 —0.0006 —0°’01
All — .0008 0.7 + .858 —456 — .0031 — .05
863 — .0192 0.8 — .804 —343 — .0006 — .01
975 — .0215 0.8 — .960 —3822 — .0002 .00
1845 — .0200 0.8 + .812 — 86 + .0023 + .04
1846 — .0200 0.7 + .812 — 86 + .0023 + .04
1924 — .0182 0.8 + .747 — 80 — .0002 .00
1925 — .0172 0.6 + .747 — 80 — .0012 — .02
2364 — .0365 0.5 — .736 + 16 + .0041 + .06
2418 — .0855 0.7 — .899 + 33 + .0013 + .02
2419 — .0343 0.5 — .899 + 33 + .0001 .00
2451 — .0359 1.0 — .986 + 51 + .0004 + .01
2452 — .0363 1.0 — .986 + 51 + .0008 + .02
3714 — .0456 1.0 — .978 +413 — .0030 — .06
3715 — .0487 1.0 — .978 +413 + .0001 -00
3729 — .0484 1.0 — ,983 +415 — .0004 — .01
3730 —0.0488 1.0 —0.983 +415 0.0000 0.00

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS 175

According to Boss the proper motions in right ascension of the
two stars are: for the brighter star — 07296 per year, and for
the fainter, — 07278. The values found from the present
photographs are — 0"277 and — 0"274 respectively.

The normal equations are:

13.7c + 3.342u — 5.10687 = — 0.4134 mm.
+ 121.4641u — 21.30257 = — 0.6833 mm.
+ 11.33267 = + 0.2942 mm.
from which:
c = — 0.02664 mm.
B = — 0.00365 mm. = — 070759, or — 07277 per year.

a = + 0.00710 mm. = + 07148 + 07009.
Probable error of plate of unit weight
+ 0.00108 mm. = + 07022.

TABLE 3

“REpucTIons FoR y Leporis, Farinrer Star (LALANDE 10981)

 

 

 

 

 

 

 

 

Solution Weight | Parallax Time in -Residual _Vp+0
Plate. (m). (p). | Factor (P). | Days (). (). in Arc.
“mm. mm.

369 —0.0354 1.0 +0.976 | —374 +0.0002 0°00
411 — .03854 1.0 + .858 —356 — .0013 — .03
863 — .0520 1.0 — .804 — 243 .0000 .00
864 — .0513 0.7 — .804 —243 — .0007 — .01
975 — .0559 0.7 — .960 —222 + .0021 + .04
1845 — .0519 0.9 + .812 + 14 + .0016 |} + .03
1846 — .0485 0.7 + .812 + 14 — .0018 — .03
1924 — .0520 0.9 + .747 + 20°} + .0010 + .02
2364 — .0652 0.6 — .736 +116 + .0008 + .01
2418 — .0673 0.6 — .899 +133°) + .0011 + .02
2419 — .0650 0.6 — .899 +133 — .0011 — .02
2451 — .0656 1.0 — .986 +151 — .0018 — .04
. 2452 —0.0676 1.0 —0.986 +151 + .0002 0.00

 

 

The normal equations are:

10.7¢ — 7.269% — 1.72577 = — 0.5770 mm.
+ °47.7070n — 6.50007 = + 0.1862 mm.
+ 8.22927 = + 0.1744 mm.
176 S. A. MITCHELL

from which:
c = — 0.00675 mm.
uw = — 0.00360 mm. = — 070748, or — 07274 per year.
wr = + 0.05528 mm. = + 07140 + 0”007.

Probable error of plate of unit weight
+ 0.00085 mm. = + 07018.

6 LEPORIS (55 47"; —20° 53’)
The only value for the parallax of this star of 3.90 magnitude
and K type is the spectroscopic result of Mt. Wilson with the

TABLE 1

Priates oF 6 Leporis

 

 

 

No. Date. Hour Angle. Observers. Weight.
3172 1916 Oct. 11 —046 M 0.9
3173 Oct. 11 —0.4 M 1.0
3376 Nov. 10 —0.5 A 0.6*
3377 Nov. 10 —0.3 A 1.0
4625 1917 Oct. 22 —0.6 Ds 0.7
4626 Oct. 22 —0.2 Ds 0.7
4633 Oct. 25 —0.7 Ds 0.5*
4634 Oct. 25 —0.1 Ds 0.6
5158 1918 Mar. 3 +0.3 M 0.8
5159 Mar. 3 +0.7 M 0.8
6247 1919 Jan. 13 +0.2 H .1.0
6248 Jan. 13 +0.6 H 1.0
6475 Feb. 6 0.0 D 1.0
6476 Feb. 6 +0.4 D 1.0
6583 Feb. 27 0.0 M 1.0
6584 Feb. 27 +0.3 M 1.0
8027 Nov. 8 +0.6 Ol 0.8
8072 Nov. 15 0.0 Ol 0.7
8073 Nov. 15 +0.5 Ol 0.7
8106 Nov. 19 —0.3 Ol 0.4*

 

 

 

 

 

* One exposure.
PARALLAXES OF 260 STARS - 177

value +0025. The total proper motion is 0696, of which
+ 0241 is in right ascension, according to Boss. Miss Hawes
measured the McCormick plates and derived the relative parallax
+ 07019 + 0°010 with a proper motion in right ascension
+ 07239. In addition to the large proper motion, the star has
a large radial velocity + 99 km. per second. (Astrophysical
Journal, 49, 179, 1919.)

*

TABLE 2

ReEDucTIONS FOR 6 LEPORIS

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp
Plate. (m). (p). | Factor (P). | Days (). (v). in Are.

mm. mm.
3172 —0.03891 0.9 +0.928 — 609 -—0.0002 0700
3173 — .0414 1:0 + .928 —609 + .0020 + .04
3376 — .0422 0.6 + .618 —579 + .0035 + .06
3377 — .0350 1.0 + .618 —579 — .0037 — .08
4625 — .0276 0.7 + .842 —233 .0000 .00
4626 — .0268 0.7 + .842 — 233 — .0008 — .O1
4633 — .0275 0.5 + .812 —230 .0000 .00
4634 — .0280 0.6 + .812 —230 + .0005 + .01
5158 — .0208 0.8 — .960 —101 — .0042 — .08
5159 — .0278 0.8 — .960 —101 + .0028 + .05
6247 — .0144 1.0 — .427 +215 — .0002 .00
6248 — .0166 1.0 — .427 +215 + .0020 + .04
e475 | — .0147 | 1.0 | — .756 | +239 | + .0006 | + .01
6476 — .01385 1.0 — .756 +239 — .0006 — .01
6583 — .0152 1.0 — .937 +260 + .0016 + .03
6584 — .0126 1.0 — .937 +260 — .0010 — .02
8027 — .0054 0.8 + .654 +514 + .0012 + .02
8072 — .0026 0.7 + .557 +521 — .0015 — .02
8073 — .0023 0.7 + .557 +521 — .0018 — .03
8106 —0.0051 0.4 +0.499 +525 +0.0011 +0.01

 

13
178 S. A. MITCHELL

CoMPARISON STARS

 

 

 

 

 

 

No. Diameter. x ee ee Y (Declination). Dependence.
mm. mm. mm.
1 0.22 —41.6 +21.2° +0.185
2 -1l —40.8 —29.2 . 242
3 .16 + 7.3 — 2.4 -201
4 .14 +33.9 z —30.7 .227
5 15 +41.2 +41.1 +0.145
Parallax star | 0.16 — 2.5 — 4.7 °

 

The normal equations are:

16.2¢ — 0.457u + 0.55067 = — 0.3412 mm.
+ 248.5092u — 22.23497 = + 0.7568 mm.
+ 9.5795xr = — 0.0730 mm.
from which:
c = — 0.02100 mm.

w= + 0.00315 mm. = + 070655, or + 07239 per year.
a+ = + 0.00089 mm. = + 07019 + 0010.

Probable error of plate of unit weight
+ 0.00127 mm. = + 0"026.

x ORIONIS (5° 48"; +20° 15’)

According to the investigations of H. C. Plummer (Monthly
Notices, R. A. S., 76, 134, 1915), this star which is of 4.62 magni-
tude and F8 type, is a member of an extended Ursa Major group,
and on this assumption should have an absolute parallax of
+ 07135. Mr. Alden measured the McCormick plates, and
found a relative parallax of + 0”105 + 0"006, so that the value
of the absolute parallax is + 07110 + 0”006, a result which
seems to substantiate the claim of Plummer. By photography
Allegheny finds the relative parallax + 0096 + 0”010, and Mt.
Wilson by the spectrograph the absolute value + 07100. The
annual proper motion in right ascension from the photographs is
— 07145, while the value from Boss is — 07186.
PARALLAXES OF 260 STARS

179

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
PLATES OF x ORIONIS

No. Date. Hour Angle. Observers. Weight.
3118 1916 Sept. 30 —0h2 M 1.0
3210 Oct. 17 —0.8 L 1.0
3211 Oct. 17 —0.5 L 0.6*
3312 Oct. 31 —0.9 L 1.0
3313 . Oct. 31 —0.6 L 1.0
3647 1917 Feb. 7 —0.5 Ol 0.8
3648 Feb. 7 —0.1 Ol 0.9
3735 Mar. 9 +0.6 L 1.0
3736 Mar. 9 +0.9 L 1.0
4496 Oct. 1 —0.1 B 1.0
4497 Oct. 1 +0.2 B 0.9
4509 Oct. 2 +0.1 A 0.9
4510 Oct. 2 +0.4 A 1.0
4530 Oct.' 6 0.0 M 0.8
4531 Oct. 6 +0.3 M 0.8
4986 1918 Jan. 22 +0.5 M 1.0
5024 Feb. 7 +0.3 A 1.0
5025 Feb. 7 +0.7 A 1.0
5177 Mar. 7 +0.5 A 0.9
» 5189 Mar. 11 +0.4 A 1.0

* One exposure.
Comparison STaRs
No. Diameter. a eee Y (Declination). Dependence.
mm. mm, mm.

1 0.15 —54.7 + 8.1 +0.2787

2 .12 + 2.3 —28.2 . 2169

3 -1l +20.0 —12.7 - 2283

4 .18 +32.4 +32.8 +0.2761

Parallax star 0.14 — 1.2 + 2.3

 

 

 

 

 
180 S. A. MITCHELL

 

 

 

TABLE 2
REDUCTIONS FOR x ORIONIS

Solution Weight Parallax Time in Residual : Vv Dp “0
Plate. (m). (p). Factor (P). | Days (). (v). in Arc.

mm. mm. 3
3118 —0.0023 1.0 +0.985 —270 —0.0010 —0%02
3210 — .0018 1.0 + .887 —253 — .0023 — .05
3211 — .0046 0.6 + .887 —253 + .0005 + .01
3312 — .0056 1.0 + .749 —239 + .0005 + .01
3313 — .0053 1.0 + .749 —239 + .0002 .00
3647 — .0149 0.8 — .768 —140 + .0002 .00
3648 — .0144 0.9 — .768 —140 — .0003 — .01
8735 — .0173 1.0 — .982 —110 + .0010 + .02
3736 — .0180 1.0 — .982 —110 + .0016 + .03
4496 — .0102 1.0 + .982 + 96 — .0001 .00
4497 — .0114 0.9 + .982 + 96 + .0011 + .02
4509 — .0080 0.9 + .978 + 97 — .0024 — .05
4510 — .0140 1.0 + .978 + 97 + .0036 + .07
4530 — .0108 0.8 + .961 +101 + .0003 -00
4531 — .0111 0.8 + .961 +101 + .0006 + .01
4986 — .0184 1.0 — .560 +209 — .0019 — .04
5024 — .0210 1.0 — .765 +225 — .0006 — .01
5025 — .0206 1.0 — .765 +225 — .0010 — .02
5177 — .0222 0.9 — .974 +253 — .0010 — .02
5189 —0.0248 1.0 —0.986 +257 +0.0014 +0.03

 

 

 

 

 

 

 

The normal equations are:

18.6c + 0.6124 + 1.94167 = — 0.2419 mm.
+ 66.7374 — 10.0602 = — 0.1868 mm.
+ 14.71967 = + 0.0677 mm.
from which:
c = — 0.01347 mm.
# = — 0.00191 mm. = — 070398, or — 07145 per year.

a = + 0.00507 mm. = + 07105 + 0”006.
Probable error of plate of unit weight
+ 0.00101 mm. = + 0021.
PARALLAXES OF 260 STARS 181

6 AURIGE (5» 517; +54° 17’)

This star is of Ko type, of magnitude 3.88, and of total proper
motion 015. Three values of the parallax have been published,
the meridian circle result of Abetti who finds the parallax + 0”107
+ 0%033, the photographic value with the Yerkes refractor
+ 07018 + 07013, and the spectroscopic value of Adams with
the parallax + 07021. The present plates were measured by
Mr. Alden who finds the proper motion in right ascension to be
+ 0078 while the value of Boss is + 07086.

TABLE 1

PuatTEes ofr 6 AURIGH

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
417 | 1914 Oct. 21 —046 M 0.8
441 Oct. 30 ~0.4 A 0.6*
629 Nov. 23 —0.5 G 0.8
922 1915 Feb. 20 —0.3 A 0.8
1810 Oct. 10 —0.2 A 1.0
1874 | . Oct. 27 —0.6 A 1.0
1875 Oct. 27 56h at “A 1.0
1951 Nov. 2 —0.7 A 1.0
1952 Nov. 2 -0.4 A -1.0
2386 1916 Feb. 8 -0.4 M 0.8
2390 Feb. 9 -0.4 G 1.0
2397 Feb. 10 -0.5 A 1.0
2398 Feb. 10 -0.1 A 1.0
4552 1917 Oct. 9 —0.2 A 1.0
4587 Oct. 15 —0.8 B 0.9
4588 Oct. 15 —0.4 B 0.8
4647 Oct. 30 -0.2 B 1.0
5010 1918 Jan. 31_ —0.8 A 1.0
5011 Jan. 31 -0.4 A 1.0
5062 Feb. 11 —0.8 A 1.0
5063 Feb. 11 —0.4 A 1.0

 

* One exposure.
182 S, A. MITCHELL

TABLE 2

Repvuctions FoR 6 AURIG#

 

 

 

 

Solution Weight Parallax Time in Residual vp-o0
Plate. (m). (p). | Factor (P). | Days (f). (). in Are.

mm. mm.
417 +0.0005 0.8 +0.864 —624 —0.0005 —0701
441 — .0020 0.6 + .775 —615 + .0021 + .03
629 + .0024 0.8 + .452 —591 — .0020 — .04
922 + .0024 0.8 — .881 —502 — .0008 — .01
1810 + .0017 1.0 + .946 —270 + .0019 + .04
1874 + .0037 1.0 + .809 —253 + .0001 -00
1875 + .0034 1.0 + .809 —253 + .0004 + .01
1951 + .0041 1.0 + .744 —247 — .0002 .00
1952 + .0038 1.0 + .744 —247 + .0001 -00
2386 + .0049 0.8 — .762 —149 + .0003 + .01
2390 + .0052 1.0 — .774 —148 .0000 .00
2397 + .0071 1.0 — .784 —147 — .0019 — .04
2398 + .0039 “1.0 — .784 —147 + .0013 + .03
4552 + .0146 1.0 + .949 +460 — .0034 — .07
4587 + .0104 0.9 + .910 +466 + .0008 + .02
4588 + .0125 0.8 + .910 +466 — .0012 — .02
4647 + .0098 1.0 + .772 +481 + .0016 + .03
5010 + .0106 1.0 — .672 +574 + .0021 + .04
5011 + .0123 1.0 — .672 +574 + .0004 + .01
5062 + .0132 1.0 — .800 +585 — .0004 — .01
5063 +0.0185 1.0 —0.800 +585 —0.0007 —0.01

 

 

 

 

 

 
PARALLAXES OF 260 STARS 183

CoMPaARISON STARS

 

 

 

 

 

 

No. Diameter. “ ae aac Y (Declination). Dependence.
mm. mm. mm.
1 0.12 —46.0 —22.6 +0.4287
2 0.12 +11.2 —17.2 .3607
3 0.19 +34.8 +39.8 +0.2106
Parallax star 0.14 — 8.4 — 7.5

 

The normal equations are:

19.5¢ + 4.7744 + 2.23747 = + 0.1332 mm.
+ 358.0811u4 — 13.52297 = + 0.4043 mm.

+ 12.48337 = — 0.0015 mm.
from which:
ec = + 0.00660 mm.
uw = + 0.00103 mm. = + 070215, or + 07078 per year.

— 0.00019 mm. = — 0°004 + 07006.
Probable error of plate of unit weight
+ 0.00097 mm. = + 07020.

Tv

n LEPORIS (55 52"; —14° 11’)

This star has had its parallax determined by Adams by the
spectroscopic method with the absolute value + 0050. The
star is of magnitude 3.77, of spectral type F5, and of total proper
motion 07138. Mr. Olivier measured the photographs and
derived a relative parallax + 07031 + 07010, and a proper
motion in right ascension — 0012 while the corresponding
value from Boss is — 0”041.
 

 

 

 

 

 

 

 

 

 

 

184 S. A. MITCHELL
TABLE 1
Piates or 7 LEeporis

No. Date. Hour Angle. Observers. Weight.
1057 1915 Mar. 14 +064 M 0.7
1067 Mar. 17 +0.7 A 0.7
1068 Mar. 17 +0.7 A 1.0
1741 Sept. 22 —0.8 Ol 0.7
1821 Oct. 11 +0.7 ol 0.7
1862 Oct. 25 —0.4 Ol 0.6*
1863 Oct. 25 0.0 ol 0.8
2046 Nov. 22 0.0 Ol 0.7
2488 1916 Mar. 16 +0.9 A 1.0
2489 Mar. 16 +1.3 A 1.0
3132 Oct. 1 —0.6 L 0.9
3274 Oct. 25 -0.3 L 0.7
3291 Oct. 27 -1.0 M 1.0
3292 Oct. 27 —0.5 M 0.9
3766 1917 Mar. 19 +0.8 ol 0.9
3767 Mar. 19 +0.2 ol 0.9
3778 Mar. 20 +1.0 M 0.7
4572 Oct. 13 0.0 B 0.9
4573 Oct. 13 +0.4 B 0.9
4617 Oct. 21 —0.1 B 1.0
“4618 * Oct. 21 +0.4 B 1.0
5116 1918 Feb. 22 +0.4 Ol 0.5*
5117 Feb. 22 +0.9 ol 0.7
5172 Mar. 5 +0.8 Ol 0.9
5173 Mar. 5 +1.4 ol 0.9

* One exposure.
Comparison STARS
No. Diameter. x cae aie Y (Declination). Dependence.
mm. mm. mm.

1 0.11 —13.6 -17.3 +0.2607

2 -15 —14.3 —38.3 . 1658

3 .12 — 5.6 +21.0 .3879

4 .14 +33.5 +34.6 +0.1856

Parallax star 0.15 — 1.8 + 3.7

 

 

 
PARALLAXES OF 260 STARS

ReEpvuctions For 7 LEPoris

TABLE 2

185

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual vVp-0
Plate. (m). (p). | Factor (P). | Days@. | = (). in Are.

mm. mm.
1057 +0.0057 0.7 —0.991 —580 —0.0002 0700
1067 + .0042 0.7 — .995 —577 + .0013 02
1068 + .0046 1.0 — .995 —577 + .0009 02
1741 + .0105 0.7 +1.003 —388 — .0024 — .04
1821 + .0126 0.7 +0.940 —369_ | — .0046 — .08
1862 + .0064 0.6 + .829 —365 + .0014 | + .02
1863 + .0057 0.8 + .829 — 365 + .0021 + .04
2046 + .0030 0.7 + .470 | —3827 + .0042 | + .07
2488 + .0050 1.0 — .994 —212 — .0001 -00
2489 + .0077 1.0 — .994 —212-) — .0028 | — .06
3132 + .0087 0.9 + .984 — 13°] — .0012 — .02
3274 + .0052 0.7 + .821 + 11 + .0020 | + .04
3291 + .0095 1.0 + .801 + 13 — .0023 — .05
3292 + .01382 0.9 + .801 + 13 — .0060 | — .12
3766 — .0011 0.9 — .996 +156 + .0054 | + .11
3767 + .0027 0.9 — .996 +156 + .0016 | + .03
3778 + .0024 0.7 — .996 +157 + .0019 | + .03
4572 + -.0031 0.9 + .923 +364 |. + .0037.| + .07
4573 + .0027 0.9 + .923 +364 |° + .0041 | + .08
4617 |~ + .0052 1.0 + .861 +372 + .0015 | + .03
4618 + .0076 1.0 + .861 +872 — .0009 | — .02
5116 + .0010 0.5 — .899 +496 + .0029 | + .04
5117 + .0060 0.7 — .899 +496 — .0021 — .04
5172 + .0062 0.9 — .964 +507 — .0024 | — .05
5173 +0.0090 0.9 —0.964 —0.0052 | —0.10

 

 

+507

 
186 S. A. MITCHELL

The normal equations are:
20.7c + 2.3774 — 0.46197 = + 0.1233 mm.

+ 268.8191 + 2.09347 = — 0.0258 mm.
+ 17.48717 = + 0.0227 mm.
from which:
c = + 0.00601 mm.
= — 0.00016 mm. = — 070083, or — 07012 per year.

ll

+ 0.00147 mm. = + 07031 + 0°010.
Probable error of plate of unit weight
+ 0.00196 mm. = + 07041.

1

6 AURIGA (55 52™; +44° 56’)

@ Aurige is a very interesting spectroscopic binary discovered
by Miss Maury from photographs taken at Harvard. Several
determinations have been made of the spectroscopic orbit by
Rambaut, Vogel, Ludendorff and Belopolsky (Lick Observatory
Bulletin, 6, 23, 1910). The star is of Ap type, of magnitude
2.07, and of small annual proper motion 0706. The period of
the spectroscopic binary is 3.96 days. According to Hertz-
sprung (Astrophysical Journal, 30, 135, 1909), 6 Aurige is a
member on an extended Ursa Major group and should have an
absolute parallax of + 07030. The star is an eclipsing binary,
and according to Shapley (Mt. Wilson Contributions, 156) should
have a parallax + 07030. The parallax of the star has been
many times determined, but with results that are not very
accordant. .Pritchard by photography obtained the parallax
+ 07062 + 07024; Kostinsky and Tikhoff derived two different
values, — 07030 + 07014, and + 07015 + 0"018; Flint by
meridian circle found s = + 07034 + 0"020; while Jewdokimov
also with meridian circle found + 07141 + 07062. Mr. Alden
measured the McCormick plates, and found a relative parallax
of + 07026 + 0°009, with a proper motion in right ascension
amounting to — 07076 per year, while the value from Boss is
— 07047.
PARALLAXES OF 260 STARS

18

i

 

 

 

TABLE 1
Priates or 6 AURIGH
No. Date. Hour Angle. Observers. Weight.
323 1914 Sept. 26 —140 M 0.9
845 Sept. 28 —0.4 G 0.9
364 Sept. 30 —0.4 A 0.7
2362 1916 Feb. 3 —0.6 M 0.8
2363 Feb. 3 —0.2 M 1.0
2425 Feb. 26 —0.1 A 1.0
2450 Mar. 9 —0.1 M 0.8
3161 Oct. 10 —0.5 A 0.8
3162 Oct. 10 —0.2 A 0.5*
3217 Oct. 19 —0.4 L 1.0
3218 Oct. 19 —0.1 L 1.0
3293 Oct. 27 0.0 M 1.0
3749 1917 Mar. 10 —0.1 M 0.7
3750 Mar. 10 —0.1 A 0.6*
3751 Mar. 11 0.0 M 0.7
3752 Mar. 12 0.0 Ol 0.7
4507 Oct. 2 —1.0 A 1.0
4508 Oct. 2 —0.5 A 1.0
4521 Oct. 5 —0.6 A 1.0
4522 Oct. 5 —0.3 A 0.9
5022 1918 Feb. 7 —0.6 A 1.0
5023 Feb. 7 —0.2 A 1.0
5047 Feb. 10 —0.7 M 0.5*
5092 Feb. 14 —0.7 A 0.9
5176 Mar. 7 0.0 A 0.7

 

 

 

 

 

* One exposure.

Comparison STARS

 

 

 

No. Diameter. x sae ots Y (Declination). Dependence.
mm. mm. mom,
1 0.16 —32.2 —22.9 +0.2721
2 .13 —11.5 +46.5 . 2412
3 .25 +16.2 + 6.2 - 2405
4 .19 +27.5 —29.8 +0.2462
Parallax star 0.26 — 0.9 — 0.9

 

 

 

 

 
188

S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 2
ReEpuctTions ror @ AURIGH.
Solution Weight Parallax Time in Residual fi vVpeo
Plate. (m). (p). | Factor (P). | Days (¢). (). in Are.
mm. - mm.
323 —0.0062 0.9 +0.998 —800 +0.0005 +0701
345 — .0078 0.9 + .994 —798 + .0021 + .04
364 — .0070 0.7 + .989 —796 + .0012 + .02
2362 — .0102 0.8 — .702 —3805 — .0025 | — .05
2363 — .0164 1.0 — .702 —305 + .0037 +.:.08
2425 — .0144 1.0 — .922 —282 + .0012 + .02
2450 — .0095 0.8 — .980 —270 — .0039 — .07
3161 — .0107 0.8 + .942 — 55 — .0025 — .05
3162 — .0098 0.5 + .942 — 55 — .0034 — .05
3217 — .0148 1.0 + .878 — 46 + .0015 + .08
3218 — .0088 1.0 + .878 — 46 — .0045 — .09
3293 — .0111 1.0 + .803 — 38 — .0024 — .05
3749 — .0154 0.7 — .982 + 96 — .0017 | — .03
3750 — .0157 0.6 — .982 + 96 — .0014 — .02
3751 — .0203 0.7 — .985 + 97 + .0032 | + .06
3752 — .0167 0.7 — .987 + 98 — .0004 | — .Ol
4507 — .0188 1.0 + .982 +302 + .0021 + .04
4508 — .0162 1.0 + .982 +302 — .0005 — .01
4521 — .0194 1.0 + .970 +305 | + .0027 + .06
4522 — .0177 | 0.9 + .970 +305 + .0010 + .02
5022 — .0154 1.0 — .755 +430 — .0047 — .10
5023 — .0226 1.0 — .755 +430 + .0025 + .05
5047 — .0218 0.5 — .788 +433 + .0016 + .02
5092 — .02386 0.9 — .828 +437 + .0033 + .07
5176 —0.0200 0.7 —0.971 +458 —0.0006 —0.01
The normal equations are:
21.1le — 0.0874 + 1.12027 = — 0.3128 mm.
+ 307.4249 — 18.63847 = — 0.3274 mm.
from which: + 17.387457 = + 0.0235 mm.
c = — 0.01489 mm. '
uw = — 0.00099 mm. = — 00207, or — 0”076 per year.
a = + 0.00124 mm. = + 0”026 + 0”009.

Probable error of plate of unit weight

+ 0.00170 mm. = + 0°035.
PARALLAXES OF 260 STARS 18°

n GEMINORUM (65 8"; +22° 32’)

This is a variable star of Ma type, and with a range of mag
nitude from 3.2 to 4.2. Reese (Lick Observatory Bulletin, 1
158, 1902) finds it to be a spectroscopic binary with long period
Mt. Wilson by the spectroscope finds the parallax + 07012

 

 

 

TABLE 1
Puates oF 7 GEMINORUM _
ic No. Date. Hour Angle. Observers. Weight.
456 | 1914 Oct. 31 OM M 0.9
962 | 1915 Mar. 1 0.3 G 0.9
963 Mar. 1 +0.2 M, G 1.0
1894 Oct. 28 0.2 ol 0.9
1895 Oct. 28 —0.2 Ol 0.6*
1959 Nov. 3 +0.1 G 0.8
2044 Nov. 21 Zn G 0.7
2426 | 1916 Feb. 26 2G. 1 A 0.5*
2439 Mar. 4 0.0 A 0.9
2440 Mar. 4 40.5 A 1.0
2494. Mar. 17 40.3 Ol, G 0.9
2517 Mar. 22 +1.0 ol 0.7*
4721 | 1917 Nov. 6 —0.8 Ds 0.9
4759 Nov. 10 —0.2 Ds 0.9
4827 Dec. 1 -0.3 B 0.8
4828 Dec. 1 G4 B 0.9

 

 

 

 

 

* One exposure.

ComPaRISON STARS

 

 

 

 

 

 

 

No. Diameter. |~ pac ¥ (Declination). Dependence.
mm. mm. mm.
1 0.13 —54.8 — 2.2 +0.1767
2 .12 —36.7 +23.0 . 1840
3 +12 +18.5 | —36.2 2085
4 16 +45.2 —30.0 2197
5 14 +27.8 +45.4 +0.2111
Parallax star 0.15 + 3.2 — 0.7

 
190 S. A. MITCHELL

Russell by photography derives the parallax of + 07034 + 0025,
and Allegheny the value + 07016 + 07008. The total proper
motion is 07065, while the value in right ascension from Boss is
—07062. Mr. Olivier measured the McCormick plates and
derived the value of proper motion in right ascension of — 07045.

 

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR 71 GEMINORUM
Solution Weight Parallax Time in Residual vp+o
Plate. (m). (p). | Factor (P). | Days (2). (0). in Are.
mm. mm. :
456 —0.0035 0.9 +0.805 —542 —0.0008 —0701
962 — .0043 0.9 — .919 —420 — .0006 — .01
963 — .0023 1.0 — .919 —420 — .0026 — .05
1894 — .0099 0.9 + .837 —179 + .0035 + ..07
1895 — .0036 0.6 + .837 —179 — .0028 — .05
1959 — .0081 0.8 + .776 —173 + .0017 + .03
2044 — .0057 0.7 + .544 —155 — .0008 — .01
2426 — .0111 0.5 — .896 — 58 + .0040 + .06
2439 — .0052 0.9 — .942 — 61 — .0019 — .04
2440 — .0084 1.0 — .942 —- 61 + .0013 + .03
2494 — .0077 0.9 — .991 — 38 + .0005 + .01
2517 — .0094 0.7 — .997 — 382 + .0022 + .04
4721 — .0114 0.9 + .736 +561 + .0006 + .01
4759 — .0098 0.9 + .689 +565 — .0010 — .02
4827 — .0078 0.8 + .382 +586 — .0031 — .06
4828 —0.0118 0.9 +0.382 +586 +0.0009 +0.02
The normal equations are: °
13.3¢ + 0.2594 — 0.66027 = — 0.0989 mm.
+ 185.1335u + 12.2553¢ = — 0.1114 mm.
+ 8.75767 = — 0.0027 mm.
from which:
c = — 0.00743 mm.
w= — 0.00059 mm. = — 070122, or — 0045 per year.
a = — 0.00004 mm. = — 0001 + 0’010.

Probable error of plate of unit weight
+ 0.001386 mm. = + 0"028.
PARALLAXES OF 260 STARS 191

2 LYNCIS (6" 10"; +59° 2’)

Abetti with the meridian circle has found the parallax of this
star to be + 07109 + 07025, the star being of magnitude 4.42,
of type A, and of small total proper motion, 07022. Mr. Olivier
measured the plates, and found a relative parallax + 07021
+ 07011 with a proper motion in right ascension + 0”005 while
the corresponding value from Boss is — 0005.

 

 

 

 

 

 

 

TABLE 1
Puates or 2 Lyncis
No. Date. Hour Angle. Observers. Weight.
3235 1916 Oct. 21 —049 M 0.9
3349 Nov. 5 —0.6 L 1.0
3389 Nov. 16 —1.2 M 0.9
3390 Nov. 16 —0.7 M 0.9
5096 1918 Feb. 17 —0.5 M 0.9
5097 Feb. 17 —0.1 M 0.8
5144 Feb. 28 —0.7 oA 0.9
5145 Feb. 28 —0.1 A 0.9
5912 Nov. 7 —0.5 C,F 0.8
5913 Nov. 7 0.0 C,F 0.8
5936 Nov. 11 —0.4 Cc 0.9
5980 Nov. 14 —0.4 H 1.0
6245 1919 Jan. 13 —1.5 H 0.9
6246 Jan. 18 —-1.2 H 1.0
6573 Feb. 2 —1.0 M 0.8
__ 6574 Feb. 2 —0.6 M 1.0

 

 

CoMPARISON STARS

 

 

 

 

 

 

 

No. Diameter. = sae a ina Y (Declination). Dependence.
mm. tam, mm.

1 0.13 —44.0 +26.6 +0.2224

2 13 —21.6 +11.0 .2358

3 20 +23.1 ; —53.7 2543

4 15 +42.5 +16.1 +0.2875
Parallax star 0.18 + 3.2 — 0.5

 
 

 

 

 

 

 

 

 

 

 

192 S. A. MITCHELL
TABLE 2
Repvuctions ror 2 Lyncis
Plate Solution Weight Parallax Time in Residual . vVp-0
: (m). (p). Factor (P). | Days (t). (2). in Are.
mm. és mm.
3235 +0.0034 0.9 +0.896 —523 —0.0016 —0703
3349 + .0036 1.0 + .751 —518 — .0019 — .04
3389 — .0011 0.9 + .612 —497 + .0027 | + .05
3390 — .0003 0.9 + .612 —497 + .0019 | + .04
5096 + .0028 0.9 — .816 — 39 — .0023 — .05
5097 + .0023 0.8 — .816 — 39 — .0018 — .03
5144 — .0020 0.9 — .910 — 28 + .0024 | + .05
5145 + .0006 0.9 — .910 — 28 — .0002 .00
5912 + .0020 0.8 + .733 +224 + .0002 .00
5913 + .0040 0.8 + .733 +224 — .0018 — .08
5936 + .0004 | 0.9 + .684 +228 + .0018 | + .04
5980 + .0030 1.0 + .645 +231 ) — .0009 — .02
6245 + .0030 0.9 — .336 +291 — .0018 — .04
6246 — .0015 1.0 — .336 +291 + .0027 | + .06
6573 — .0011 0.8 — .893 +835 + .0018 | + .03
6574 +0.0020 1.0 —0.893 +335 —0.0013 —0.03
The normal equations are:

14.4¢ — 0.495u — 0.17867 = + 0.0190 mm.

+ 150.6440un — 14.80497 = — 0.0040 mm.

+ 7.92997 = + 0.0066 mm.

from which:

c = + 0.00133 mm.
+ 0.00007 mm.
+ 0.00099 mm.

Probable error of plate of unit weight

LK
T

+ 0.00130 mm. = + 07027.

= + 07021 + 07011.

+ 070015, or + 07005 per year.
This star is of magnitude 5.2, of spectral type Ma, and of

PARALLAXES OF 260 STARS 193

BOSS 1599 (65 15"; —2° 54’)

total proper motion 07009. Adams has found a radial velocity

+ 48.3 km. per second, and a spectroscopic parallax + 07012.
Mr. Olivier measured the photographs and derived a relative
parallax of — 07009 + 07010, with a proper motion in right

ascension — 07012 while the corresponding value from Boss is —

 

 

 

 

 

 

 

 

 

 

 

 

 

07009.
TABLE 1
Puiates oF Boss 1599
No. Date. Hour Angle. Observers. Weight.
3163 1916 Oct. 10 +041 A 1.0
3360 Nov. 7 —0.6 L 0.9
3361 Nov. 7 —0.3 L 1.0
3423 Nov. 21 —1.0 L 0.6*
5050 1918 Feb. 10 +0.5 M 1.0
5051 Feb. 10 +0.9 M 1.0
5193 Mar. 15 +1.0 Ol 0.9
5885 Nov. 5 —0.7 M 1.0
5886 Nov. 5 —0.3 M 1.0
6258 1919 Jan. 15 +0.6 D 0.9
6288 Jan. 20. —0.5 F 0.9
6289 Jan. 20 0.0 F 0.7*
6321 Jan. 23 +0.6 D 0.7
6477 Feb. 6 +0.6 D 1.0
6478 Feb. 6 +1.0 D 1.0
* One exposure.
ComPaRISON STARS

No. | Diameter. eo saa Y (Declination). Dependence.

1 0.11 —25.2 —25.1 +0.2248

2 13 —14.8 +33.8 -4656

3 18 +40.0 — 8.7 +0.3096

Parallax star 0.13 — 0.2 + 7.4

 

14
194 S, A. MITCHELL

TABLE 2

Repvuctions For Boss 1599

 

 

 

 

 

 

 

 

 

 

Solution Weight | Parallax Time in Residual Vp-w

Plate. ~ (m). (p Factor (P). | Days (f). (). in Are.
* mm. : mm.

3163 +0.0099 1.0 +0.967 —542 +0.0009 +0702
3360 + .0128 0.9 + 736 —514 — .0019 — .04
3361 + .0093 1.0 + .736 —514 + .0016 + .03
3423 + .0122 0.6 + .552 —500 — .00138 — .02
5050 + .0097 1.0 — .732 — 54 + .0011 + .02
5051 + .0100 1.0 — .732 — 54 + .0008 + .02
5193 + .0130 0.9 — .982 — 21 — .0022 — .04
5885 |; + .0110 1.0 + .765 +214 — .0013 — .03
5886 + .0086 1.0 + .765 +214 + .0011 + .02
6258 + .0108 0.9 — .358 +285 - — .0007 — .01
6288 + .0126 0.9 — .487 +290 — .0025 — .05
6289 + .0106 0.7 — .487 +290 — .0005 — .01
6321 + .0080 0.7 — .484 +293 + .0021 + .04
6477 + .0084 1.0 — .680 +307 + .0018 + .04
6478 +0.0100 1.0 —0.680 +307 +0.0002 0.00

The normal equations are:

18.6c + 0.221n — 0.84147 = + 0.1415 mm.
+ 149.9812u — 17.94847 = — 0.0134 mm.
+ 6.76687 = — 0.0089 mm.
from which:
c = + 0.01038 mm.
uw = — 0.00016 mm. = — 070033, or — 0012 per year.
a~ = — 0.00044 mm. = - 0009 + 0”010.

Probable error of plate of unit weight
+ 0.00105 mm. = + 07022.
PARALLAXES OF 260 STARS

uw GEMINORUM (65 16"; +22° 33’)

195

This is a star of Ma type, of magnitude 3.19, and of total
proper motion 0713. The parallax of Allegheny Observatory
gives the value + 07030 + 07008, while Mt. Wilson by the

TABLE 1

PLATES OF » GEMINORUM

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
501 1914 Nov. 4 —011 M 1.0
617 Nov. 22 —0.1 A 1.0
887 1915 Feb. 17 —0.5 G 0.8
888 Feb. 17 +0.1 G 0.8
909 Feb. 19 —0.3 G 0.6
910 Feb. 19 +0.1 G 0.7
1086 Mar. 19 +0.3 M,G 0.9
1791 Oct. 8 —0.3 G 0.7*
1792 Oct. 8 +0.2 G 0.8
1847 Oct. 24 —0.4 G 0.7
1848 Oct. 24 —0.1 G 0.6
1910 Oct. 29 —-1.1 G 0.7
1911 Oct. 29 —0.6 G 0.9
2406 1916 Feb. 14 +0.9 G 0.6*
2407 Feb. 14 +1.3 G 0.5
2447 Mar. 8 +0.2 G 0.7
2476 Mar. 15 +0.2 G 0.8
2477 Mar. 15 +0.6 G 0.8
3186 Oct. 12 —0.8 L 0.8
3187 Oct. 12 —0.4 L 0.9
3212 Oct. 17 —0.4 L 1.0
3226 Oct. 20 0.0 L 0.9
3808 1917 Mar. 25 +0.8 M 0.8
4548 Oct. 7 —0.4 Ol 0.8
4574 Oct. 13 +0.6 B 0.9
4871 Dec. 14 0.0 Ol 0.9
4872 Dec. 14 +0.6 Ds 1.0

 

* One exposure.
196 S. A. MITCHELL

spectroscope finds + 07013. The McCormick value of the proper
motion in right ascension is + 07043 while the value from Boss
is + 0%061. Mr. Graham measured the first eighteen plates of
the series. Mr. Olivier measured all of the plates with the ex-
ception of plates 910 and 1848.

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR » GEMINORUM

Solution Weight Parallax Time in, Residual vVp-o
Plate. (m). (p). Factor (P). | Days (t). (»). in Are.

mm. mm.
501 —0.00388 1.0 +0.781 —490 +0.0010 +0702
617 — .0064 1.0 + .551 —472 + .0035 + .07
887 + .0012 0.8 — .801 —385 — .0043 — .08
888 — .0030 0.8 — .801 —385 — .0001 .00
909 | — .0025 0.6 — .821 —383 — .0006 — .01
910 — .0026 0.7 — .821 —383 — .0005 — .01
1086 + .0004 0.9 — .990 —3855 — .0034 — .07
1791 — .0012 0.7 + .980 —152 + .0004 + .01
1792 — .0003 0.8 ; + .980 —152 — .0005 — .01
1847 — .0023 0.7 + .888 —136 + .0015 + .03
1848 + .0012 0.6 + .888 —136 — .0020 — .03
1910 + .0018 0.7 + .844 | --—181 — .0026 — .04
1911 — .0038 0.9 + .844 -—131 + .0030 + .06
2406 — .0014 0.6 — .767 — 23 + .0004 + .01
2407 — .0025 0.5 — .767 — 23 + .0015 + .02
2447 — .0046 0.7 — .954 0 + .0036 + .06
2476 — .0023 0.8 — .982 + 7 + .0013 + .02
2477 — .0022 0.8 — .982 + 7 + .0012 + .02
3186 + .0010 0.8 + .960 +218 + .0003 + .01
3187 + .0055 0.9 + .960 +218 — .0042 — .08
3212 + .0020 1.0 + .982 +223 — .0007 — .01
3226 + .0007 0.9 + .912 +226 + .0006 + .01
3808 + .0015 0.8 — .997 +382 — .0003 — .01
4548 + %.0027 0.8 + .982 +578 + .0006 + .01
4574 + .0059 0.9 + .956 +584 — .0025 — .05
4871 + .C029 0.9 + .194 +646 | + .0004 + .01
4872 +0.0014 1.0 +0.194 +646 +0.0019 +0.04

 

 

 
PARALLAXES OF 260 STARS 197

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. i ee Y (Declination). Dependence.
1 0.24 —45.8 + 6.5 +0.3519
2 14 —16.0 +36.4 .2311
3 .16 +20.2 —46.5 - 2747
4 .10 +41.6 + 3.6 +0. 1423
Parallax star 0.20 ~- 8.4 — 1.6
The normal equations are:
21.6c + 2.941u + 3.58607 = — 0.0066 mm.

+ 275.1326y + 16.65907 = + 0.1641 mm.
+ 15.77577 = + 0.0163 mm.

from which:
c = — 0.00047 mm.
pw = + 0.00057 mm. = + 070118, or + 07043 per year.

ar = + 0.00054 mm. = + 07011 + 0"007.
Probable error of plate of unit weight

+ 0.00135 mm. = + 07028.

8 CANIS MAJORIS (65 18"; —17° 54’)

This is a B-type star, of magnitude 1.99, and of very small
total proper motion which is less than 0701 per year. From
these considerations one would naturally expect a small parallax.
Flint by the meridian circle finds the parallax of + 07163
+ 0"031. Henroteau (Lick Observatory Bulletin, 311) finds this
star to be an interesting spectrospocic binary of very short
period 0.225. The McCormick plates were measured by Mr.
Mitchell who finds the proper motion in right ascension of
+ 0”024, while the value of Boss is — 07006. The parallax
from the present photographs is + 07007 + 07010.
198 S. A. MITCHELL

TABLE 1

Puates oF 6 Canis Masoris

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
937 1915 Feb. 22 —052 M ! 0.7
1036 : Mar. 12 0.0 A : 0.9
1037 / Mar. 12 +0.4 A | 1.0
1111 Mar. 27 +1.1 A 1.0
1876 Oct. 27 0.0 A ~ 1.0
1926 Oct. 30 —0.6 M 0.8
1927 Oct. 30 —0.3 M 0.8
2103 Dec. 2 —0.5 M 0.8
2104 Dec. 2 —0.1 M 0.8
2420 1916 Feb. 20 +0.2 M 0.8
2421 Feb. 20 +0.6 M 0.6*
2430 Feb. 29 +0.5 A 1.0
2456 Mar. 11 +0.1 A 1.0
2457 Mar. 11 +0.4 A 1.0
4731 1917 Nov. 7 —1.0 B 0.8
4732 Nov. 7 —0.7 B 0.8
4744 Nov. 9 —0.6 B 0.8
4745 Nov. 9 —0.2 B 0.8

 

* One exposure.

Comparison STars

 

 

 

 

 

 

 

No. Diameter. = SRD AeCELE Y (Declination). Dependence.
mm. mm. mm.
1 0.18 —38.3 —20.9 +0.280
2 12 —25.9 +25.2 -301
3 23 +16.9 —44.0 -196
4 14 +47.3 +39.7 +0.223
Parallax star 0.23 — 4.6 + 2.0

 
PARALLAXES OF 260 STARS 199

 

 

 

TABLE 2
REDUCTIONS FOR B Canis Magoris
' ca foe oe
Plate. ee ee |e | es ane
mm. mm.
937 | +0.0168 | 0.7 | —0.847 | —400 | —0.0001 0”00
1036 | + .0134 | 0.9 | — .968 | —382 | + .0034 | + .07
1037 | + .0177 | 1.0 | — .968 | —382 | — .oo09 | — .02
ait | 4 ceias | ale 1 = oer | ge |. 4 0018) | 4 268
1876 | + .0182 | 1.0 | + .864 | —153 | — .o001 .00
1926 | + .0165 | 0.8 | + .838 | —150 | + .0016 | + .03
1927 | + .o162 | 0.8 | + .838 | —150 | + .oo19 | + .04
2103 | + .0222 | 0.8 | + .407 | —117 | — .0042 | — .08
2104 | + .0206 | 0.8 | + .407 | —117 | — .0026 | — .05
2420 | + .0188 | 0.8 | — .826 | — 37 | — .0009 | — .02
2421 | + .o194 | 0.6 | — .926 | — 37 | — .0015 | — .02
2430 | + .0170 | 1.0 | — .903 | — 28 | + .0009 | + .02
ga56 | noe || ia | = er | ae | tetas | 88
gase | ae ae | ia | — 67 | —i7 | = 20003 | = .01
4731 | + .0220 | 0.8 | + .748 | +589 | — .0016 | — .03
4732 | + .o164 | 0.8 | + .748 | +589 | + .0040 | + .07
4744 | + .0213 | 0.8 | + .724 | +591 | — .0009 | — .02
4745 | +0.0199 | 0.8 | +0.724 | +591 | +0.0005 | +0.01

 

 

 

 

 

 

 

The normal equations are:
15.4¢c — 1.7884 — 2.21137 = + 0.2804 mm.
+ 172.2458u + 23.86617 = + 0.0300 mm.
+ 10.78637 = — 0.0294 mm.

ll

from which:
c = + 0.01829 mm.
nw = + 0.00032 mm. = + 070066, or + 07024 per year.
a = + 0.00032 mm. = + 07007 + 07010.
Probable error of plate of unit weight
+ 0.00132 mm. = + 07027.

47 AURIGZ (6 22"; +46° 45’)

This star is of type K3, of magnitude 6.0, and of small total
proper motion 0”007. Adams and Kohlschiitter have found the
200 S. A. MITCHELL

radial velocity of — 41 km. per second. The spectroscopic
parallax of Mt. Wilson is + 07009. Miss Darkow measured
the McCormick plates, and derived a relative parallax of
+ 07012 + 0"010 with a proper motion in right ascension
+ 07006 while the value from Boss amounts to + 07005.

 

 

 

TABLE 1
Puates or 47 AuRIc&
No. Date. Hour Angle. _ Observers. ‘Weight.
3236 1916 Oct. 21. —043 M 1.0
3406 Nov. 19 —1.3 L 1.0
3407 Nov. 19 —0.9 L 1.0
3448 Nov. 27 —0.7 A 1.0
5067 1918 Feb. 12 0.0 ol 0.4
5127 Feb. 23 —0.9 M 0.6
5128 Feb. 23 —0.6 M 0.5
5186 Mar. 8 —0.2 Ol 1.0
5829 Oct. 21 —1.0 M 0.7
5830 Oct. 21. —0.5 M 0.9
5858 Nov. 2 —1.1 M 0.9
5859 Nov. 2 —0.7 M 1.0
6307 1919 Jan. 21 —1.0 D 0.9
6308 Jan. 21 - —0.5 D 1.0
6364 Jan. 27 —0.2 D 1.0
6569 Feb. 24 —0.4 H 1.0
6596 Mar. 1 —0.5. M 1.0
6597 Mar. 1 —0.1 M 0.9

 

 

 

 

 

Comparison STArs

 

 

 

 

 

 

 

No. "Diameter. | Pe Y (Declination). Dependence.
mm, mm. mm.
1 0.11 —25.6 +47.0 +0.261
2 .10 —14.1 —35.8 223
3 15 + 2.3 —33.7 - 233
4 -11 +37.4 +22.5 +0.283
Parallax star 0.13 + 1.3 + 2.8

 
 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 20
TABLE 2
RepvucTIoNns For 47 AURIGE
as ai oie : =
sintes | Paton | ee) eats, | ae | ae | lee
mm. s mm.
3236 +0.0196 1.0 +0.914 —558 —0.0034 —0"07
3406 + .0164 1.0 + .606 —529 — .0004 — .01
3407 + .0148 1.0 + .606 —529 + .0017 + .04
3448 + .0150 1.0 + .490 —521 + .0010 + .02
5067 + .0138 0.4 — .734 — 79 + .0018 + .02
5127 + .0161 0.6 — .848 — 68 — .0006 — .0O1
5128 + .0161 0.5 — .848 — 68 — .0006 —,.01
5186 + .01380 1.0 — .944 — 55 + .0025 + .05
5829 + .0182 0.7 + .918 +172 — .0015 — .03
5830 + .0154 0.9 + .918 +172 + .00138 + .02
5858 + .0169 0.9 + .816 +184 — .0003 — .01
5859 + .0141 1.0 + .816 +184 + .0025 + .05
6307 | + .0180 | 0.9 | — .424 | +264 | — .0020 | — .04
6308 + .0176 1.0 — .424 +264 — .0016 — .03
6364 + .0142 1.0 — .516 +270 + .0017 + .04
6569 + .0186 1.0 a -855 +298 — .0028 — .06
6596 + .0148 1.0 — .897 +303 + .0010 + .02
6597 +0.0159 0.9 —0.897 +303 —0.0002 0.00
The normal equations are:

15.8c — 0.2838u — 0.41617 = + 0.2532 mm.

+ 173.33194 — 18.53197 = — 0.0026 mm.

+ 9.18877 = — 0.0028 mm.

from which:
c = + 0.01604 mm.

be
Ww

+ 0.00007 min.

+ 0.00056 mm. = + 0012 + 0°010.
Probable error of plate of unit weight
+ 0.00125 mm. = + 07026.

+ 0%0015, or + 07006 per year.
202 S. A. MITCHELL

e GEMINORUM (6° 37"; +25° 13’)

This star of magnitude 3.18, of spectral type G5 and of total
proper motion 0”02 has had its parallax twice determined. Alle-
gheny Observatory by photography secured the value + 07008
+ 0”008 and Adams and Joy by the spectrograph + 07013.
Mr. Oliver measured the McCormick plates deriving the proper
motion in right ascension + 0014 while the corresponding value

 

 

 

from Boss is 07000. ri
TABLE 1
PLATES OF ¢€ GEMINORUM
No. Date. Hour Angle. Observers. Weight.
2405 1916 Feb. 14 +045 G 0.5
3424 | Nov. 21 —0.8 L 0.9
3425 Nov. 21 —0.2.- L 0.8
3448 Nov. 27 —0.4 A 0.9
3449 Nov. 27 0.0 A 0.9
3753 1917 Mar. 12 —0.1 L 1.1*
3758 Mar. 15 —0.2. M,A 0.6
3765 Mar. 17 -—0.3 M, L 0.7
4767 Nov. 16 —1.0 B 0.9
4778 | Nov. 17 —0.9 Ds 0.9
4779 Nov. 17 —0.5 Ds 0.9
5049 1918 Feb. 10 —0.3 M 0.8
5081 Feb. 13 —0.4 M 0.7
5147 Mar. 1 —0.3 Ol 1.0*

 

 

 

 

 

* Three exposures.

Comparison STARS

 

 

 

No. “Diameter. x ea ¥ (Declination). Dependence.
mm. mm. mm.
1 0.12 —52.6 —12.1 +0.2880
2 13 — 3.5 —15.6 .2212
3 14 +11.5 —28.7 -1915
4 -16 +37.6 +56.4 +0.2993
Parallax star‘ 0.15 ~— 0.9 + 4.4 4

 

 

 

 

 
PARALLAXES OF 260 STARS

TABLE 2

REDUCTIONS FOR ¢ GEMINORUM

203

 

 

 

 

 

 

 

 

 

 

S 1 : Ww : hi < : . eas
ae a | MOR Vaeemey |eou bee || See
mm. mm.

2405 | +0.0028 | 0.5 | —0.711 | —461 | —0.0017 | —o"02
3424 | + .0018 | 0.9 | + .623 | —180 | — .0002 .00
3425 | + .0009 | 0.8 | + .623 | —180 | + .0007.| + .O1
3448 | + .0020 | 0.9 | + .538 | —172 | — .0004 | — .01
3449 | © .0000 | 0.9 | + .588 | .-172 | + .0016, | + .03
3753 | + .0031 | 1.1 | — .948 | — 69 | — .0013: | — .03
3758 | — .0020 | 0.6 | — .963 | '— 66 | + .0038 | + .06
3765 | + .0026 | 0.7 | — .o71 | — 64 | — .0008 | — .o1
4767 | + .0030 | 0.9 | + .692 | +180 | — .0007,| — .O1
4778 | + .0021 | 0.9 | + .679 | +181 | + .0002, 00
4779 | + .0033 | 0.9 | + .679 | +181 | — .0010 | — .02
5049 | + .0029 | 0.8 | — .667 | +266 | — .0005 | — .O1
5081 | — .0016 | 0.7 | — .705 | +269 | + .0040:| + .07
5147 | +0.0042 | 1.0 | —0.871 | +285 | —0.0018| | —0.04

The normal equations are:

11.6c + 1.6754 — 0.68147 = + 0.0225 mm.
+ 50.1922u — 2.293837 = + 0.0123 mm.
+ 6.36197 = — 0.0017 mm.
from which:

c = + 0.00192 mm.

w=+ d patok mm. = + 070038, or + 07014 per year.

7 = + 0.00001 mm. = 07000 + 07009.
Probable error of plate of unit weight
+ 0.00114 mm. = + 07024.

¢ GEMINORUM (6° 39"; +13° 0’)

This star has a total proper motion of 0728, it is of 3.40
magnitude, and of type F5. Allegheny Observatory by photog-

raphy finds the parallax of + 07055, Mt. Wilson obtains

the
204 S. A. MITCHELL

spectroscopic value of + 07042. The fifteen plates of the series
were measured by Mr. Olivier, who finds the proper motion in
right ascension to be — 07118 per year, while the value from
Boss is — 07114.

TABLE 1

Puates oF & GEMINORUM

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
559 1914 Nov. 11 +041 A 1.0
964 1915 Mar. 1 +0.2 G 0.9
965 Mar. 1 +0.6 G 0.9
1134 Mar. 31 +0.9 G 1.0
1895 Oct. 28 —0.2 ol 0.8
1896 Oct. 28 +0.3 Ol 1.0
1942 : Nov. 1 —0.3 Ol 0.9
1943 Nov. 1 +0.2 Ol 0.8
2034 Nov. 17 +0.2 A 0.8
2035 Nov. 17 +0.6 A i)
2496 1916 Mar. 17 +1.0 ol 0.7
2497 Mar. 17 +1.4 Ol 0.6
2518. Mar. 23 +1.2 Ol 0.9
2537 Mar. 31 +1.1 G 0.7
2538 Mar. 31 +1.5 G 0.8

ComPaARISON STARS
No. Diameter. ey a Y (Declination). Dependence.
mm. mm. mm.

ad 0.20 —60.8 +31.9 +0.2625

2 -1l —40.8 —12.4 - 2208

3 21 +50.8 + 9.3 2795

4 .19 +50.8 —28.8 +0.2372

Parallax star 0.20 + 1.3 + 1.4

 

 

 

 
PARALLAXES OF 260 STARS 205

 

 

 

 

 

 

 

 

 

TABLE 2
REDUcTIONS FoR. GEMINORUM
Solutic Weigh Parall: ime i i D-
inin:, | Boutin | went | Dalles, | cele | Saldal | ee
559 +0.0128 1.0 +0.759 —334 —0.0003 | —0"01
964 + .0084 0.9 — 865 —225 — .0005 — .01
965 + .0061 0.9 — .865 —225 + .0018 | + .03
1134 + .0082 1.0 — .997 —195 — .0010 — .02
1895 + .0079 0.8 + .894 + 17 — .0006 — .01
1896 + .0062 1.0 + .894 + 17 + .0011 + .02
1942 + .0090 0.9 + .862 + 21 — .0018 — .03
1943 + .0051 0.8 + .862 + 21 + .0021 + .04
2034 + .0084 0.8 + .691 + 387 — .0017 | — .03
2035 + .0058 0.9 + .691 + 37 + .0009 | + .02
2496 + .0026 0.7 — .970 +158 — .0008 | — .01
2497 — .0006 0.6 — .970 +158 + .0024 | + .04
2518 + .0041 0.9 — .989 +164 — .0024 — .05
2537 — .0005 0.7 — .997 +172 + .0020 | + .03
2538 +0.0018 0.8 —0.997 +172 —0.0003 0.00

 

The normal equations are:
12.7¢ — 1.9384 — 1.1923¢ = + 0.0769 mm.
+ 34.53394 — 2.09617 = — 0.0688 mm.
+ 10.02497 = + 0.0140 mm.
from which: ,
c = + 0.00599 mm.
uw = — 0.00155 mm. = — 070322, or — 07118 per year.
x = + 0.00179 mm. = + 07037 + 07007.
Probable error of plate of unit weight
+ 0.00101 mm. = + 07021.

97 MONOCEROTIS (6" 45"; —0° 25’)

This star, Lalande 13198, is a double star, 8897. The principal
star has considerable proper motion of 0718, and this is shared
by the companion. The principal star is of A type, and of
206

magnitude 5.83. The companion is of 12th magnitude, and

S. A. MITCHELL

at a distance of nearly 6”. The rotating sector eliminated the

companion.

Flint by means of the meridian circle finds a
parallax of + 0725 + 07065. At Swarthmore, by photography,

TABLE 1

Puates oF 97 Monocerotis

 

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
419 1914 Oct. 21 040 M 0.9
442 Oct. 30 —0.8 A 0.8
443 Oct. 30 —0.2 A 1.0
534 Nov. 9 —0.1 G 0.9
865 1915 Feb. 9 +0.3 M 1.0
866 Feb. 9 +0.8 M 0.9
923 Feb. 20 —0.6 A 0.7
1048 Mar. 13 +0.2 A 0.8
1049 Mar. 13 +0.6 A 1.0
1799 Oct. 9 —0.5 M 0.7*
1800 Oct. 9 —0.2 M 0.9
1811 Oct. 10 —0.5 A 1.0
1812 Oct. 10 —0.2 A 1.0
5203 1918 Mar. 18 +0.5 M 1.0
5204 Mar. 18 +0.8 M 1.0
* One exposure.
Comparison STars
No. Diameter. a Rugby AsceO Y (Declination). Dependence.
mm. mm. mm.

1 0.12 —30.1 —43.0 +0.1771

2 15 —19.8 —27.7 -1737

3 .16 —18.6 + 6.9 . 1862

4 11 — 0.1 +35 .6 .1807

5 15 + 7.9 +50.1 -1792

6 .18 +60.7 —21.9 +0.1031

Parallax star 0.16 — 4.6 + 2.0

 

 

 
PARALLAXES OF 260 STARS

207

the parallax has been determined to be + 0015 + 0”008.
The plates were measured by Mr. Alden, who found a proper
motion in right ascension of + 0”001 while the value from
Porter is + 0”008.

TABLE 2

Repvuctions ror 97 Monocerotis

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp-o
Plate. ‘m). (p). Factor (P). | Days (). (x). in Are.
mm. mm.
419 —0.0015 0.9 +0.946 —305 —0.0012 —0702
442 — .0006 0.8 + .886 —296 — .0022 — .04
443 — .0026 1.0 + .886 —296 — .0002 .00
5384 — .0022 0.9 + .795 —286 — .0007 — .01
865 — .0028 1.0 — .627 —194 — .0019 — .04
866 — .0028 0.9 — .627 —194 — .0019 = .04
923 — .0065 0.7 — .762 —183 + .0017 + .03
1048 — .0094 0.8 — .940 —162 + .0043 + .08
1049 — .0050 1.0 — .940 —162 — .0001 .00
1799 — .0026 0.7 + .991 + 48 .0000 -00
1800 — .0058 0.9 + .991 + 48 + .0032 + .06
1811 — .0034 1.0 + .989 + 49 + .0008 + .02
1812 — .0028 1.0 + .989 + 49 + .0002 -00
5203 - — .0034 1.0 — .967 +939 — .0016 — .03
5204 —0.0053 1.0 —0.967 +939 +0.0003 +0.01
The normal equations are:

13.6c + 1.9984 + 1.37467 = — 0.0507 mm.

+ 222.9168 — 19.76547 = — 0.0303 mm.

+ 10.92897 = + 0.0083 mm.

from which:

c = — 0.00386 mm.
uw = + 0.00001 mm. = + 070002, or + 07001 per year.
x = + 0.00126 mm. = + 07026 + 07009.

Probable error of plate of unit weight
+ 0.00125 mm. = + 07026.
208

This star of magnitude 8.2, of type K1 has a total proper
Its parallax has been twice determined

LALANDE 13427 (6 54™; +48° 32’)

motion 0°71 per year.

trigonometrically: Chase with the Yale heliometer deriving
the value + 07011 + 07029, and Schlesinger by photography
with the 40-inch Yerkes refractor the result + 07049 + 07011.
The spectroscopic parallax is + 07048. Miss Hawes measured
the McCormick plates and found a relative parallax + 07007
+ 0.007. The proper motion in right ascension determined
by her was + 07556 per year while the corresponding value

S. A. MITCHELL

from Porter amounted to + 07548.

TABLE 1

Piates oF LALANDE 13427

 

 

 

No. Date. Hour Angle. Observers. Weight.
3203 1916 Oct. 14 —043 M 1.0
3204 Oct. 14 0.0 M 1.0
3376 Nov. 10 —0.9 A 1.0
3392 Nov. 16 —0.3 M 1.0
5129 1918 Feb. 23 —0.5 M 0.8
5130 Feb. 23 —0.2 M 1.0
5153 Mar. 2 —0.8 | M 1.0
5154 Mar. 2 —0.4 M 1.0
5831 Oct. 28 —0.7 M 1.0
5832 Oct. 28 —0.3 M 1.0
5860 Nov. 2 —0.8 M 1.0
5861 Nov. 2 —0.4 M 1.0
6336 1919 Jan. 24 —1.0 D 1.0
6337 Jap. 24 —0.5 D 1.0
6602 Mar. 3 —0.3 D 1.0
6603 Mar. 3 +0.1 D 1.0
6689 Mar. 18 —0.2 Ol 1.0
7977 Oct. 27 —0.7 F 1.0
* 8045 Nov. 13 -0.8 F 1.0
8046 Nov. 13 —0.4 F 1.0

 

 

 

 

 
PARALLAXES OF 260 STARS

Comparison Stars

2¢

 

 

 

 

 

 

 

 

No. Diameter. |* aE peel Y (Declination). Dependence.

mm. mm. mm.

1 0:12 —32.2 +28.4 +0.246

2 08 —34.9 —42.1 .290

3 12 +11.8 + 8.5 .240

4 -10 +55.3 + 5.2 +0.224
Parallax star 0.12 — 2.0 — 2.8

TABLE 2

Repuctions For LananpE 13427

 

 

 

 

 

 

 

 

 

“| Soluti Weight | _ Paral Time i id D:
mat: ce ene | eee | ede | Begin te
mm. mm.

3203 +0.0210 1.0 +0.980 —635 —0.0007 —0"01
3204 + .0205 1.0 + .980 —635 — .0002 .00
3376 + .0224 1.0 + .802 —608 — .0002 .00
3392 + .0196 1.0 + .732 —602 + .0030 + .06
5129 + .0575 0.8 — .775 —138 — .0014 — .03
5130 + .0558 1.0 — .775 —138 + .0003 + .01
5153 + .0562 1.0 — .845 —-131 + .0004 ; + .01
5154 + .0582 1.0 — .845 —131 — .0016 — .03
5831 + .0793 1.0 + .914 +109 — .0046 — .10
5832 + .0770 1.0 + .914 +109 — .0023 — .05
5860 + .0719 1.0 + .877 +114 + .0032 + .07
5861 + .0740 1.0 + .877 +114 + .0011 + .02
6336 + .0802 1.0 — .3856 +197 + .0005 + .01
6337 + .0820 1.0 — .356 +197 — .0013 — .03
6602 + .0810 1.0 — .852 +235 + .0023 + .05
6603 + .0829 1.0 — .852 +235 + .0004 + .01
6689 + .0850 1.0 — .955 +250 — .0006 — .0l1
7977 + .1012 1.0 + .922 +473 + .0002 .00
8045 + .1014 1.0 + .775 +490 + .0012 + .02
8046 +0.1025 1.0 +0.775 +490 +0.0001 0.00

 

15
210 S. A. MITCHELL

The normal equations are:

19.8¢ + 0.226u + 3.09207 = + 1.3181 mm.
+ 261.1370u — 9.48627 = + 1.9236 mm.
+ 13.48677 = + 0.1410 mm.
from which:

c = + 0.06643 mm.
pw = + 0.00732 mm. = + 071523, or + 07556 per year.
x = + 0.00035 mm. = + 07007 + 07007.

Probable error of plate of unit weight
+ 0.00127 mm. = + 07026.

BOSS 1846 (75 5"; +51° 35’)

This staris of small proper motion 07019, of magnitude 5.69,
and of type Ma. It hasa radial velocity — 49 km. per second.
The spectroscopic parallax is + 07011. Miss Hawes measured
the plates and found a relative parallax — 07011 + 07012,
with a proper motion in right ascension + 07019 while the
corresponding value from Boss is + 07018.
PARALLAXES OF 260 STARS

211

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Puates or Boss 1846
No. Date. Hour Angle. Observers. Weight.
3276 1916 Oct. 25 —045 L 1.0
3277 Oct. 25 —0.2 L 0.9
3314 Oct. 31 —1.2 L 1.0
3315 Oct. 31 —0.8 L 1.0
5187 1918 Mar. 8 —0.4 Ol 0.8
5188 Mar. 8 0.0 Ol 1.0
5190 Mar. 11 —0.4 A 0.8
5191 Mar. 11 0.0 A 0.8
5925 Nov. 10 —0.6 M 0.8 *
5937 Nov. 11 —0.7 F 0.9
5938 Nov. 11 —0,2 Cc 0.5
6033 Nov. 30 —0.7 M 1.0
6365 1919 Jan. 27 —0.2 D 1.0
6403 Jan. 30 —0.8 H 1.0
6404 Jan, 30 —0.3 H 1.0
6598 Mar. 1 —0.3 M 1.0
6599 Mar. 1 0.0 M 1.0
6709 Mar. 21 —0.3 D 1.0
6720 Mar. 22 -6.1 H 1.0
6729 Mar. 23 0.0 M 1.0
Comparison Stars
No. Diameter. X (Right Ascen-) y (Declination). Dependence.
sion).
1 0.12 —46.6 +34.7 +0.147
2 .14 —35.9 —15.6 -255
3 .08 +18.8 —22.3 . 240
4 .13 +28.9 —33.4 . 260
5 .13 +84.8 +36.6 +0.698
Parallax star 0.13 — 0.6 — 9.4

 

 

 

 

 
212 S. A. MITCHELL

 

 

 

TABLE 2
Repuctions ror Boss 1846

Solution Weight | Parallax Time in Residual vp-o
Plate. (m). (p). | Factor (P). | Days (2). (0). in Are.

mm. mm.
3276 +0.0268 1.0 +0.943 —592 —0.0018 —0"04
3277 + .0230 0.9 + .943 —592 + .0020 + .04
3314 + .0252 1.0 + .906 — 586 — .0001 .00
3315 + .0266 1.0 + .906 | —586 — .0015 — .03
5187 + .0275 0.8 — .872 — 98 — .0002 .00
5188 + .0269 1.0 — .872 — 93 + .0004 + .01
5190 + .0277 0.8 — .896 — 90 — .0004 — .01
5191 + .0231 0.8 — .896 — 90 + .0042 + .08
5925 + .0236 0.8 + .828 +154 + .0034 + .06
5937 + .0277 0.9 + .818 +155 — .0007 — .01
5938 + .0230 0.5 + .818 +155 + .0040 + .06
6033 + .0298 1.0 + .592 +174 — .0027 — .06
6365 + .0267 1.0 — .862 +232 + .0011 + .02
6403 + .0307 1.0 — .410 +235 — .0029 — .06
6404 + .0250 1.0 — .410 +235 + .0028 + .06
6598 + .03138 1.0 — .806 +265 — .0032 — .07
6599 + .0316 1.0 — .806 +265 — .0035 — .07
6709 + .0249 1.0 — .955 +285 + .0033 + .07
6720 + .0294 1.0 — .960 +286 — .0012 — .02
6729 +0:0278 1.0 —0,.964 +287 +0.0004 +0.01

 

 

 

 

 

 

 

The normal equations are:

18.5¢ — 0.040u — 2.67297 = + 0.5014 mm.
+ 201.4200u — 29.92262 = + 0.0650 mm.
+ 12.34967 = — 0.0863 mm.

from which:
c = + 0.02702 mm.
w= + 0.00025 mm. = + 070052, or + 07019 per year.
a7 = — 0.00053 mm. = — 07011 + 0’012.

Probable error of plate of unit weight
+ 0.00164 mm. = -t 07034.
PARALLAXES OF 260 STARS 213

LALANDE 14146 (75 11™; —12° 53’)

This star of 7.3 magnitude, of G type, and of total proper
motion 0755 has had its parallax twice determined. Chase
with the Yale heliometer derives the relative parallax of + 0”072
+: 07020, and Adams with the spectrograph the absolute parallax
of + 07023. Mr. Alden measured the McCormick plates, and
found the relative parallax of + 07031 + 07010. The proper
motion in right ascension from the plates is — 07488 per year,
while the value from Porter is — 0"501.

TABLE 1

Puates oF LALANnDE 14146

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
3266 1916 Oct. 24 ~057 M 1.0
3267 Oct. 24 203° 4 M 1.0
3350 Nov. 5 0.9. L 0.7%
3362 Nov. 7 <a 3 L 0.9
3673 1917 Feb. 16 +0.2 © ol 1.0
3674 Feb. 16 40.5 ol 0.7
3716 Mar. 6 20.5. ° M 0.9
3737 Mar. 9 +0.3 Ol 1.0
3738 Mar. 9 +0.8 Ol 1.0
4607 Oct. 20 —0.5 M 0.8
4746 Nov. 9 - 0.3 B 1.0
4747; Nov. 9 +0.1 B 1.0
4780 Nov. 17 -0.5 Ds :0.8
4781 Nov. 17 -0.2 Ds :0.8
5100 | 1918 Feb. 17 +0.7 M 1.0
5216 | Mar. 25 +0.6 A 0.8
5230! Mar. 27 +0.6 M 1.0
5231 Mar. 27 +1.0 M 1.0

 

* One exposure.
S. A. MITCHELL

ComPARISON STARS

 

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. = Cent Aener Y (Declination). Dependence.
mm. mm. mm,
1 0.10 —42.5 +36.1 +0.2040
2 10 —28.5 —18.1 .1767
3 11 — 5.3 —22.1 .1841
4 ell +13.6 —15.9 . 1960
5 -10 +62.7 +20.0 +0.2392
Parallax star 0.12 + 3.0 + 1.8
TABLE 2
REDUCTIONS FOR LALANDE 14146
Solution | Weight | Parallax | Time in Residual vp+o
Plate. ‘m). (p). -| Factor (P). | Days (#). (). in Are.
mm. mm. :
3266 +0.0045 1.0 +0.953 —269 +0.0007 | +0701
3267 + .0068 1.0 + .953 —269 — .0016 | — .03
3350 + .0080 0.7 + .876 —257 — .0036 | — .06
3362 + .0012 0.9 + .860 —255 + .0030 + .06
3673 — .0050 1.0 — .647 —154 + .0005 + .01
3674 + .0010 0.7 - 647 —154 — .0055 — .10
3716 — .0072 0.9 — .847 —136 + .0012 | + .02
3737 — .0069 1.0 — .873_| —133 + .0007 + .01
3738 — .0086 1.0 — .873 —1383 + .0024 | + .05
4607 — .0191 0.8 + .970 + 92 + .0012 | + .02
4746 — .0180 1.0 + .844 +112 — .0014 | — .08
4747 — .0197 1.0 + .844 +112 + .0003 + .01
4780 — .0254 0.8 + .764 | +120 + .0054 | + .10
4781 — .0166 0.8 + .764 +120 — .0034 | — .06
6100 — .0264 1.0 — .657 +212 — .0017 — .04
5216 — .0302 0.8 — .968 +248 — .0006 | — .01
5230 — .0318 1.0 — .975 +250 + .0008 | + .02
5231 —0.0308 1.0 | —@.975 +250 —0.0002 0.00

 

 

 

 

 

 
PARALLAXES OF 260 STARS 215

The normal equations are:

16.4¢ — 1.9764 — 0.01007 = — 0.2080 mm.
+ 61.5867n — 7.74107 = — 0.3805 mm.
+ 12.09467 = + 0.0679 mm.
from which:
¢ = — 0.01346 mm.
w= — 0.00642 mm. = — 071336, or — 0488 per year.

+ 0.00149 mm. = + 07031 + 0”010.
Probable error of plate of unit weight
+ 0.00164 mm. = + 07034.

wv

6 GEMINORUM (75 14™; +22° 9’)

This star of magnitude 3.51 and of type F has a companion
of 8.2 magnitude at a distance of 7” which is in very slow motion
about the principal star, the two stars having a common proper
motion of 07035 per year. The parallax of Allegheny by pho-
tography is + 07055. Adams and Joy find the spectroscophic
parallax + 07026. The McCormick result is + 07060 + 0”006,
with a proper motion in right ascension of — ”%0041 while Boss
gives the value — 07016. Mr. Olivier measured the series of
plates.

Comparison STaRs

 

 

 

 

 

 

No. Diameter. Be a Naa Y (Declination). Dependence.
mm. mm. mm.
1 0.31 +83 .2 —12.3 +0.2888
2 .19 + 8.2 —36.0 .3133
3 ll + 5.0 +33 .2 . 1987
4 .16 —46.4 +15.1 +0.1992
Parallax star 0.26 + 3.9 — 5.2

 
216 S. A. MITCHELL

TABLE 1

Puates oF 6 GEMINORUM

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
485 1914 Nov. 3 —141 G 0.8
486 Nov. 3 —0.6 G 0.9
535 : Nov. 9 0.0 G 0.9
536 Nov. 9 +0.5 G 0.9
890 1915 Feb. 17 +0.7 G 0.9
953 Feb. 26 +0.8 G 0.6*
1088 Mar. 19 +0.5 G 1.0
1145 Apr. 4 —0.7 M 0.6*
1849 Oct. 24 —0.6 G 0.6*
1912 Oct. 29 —1.1 G 0.6*
1913 Oct. 29 —0.6.- G 0.6*
1960 Nov. 3 —0.4 G 0.7*
2005 Nov. 10 —0.3 G 0.6*
2448 1916 Mar. 8 —0.2 G 1.0
2449 Mar. 8 +0.3 G 0.8
2478 Mar. 15 +0.4 G 0.9
2479 Mar. 15 +0.9 G 0.7
3219 Oct. 19 —0.8 L. 0.7*
3247 Oct. 22 —0.8 L 0.8
3248 Oct. 22 —0.4 L 0.5
3325 Nov. 1 —0.8 A 0.9
3326 Nov. 1 -0.4 A 1.0
3768 1917 Mar. 19 +0.3 ol 0.9
3769 ( Mar. 19 +0.8 Ol 0.8
3832 Mar.31 | | +0.5 Ol 0.8
3833 _ Mar. 31 +0.9 A 0.9
3848 =f | Apr. 7 +1.5 A 0.9
4590 Oct. 15 —0.6 B 0.8
4769 Nov. 16 » =—0.5 B | 0.9
4770 ‘Nov. 16 '  —0.2 B : 0.9
4829 Dec. 1 —0.3 B 0.9
4830 Dec. 1 +0.1 B 1.0

 

 

* One exposure.
PARALLAXES OF 260 STARS

Repvucrions FoR 6 GEMINORUM

TABLE 2

217

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp-o

Plate. (m). (p). | Factor (P). | Days (2). v). in Are.
. mm. mm.
485 —0.0046 | 0.8 | +0.900 | —558 | —0.0008 | —0”01
486 — .0047 | 0.9 | + .900 | —558 | — .0007 | — .O1
535 — .0098 | 0.9 | + .852 | —552 | + .0042 | + .08
536 | — .0030 | 0.9 | + .852 | —552 | — .0026 | — .05
890 — .0127 | 0.9 | — .648 | —452 | + .0022 | + .04
953 — .0077 | 0.6 | — .753 | —443 | — .0031 | — .05
1088 — .0136 | 1.0 | — .933 | —422 | + .0021 | + .04
1145 — .0091' | 0.6 | — .991 | —406 | — .0027 | — .04
1849 |°— .0100 | 0.6 | + .959 | —203 | + .0028 | + .05
1912 — .0075 | 0.6 | + .934 | —198 | + .0002 .00
1913 — .0088 | 0.6 | + .934 | —198 | + .0015 | + .02
1960 — .0075 | 0.7 | + .903 | —193 | + .0001 .00
2005 — .0062 | 0.6 | + .846 | —186 | — .0014 | — .02
2448 — .0114 | 1.0 | — .860 | — 67 | — .0018 | — .04
2449 — .0111 | 0.8 | — .860 | — 67 | — .0021 | — .04
2478 — .0117 | 0.9 | — .913 | ~ 60 | ~ .0017 | — .03
2479 — .0124 | 0.7 | — .913 | ~— 60 | ~ .0010 | — .02
3219 — .0096 | 0.7 | + .974 | +158 | + .0005 | + .01
3247 — .0097.| 0.8 | + .964 | +161 | + .0006 | 4+ .O1
3248 — .0080 | 0.5 | + .964 | +161 | — .0011 | — .02
3325 — .0069 | 0.9 | + .910 | +171 | — .0024 | — .05
t

3326 — .0112 | 1.0 | + .910 | +171 | + .0019 | + .04
3768 — .0180 | 0.9 | — .937 | +309 | + .0026 | + .05
3769 — .01922 | 0.8 | — .937 | +309 | +4 .0038 |) + .07
3832 _ 0145 | 0.8 | — .984 | +821 | — .oo11 | — ‘02
3833 + .0171 | 0.9 | — .984 | +321 | + :0015 | + .03
3848 + .0150 | 0.9 — .993 | +328 | — .0007 | — .O1
4590 | .0100 | 0.8. | + .984 | +519 | — .0010 | — .02
4769 + .0113 | 0.9 | + .782 | +551 | — .0004 | — .01
4770 = -0103 | 0.9 | + .782 | +551 ) — .0014 | — .03
4829 - 9132 | 0.9 | + .599 | +566-| + .0008 | + .02
4830 —0.0120 | 1.0 | +0.599 | +566 | —0.0004 | —0.01

 
218 S. A. MITCHELL

The normal equations are:

25.8¢ + 3.9038u + 3.1701q = — 0.2780 mm.
+ 370.0527n + 1.438957 = — 0.2384 mm.
+ 20.14827 = + 0.0226 mm.
from which: °
c = — 0.01105 mm.
w = — 0.00054 mm. = — 070112, or — 07041 per year.
a = + 0.00290 mm. = + 07060 + 07006.

Probable error of plate of unit weight
+ 0.00121 mm. = + 07025.

t GEMINORUM (7° 197; +28° 0’)

The spectroscopic parallax of this star is -+ 07013. The Alle-
gheney value by photography is + 07035 + 07008. The star is
of K type, of magnitude 3.89, and of total proper motion 07145.

TABLE 1

PLaTEs oF « GEMINORUM

 

 

 

 

 

 

No. Date. Hour Angle. | Observers. Weight.
572 1914 Nov. 12 040 M 0.9
618 Nov. 22 —0.5 A 1.0
924 1915 Feb. 20 —0.6 A 0.7*
1001 Mar. 8 +0.1 G 0.9
1014 Mar. 9 —0.6 A 1.0
1015 Mar. 9 0.0 A 1.0
1077 Mar. 18 0.0 A, Ol 0.9
1878 Oct. 27 —0.1 A 0.9
1953 Nov. 2 —1.2 A 1.0
1954 Nov. 2 —0.9 A 1.0
2201 Dec. 22 —0.1 G 0.9
2214 Dec. 23 —0.1 A 1.0
2441 1916 Mar. 4 —0.2 A 1.0
2442 Mar. 4 +0.1 A 1.0

 

 

* One exposure.
PARALLAXES OF 260 STARS 219

The McCormick value of proper motion in right ascension is
— 07085, while that due to Boss is — 07082. The series of
plates was measured by Mr. Alden.

~

Comparison Srars

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. |~ | ¥ (Declination). Dependence.
mm. nm. mm.

1 0.20 —41.3 —14.8 +0.3002

2 .16 —27.9 —32.2 - 2571.

3 15 +22.4 —23.5 -2130

4 -18 +46.8 +40.9 +0.2297
Parallax star 0.22 — 4.1 + 0.5

TABLE 2
REDUCTIONS FOR « GEMINORUM .

z luti i 1 Time i i .
ete, | | |e t,| Beod. | a | ae
mm. mm.

572 +0.0041 0.9 +0.836 —244 +0.0001 0°00
618 + .0030 1.0 + .732 —234 + .0010 | + .02
924 + .0036 0.7 — .665 —144 — .0011 — .02
1001 + .0010 0.9 — .841 —128 + .0012 | + .02
1014 + .0041 1.0 — .850 —127 — .0019 — .04
1015 + .0016 1.0 — .850 —127 + .0006 + .01
1077 + .0022 0.9 — .919 —118 — .0001 .00
1878 + .0021 0.9 + .949 +105 — .0018 — .03
1953 — .0008 1.0 + .916 +111 + .0010 | + .02
1954 + .0018 1.0 + .916 +111 — .0016 — .02
2201 — .0012 0.9 + .306 +161 + .0006 | + .01
2214 — .0019 1.0 + .290 +162 + .0013 | + .03
2441 — .0018 1.0 — .810 +234 .0000 .00
2442 —0.0020 1.0 —0.810 +234 +0.0002 0.00

 

 

 

 

 

 

 

The normal equations are:

13.2¢c + 0.6164 — 0.63367 = + 0.0139 mm.
+ 37.6038 + 1.27817 = — 0.0410 mm.
+ 8.28537 = + 0.0011 mm.
220 S. A. MITCHELL
from which:
c = + 0.00112 mm.
mw = — 0.00112 mm. = — 070233, or — 07085 per year.

+ 0.00039 mm. = + 07008 + 07006.
Probable error of plate of unit weight
+ 0.00081 mm. = + 07017.

Tv

p GEMINORUM (7> 22"; +31° 59’) :

The parallax for this star by the meridian circle of Jost is
+ 07045+ 07028. Adamsand Joy give the spectroscopic parallax

 

 

 

TABLE 1
Puates OF p GEMINORUM
No. Date. Hour Angle. | Observers. Weight.
3294: 1916 Oct. 27 —141 M 1.0
3336 Nov. 2 —0.9 M 1.0
3337 Nov. 2 —0.6 M °1.0
3408 Nov. 19 sa G 1.0
3409 Noy.19 |  —1.0 L (1.0
3750, | 1917 Mar. 10 -0.4 A 0.8
3759 Mar. 15 —0.4 A 0.9
3760 Mar. 15 0.0 A 0.8
4619 Oct. 21 —0.5 B “1.0
4620 Oct. 21 20,4 B 0.9
4648 Oct. 30 -1.1 B 1.0
4649 Oct. 30 —0.8 B 1.0
4803: Nov. 22 —0.9 B '1.0
5098- | (1918 Feb. 17 —0.6 M 0.9
5099 Feb. 17 ~0.2 M 0.9.
5155 Mar. 2 -0.4-- M 1.0
5156 Mar. 2 0.0— M 1.0
5833 Oct. 21 —0.3 M 1.0
5834 Oct. 21 0.0 M 1.0
5887 Nov. 5. =i M 1.0
5888 Nov. 5. —0.8 M 1.0

 

 

 

 

 
PARALLAXES OF 260 STARS

Comparison STARS

22

 

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. |* oe Y (Declination). Dependence.
mm. mm, mm.
1 0.14 —28.8 +44.9 +0.2959
2 12 = 7.3 —40.8 2493
3 12 + 0.1 —22.5 2446
4 10 +36.0 +18.4 +0.2102
Parallax star 0.12 — 2.7 + 1.5
TABLE 2 :
REDUCTIONS FOR p GEMINORUM
Soluti igh’ Parall: Time i i ‘D-
Eun | ee \aeter te, Deel Ge aa kee
mm. mm.
3294 +0.0024 1.0 +0.948 —342 +0.0001 0700
3336 + .0024 1.0 | + .915 —336 + .0001 00
3337 + .0017 1.0 + .915 —336 + .0008 | + .02
3408 + .0004 1.0 + .767 —319 + .0021 + .04
3409 + .0035 1.0 + .767 —319 — .0010 — .02
3750 + .0006 0.8 — .856 —208 + .0004 ; + .01
3759 — .0012 0.9 — .896 — 203 + .0022 + .04
3760 + .0026 0.8 — .896 —203 — .0016 — .03
4619 + .0142 1.0 + .972 | + 17 — .00385 | — .07
4620 + .0092 0.9 + .972 + 17 + .0015 + .03
4648 + .0136 1.0 + .934 + 26.) — .0028 — .06
4649 + .0096 1.0 + .934 + 26 + .0012 + .02
4803 + .0121 1.0 + .736 + 49 — .0013 — .08
5098 + .0115 0.9 — .619 +136 — .0021 — .04
5099 + .0075 0.9 — .619 | +136 + .0019 | + .04
5155 + .0082 1.0 — .777 +149 + .0011 | + .02
5156 + .0114 1.0 — .777 +149 — .0021 | — .04
5833 + .0202 1.0 + .973 +382 — .0012 | — .02
5834 + .0180 1.0 + .973 +382 + .0010 + .02
5887 |, + .0160 1.0 + .897 +397 + .0031 | + .06
5888 if +0.0190 | 1.0 | +0.897 | +397 | +0.0001 | 0.00

 

 

 

 

 

 
222 S. A. MITCHELL

+0"025. The star is of magnitude 4.18, and of type F, and a
total proper motion 0723. Eleven of the McCormick plates were
measured by Mr. Mitchell, the other ten by Mr. Briggs. The
relative parallax is + 0"052 + 07007, with a proper motion in
right ascension + 07173, while the corresponding value from
Boss is + 07149.

The normal equations are:

20.2¢c + 0.706u + 7.62667 = + 0.1796 mm.
+ 134.0007 + 2.1175c = + 0.3157 mm.
+ 15.18207 = + 0.1029 mm.
from which:

c = + 0.00786 mm.
uw = + 0.00227 mm. = + 070473, or + 07173 per year.
x = + 0.00251 mm. = + 07052 + 07007.

Probable error of plate of unit weight-
+ 0.00126 mm. = + 07026.

a GEMINORUM (7 28"; +-32° 6’)

This brilliant pair needs no detailed description. According
to Burnham’s General Catalogue, ‘‘the period and all other
details of the orbit are wholly unknown, and the problem of
finding the elements of the orbit is absolutely indeterminate at
this time, and likely to remain so for another century or longer.”
The periods range all the way from 232 years to 1000 years.
The stars are of A type, the preceding star of magnitude 2.85
and the following of magnitude 1.99. Each component is a
spectroscopic binary. The angular separation is approximately
5’... On account of the brilliancy and the close proximity of the
pair, it is only natural that the determinations of the parallax
should be rather discordant. Those published are as follows:

we
PARALLAXES OF 260 STARS 223

 

 

 

Authority. Method. Brighter Star. Mean. Fainter Star.
Johnston | Heliometer +07198+0"062
Flint, 1 /Merid. Circle AY 04t
Flint, 2 |Merid. Circle 1744 .081

Russell {Photography} +0”7102-+07028 -103+ .023 | +07104+.07036
Smith Heliometer | + .022+ .010
Yerkes |Photography| + .063+ .008 059+ .006|-+ .053+ .010

Allegheny|Photography} 054+ .007 070+ .005 085+ .007

+ +41

 

The system has a considerable proper motion 07204 per year.
Mr. Alden measured the McCormick plates except five which
were measured by Mr. Mitchell. The parallaxes of brighter
and fainter stars are, + 07067 + 07010 and + 07086 + 0°007,
respectively. Taking the mean of the two results, the parallax
of the system is:

+ 07076 + 07006

According to Boss, the proper motion of the center of gravity
of the system in right ascension is — 0%172 per year. The
proper motions determined from the plates are, — 07182 and
- 07119 for the brighter and the fainter stars respectively.
This would show that the brighter star is the more massive, but
on account of the uncertainties in the proper motions of the
center of gravity and of the two components, it is regarded that
the present investigation can tell but little of the relative masses
of the components. From all the evidence at present available,
we must conclude that we know as little of the relative masses
of the components as we know of the period.

ComPARISON STARS

 

 

 

 

 

 

No. Diameter. |X oer ad Y (Declination). | Dependence.
mm. mm. mm.

1 0.13 —57.4 —19.9 +0.1937

2 .10 —24.7 —16.3 -2018

3 .13 — 5.6 — 8.4 . 2032

4 .16 +30.8 +53.4 .1785

5 ll +56.9 — 8.8 +0.2228

Brighter star 17

Fainter star 0. ue 08 = 8

 
224 S. A. MITCHELL

 

 

 

 

 

 

 

 

TABLE 1
Puatres OF a GEMINORUM
No. Date. _Hour Angle. Observers. Weight.
1832 1915 Oct. 21 —049 M 0.5*
1931 Oct. 30 0.0 M 0.7
1966 Nov. 4 —0.7 M 0.8
2106 Dec. 2 —0.9 M 0.6*
2165 Dec. 18 —0.2 M 0.5*
2453 1916 Mar. 9 —0.2 A * 0.9
2454 Mar. 9 0.0 A 0.7*
2512 Mar. 19 —0.3 M 0.9
2513 Mar. 19 0.0 M 0.5*
3302 Oct. 28 —1.2 M 1.0
3308 Oct. 28 —0.9 M 0.9
3716 1917 Mar. 8 —0.5 M 0.9
3717 Mar. 8 —0.4 M 0.7
3790 Mar. 22 —0.2 M, A 0.8
3791 ‘ Mar. 22 +0.1 A 0.9
3795 Mar. 24 —0.5 M 0.7
3796 Mar. 24 —0.2 M 0.7
4553 Oct. 9 —1.2 A 0.8
4554 Oct. 9 —0.9 A 0.8
4660 Oct. 31 —0.8 A 0.8
4684 Nov. 2 —0.8 M 0.6*
5215 1918 Mar. 25 —0.4 A 0.9
§219 Mar. 26 —0.2 Ol 1.0
5229 Mar. 27 —0.2 M 1.0
5235 Mar. 28 —0.2 A 0.9
5862 Nov. 2 —0.6 M 1.0
5863 Nov. 2 —0.3 M 1.0
5889 Nov. 5 ~0.6 M 1.0
5890 Nov. 5 —0.2 M 1.0
* One exposure.
The normal equations are:
23.5¢ + 11.034u + 0.33542 = — 1.6042 mm.
+ 323.3680u + 9.23707 = — 1.2131 mm.
+ 19.445387 = + 0.0432 mm.
PARALLAXES OF 260 STARS

TABLE 2
RepvucTions oF a GERMINORUM, BricHTER STAR

22

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual vp-v
Plate. (m). (p Factor (P). | Days (f). (). in Arc.
mm. . mm.
1832 —0.0530 0.5 +0.976 —533 —0.0022 —0"03
1931 — 10570 0.7 + .942 —524 + .0015 |.+ .02
1966 — .0561 0.8 + .914 —519 + .0004 + .01
2106 — .05381 0.6 + .635 —491 — .0042 — .07
2165 — .0580 0.5 + .402 —475 — .0005 — .01
2453 — .0662 0.9 — .830 —393 + .0013 + .03
2454 — .0671 0.7 — .830 —393 + .0022 + .04
2512 — .0654 0.9 — .915 —383 .0000 -00
2513 — .0669 0.5 — .915 —383 + .0015 + .02
8302 — .0578 1.0 + .948 —160 — .0034 — .07
3303 — .0650 0.9 + .948 —160 + .0038 + .07
3716 — .0728 0.9 — .825 — 29 + .0022 + .04
8717 — .0697 0.7 — .825 — 29 — .0008 — .01
3790 — .0720 | 0.8 — .932 — 15 + .0008 + .01
3791 — .0718 0.9 — .982 — 15 + .0006 + .01
8795 — .0744 0.7 — .943 — 13 + .0031 + .05
3796 — .0688 0.7 — .943 — 18 — .0025 — .04
4553 — .0610 0.8 + .984 +186 — .0054 — .10
4554 — .0695 0.8 + .984 +186 + .0031 + .06
4660 — .0647 0.8 + .934 +208 — .0023 — .04
4684 — .0675 0.6 + .923 +210 + .0004 + .01
5215 — .0786 0.9 — .947 +353 | + .0016 + .03
5219 — .0763 1.0 — .952 +354 — .0008 — .02
5229 — .0746 1.0 — .957 +355 — .0025 — .05
5285 — .0726 0.9 — .961 +3856 — .0045 — .09
5862 — .0735 1.0 + .924 +575 + .0007 + .01
5863 — .0752 1.0 + .924 +575 + .0024 + .05
5889 — .0739 1.0 + .905 +578 + .0010 + .02
5890 —0.0739 1.0 +0.905 +578 +0.0010 +0.02
from which:

c = — 0.06759 mm.

w= — 0.00156 mm. = — 070325, or — 07119 per year.

x = + 0.00413 mm. = + 07086 + 07007.

Probable error of plate of unit weight

16

+ 0.00153 mm. = + 07032.
226

S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 3

Repuctions For a Grminorum, Faintar Star

Solution Weight Parallax Time in Residual Vp-0
Plate. (m). (p). Factor (P). | Days (t). (2). in Arc.

mm. mm.
1832 +0.0990 0.5 +0.976 —533 +0.0036 | +0705
1931 + .1031 0.7 + .942 —524 — .0008 | — .O1
1966 + .1027 0.8 + .914 —519 — .0006 | — .O1
2106 + .1037 0.6 + .635 —491 — .0032 | — .05
2165 + .1017 0.5 + .402 —475 — .0023 | — .04
2453 + .0973 0.9 — .830 —393 — .0039 | — .08
2454 + .0945 0.7 — .830 —393 — .0011 — .02
2512 | + .0882 0.9 — .915 —383 + .0047 | + .09
2513 + .0915 0.5 — .915 —383 + .0014 | + .02
8302 + .0928 1.0 + .948 —160 + .0008 | + .02
3303 + .0896 0.9 + .948 —160 + .0040 | + .08
3716 + .0835 0.9 — .825 — 29 + .0012 | + .02
3717 + .0818 0.7 — .825 — 29 + .0029 | + .05
3790 + .0824 0.8 — .932 — 15 + .0016 | + .03
3791 + .0848 0.9 — .932 — 15 — .0008 | — .0O1
3795 + .0816 0.7 — .943 — 13 + .0023 | + .04
3796 + .0824 0.7 — .943 | — 138 | + .0015 | + .03
4553 + .0907 0.8 + .984 +186 — .0053 | — .10
4554 + .0830 0.8 + .984 +186 + .0024 | + .04
4660 + .0932 0.8 + .934 +208 — .0085 | — .16
4684 + .0862 0.6 + .923 +210 — .0016 | — .02
5215 + .0786 0.9 — .947 +353 — .0034 | — .07
5219 + .0735 1.0 — .952 +354 + .0016 | + .03
5229 + .0793 1.0 — .957 +355 — .0042 | — .09
5235 + .0760 0.9 — .961 +356 — .0010 | — .02
5862 + .0770 1.0 + .924 +575 — .0012 | — .02
5863 + .0736 1.0 + .924 +575 + .0022 | + .05
5889 4+ .0714 1.0 + .905 +578 + .0043 | + .09
5890 +0.0736 1.0 +0.905 +578 +0.0021 | +0.04
The normal equations are:

23.5¢ + 11.084 + 0.33547 = + 2.0114 mm.
+ 323.3680u + 9.23707 = + 0.2101 mm.

+ 19.44537

+ 0.0695 mm.
PARALLAXES OF 260 STARS 227

from which:
c = + 0.08667 mm.
w= — 0.00240 mm. = — 070499, or — 07182 per year.
a = + 0.00322 mm. = + 0067 + 07010.
Probable error of plate of unit weight
= 0.00200 mm. = + 07042.

a CANIS MINORIS (75 34™; +5° 29’)

There are few more interesting stars in the sky than Procyon.
Its large parallax makes it one of the ten nearest stars. Its
companion, discovered by Schaeberle in 1896, greatly enhances
the interest. It has a large annual proper motion of 1723, and
it is of type F5. Its great brilliancy, 0.48 magnitude, rendered
it a difficult object on which to obtain satisfactory photographs,

 

 

 

TABLE 1
Puates or Procyon
No. Date. | Hour Angle. Observers. Weight.
1050 1915 Mar. 13 +052 A 0.7
1059 Mar. 16 +0.2 M 0.7
1069 Mar. 17 +0.2 A 1.0
1123 Mar. 28 +0.8 M 1.0
19382 Oct. 30 +0.4 M 1.0
1933 Oct. 30 +0.7 M 1.0
1981 Nov. 7 —0.6 A 0.8
1982 Nov. 7 —0.3 A 0.9
1995 Nov. 9 —1.0 A 0.9
1996 Nov. 9 —0.8 A 0.9
2083 Nov. 27 +0.1 M 0.7
2084 Nov. 27 +0.4 M 0.7*
2460 1916 Mar. 11 +0.6 A 1.0
2461 Mar. 11 +1.0 A 0.7
2523 Mar. 25 +0.2 A 1.0
2524 Mar. 25 +0.7 A 0.8

 

 

 

 

 

* One exposure.
228 S, A. MITCHELL

and it was necessary to have the guiding at the telescope as
nearly perfect as possible. The series of plates were measured
by Mr. Mitchell. The McCormick results, given below, have
already been published in Popular Astronomy, 25, 38, 1917.

ComPARISON STARS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. x: he Teal Y (Declination). Dependence.
mm. mm. mm.

1 0.12 —53.6 +19.1 +0.203

2 .19 — 40.0 —31.6 .214

3 .14 +16.7 +54.4 -183

4 21 +16.8 + 2.8 .197

5 23° +60.1 —44.7 +0.203
Parallax star 0.28 — 0.9 — 1.5

TABLE 2
REDUCTIONS FOR Procyon
sale | Se | oe | | and
mm. mm.

1050 —0.0263 0.7 —0.853 —230 +0.0019 +0703
1059 — .0222 0.7 — .862 —229 — .0024 — .04
1069 — .0249 1.0 — .886 || —226 — .0003 — .01
1123 — .0278 1.0 — .953 —215 + .0006 + .01
1932 — .0213 1.0 + .947 + 1 + .0027 + .05
1933 — .0200 1.0 + .947 + 1 + .0014 + .03
1981 — .0182 0.8 + .901 + 9 — .0018 — .03
1982 — .0202 0.9 + .901 + 9 + .0002 .00
1995 — .0208 0.9 + .887 + 11 + .0004 + .01
1996 — .0206 0.9 + .887 + 11 + .0002 .00
2083 — .0225 0.7 + .712 + 29 — .0021 — .04
2084 — .0213 0.7 + .712 + 29 — .0033 — .06
2460 — .0574 1.0 — .843 +134 + .0002 -00
2461 — .0551 0.7 — .843 +134 — .0021 — .04
2523 — .0599 1.0 — .942 +148 — .0001 .00
2524 — .0624 0.8 —0.942 +148 +0.0025 +0.04

 

 

 
PARALLAXES OF 260 STARS 229

The normal equations are:
13.8¢ — 1.904u — 0.14917 = — 0.43844 mm.

+ 24.2527u + 2.998lr = — 0.11385 mm.
+ 10.82767 = + 0.1385 mm.
from which:
c = — 0.03257 mm.
uw = — 0.00907 mm. = — 07189, or — 0690 per year.
wr = + 0.01486 mm. = + 07309 + 07007.

Q

Probable error corresponding to unit weight
= + 0.00116 mm. = + 07024.

There is a surprisingly good agreement between the values of
the parallax already published:

 

 

 

Parallax. Authority. Method.
+0"299+0"038 Wagner Meridian Circle

.34 + .039 Flint Meridian Circle

8844 .015 Elkin Heliometer
+0.287+ .012 Miller Photography

 

 

 

Weighting these results according to their probable errors, the
parallax of a Canis Minoris (including the McCormick results),

comes out to be:
+ 07309.

Adams finds the spectroscopic value of + 07331.

During the time that the above photographs were being taken,
the motion of the companion was mainly in declination. Con-
sequently, the proper motion of Procyon itself as determined
by these photographs should have the same value as the proper
motion of the center of gravity of the system. The annual
proper motion in right ascension from the photographs is — 07690
while the corresponding value from Boss is — 07666, If we
assume a period of 39.0 years, anda = 4"05, the mass of Procyon
is 1.41 times that of the sun.
230 S. A. MITCHELL

y MONQCEROTIS (75 37"; —9° 19’)

The only parallax of this star is the spectroscopic value + 07013.
The star is of K type, of 4.07 magnitude, and of an annual proper

TABLE 1

Puates oF y MoNocEROTIS

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
560 1914 Nov. 11 0+0 A 1.0
586 Nov. 17 —0.4 Ol 0.6*
619 Nov. 22 —0.2 A 1.0
666 Dec. 14 —0.2 M 0.8
699 Dec. 22 +0.1 Ol 1.0
714 Dec. 26 +0.1 Ol 0.7
925 1915 Feb. 20 —0.2 A 0.8
926 Feb. 20 +0.1 A 1.0
939 Feb. 22 +0.8 M 0.8
977 Mar. 2 +0.5 M 0.7
» 1112 Mar. 27 +0.3 A 0.9
1879 Oct. 27 +0.1 A 1.0
1880 Oct. 27 +0.3 A 0.5*
1955 Nov. 2 —0.6 A 0.7
1961 Nov. 3 —0.1 G 0.5*
1962 Nov. 3 +0.2 G 0.5*
2098 Nov. 30 —0.7 A 0.8
2215 Dec. 23 +0.2 A 0.9

 

 

* One exposure.

CoMPARISON STARS

 

 

 

 

 

 

No. Diameter. = er gas Y (Declination). Dependence.
mm. mm. mm.
1 0.20 —26.3 +34.0 +0.2460
2 .16 — 23.3 —18.6 -1612
3 -26 —19.3 + 4.6 -2005
4 HU + 8.1 —24.4 -1630
5 21 +60.8 + 4.4 +0.2293
Parallax star 0.22 + 1.2 + 3.3

 
PARALLAXES OF 260 STARS

231

motion 0708. The McCormick value of the proper motion in
right ascension, — 07076 is in exact agreement with that given

 

 

 

 

 

 

 

 

 

 

by Boss. Mr. Alden measured the series of plates.
TABLE 2
Repvuctions ror y Monocerotis
clits ; ae ; =
pistes. | Sato | Nae eee eee | ee | ee
mm. mm.
560 —0.0100 1.0 +0.873 —180 —0.0012 —0'02
586 — .0159 0.6 + .821 —174 + .0046 + .07
619 — .0103 1.0 + .738 | ,—169 — .0010 — .02
666 — .0122 0.8 + .487 —147 + .0006 + .01
699 — .0122 1.0 + .363 —139 + .0006 + .01
714 — .0102 0.7 + .298 —135 — .0015 — .02
925 — .0136 0.8 — .612 — 79 + .0014 + .03
926 — .0132 1.0 — .612 — 79 + .0010 + .02
939 — .0090 0.8 — .639 — 77 — .0032 — .06
977 — .0148 0.7 — .737 — 69 + .0025 + .04
1112 — .0106 0.9 — .941 — 44 — .0020 — .04
1879 — .0152 1.0 + .961 +170 + .0004 + .01
1880 — .0135 0.5 + .961 +170 — .0013 — .02
1955 — .0143 0.7 + .934 +176 — .0005 — .01
1961 — .0120 0.5 + .928 +177 — .0028 — .04
1962 — .0114 0.5 + .928 +177 — .0034 — .05
2098 — .0183 0.8 + .683 +204 + .0032 + .06
2215 —0.0165 0.9 +0.350 +227 +0 .0012 +0 .02
The normal equations are:
14.2¢ — 1.7354 + 3.97397 = — 0.1833 mm.
+ 32.5576u + 4.03147 = — 0.0104 mm.
+ 7.613847 = — 0.0560 mm.
from which:
c = — 0.01302 mm.
# = — 0.00101 mm. = — 070210, or — 07076 per year.
a = — 0.00002 mm. = 07000 + 07011.

Probable error of plate of unit weight
+ 0.00131 mm. = + 07027.
232 S, A. MITCHELL

« GEMINORUM (75 38"; +24° 38’)

The Allegheny Observatory, by photography, derives the
parallax of + 0”025 + 0”007, and Adams and Joy the spectro-
scopic parallax + 07022. This is a double, OX 179, the principal
star being of G5 type, and of magnitude 3.68, while the com-

TABLE 1

PLatEes oF « GEMINORUM

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
420 1914 Oct. 21 —042 M 0.8
430 Oct. 27 —0.5 ol 0.4*
431 Oct. 27 —0.1 Ol 0.5
445 Oct. 30 0.0 A 0.8
679 Dec. 16 —0.7 G 1.0
889 1915 Feb. 17 —0.4 G 0.9
911 Feb. 19 —0.8 G 0.5*
912 Feb. 19 —0.3 G 0.8
951 Feb. 26 —0.6 G 0.5
952 Feb. 26 —0.2 G 0.5
1087 Mar. 19 —0.5 G 1.0
1850 Oct. 24 —0.6 G 0.5
1851 Oct. 24 —0.2 G 0.5
1914 Oct. 29 —0.5 G 0.6
1915 Oct. 29 —0.1 G 0.8
3393 1916 Nov. 16 —0.4 M 0.9
3394 Nov. 16 0.0 M 0.9
3426 Nov. 21 —0.6 L 1.0
3427 Nov. 21 —0.2 L 0.9
3487 Dec. 6 -1.1 A 1.0
3488 Dec. 6 —0.8 A 1.0
3731 1917 Mar. 8 —0.6 L 1.0
3732 Mar. 8 —0.4 L 0.9
8754 Mar. 12 —0.5 L 0.6
3755 Mar. 12 —0.2 L 0.6
3779 Mar. 20 —0.4 M 0.9
3839 Apr. 3 +0.1 M 0.9

 

* One exposure.
PARALLAXES OF 260 STARS 233

panion of tenth magnitude is at a distance of 6"5. The rotating
sector eliminated the companion. The series of plates were
measured by Mr. Lamb, who finds a proper motion in right
ascension of — 0019 while the value from Boss is — 07022.

TABLE 2

REDUCTIONS FOR « GEMINORUM

 

 

 

 

 

 

 

 

 

uti ‘ 1 | rime i ‘dual =a
pista |) a || MGR | aemer ee Daye. | we | akan
mim. mm.
420 —0.0008 0.8 +0.977 —453 +0.0024 | +0704
430 + .0052 0.4 | + .961 —447 — .0087 | — .05
431 + .0060 0.5 + .961 —447 | -— .0045 | — .07
445 + .0050 0.8 + .949 ~—444 — .0035 | — .06
679 — .0008 1.0 + .464 —397 + .0019 | + .04
889 + .0011 0.9 — .563 —334 — .0009 | — .02
911 + .0041 0.5 — .591 —332 — .0039 | — .06
912 + .0014 0.8 — .591 —332 — .0012 | — .02
951 | — .0040 0.5 — .682 —3825 + .0041 | + .06
952 — .0022 0.5 — .682 —325 + .0023 | + .03
1087 — .0018 1.0 — .892 —304 + .0017 | + .04
1850 — .0042 0.5 + .971 — 8 | + .0048 | + .07
1851 + .0015 0.5 + .971 — 85 — .0009 | — .0O1
1914 + .0026 0.6 + .954 — 80 — .0020 | — .03
1915 — .0022 0.8 + .954 — 80 + .0028 | + .05
3393 + .0001 0.9 + .830 +304 — .0005 | — .0O1
3394 — .0016 0.9 + .830 +304 + .0012 | + .02
3426. | — .0021 1.0 + .781 +309 + .0016 | + .03
3427 + .0005 0.9 + .781 +309 — .0010 | — .02
3487 — .0012 1.0 + .600 +3824 + .0006 | + .01
3488 + .0010 1.0 + .600 +3824 — .0016 | — .03
3731 — .0011 1.0 — .800 +416 — .0007 | — .01
3732 — .0019 0.9. — .800 | +416 + .0001 | + .00
3754 — .0041 0.6 — .839 +420 + .0022 | + .04
8755 — .0031 0.6 — .839 +420 + .0012 | + .02
3779 — .0013 0.9 — .903 +428 — .0006 | — .OL
3839 +0.0008 0.9 —0.973 +442 —0.0028 | —0.06

 
234 8S. A. MITCHELL

CoMPARISON STARS

 

 

 

No. Diameter. Ge a ented Y (Declination). Dependence.

1 0.10 —41.4 —28.6 +0 .2320

2 15 —23.1 +10.9 -2158

3 .10 —17.3 +19.8 .2110

4 14 + 4.7 +36.6 . 1938

5 18 +77.1 —38.7 +0.1474
Parallax star 0.15 — 5.96 + 1.28

 

 

 

 

 

1

The normal equations are:

20.7¢ + 7.8464 + 2.29007 = — 0.0054 mm.
+ 255.61254 — 10.22797 = — 0.0729 mm.
+ 13.5133 = + 0.0112 mm.
from which:
c = — 0.00024 mm.
pw = — 0.00025 mm. = — 070052, or — 07019 per year.

x = + 0.00068 mm. = + 0014 + 07008.
Probable error of plate of unit weight
+ 0.00136 mm. = + 07028.

LALANDE 15290 (75 47™; +30° 55’)

This star is of more than usual interest since it has a total
proper motion 1797 and a very large radial velocity amount-
ing to — 242 km. per sec. (Adams, Astrophysical Journal, 49,
149, 1919). It is of magnitude 8.2 and of G type. Its parallax
has been several times determined as follows: Peter with the
heliometer derived the value + 0702 + 0021, Flint with the
meridian circle — 0701 + 07030, Chase with the heliometer
+ 0°075 + 07046, Schlesinger by photography with the 40-inch
refractor + 07072 + 07019, and Mt. Wilson with the spectro-
graph the absolute value + 07035. Ten of the eighteen plates
of the series were measured by Mr. Mitchell, the balance by
Miss Hawes. A relative parallax + 0”033 + 0007 resulted
with a proper motion in right ascension + 0”701, where the
corresponding value from Porter is + 0%732.
PARALLAXES OF 260 STARS

TABLE 1

Puates oF LALANDE 15290

235

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
5148 1918 Mar. 1 —048 Ol 1.0
5244 Mar. 29 —0.1 Ol 1.0*
5946 Nov. 12 —1.0 F 1.0
5947 Nov. 12 * 08 F 1.0
6034 Nov. 30 —0.8 M 1.0
6035 Nov. 30 —0.4 M 1.0
6533 1919 Feb. 17 —0.9 H 1.0
6534 Feb. 17 —0.5 H 1.0
6742 Mar. 24 —0.5 F 1.0
6743 Mar. 24 —0.1 F 1.0
8012 Nov. 5 —0.8 F _1.0
8013 Nov. 5 —0.5 F 1.0
8090 Nov. 17 —1.0 Ol 1.0
8091 Nov. 17 —0.6 Ol 1.0
8648 1920 Feb. 27 —0.3 M 1.0
8649 Feb. 27 0.0 M 1.0
8693 Mar. 2 —0.6 Ol 1.0
8694 Mar. 2 —0.2 Ol 1.0

* Three exposures.
Comparison STARS
No. Diameter. |* ight eel Y (Declination). Dependence.
mm. mm. mm.

1 0.11 —59.9 +12.9 +0.242

2 11 — 0.6 —26.7 -184

3 .10 + 6.2 + 8.9 - 202

4 .12 +21.2 +381.2 .207

5 -12 +33.1 —26.3 +0.165

Parallax star 0.11 — 3.5 af Dial

 

 

 

 

 
236 S. A. MITCHELL

TABLE 2

Repvuctions ror LaLanpE 15290

 

 

 

 

 

 

 

 

i i ll: Time i Residual Dp:
pce, | Sauter | apie eas | | eee | ee
5148 —0.0234 1.0 —0.696 —443 —0.0014 —0°03
5244 — .0224 1.0 — .941 —415 — .0002 -00
5946 + .0032 1.0 + .882 —187 — .0019 — .04
5947 + .0001 1.0 + .882 —187 + .0012 + .02
6034 + .0001 1.0 + .707 —169 + .0026 + .05
6035 + .0030 1.0 + .707 —169 |. — .0003 — .01
6533 + .0109 1.0 — .533 — 90 — .0029 — .06
6534 + .0066 1.0 — .533 — 90 + .0014 + .03
6742 + .0108 1.0 — .910 — 55 — .0001 -00
6743 |. + .0074 1.0 — .910 — 55 + .0033 + .07
8012 .| + .0358 1.0 + .928 +171 — .0014 — .03
8013 + .0348 1.0 + .928 +171 — .0004 — .01
8090 + .0332 1.0 + .844 +183 + .0022 + 05
8091 + .0366 1.0 + .844 +183 — .0012 — .02
8648 + .0440 1.0 — .665 +285 — .0016 — .03
8649 + .0424 1.0 — .665 +285 -0000 -00
8693 + .0420 1.0 — .714 +289 + .0008 + .02
— 8694 +0.0430 1.0 —0.714 +289 —0.0002 0.00

 

 

The normal equations are:

18.0c — 0.040u — 0.55907 = + 0.3081 mm.
+ 97.2736u + 1.60597 = + 0.8998 mm.

+ 11.20097 = + 0.0229 mm.
from which:
c = + 0.01719 mm.
w= + 0.00923 mm. = + 071920, or + 07701 per year.

a = + 0.00158 mm. = + 07033 + 0"007.
Probable error of plate of unit weight

+ 0.00119 mm. = + 0”025.
PARALLAXES OF 260 STARS 237

9 PUPPIS (75 47"; —13° 38’)

This star, called also 9 Argus, is of type F8 and of magnitude
5.34. It is an interesting double 8 101, with considerable proper
motion, 0735 per year. According to Lohse (Publ. Potsdam Obs.,
20, 93, 1908), it has a period of 23.34 years, and a semi-major
axis of 0769. The plates of the series were measured by Mr.
Mitchell. The plates themselves were taken in six different
seasons. According to the ephemeris by Aitken (Lick Observatory
Publications, 12, 52, 1914), the ‘position angles and distances
of the components at the means of the times for each of the six
seasons at which photographs were taken are as follows:

1915.25 98°6 0741
15.84 180 .00+
16.28 263.0 11
16.81 274.5 30
17.22 280.3 -40

» 17.85 282.4 0.47

A first solution of the measures as given in Table 2 was made
without making any allowance for the orbital motion. This
gave the solution below, where the parallax has the value + 07036
+ 0"008. The proper motion has the value +.0°7035 per year,
while the value of Boss for the center of gravity is — 0”060.
The difference in the values of the proper motion is due mainly
to orbital motion. Any proper motion of the comparison stars,
or any apparent motion of the comparison stars caused by the
solar drift through space will also make a difference in the two
proper motions. The motion of the comparison stars caused
by the motion of the sun will amount to approximately — 07007
in right ascension. Hence, the proper motion of the center of
gravity of the system of 9 Argus referred to the comparison
stars used will be — 07053 in right ascension. Making use of
the orbital motion, as shown in the above ephemeris, and com-
paring the results of the first four plates of the series, 1060 to
1187, inclusive, with the last ten plates taken, and correcting the
measures for parallax, it is readily derived that the masses
of the components A and B are in the ratio 0.73 to 0.27, where
1.0 represents the total mass of the system.
238

PiatTes or 9 Puppis

S. A. MITCHELL

TABLE 1

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1060 | 1915 Mar. 14 +048 M 1.0
1135 Mar. 31 +0.4 G 1.0
1186 Apr. 13 +0.9 M 1.0
1187 Apr. 13 +1.3 M 1.0
1864 Oct. 25 —1.0 Ol 0.7
1865 Oct. 25 —0.6 Ol 0.7
2036 Nov. 17 +0.2 A 0.7
2037 Nov. 17 +0.6 A 0.7
2555 1916 Apr. 6 +1.0 M 0.7
2565 Apr. 15 +1.3 Ol 0.5*
3268 Oct. 24 —0.4 M 0.7
3269 Oct. 24 0.0 M 0.7
3718 1917 Mar. 6 +0.2 M 0.8
8719 Mar. 6 * +0.6 M 0.8
3791 Mar. 22 +0.1 A 0.8
3792 Mar. 22 +0.2 A 0.8
3868 Apr. 10 +0.9 M 0.7
3871 Apr. 11 +1.0 A 0.8
4710 Nov. 5 —0.8 B 1.0
4711 Nov. 5 —0.4 B 0.9
4733 Nov. 7 —1.4 B 0.8
4734 Nov. 7 —1.0 B 0.8

 

* One exposure.
239

 

 

 

 

PARALLAXES OF 260 STARS
TABLE 2
ReEDvucTIONS For 9 Purris
pits, || PE Ee eee. | See | ahs
mm. mm.
1060 —0.0154 1.0 —0.833 —514 —0.0007 —0"01
1135 — .0162 1.0 — .950 —497 .0000 -00
1186 — .0148 1.0 — .986 —484 — .0015 — .03
1187° — .0198 1.0 — .986 —484 + .0035 + .07
1864 — .0134 0.7 + .971 —289 + .0014 | + .02
1865 — .0136 0.7 + .971 —289 + .0016 | + .03
2036 — .0079 0.7 + .843 —266 — .0042 — .07
2037 — .0092.| 0.7 + .843 —266 — .0029 — .05
2555 — .0150 0.7 — .975 —125 + .0004 | + .01
2565 — .0168 0.5 — .987 —116 + .0022 | + .03
3268 — .0132 0.7 +. .971 + 76 + .0029 + .05
3269 — .0099 0.7 + .971 + 76 — .0004 — .01
3718 — .01384 0.8 758 +209 + .0007 | + .01
3719 — .0094 0.8 — .758 +209 — .0033 — .06
8791 — .0106 0.8 — .901 +225 — .0022 — .04
3792 — .0124 0.8 — .901 +225 — .0004 — .01
3868 — .0122 0.7 — .983 +244 — .0007 — .O1
3871 — .0152 0.8 — .984 +245 + .0023 | + .04
4710 — .0080 1.0 + .925 +453 — .0006 — .01
4711 — .0068 0.9 + .925 +453 — .0018 — .04
4733 — .0086 0.8 + .914 +455 -0000 .00
4734 —0.0130 0.8 +0.914 +455 +0.0044 | +0.08

 

 

 

 

 

 
240 S. A. MITCHELL

Assuming the’ masses to be in this ratio, a second solution
was made making allowance for the orbital motion. The parallax
resulted + 0”033 + 07008, differing 0003 from the first solu-
tion, but the orbital motion from the second solution is found to
be — 07062 per year, in substantial agreement with the value
from Boss.

It is thought that this second solution gives the more reliable
value for the parallax. Using the orbit of Lohse, the mass of
the system is 11.0 times that of the sun, and the masses of
A and B are 7.9© and 3.1© respectively.

ComPaRISON STARS

 

 

 

 

 

 

No. Diameter. = eee Y (Declination). Dependence.
mm. mm. mm.
1 0.18 ; —45.2 +21.0 +0.288
2 12 — 2.2 —19.0 .356
3 26 +47.4 — 2.0 +0.356
Parallax star 0.18 + 3.1 — 1.4

 

The normal equations are:

17.6¢ — 1.452u — 1.94187 = — 0.2209 mm.
+ 218.3179 + 19.1678r = + 0.1514 mm.
+ 14.9597 = + 0.0586 mm.

from which:
e = — 0.01232 mm.
w= + 0.00046 mm. = + 070096, or + 07085 per year.
w= + 0.00173 mm. = + 07036 + 07008.
Probable error of plate of unit weight
+ 0.00140 mm. = + 07029.

p PUPPIS (8 3™; —24° 0’)

This star, also called « Navis, is of magnitude 2.88, and of
type F5. Campbell (Lick Observatory Bulletin, 2, 29, 1903)
finds it to be a spectroscopic binary of long period. Mt. Wilson,
finds the spectroscopic parallax + 0.029. The annual proper
motion in right ascension from the present photographs is
PARALLAXES OF 260 STARS

241

— 0°060, while Boss gives the value — 0.029. Mr. Olivier
measured the series of plates.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
PLaTES OF p PupPis
No. Date. Hour Angle. Observers. Weight.
715 1914 Dec. 26 +064 Ol 0.9
723 Dec. 27 +0.7 G 0.6*
751 1915 Jan. 7 +0.3 M 0.8
1016 Mar. 9 0.0 A 1.0
1017 Mar. 9 +0.7 A 0.7*
1088 Mar. 12 0.0 A 1.0
1125 Mar. 29 +0.2 Ol 1.0
1126 Mar. 29 +1.0 Ol 0.8
1897 Oct. 28 —0.5 Ol 0.7
2006 Nov. 10 —0.5 G 0.7
2007 Nov. 10 +0.2 G 0.8
2068 Nov. 25 —0.3 Ol 0.8
3518 1916 Dec. 10 —1.2 L 0.9
3519 Dec. 10 —0.6 L 0.8
3520 Dec. 12 —0.6 M 0.9
3537 Dec. 25 —0.7 = L 0.9
3538 Dec. 25 —0.4 L 0.9
3733 1917 Mar. 8 —0.3 L 0.9
8734 Mar. 8 +0.1 L 0.8
* One exposure.
ComPARISON STARS
No. Diameter. |~ Cn eee Y (Declination). Dependence.
mm. mm. mm.

1 0.20 —62.3 +22.9 +0.2111

2 .19 —45.2 —37.8 .2071

3 24 +10.0 +23.3 -1988

4 ll +41.5 +21.3 - 1932

5 .16 +56.0 —29.7 .+0.1898

0.20 — 1.9 + 0.1

Parallax star
17
242 S. A. MITCHELL

TABLE 2

REDUCTIONS FOR p PUPPIS

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp “v
Plate. (m). 7 (p). Factor (P). | Days (é). (v). in Are

mm. mm.
715 +0.0001 0.9 +0.394 —364 —0.0003 —0’01
723 + .0003 0.6 + .378 —363 — .0005 — .01
751 + .0002 0.8 + .249 —352 — .0006 — .01
1016 — .0030 1.0 — .740 —291 + .0008 + .02
1017 — .0004 0.7 — .740 —291 — .0018 — .03
1038 — .0030 1.0 — .772 —288 + .0008 + .02
1125 — .0044 1.0 — .916 —271 + .0018 + .04
1126 — .0011 0.8 — .916 —271 — .0014 | — .03
1897 — .0001 0.7 + .967 — 58 — .0018 — .03
2006 - 0000 0.7 + .916 — 45 — .0020 — .04
2007 — .0032 0.8 + .916 — 45 + .0012 + .02
2068 — .0046 0.8 + .799 — 30 + .0023 + .04
3518 — .0054 0.9 + .618 +3851 — .0001 -00
3519 — .0059 0.8 |; + .618 +351' + .0004 + .01
3520 — .0036 0.9 + .592 +353 — .0020 — .04
3537 — .0081 0.9 + .402 +366 + .0022 + .04
3538 — .0070 0.9 + .402 +366 + .0011 ob .02
3733 — .0085 0.9 — .734 +439 + .0006 + .01
8734 —0.0053 0.8 —0.734 +439 —0.0026 —0.05

 

The normal equations are: i

15.9¢ + 0.8994 + 0.85117 = — 0.0557 mm.
+ 155.2975 + 9.0734r = — 0.1138 mm.
+ 7.90767 = — 0.0002 mm..
from which:
c = — 0.00353 mm.
& = — 0.00079 mm. = — 070163, or — 0”060 per year.

+ 0.00126 mm. = + 0026 + 0008.
Probable error of plate of unit weight
+ 0.00098 mm. = + 0”020.

T
PARALLAXES OF 260 STARS

LALANDE 15950 (8° 5"; +32° 46’)

243

This star is of G2 type, of magnitude 6.7, and of total proper
motion 0782. The parallax has been twice measured. Chase
with the Yale heliometer derives the value + 07040 + 0’042,
and Jost with the meridian circle the result + 07040 + 07024.

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Puates or LALANDE 15950
No. Date. Hour Angle. Observers. Weight.
3295 1916 Oct. 27 —141 M 0.9
3363 Nov. 7 —0.4 L 0.9
3489 Dec. 6 —0.7 A 1.0
3490 Dec. 6 —0.4 A 0.7*
3809 1917 Mar. 25 —0.6 M 0.8
3810 Mar. 25 —0.2 M 0.9
3823 Mar. 28 —0.7 Ol 0.8
3824 Mar. 28 —0.2 Ol 0.7
4629 Oct. 22 —0.4 Ds 0.5*
4636 Oct. 25 —0.8 Ds 0.7
4685 Nov. 2 —0.8 M 0.8
4686 Nov. 2 —0.3 M 0.6
5131 1918 Feb. 23 —0.5 M 0.8
5192 Mar. 11 —0.4 A 0.9
5253 Mar. 30 —0.2 M 1.0
5257 Mar. 31 —0.2 M 1.0
5262 Apr. 2 -0.2 M 0.7*
* One exposure.
CoMPARISON STARS
No. Diameter. « ae aaa Y (Declination). Dependence.
mm. mm. mm.
1 0.11 —71.3 +18.1 +0.1855
2 -10 + 4.8 —21.3 .8054
3 .08 +16.0 + 0.7 «2524
4 -11 +50.5 + 2.5 +0.2567
Parallax star 0.14 + 5.2 — 2.3

 

 

 

 
244 S. A. MITCHELL

Mr. Alden measured the McCormick plates, and found a proper
motion in right ascension of — 07456 per year, while the value
from Porter is — 07454. Mt. Wilson finds the spectroscopic
parallax + 07072.

 

 

 

 

 

 

 

 

 

 

TABLE 2
Repvuctions ror LALANDE 15950
Solution Weight Parallax Time in Residual Vp-
Plate. (m). (p). Factor (P). | Days (t). (»). in Arc.
mm. mm.
3295 +0.0106 0.9 +0.967 —277 +0.0038 +0707
3363 + .0132 0.9 + .930 —266 + .0004 + .01
3489 + .0130 1.0 + .676 —237 — .0016 — .03
3490 + .0145 0.7 + .676 —237 — .0031 — .05
3809 + .0022 0.8 — .886 —128 — .0003 .00
38810 + .0015 0.9 — .886 —128 + .0004 + .01
3823 — .0007 0.8 — .907 —125 + .0024 + .04
3824 + .0050 0.7 — .907 —125 — .00338 — .06
4629 — .0075 0.5 + .973 + 83 + .0003 -00
4636 — .0051 0.7 + .970 + 86 — .0023 — .04
4685 — .0066-| 0.8 + .952 + 94 — .0013 — .02
4686 — .0110 0.6 + .952 + 94 + .0031 + .05
5131 — .0159 0.8 — .558 +207 — .0017 — .03
5192 — .0221 0.9 — .757 +223 + .0032 + .06
5253 — .0215 1.0 — .918 +242 + .0012 + .02
5257 — .0195 1.0 — .924 +243 — .0009 — .02
5262 —0.0191 0.7 —0.936 +245 —0.0014 —0.02
The normal equations are:
13.7¢ — 0.4064 — 1.13689" = — 0.0556 mm.
+ 53.9172u — 10.00717 = — 0.3408 mm.
+ 10.44077 = + 0.0845 mm.
from which:
c = — 0.00408 mm.
# = — 0.00600 mm. = —~ 071248, or — 07456 per year.
7 = + 0.00190 mm. = + 0040 + 0”010.

Probable error of plate of unit weight
+ 0.00140 mm. = + 07029.
PARALLAXES OF 260 STARS 245

8 CANCRI (8 117; +9° 30’)

This star is of 3.76 magnitude, and of type K2. The trigo-
nometric value of Alleghenyis — 07003 + 07009, while the spectro-
scopic work of Adams gives the result + 07016. Boss gives the
proper motion in right ascension — 07052. The plates of this
series were measured by Mr. Olivier, with the exception of the last
five plates which were measured by Mr. Mitchell. The proper
motion in right ascension from the plates is — 0"079, and the
relative parallax — 07002 + 07010.

TABLE 1

Puates or 6 Cancri

 

 

 

 

 

 

 

No. . Date. Hour Angle. — Observers. Weight.
700 1914 Dec. 22 +055 ol 0.7
722 _ Dec. 27 —0.3 G 0.8
992 1915 Mar. 3 —0.2 G 1.0
993 Mar. 3 +0.2 G 1.0
1972 Nov. 5 0.6 Ol 0.8
1985 Nov. 8 =i Ol 0.9
"1986 | ‘Nov. 8 +0.4 Ol 0.8
1997 Nov. 9 —0.8 A 1.0
1998 Nov. 9 -0.5 A 1.0
2120 Dec. 6 0.9 Ol 0.8
2450 1916 Mar. 8 =(,9 G 0.9
2454 Mar. 10 +0.1 ol 0.9
2480 Mar. 15 +0.4 G 0.7
2498 Mar. 17 +0.4 ol 1.0
2499 Mar. 17 +0.9 Ol 1.0
5118 1918 Feb. 22 —0.5 Ol 0.6
5119 _ Feb. 22 +0.1 Ol 0.8
5194 | Mar. 15 (1 Ol 0.8
5864 Nov. 2 —0.6 M 0.8
5865 Nov. 2 —0.2 M 1.0
5891 Nov. 5 -0.5 M 0.9
5892 Nov. 5 —0.2 M 0.9

 
246 S. A. MITCHELL

TABLE 2

Repuctions ror 6 CANcRI

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual 4 vVp-0
Plate. (m). (p). Factor (P). | Days (t). @). in Are.
, mm. mm.
700 +0.0166 0.7 +0.483 —613 —0.0051 —0°09
722 + .0148 0.8 + .408 —608 — .0028 — .05
992 + .0137 1.0 — .643 —542 — .0028 — .06
993 + .0140 1.0 — .643 — 542 — .0031 — .06
1972 + .0068 0.8 + .946 —295 + .0014 + .02
1985 + .0077 0.9 + .933 —292 + .0004 | + .01
1986 + .0065 0.8 + .933 —292 + .0016 + .03
1997 + .0072 1.0 + .929 —291 + .0009 + .02
1998 + .0078 1.0 + .929 —291 + -0003 + .01
2120 + .0059 0.8 + .700 —264 + .0020 + .04
2450 + .0051 0.9 — .713 —171 + .0019 + .04
2454 + .0054 0.9 — .736 —169 + .0016 + .03
2480 + .0068 0.7 — .789 —164 + .0002 -00
2498 + .0022 1.0 — .809 —162 + .0048 + .10
2499 + .0034 1.0 — .809 —162 + .0036 + .07
5118 — .0019 0.6 — .624 +545 + .0015 + .02
5119 + .0032 0.8 — .524 +545 — .0036 — .07°
5194 + .00382 0.8 — .784 +566 — .0038 — .07
5864 — .0033 0.8 + .955 +798 + .0001 .00
5865 — .0020 1.0 + .955 +798 — .0012 — .02
5891 — .0050 0.9 + .945 +801 + .0018 | + .04
5892 —0.0022 0.9 +0.945 +801 —0.0010 —0.02

 
PARALLAXES OF 260 STARS 247

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. X (Right Ascen-| y (Declination). Dependence.
sion).
mm. mm. mm.
1 0.22 — 8.5 +42.0 +0.4374
2 .12 —10.1 —12.1 - 1288
3 .14 +18.6 —29.9 +0.4338
Parallax star 0.16 + 3.05 + 3.84

 

The normal equations are:

19.1le — 1.7594 + 2.72427 = + 0.1007 mm.
+ 468.2571 + 14.70227 = — 0.4981 mm.

+ 12.25227 = — 0.0023 mm.
from which:
c = + 0.00519 mm. : :
w= — 0.00104 mm. = — 070217, or — 07079 per year.
a = — 0.00009 mm. = — 07002 + 07010.

Probable error of plate of unit weight
+ 0.00169 mm. = + 07035.

. LALANDE 16304 (8' 13"; —12° 17’)

This star has a total proper motion 1703, it is of magnitude
6.8, and of type G9. Its parallax has been determined as
follows: Flint by the meridian circle obtained the value + 0712
+ 0030; Chase with heliometer the result + 07095 + 07017;
and by photography at Swarthmore, + 07075 + 07007. The
McCormick plates were measured by Mr. Olivier who determined
a relative parallax of + 07060 + 07007 with a proper motion
in right ascension amounting to + 07285 while the corresponding
value from Porter is + 0"279. Mt. Wilson furnishes the spectro-
scopic parallax of + 07123.
248 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Puates or LALANDE 16304
No. Date. Hour Angle. Observers. Weight.
3410 1916 Nov.19_ —1%0 L 0.9
3411 Nov. 19 —0.6 L 0.9
3502 Dec. 7 —0.5 M 1.0
3811 1917 Mar. 25 —0.5 M 0.8
8812 Mar. 25 - —1.0 M 0.8
3824 Mar. 28 —0.2 Ol 0.7
3825 Mar. 28 +0.1 Ol 0.7
4735 Nov. 7 —0.8 B 0.9
4736 Nov. 7 —0.4 B 0.9
4748 Nov. 9 —0.4 B 1.0
4749 Nov. 9 0.0 B 1.0 >
5254 1918 Mar. 30 +0.1 M 1.0
5255 - Mar. 30 +0.6 M 0.9
5264 Apr. 4 —0.1 A 1.0
5265 Apr. 4 +0.4 A 1.0
5914 Nov. 7 —0.4 F 0.6*
5915 Nov. 7 +0.1 F 0.7
6092 Dec. 17 —0.2 D 1.0
6093 Dec. 17 +0.4 D 1.0
6105 Dec. 18 —0.1 F 1.0
6624 1919 Mar. 4 +0.2 H 0.8
6625 Mar. 4 +0.7 H 0.8
6690 Mar. 18 —0.9 ol 1.0
6691 Mar. 18 —0.3 Ol 0.9
* One exposure.
Comparison STARS
No. Diameter. |* oe Y (Declination). Dependence.
|
mm. mm, mm.

1 0.11 —51.8 +45.8 +0.1557

2 .08 —30.1 —44.7 .1904

3 .09 — 6.5 — 0.9 .1959

4 10 +33.3 —36.6 2301

5 .12 +55.1 +36.4 +0.2279

Parallax star 0.10 + 5.1 ji — 1.7

 

 

 

 
PARALLAXES OF 260 STARS 24

 

 

 

 

 

 

 

TABLE 2
ReEpDvucTIONS FOR LALANDE 16304

1 . no bh: i res Ti : . ae
plate Cae || ea ay Ve ea i eae

mm. mm. z
3410 —0.0020 0.9 +0.864 —489 +0.0011 +0702
3411: + .0014 0.9 + .864 —489 — .0023 — .05
3502 + .0032 1.0 + .685 —471 — .0040 | — .08
3811 — .0029 0.8 — .870 —363 + .0017 | + .03
3812 — .0037 0.8 — .870 —363 + .0025 | + .05
3824 — .0044 0.7 — .892 —360 + .0083 | + .06
3825 — .0029 0.7 — ,892 —360 + .0018 | + .08
4735 + .0116 0.9 + .937 —136 + .0010 | + .02
4736 + .0120 0.9 + .937 —136 + .0006 | + .01
4748 + .0133 1.0 + .928 —134 — .0007 — .01
4749 + .0130 1.0 + .928 —134 — .0004 — .01
5254 + .0112 1.0 — .904 + 7 + .0014 + .03
5255 + .0142 0.9 — .904 + 7 — .0016 | — .03
5264 + .0136 1.0 — .933 + 12 — .0008 | — .02
5265 + .0160 1.0 — .933 + 12 — .0032 — .07
5914 + .0235 0.6 + .938 +229 + .0028 .) + .04
5915 + .0261 0.7 | + .938 +229 + .0002 | -00
6092 + .0254 1.0 + .562 +269 + .0013,) + .03
6093 + .0265 1.0 + .562 +269 + .0002 . .00
6105 + .0250 |} 1.0 + .548 +270 + .0017 + .04
6624 + .0270 0.8 — .648 +346 — .0009 — .02
6625 + .0256 0.8 — .648 +346 + .0005:|}°+ .01
6690 + .0294 1.0 — .805 +860 - -0032 | — .07
6691 +0.0258 0.9 —0.805 +360 +0.0004: | +0.01

 

 

 

The normal equations are:
21.3¢ — 5.682y — 0.11657 = + 0.2974 mm.
+ 183.7696n — 8.20557 = + 0.5825 mm.
+ 14.7132 = + 0.0095 mm.

from which:
c = + 0.01498 mm.
uw = + 0.00376 mm. = + 070782, or + 07285 per year.

_ @ = + 0.00286 mm. = + 07060 + 07007.
Probable error of plate of unit weight
+ 0.00129 mm. = + 07027.
250 S. A. MITCHELL

LALANDE 17046 (8% 34"; +11° 53’)

The spectroscopic parallax determined for this star which has
a total proper motion of 0752 per year, and of magnitude 8.1 is
+ 07048. Mr. Alden measured the McCormick plates, and found
the relative parallax of + 07026 + 07009. The proper motion in

TABLE 1

Puates oF LALANDE 17046

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
3338 1916 Nov. 2 —054 M 0.7
3412 Nov. 19 —0.3 L 0.9
3491 Dec. 6 —0.3 A 1.0
3492 Dec. 6 0.0 A 1.0
3513 Dec. 9 —0.4 Ol 1.0
3797 1917 Mar. 24 +0.1 M 0.8
3798 Mar. 24 +0.4 M, L 0.8
3869 Apr. 10 +0.6 M 0.8
3870 Apr. 10 +1.0 M 0.8
3890 Apr. 18 +0.7 Ol 0.7
3891 Apr. 18 +1.1 Ol 0.7
4660 Oct. 31 —0.8 A 0.8
4771 Nov. 16 —0.7 B 0.8
4772 Nov. 16 —0.3 B 0.8
5217 1918 Mar. 25 —0.2 A 1.0
5218 Mar. 25 +0.2 A 1.0
5232 Mar. 27 0.0 M 1.0
§233 Mar. 27 +0.4 M 1.0

Comparison Stars
No. Diameter. x cine, meet Y (Declination). Dependence.
mm. m. mm.

1 0.10 —44.1 + 0.6 +0.3366

2 .10 + 3.4 +11.9 -2767

3 .08 +40.7 —12.5 +0.3867

Parallax star 0.11 + 1.8 — 1.3

 

 

 

 
PARALLAXES OF 260 STARS

251

right ascension from the plates is — 07113 per year, while the
value from Porter is — 0°104.

 

 

 

 

 

 

 

 

 

 

TABLE 2
Repuctions ror LALANDE 17046
Soluti Weight | Parall: Time i i Fi
Plate, Sone ee eee eee | ee | ae
mm. mm.
3338 +0.0073 0.7 +0.958 —234 —0.0033 —0"06
3412 + .0026 0.9 + .891 —217 + .0010 + .02
3491 + .0022 1.0 + .747 —200 + .0010 + .02
3492 + .0043 1.0 + .747 —200 — .0011 — .02
3513 + .0050 1.0 + .714 —197 — .0019 — .04
3797 + .0018 0.8 — .814 — 92 — .0022 — .04
3798 — .0039 0.8 — .814 — 92 + .0035 + .07
3869 + .0014 0.8 — 9384 — 75 — .0022 — .04
3870 — .0036 0.8 — .934 — 75 + .0028 + .05
3890 — .0028 0.7 — .963 — 67 + .0019 + .08
3891 — .0018 0.7 — .963 — 67 + .0009 + .01
4660 — .0028 0.8 + .960 +129 + .0014 + .02
4771 — .0042 0.8 + .910 +145 + .0024 + .05
4772 — .0022 0.8 + .910 +145 + .0004 + .01
5217 — .0043 1.0 — .820 +274 — .0015 — .03
5218 | — .0054 | 1.0 | — .820 | +274 | — .ooo4 | — .o1
5232 — .0038 1.0 — .8388 +276 — .0021 — .04
5233 —0.0065 1.0 —0.838 +276 +0.0006 +0.01
The normal equations are:
15.6c + 1.181n — 1.55657 = — 0.0151 mm.
+ 57.7802u — 10.49907 = — 0.1002 mm.
+ 11.54857 = + 0.0313 mm.
from which:
c = — 0.00073 mm.
uw = — 0.00149 mm. = — 070310, or — 07113 per year.

T

Probable error of plate of unit weight
+ 0.00130 mm. = + 07027.

+ 0.00126 mm. = + 07026 + 07009.
252 S. A. MITCHELL

6 CANCRI (8* 39"; +18° 31’)

This star is of magnitude 4.17, and of type K. Adams furn-
ishes the value of the spectroscopic parallax to be + 07017.
Allegheny finds the trigonometric parallax — 07012 + 07012.
The total proper motion is 0724, that in right ascension being
— 07017. Burnham’s General Catalogue gives the measures of 6
Cancri with respect to a fifteenth magnitude star at a distance
of 45’. The change in position angle and distance is entirely due
to the proper motion of 6 Cancri. Mr. Olivier measured the
twenty-one plates of the series, and found the proper motion in
right ascension equal — 07009.

TABLE 1

Puates oF 6 CANcRI

 

 

 

 

No. Date. Hour Angle. Obsefvers. Weight.
698 1914 Dec. 21 —054 A 0.9
734 1915 Jan. 4 +0.2 G 0.6*
784 Jan. 13 0.0 G 0.8
810 Jan. 20 +0.7 G 0.8
978 Mar. 2 +0.1 M 0.9

1062 Mar. 14 +1.1 M 0.7

1079 Mar. 18 +0.6 | Ol 1.0

1080 Mar. 18 +1.1 | Ol 1.0

1226 Apr. 18 +0.4 Ol 0.8

1973 Nov. 5 —0.4 Ol 0.9

2013 Nov. 15 —0.9 Ol 0.7

2014 Nov. 15 —0.4 Ol 0.7

2121 Dec. 6 —0.7 Ol 0.7

2122 Dec. 6 —0.1 Ol 0.9

2203 Dec. 22 —0.4 G 0.6*

2204 Dec. 22 0.0 G 0.7

2234 Dec. 26 —0.6 A 1.0

2235 Dec. 26 —0.2 A 0.9

2500 1916 Mar. 17 +1.4 Ol 0.9

2519 Mar. 23 —0.1 Ol 0.8

2520 Mar. 23 +0.3 Ol 0.8

 

 

 

 

* One exposure.
 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 25
Compakison Stars
No. Diameter. |* ase ala Y (Declination). Dependence.
mm. mm. mm.
1 0.18 —63.3 0.0 +0.2556
2 .17 —19.2 —42.8 . 2236
3 14 +19.7 +36.9 - 2725
4 .17 +62.8° + 5.9 +0.2483
Parallax star 0.17 + 0.5 + 1.9
TABLE 2
ReEpuctTions For 6 CaNcRI
Solution Weight Parallax Time in Residual vp-0
Plate. (m). (p). Factor (P). | Days (t). 2). in Are.
mm. mm.
698 +0.0050 0.9 +0.585 —249 —0.0015 —0'03
734 + .0044 0.6 + .3882 —285 — .0013 — .02
784 + .0054 0.8 + .239 —226 — .0025 — .05
810 — .0006 0.8 + .122 —219 + .0033 + .06
978 — .0011 0.9 |.-— .535 —178 + .0026 + .05
1062 + .0029 0.7 — .691 —166 — .0016 — .03
1079 + .0005 1.0 — .736 —162 + .0007 + .01
1080 — .0002 1.0 — .736 —162 + .0014 + .03
1226 | + .0030 0.8 — .957 —1381 — .0022 — .04
1973 + .0057 0.9 + .922 + 70 — .0012 — .02
2013 + .0042 0.7 + .954 + 80 + .0003 + .01
2014 + .0065 0.7 + .954 + 80 — .0020 — .03
2121 + .0019 0.7 + .764 +101 + .0023 + .04
2122 + .0018 0.9 + .764 +101 + .0024 + .05
2203 + .0049 0.6 + .574 +117 — .0010 — .02
2204 + .0047 | 0.7 + .574 +117 — .0008 — .O1
2234 + .0033 1.0 + .519 +121 + .0005 + .01
2235 + .0031 0.9 + .519 +121 + .0007 + .01
2501 + .0044 0.9 — .733 +203 — .0028 — .05
2519 + .0004 0.8 — .796 +209 + .0011 + .02
2520 +0.0012 0.8 —0.796 +209 +0.0003 + .01

 

 

 

 

 

 

 
254 S. A. MITCHELL

The normal equations are:
17.1e — 1.906u + 1.02857 = + 0.0478 mm.
+ 46.4470u + 3.50137 = + 0.0066 mm.
+ 8.27177 = + 0.0182 mm.

from which:
c = + 0.00270 mm.
pw = + 0.00012 mm. = + 070024, or + 07009 per year.
x = + 0.00181 mm. = + 07038 + 07009.
Probable error of plate of unit weight
+ 0.00137 mm. = + 07028.

ll

. CANCRI (8 40"; +29° 7’)

This is a wide double, = 1268, separated 30”, of magnitudes
4.20 and 6.61 respectively, the brighter star being of type G5.
According to Lewis (Mem. R. A. 8., 56, 253), the two stars are
to be considered as physically connected. The common value
of the parallax as determined by the McCormick plates confirms
this idea. The plates were measured by Mr. Mitchell. The
rotating sector was used to reduce the size of the parallax stars.
Some of the plates were used showing both stars, some in which
the sector was still further reduced to diminish the size of the
brighter star. The diameters as given below were measured on a
plate which showed the two parallax stars. Boss gives the
proper motion of the brighter star in right ascension — 07020
per year. The spectroscopic parallax of the brighter star is
+ 0"011. Combining the two values of the parallax, we derive
the parallax of the system to be:

+ 07028 + 07004.

Comparison STARS

 

 

 

 

 

 

 

 

Dependence.
X (Righ ¥ (Declina-
es be ines 4 eae co Principal B
Star. Companion.
mm. mm. mm.
1 0.20 —29.6 —45.5 +0.271 +0.268
2 .10 —21.9 +41.9 -408 -427
3 27 +51.5 + 3.6 +0.321 +0.305
Brighter star 10) — 0.4 + 5.9
Fainter star 0.12 — 1.6 + 6.8

 
 

 

 

PARALLAXES OF 260 STARS 255
TABLE 1
Piates oF « CANCRI

No. Date. Hour Angle. Observers. Weight.
561 1914 Nov. 11 —042 A 0.7
608 Nov. 21 —0.7 M 0.7
620 Nov. 22 —0.5 A 1.0
633 Nov. 23 —0.8 G 0.7
1051 1915 Mar. 13 —0.2 A 0.7
1070 Mar. 17 +0.1 A 0.8
1146 Apr. 4 —0.2 M 0.8
1154 Apr. 7 —0.6 G 0.7
1162 Apr. 8 —0.6 M (Oy fe
1163 Apr. 8 —0.1 M, A 1.0
2100 Nov. 30 —0.8 A 1.0
2138 Dec. 9 —0.9 A 0.8
2139 Dec. 9 —0.5 A 1.0
2166 Dec. 18 —0.9 M 1.0
3465 1916 Dec. 1 -1.0 A 0.9
3502 Dec. 7 —0.4 M 0.8
3503 Dec. 7 —0.1 M 0.8
3522 Dec. 12 —0.2 M 0.7*
3529 Dec. 17 —0.8 L 0.7
3530 Dec. 17 —0.4 L 0.7
3756 1917 Mar. 12 —0.7 L 0.8
3757 Mar. 12 —0.3 L 0.8
3780 Mar. 20 —0.8 M 0.6
3797 Mar. 24 —0.8 M 0.8
3798 Mar. 24 —0.5 M 0.8
3810 Mar. 25 —0.4 M 0.8,
3827 Mar. 29 —0.4 L 0.9
3828 ‘Mar. 29 —0.1 L 0.9

 

 

 

 

 

* One exposure.

The normal equations are:

21.0c + 13.634 + 18.26367 = + 0.4870 mm.
+ 240.7185u — 6.04117 = + 0.2098 mm.
+ 13.11457 = + 0.0447 mm.
256 S. A. MITCHELL

TABLE 2

Repuctions For . Cancri, Bricutar STar

 

 

 

 

 

 

 

 

 

 

x . . . R id 1 et
wae | | ae eee.) Deedee | kia
561 | +0.0231 | 0.7 | +0.938 | —402 | +0.0c01 000
608 | + .0256 | 0.7 | + .890 | —392 | — .0024 | — .04
620 | + .0230 | 1.0 | + .883 | —391 | + .0001 .00
633 | + .0204 | 0.7 | + .877 | —390 | + .0027 | + .05
1051 | + .0226 | 0.7 {| — .672 | —280 | — .0017 | — .03
1070 | + .0186 | 0.8 | — .718 | —276 | + .0022 | + .04
1146 | + .0184 | 0.8 | — .884 | ~258 | + .oo21 | + .04
1154 | + .0222 | 0.7 | — .903 | —255 | — .0017 | — .03
1162 | + .0206 | 0.7 | — .909 | —254 | — .0001 .00
1163 | + .0192 | 1.0 | — .909 | —254 | + .o018 | + .08
2100 | + .0225 | 1.0 | + .825| — 18 | — .0005 | — .o1
2188 | 4 0222 | O.8 | + .28e] — 9 | = 0008 | =o
2139 | + .0248 | 1.0 | + .738 | — 9 | — .o029 | — .06
2166 | + .0234 | 1.0 | + .632 o | — .0017 | — .04
3465 | + .0203 | 0.9 | + .809 | +349 | + .0007 | + .01
3502 | + .0170 | 0.8 | + .751 | +355 | + .0039 | + .07
3503 | + .0187 | 0.8 | + .751 | +355 | + .0022 | + .04
3522 | + .0192 | 0.7 | + .694 | +360 | + .o016 | + .03
3529 | + .0221 | 0.7 | + .636 | +365 | — .0014 | — .02
3530 | + .0220 | 0.7 | + .636 | +365 | — .0013 | — .02
3756 | + .0170 | 0.8 | — .664 | +450 | + .0018 | + .03
3757 | + .0188 | 0.8 | — .664 | +450 .0000 .00
3780 | + .0193 | 0.6 | — .756 | +458 | — .0006 | — .O1
3810 | + .0210 | 0.8 | — .804 | +463 | — .0024 | — .04
3827 | + .0197 | 0.9 | — .842 | +467 | — .0012 | — .02
3828 | +0.0186 | 0.9 | —0.842 | +467 | —0.0001 0.00

from which: ,
c = + 0.02092 mm.
» = — 0.00028 mm. = — 070059, or — 07022 per year.

a = + 0.00126 mm. = + 07026 + 07006.
Probable error of plate of unit weight
+ 0.00112 mm. = + 07023.
 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 25
TABLE 3
REDUCTIONS FOR . CaNcrI, FaInTER Star
sh . : . *. . te
piste, || Reman | lene | rats, | aimee | Bathe | sa
mm. ‘ mm.
561 +0.0051 0.7 +0.938 —402 —0.0002 0700
608 + .0069 0.7 + .890 | —392 — .0021 — .04
620 + .0046 1.0 + .883 —391 + .0002 -00
633 | + .0054 | 0.7 | + .877 | —390 | — .o006 | — .o1
1051 + .0046 0.7 — .672 —280 — .0027 — .05
1070 — .0004 0.8 — .718 —276 + .0022 ) + .04
1146 “— 0002 0.8 — .884 = 258 + .0017 + .02
1154 + .0050 0.7 — .903 —255 — .0035 — .06
« 1162 — .0005 0.7 — .909 —254 + .0020 + .03
1163 — .0010 1.0 — .909 —254 + .0024 + .05
2100 + .0022 1.0 | + .825 — 18 + .0007 + .01
2138 + .0042 0.8 + .738 - 9 — .0015 — .03
2139 || + .00382 1.0 + .738 - 9 — .0005 — .01
2166 + .0030 1.0 + .632 0 — .0005 — .01
3465. + .0018 0.9 + .809 +349 -| — .0007 — .01
3502 + .0003 0.8 + .751 +3855 + .0007 + .01
3503 .0000 0.8 + .751 +355 + .0010 + .02
3522 — .0018 0.7 + .694 +360 + .0026 + .05
3529 — .0012 0.7 + .636 | +365 + .0019 + .03
3797 + .0003 0.8 — .794 +462 — .0022 — .04
3798 — .0016 0.8 — .794 +462 — .0002 .00
3810 — .0002 0.8 — .804 +463 — .0017 — .03
3828 —0.0020 0.9 —0.842 +467 +0.0001 0.00
The normal equations are:
18.8¢ + 4.3204 + 1.82187 = + 0.0302 mm.
+ 200.9299n — 3.18817 = — 0.0953 mm.
+ 12.15367 = + 0.0224 mm.
from which:
ce = + 0.00157 mm.
w= — 0.00048 mm. = — 070101, or — 07037 per year.
a = + 0.00148 mm. = + 07031 + 07006.

Probable error of plate of unit weight

18

+ 0.00107 mm. = + 07022.
258 S. A. MITCHELL

« HYDRE (8 41™; +6° 47’)

This forms a system of more than ordinary interest. Almost
from the time of discovery in 1888, it has been found that the
star called AB of ¢ Hydre formed a binary system in rapid
motion. In Lick Observatory Publications, 12, 58, 1914, Aitken
finds a period of 15.3 years. The pair is never separated more
than 0725, and the magnitudes of A and B are 3.9 and 4.4
respectively. About 3’’ distant from this close pair AB is a
star of 7.8 magnitude, forming with AB the double star 2 1273.
This Struve companion is in slow direct motion about the brighter
pair, and according to Burnham, must have a period in the
neighborhood of 650 ‘years. There is still another star 20”
distant, and with the same proper motion as the other three
stars, and consequently, must belong to the same system. We
thus have a quadruple system. To add to the interest, Curtis
(Lick Observatory Bulletin, 1, 23, 1901) has found e Hydre to be
a spectroscopic binary with the velocity of the center of gravity
+ 36.8 km. The total proper motion of these stars is 0720
per year. ;

In discussing the orbit, Aitken has the unique opportunity of
deriving the orbit from both visual and spectrographic measures.
Assuming the correctness of Seeliger’s mass ratio, he finds the
mean distance between the two components to be 1,359,000,000
km., the parallax of the system + 07025, and its mass 3.33 of
the sun’s mass. By photography, at Swarthmore the parallax
of — 07002 + 07011 has been found, and at Allegheny the
value + 0”026 + 0"009. Adams by the spectroscopic method
finds the parallax of + 07041 for the pair.

The present series of plates were reduced without making
allowance for the orbital motion. The mean of the times when
the plates were taken was 1916.28, which from Aitken’s ephem-
eris, corresponds to a position angle of the component of 14°4
and to a distance 0708. Since the series of photographs were
symmetrical with respect to this time, the orbital motion should
have little effect on the parallax. The rotating sector was used
to reduce the brightness of the parallax star in the present series
of plates. Boss finds the proper motion in right ascension of the
PARALLAXES OF 260 STARS 259

 

 

 

 

 

 

 

 

 

 

 

. TABLE 1
Puiates or « Hypra
No. Date. Hour Angle. Observers. Weight.
954 1915 Feb. 26 040 G 0.7
1004 Mar. 8 +0.4 G 0.5
1136 Mar. 31 0.0 G 1.0
1172 Apr. 9 +0.8 G 1.0
1963 Nov. 3 —0.2 G 0.4*
2008 Nov. 10 +0.1 G 0.7
2027 Nov. 16 +0.1 G 0.7
2152 Dec. 10 0.0 G 0.5*
2482 1916 Mar. 15 +1.2 G 0.6
2521 Mar. 23 +1.0 Ol 0.7
2539 Mar. 31 —0.2 G 0.6
3318 Oct. 31 —0.9 L 0.7
3319 Oct. 31 —0.5 L 1.0
3327 . Nov. 1 —1.0 A 0.9
8328 Nov. 1 —0.6 A 1.0
3364 Nov. 7 —0.3 L 1.0
3365 Nov. 7 +0.1 L 1.0
3739 1917 Mar. 9 +1.1 Ol 0.9
3847 Apr. 5 —0.1. A 0.7*
3849 Apr. 7 +0.6 A 0.6*
3850 Apr. 7 +1.0 A 0.8
* One exposure. t Three exposures.
ComPaRISON STARS
No, Diameter. * ad Y (Declination). Dependence.
mm, mm. mm.

1 0.16 —38.3 +29.4 +0.2193

2 .16 —35.9 + 3.4 -2198

3 .12 — 4.7 +17.3 .2017

4 .22 + 5.3 —40.0 .1998

5 p22 +73.6 —10.1 +0.1604

Parallax star 0.19 — 4.4 + 1.1

 

 

 

 

 
260 . S. A. MITCHELL

center of gravity of the system to be — 07189 per year, while
the McCormick plates give the value of — 07177. The solar
drift should cause a motion of the comparison stars which, in
right ascension, will amount to approximately — 07010. ‘Hence,
the proper motion from the McCormick plates referred to the
equator instead of to the system of comparison stars used, will
amount to — 0187 per year. The photographic plates:give the
proper motion of the center of brightness. But there is little
difference between the magnitude of the components, and it
would therefore seem from the agreement between the proper
motion of the center of brightness and the center of gravity

\

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR « HypR&
Solution Weight Parallax Time in Residual vp. i:
Plate. | /(m). (p). ‘| Factor (P). | Days (t). (). in Arc
‘mm. mm, ~

954 —0.0042 0.7 —0.468 — 423 +0.0043 -+0°07
1004. — .0034 0.5 — .607 —393 + .0027 + .04
1136 | + .0002 | 1.0 | — .852 | —370 | — .0014 } — .03
1172 + .0020 1.0 | — .914 —361 — .0035 — .07
1963 — .0067 0.4 + .957 —153 | + -0008 } + .01
2008 — .0043 0.7 + .942 —146 — .0018 } — .08
2027 | — .0062 | 0.7 | + .919 | -140 | — .0o01 00
2152 — .0044 0.5 + .728 —116 — .0024 — .04
2482 - — .0118 0.6 — .703 — 20 + .0024 + .04
oper | = 0001 | OF | — 788 | = 412 | = 000s | = 01
2539 — .01381 0.6 — .858 — 4 + .0083 + .05
3318 — .0189 0.7 + .958 +210 + .0045 + .08
3319 — .0111 1.0 + .958 +210 “~ 0033 — .07
3327 — .0113 0.9 + .958 +211 — .0031 — .06
3328: — .0144 1.0 + .958 +211 .0000 .00
3364 — .0150 1.0 + .948 +217 + 0004: + .01
3365 — .0182 1.0 + .948 +217 + 0036 + .07
3739 | — .0178 | 0.9 | — .627 | +839 -0000 .00
3847 | — .0174 | 0.7 | — .893 | +366 | — .oo10 | — .02
3849 — .0191 0.6 — .906 +368 + -0006 + .01
8850 _| —0.0172 0.8 | —0.906 | +368 0.0013. | —0.02_

 
PARALLAXES OF 260 STARS 261

that the two components must be of nearly equal mass. The
McCormick value of the parallax requires a separation between
A and B of 25 times the distance between the earth and the sun,
with a consequent mass of the system of 71.3 times that of the
sun. The plates of the series were measured by Mr. poe

The normal equations are:

16.0c + 7.026 + 1.05127 = — 0.1715 mm.
+ 115.5309u + 8.8868r = — 0.3359 mm.
+ 12.07807 = — 0.0284 mm.
from which:
~¢ = — 0.00971 mm.
w= — 0.00232 mm. = — 070485, or — 0177 per year.

a = + 0.00020 mm. = + 07004 + 0010.
Probable error of plate of unit weight
+ 0.00156 mm. = + 07032.

 

53 CANCRI (8" 46; +28° 38’)
55 CANCRI (8 46"; +28° 43’)

53 Cancri is of small proper motion 0"02, while 55 Cancri has a
total proper motion of 0"55 per year. | 53 Cancri is of fosgitude
6.31 and type Mb, and 55 Cancri is of magnitude; 6.06 and
of type K5. The same series of photographs was utilized to
derive the parallaxes of both stars. These plates were measured
by Mr. Olivier except the three last measured by Mr. Mitchell.
The only trigonometric value of the parallax of 53 Cancri is that
of van Maanen who derives the relative parallax of — 0”001
+ 07009. The McCormick value is in good agreement with
this, since it amounts to — 07005 + 07012. The McCormick

-proper motion is +- 07002 in right ascension, wile the corre-
sponding value from Boss is — 07016.

Three values of the parallax of 55 Cancri have been published:
+ 07086 + 07037 by Jost with the meridian circle, + 07057
+ 07038 by Chase with the heliometer, and.+ on 069 + 07006
by photography at Allegheny. The McCormick relative parallax
is + 07076 + 07011. ‘The proper motion in right ascension from
the plates is — 07523 while the value from Boss amounts to
— 07481. Mt. Wilson by the spectrograph finds the parallax is
+ 07010 and + 07100 for 53 and 55 Cancri, respectively.
 

 

 

 

 

 

 

 

 

 

 

262 S. A. MITCHELL
TABLE 1 ‘
PLaTEs OF 53 AND 55 CaNncri
No. Date. Hour Angle. Observers. Weight.
3395 1916 Nov. 16 —046 M 1.0
3396 Nov. 16 —0.2 M 0.8
3428 Nov. 21 —0.7 L 0.9
3429 Nov. 21 —0.2 L 0.8
3873 1917 Apr. 13 —0.1 M 0.9
3883 Apr. 14 0.0 M 0.9
4673 Nov. 1 —0.5 Ds 0.8
4674 Nov. 1 —0.1 Ds 0.7
4693 Nov. 3 —0.8 Ds 0.8
4694 Nov. 3 —0.4 Ds 0.8
5220 1918 Mar. 26 —0.9 Ol 0.8
5274 Apr. 5 —0.6 M 1.0
5275 Apr. 6 —0.6 M 1.0
5276 Apr. 6 —0.1 M 0.9
5965 Nov. 13 —0.9 M 1.0
5966 Nov. 13 —0.6 M 1.0
5967 Nov. 13 —0.2 M 1.0
CoMPARISON STARS
snd P Dependence.
ee X (Right Y (Declina-
No. D: : Fi j
0. iameter Ascension). tion). 55 53
mm. mm. mm.
1 0.12 —64.9 —36.1 +0.3741 | +0.3556
2 13 — 9.3 —45.7 . 2290 .0982
3 15 +20.2 +47.7 . 2463 . 8673
4 13 +54.0 +34.1 +0.1506 | +0.1789
55 Cancri .12 —13.3 — 7.1
53 Cancri 0.14 — 6.9 + 6.3

 

 

 

 
\ PARALLAXES OF 260 STARS 26

TABLE 2

RepvuctTions FoR 53 CaNcRI

 

 

 

 

 

 

 

 

 

Solution Weight | Parallax Time in Residual vp-»
Plate. | (m). (p). | Factor (P). | Days (). (2). in Arc.
mm. mm.

3395 —0.0013 1.0 +0.919 —347 —0.0004 —0%01
3396 — .0062 0.8 + .919 —347 + ..0045 | + .09
3428 — .0022 0.9 + .893 —342 + .0006 | + .01
3429 — .0028 0.8 + .893 —342 + .0012 | + .02
3873 + .0026 0.9 — .929 —199 — .00388 — .07
3883 — .0008 0.9 — .934 —198 — .0004 | — .01
4673 + .0032 0.8 + .956 +: 3 — .0048 — .09
4674 — .0024 0.7 + .956 + 3 + .0008 | + .01
4693 | + .0014 0.8 + .955 + 5 — .0030 — .05
4694 — .0020 0.8 + .955 + 5 + .0004 | + .01
5220 + .0036 | 0.8 |‘'— .798 +148 — .0047 — .09
5274 — .0009 1.0 — .880 +158 — .0002 .00
5275 — .0039 1.0 — .887 +159 + .0028 | + .06
5276 — .0062 0.9 _ .887 +159 + .0051 + .10
5965 — .0017 1.0 + .934 +380 + .0003 + .01
5966 + .0002 1.0 + .934 +380 — .0016 — .03
5967 —0.0036 1.0 +0.934 +380 +0.0022 +0.05

 

The normal equations are:

15.1¢ + 1.6774 + 4.05597 = — 0.0211 mm.
+ 101.0274u — 1.85167 = + 0.0013 mm.
+ 12.66367 = — 0.0085 mm.
from which:
c = — 0.00133 mm.
uw = + 0.00003 mm. = + 070006, or + 07002 per year.
a = — 0.00024 mm. = -- 07005 =. 07012.

Probable error of plate of unit weight
+ 0.00192 mm. = + 07040.
264 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

TABLE 3
Repuctions ror 55 Cancri
Solution | Weight | Parallax | Time in Residual _Vp-2
Plate. : (m). 4 (p). Factor (P). | Days (t). (v). in Are.
mm. mm. .
3395 | —0.0102 | 1.0 +0.919 —347 +0.0009 | +0”02-
3396 | — .0069 | 0.8 + .919 —347 — .0024 | — .04
3428 — .0084 0.9 ++ .893 —342.- — .0013 — .03
3429 | — .0132 0.8 + .893 —342 + .0035 | + .06
3873 — .0250 0.9 — .929 —199 — .0012 — .02
3883 | — .0272 0.9 — .934 —198 + .0009 + .02
4673 | — .0300 | 0.8 |, + .956 | + 3 | — .0033 | — .06
4674 ‘} — .0378 0.7 |'+ .956 | + 38 + .0045 | + .08
4693 — .0321 0.8 |’ + .955 | + 5 — .0013 | — .02
4694 ‘| — .0334 0.8 + .955 + 6 .0000 -00
5220 — .0454 | 0.8 |'— .798 | +148 — .0043 | — .08
5274 : — .0498 1.0 |: — .880 +158 — .0008 — .02
5275 — .0530 | 1.0 |! = .887 | +159 | + .0022 | + .05
5276 3} — .0531 0.9 |,— .887 | +159 + .0024 } + .05
5965 || — .0628 1.0 j: + .934 | +380 + .0034 ‘| + .07
5966 | — .0558 1.0 |; + .984 +380 — .0036 ;| — .07
5967 ,| —0.0597 1.0 +0.934 +380 +0.0003 ‘| +0.01

 

The normal equations are:
15.1¢e + 1.6774 + 4.05597 = — 0.5489 mm.
+ 101.0274» — 1.85167 = — 0.7646 mm.
+ 12.66367 = — 0.0895 mm.

from which:
c = — 0.03656 mm.
uw = — 0.00689 mm. = — 01434, or — 0523 per year.

a = + 0.00364 mm. = + 07076 + 0”011.
Probable error of plate of unit weight
+ 0.00174 mm. = + 07036.

¢ HYDRZE (8 507; +6° 19’)

Two parallax. values have been published for this star which
are of magnitude 3.30, and of type K. The Allegheny result
from photography is + 07024 + 0”008, and the spectroscopic
value + 07019. Mr. Alden measured the series of plates, and
PARALLAXES OF 260 STARS

265

the measures give a proper motion in right ascension of — 07105,

while Boss finds a corresponding value of — 07103.

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Puates oF ¢ Hypra
No. Date. Hour Angle. Observers. ' Weight.
505 | 1914 Nov. 4 —04 M 0.9
537 Nov. 9 —0.1 -G ; 0.8
562 — Nov. 11 +0.3 A ' 0.9
668 . Dec. 14 0.0 'M : 0.7*
1039 : 1915 Mar. 12 0.0 A i 1.0
1040 © Mar. 12 - +0.6 JA : 0.7*
1053 | Mar. 13 40.6, A 1.0
1164 Apr. 8 +0.4 ‘A 0.8
1165 — Apr. 8 +0.9 A 0.9
1957 Nov. 2 —0.9 A 0.8
1958 : Nov. 2 —0.5 A 0.9
2216 Dec. 23 —0.5 A 0.9
2217 Dec. 23 9.2 ° A 0.9
2490 . 1916 Mar. 16 —0.2 |: A 1.0
2491 | Mar. 16 +0.2 A 0.9
2525 | Mar. 25 +0.1 A 1.0
2526 » Mar. 25 +0.6 A 0.9
3455 - Nov. 30 - 0.0 M 1.0
3456 Nov. 30 +0.3 M 1.0
3467 Dec. 1 —0.2 A 1.0
3468 Dec. 1 +0.4 A 0.8
* One exposure.
Comparison Stars
No. Diameter. a (Right. Aston Y (Declination). Dependence.
mm. mm. mm.

1 0.14 —33.5 +32.6 +0.1983

2 .10 —29.7 —34.4 .2528

3 .10 —18.5 +23 .2 . 1946

4 .20 + 7.1 +33.3 . 1658

5 13 +74.6 —54.7 +0.1885

Parallax star 0.19 — 2.5 — 2.5

 

 

 

 

 
266

S. A. MITCHELL

Repvuctions ror ¢ HyprR#

TABLE 2

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp+v
Plate. (m). (p). Factor (P). | Days (#). 2). in Are.
mm. mm.
505 +0.0026 0.9 +0.954 —259 +0.0044 +009
537 + .0107 0.8 + .946 —254 — ,0038 — .07
562 + .0086 0.9 + .942 —252 — .0017 — .03
668 + .0022 0.7 + .702 —219 + .0042 + .07
1039 + .00382 1.0 — .639 —131 + .0020 + .04
1040 + .0004 0.7 — .639 —131 + .0048 + .08
10538 + .0084 1.0 — .642 —130 — .0032 — .07
1164 + .0073 0.8 — .893 —104 — .0025 — .04
1165 + .0059 0.9 — .893 —104 — .0011 — .02
1957 + .0012 0.8 + .955 +104 + .0007 + .01
1958 + .0041 0.9 + .955 +104 — .0022 — .04
2216 + .0026 0.9 + .595 +155 — .0014 — .03
2217 + .0029 0.9 + .595 +155 — .0016 — .03
2490 + .0006 1.0 — .688 +239 — .0006 — .01
2491 + .0004 0.9 — .688 +239 — .0004 — .01
2525 — .0002 1.0 — .785 +248 + .0001 -00
2526 — .0025 0.9 — .785 +248°> | + .0024 + .05
3455 — .0045 1.0 + .834 +498 + .0010 + .02
3456 — .0051 1.0 + .884 +498 + .0016 + .03
3467 — .0024 1.0 |' + .826 +499 — .0012 — .02
3468 —0.0037 0.8 +0.826 +499 +0.0002 0.00
The normal equations are:
18.8¢ + 19.294u + 2.75887 = + 0.0364 mm.
+ 149.8402u + 8.72897 = — 0.1436 mm.
+ 12.01777 = — 0.0027 mm.
from which:
c = + 0.00336 mm.
# = — 0.00139 mm. = — 070289, or — 07105 per year.
wz = + 0.00002 mm. = 0”000 + 0”010.

Probable error of plate of unit weight

= + 0.00158 mm. = + 07033.
PARALLAXES OF 260 STARS 267

38 LYNCIS (95 12"; +37° 13’)

‘This is,a double = 1334, the brighter star having a magnitude
3.82 and being of A type, and the companion of magnitude 6.6.
There is no relative change. The stars have a common proper
motion 0”122. Miss Darkow measured the plates with the
exception of the four last measured by Mr. Mitchell. A parallax
+ 07039 + 07010 resulted, and a proper motion in right ascen-
sion + 07016 where the corresponding value from Boss is — 0026.
Allegheny Observatory has determined the photograph parallax
+ 07026 + 07008.

TABLE 1

Puates or 38 Lyncis

 

 

 

 

 

 

No. Date. Hour Angle. Observers, Weight.
2297 1916 Jan. 8 —054 M 0.7
2308 Jan. 13 _ 0.6 M 0.4*
8874 1917 Apr. 13 —0.1 M 0.8
3884 Apr. 14 —0.1 A 0.8
4762 Nov. 10 —0.7 Ds 0.5*
4763 Nov. 10 —0.4 Ds 0.5*
6039 Nov. 30 —0.3 M 0.7
6106 Dec. 18 —0.3 F 0.8
6179 1919 Jan. 6 —1.0 F 0.7*
6180 Jan. 6 —0.6 F 1.0
6202 Jan. 8 —0.2 H 0.8
6656 Mar. 11 —1.1 H 0.7
6657 Mar. 11 —0.7 H 0.8
6712 Mar. 21 —0.5 D 1.0
6713 - Mar. 21 +0.1 D 1.0
6753 Mar. 25 —0.6 D 1.0
6754 Mar. 25 —0.2 D 1.0
8124 Nov. 20 —0.8 F 1.0
8125 Nov. 20 —0.4 F 1.0

_ 8143 Nov. 26 —0.6 M 0.6*
8144 Nov. 26 -0.1 M 1.0

 

 

* One exposure.
268 S. A. MITCHELL

TABLE 2

Repvuctions For 38 Lyncis

 

 

 

 

 

 

 

 

 

" elistion Weight | Parallax | Time in Residual ape:
Plate. (m). (p). ’ | Factor (P); | Days (6). (). in Are.
mm. mm. | io
2297 | +0.0040 | 0.7 | +0.445 | —969 | —0.0007 | —0701
2308 | + .0009 | 0.4 | + .870 | —964 | + .0023 | + .03
3874 | + .0028 | 0.8 | — .885 | —508 | — .0010 | — .02
3884 | + .0049 | 0.8 | — .891 | —507 | — .0031 | — .06-
4762 | + .0050 | 0.5 | + .944 | ~—297 | + .0007 | + .O1
4763 .0000 | 0.5 | + .944 | —297 | + .0057 | + .08
6039 | + .0093 | 0.7 | + .870 | +88 |; — .0029 | — .05
6106 | + .0065 | 0.8 | + .718 | +106 | — .0004 | — .01,
6179 | + .0064 | 0.7 | + .470 | +125 | — .0007 | — .01
6180 | + .0062 | 1.0 | + .470 | +125 | — .0005 | — .o1
6202, | + .0050 | 0.8 | + .441 | +127 | + .0007 | + .01
6656 ; + .0004 | 0.7 | — .5387 | +189 | + .0036 | + .06
6657 | + .00388 | 0.8 | — .587 | +189 | + .0002 .00
6712 | + .0018 | 1.0 | — .666 | +199 | + .0024 | + .05
6713 | + .0016 | 1.0 | — .666 | +199 | + .0022 | + .05
6753 | + .0040 | 1.0 | — .712 | +203 | — .0003 | — .O1
6754 | + .0066 | 1.0 | — .712 | +203 | — .0029 | — .06
8124 | + .0094 | 1.0 | + .922 | +443 | — .0022 | — .05
8125 | + .0081 | 1.0 | + .922 | +443 | — .0009 | — .02
8143 | + .0079 | 0.6 | + .895 | +449 | — .0007 |-—-.01
8144 | +0.0054 | 1.90 | + .895 | +449 | +40.0018 | +0.04
1 S T
i
'
i
PARALLAXES OF 260 STARS 269

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. x a seeee Y (Declination). Dependence.
mm. mm. ; ‘mm. : - - t
1 0.14 —60-0 +23.8 +0.223-
2° 18 ~—51.4 —38974 ~~ 174
3 .19 +13.8° ~—51.7 5 .159
4 -22 +27.3° +34.5 .224
5° : 17 +70.3° +32.8 +0.220
Parallax star: 0.15 , + 1.46 , +5.17

 

The normal equations are:

16.8¢ + 9.7954 + 2.02847 = + 0.0827 mm.
+ 251.3427u + 10.08397 = + 0.1170 mm.
+ 9.12927 = + 0.0284 mm.

from which:
c = + 0.00457 mm.
w= + 0.00021 mm. = + 070044, or + 07016 per year.
a+ = + 0.00186 mm. = + 07039 + 07010.
Probable error of plate of unit weight
+ 0.00134 mm.’ = -£ 07028.

\ LEONIS (9% 26"; +23° 24’)

No other parallax has been published for this star which is of
magnitude 4.48, of spectral type K5p, and of small proper motion
than the spectroscopic parallax of Adams and Joy + 0“011.
Mr. Alden measured the! McCormick plates. with the exception
of the. three last plates measured by Mr. Mitchell. The proper
motion in-right ascension from the plates is — 0”009 while the
corresponding value from Boss is — 07023.
 

 

 

270 S. A. MITCHELL
TABLE 1
Puates oF \ LEonIs

No. Date. Hour Angle. 7 Observers. Weight.
2140 1915 Dec. 9 —055 A 0.6
2254 1916 Jan. 2 —1.3 G 0.8
2255 Jan. 2 —1.0 G 0.8
2274 Jan. 3 —0.7 Ol 0.7
2567 Apr. 17 —0.2 G 0.7
2568 Apr. 17 +0.2 G 0.8
3569 1917 Jan. 9 —1.0 L 0.9
3570 Jan. 9 —0.6 L 0.9
3772 Mar. 19 +0.7 Ol 0.8

* 3773 Mar. 19 +0.7 Ol 0.8
8915 Apr. 26 +0.4 A 0.8
8916 Apr. 26 +0.8 A 0.8
4713 Nov. 5 —0.9 B 0.8
4725 Nov. 6 —0.9 Ds 0.6*
4750 Nov. 9 —0.7 B 1.0
4773 Nov. 16 —0.6 B 1.0
4786 Nov. 17 +0.3 Ds 0.8
4832 Dec. 1 —0.6 B 0.8
4833 Dec. 1 —0.2 B 0.8
5256 1918 Mar. 30 0.0 M 0.8
5277 Apr. 6 +0.2 M 0.7*
5278 Apr. 14 +0.2 M 1.0
5279 Apr. 14 +0.7 M 1.0
5293 Apr. 15 —0.2 A 1.0
5866 Nov. 2 —1.0 M 0.9
5893 Nov. 5 —1.0 M 1.0
5894 Nov. 5 —0.7 M 1.0

 

 

 

 

 

* One exposure,
PARALLAXES OF 260 STARS 271

TABLE 2

ReEDvucTIONS FOR \ LEONIS

 

 

 

 

 

 

 

 

 

eae = =
Finis |, Beem, | | ee eS | ae ee | Nee
mm. mm.
“2140 +0.0018 0.6 +0.827 —573 +0.0007 +001
2254 + .0046 0.8 + .572 —549 — .0025 — .05
2255 + .0047 0.8 + .572 —549 — .0026 — .05
2274 + .00038 0.7 + .559 —548 + .0018 + .03
2567 — .0018 0.7 — .886 —443 + 0014 + .02
2568 + .0008 0.8 — .886 —443 — 0012 — .02
3569 — .0012 0.9 + .465 —176 + .0027 + .05
3570 | — .0022 0.9 + .465 —176 + .0037 + .07
3772 — .0004 0.8 — .603 —107 + .0001 .00
8773 — .0036 0.8 — .603 —107 + .0033 + .06
3915 — .0017 0.8 — .931 — 69 + .0008 + .01
3916 — .0008 0.8 — .931 — 69 — .0001 .00
4713 — .0001 0.8 + .936 +124 + .0020 + .04
4725 + .0041 0.6 + .988 +125 — .0022 — .04
4750 + .0027 1.0 + .940 +128 — .0008 — .02
4773 + .0048 1.0 + .985 +135 — .0030 — .06
4786 + .0016 0.8 + .983 +136 + .0002 .00
4832 + .0014 0.8 + .878 +150 + .0003 + .01
4833 + .0064 0.8 + .878 +150 — .0047 — .09
5256 — .0014 0.8 — .729 +269 + .0004 + .01
5277 + .0009 0.7 — .798 +276 — .0020 — .04
5278 + .0020 1.0 — .863 +284 — .00382 — .07
5279 — .0002 1.0 — .863 +284 — .0010 — .02
5293 — .0029 1.0 — .870 +285 + .0017 + .04
5866 + .0001 0.9 + .930 +486 + .0018 + .08
§893 + .0036 1.0 + .936 +489 — .0022 — .05
5894 —0.0037 1,0 +0.936 +489 +0.0051 +0.11

 
272 S. A. MITCHELL

CoMPARISON STARS

 

 

 

 

 

 

No. | Diameter. a Pee Y (Declination). Dependence.
mm. mm. mm,

1 0.14 —16.8 +40.5 +0.2940

2 .09 —13.2 —32.9 . 2524

: 3 .10 +30.0 — 7.6 +0.4536
Parallax star 0.13 + 5.3 + 0.2

The normal equations are:

22.6¢ + 5.941u + 3.16537 = + 0.0156 mm.
+ 241.7167 + 6.41237 = — 0.0157 mm.
+ 15.25227 = + 0.0254 mm.

from which:
c = + 0.00050 mm.
“4 =:1— 0.00012 mm. = — 070025 or -- 07009 per year.

am ='+ 0.00161 mm. = + 07034 + 07008.
Probable error of plate of unit weight
+ 0.00154 mm. = + 040382.

9 URS MAJORIS (9 26"; +52° 7’)

A'star of 3.26 magnitude, and type F8, accompanied by a star
of 13.7 magnitude, and at a distance of 5’. It has a large proper
motion of 1709 per year. Several determinations have been
made of the parallax as follows: Kapteyn by meridian circle
obtains the value + 07052 + 07026, Peter by the heliometer
derives the value + 0"09 + 07018, while Flint and Abetti by
the meridian circle find the values +.0”09 - 0”030, and + 07103
+ 0"038, respectively. Allegheny derives the parallax by pho-
tography + 07057 + 07009. Adams by the spectroscopic method
gives the parallax + 07110. The McCormick value, derived
by plates measured by Mr. Mitchell gives a value smaller than
any of the above, viz. + 07032 + 07008. The proper motion
in right ascension as determined by Boss is — 0°945 per year,
while that from the present series of plates is — 0”952.
PARALLAXES OF 260 STARS 273

TABLE 1
Puiates oF 6 Urs# Masoris

 

 

 

 

 

 

 

 

 

 

 

No. [{ Date. Hour Angle. Observers. Weight.
1114 1915 Mar. 27 —0h2 A 1.0
1150 Apr. 6 —0.6 M 0.9
1216 Apr. 17 —0.4 A 1.0
_ 1230 Apr. 23 0.0 M 0.8 °
2158 Dec. 14 —0.4 M 0.7
2159 Dec. 14 0.0 M 0.7
2168 Dec. 18 —0.7 M 0.9
2169 : Dec. 18 —0.3 M 0.6
2289 1916 Jan. 7 —0.9 Ol 0.6
2290 Jan. 7 -—0.1 ~ Ol 0.6
2556 Apr. 6 —0.1 M 0.9
2577 Apr. 19 —0.2 Ol 0.7
2581 Apr. 20 0.0 G 0.6
3397 Nov. 16 —0.1 M 0.7*
8412 f Nov. 19 —0.6 L 1.0
3413 Nov. 19 —0.1 L 0.9
3430 Nov. 21 —0.1 L 0.8
3527 Dec. 13 —0.4 A 0.8
3531 Dec. 17 —0.6 L 0.8
3532 Dee. 17 —0.1 L 1.0
3539 Dec. 25 —-1.1 Tig 0.8
3540 Dec. 25 —0.6 L * 0.9
3840 1917 Apr. 3 —0.2 L 1.0
__ 3903 Apr. 20 —0.2 Ol 0.7
* One exposure.
Comparison STARS
No. Diameter. a oh aad Y (Declination). Dependence.
mm. mm. mm.
1 0.12 —22.0 +17.9 +0.209
2 .18 —17.9 —16.6 -257
3 11 +15.5 +45.3 : . 204
4 .08 +24.4 —46.6 +0.330
Parallax star | 0.18 + 2.0 — 6.7

 

 

 

 

19
274

S. A. MITCHELL

TABLE 2

Repvuctions ror 6 Urs® Masoris

 

 

 

 

 

 

 

 

 

 

Solution | Weight | Parallax | Time in Residual Vpeo
Plate. (m). p). | Factor (P). | Days (2). (). in Are.
mm. mm.
1114 +0.0282, 1.0 —0.692 —366 —0.0019 —0704
1150 + .0224 0.9 — .795 —356 + .0025 + .05
1216 + .0238 1.0 — .881 —345 — .0004 — .01
1230 + .0226 0.8 | — .915 —339 “0000 -00
2158 — .0024 0.7 + .785 —104 — .0019 — .03
2159 — .0076 0.7 + .785 —104 + .0033 + .06
2168 — .0032 0.9 + .747 —100 — .0016 | — .03
2169 — .0062 0.6 + .747 —100 + .0014 + .02
2289 — .0056 0.6 + .506 — 80 — .0021 | — .08
2290 — .0044 0.6 + .506 — 80 — .0033 “| — .05
2556 — .0212 0.9 — .802 + 10 + .0002 00
2577 — .0268 0.7 — .898 + 23 + .0040 | + .07
2581 — .0224 0.6 — .903 + 24 — .0005 — .01
3397 — .0469 0.7 + .985 +234 + .0005 + .01
8412 — .0477 1.0 + .928 +237 + .0009 + .02
3413 — .0490 0.9 + .928 +237 + .0022 + .04
3430 — .0494 0.8 + .922 +239 + .0024 + .04
3527 — .0476 0.8 + .780 +261 — .0024 | — .05
3531 — .0480 0.8 + .750 +265 — .0026 — .05
3532 — .0506 1.0 + .750 +265 .0000 -00
3539 — .0502 0.8 + .663 +273 — .0015 — .03
3540 — .0538 0.9 + .663 +273 + .0021 + .04
3840 — .0654 1.0 = fT, +372 — .0009 — .02
3903 —0:0673 0.7 —0.902 +389 —0.0013 —0.02
The normal equations are:
19.4c + 9.448u + 2.76807 = — 0.4730 mm.
+ 124.0265u + 17.93697 = — 1.7016 mm.
from which: + 12.47197 = — 0.2568 mm.
c = — 0.01850 mm.
w= — 0.012538 mm. = — 072607, or — 07952 per year.

T

+ 0.00154 mm. = + 07032 + 0”008.
Probable error. of plate of unit weight

+ 0.00125 mm. = + 07026.
by Campbell (A strophysical Journal, 8, 291, 1898) to be a spectro-
scopic binary, with a velocity of the center of gravity of the
system equal to 27 km. Adams has found the absolute parallax
from spectroscopic measurements to be + 07011, while Alle-
gheny derived the relative parallax + 07024 + 07008 Mr.
Alden measured the series of plates, and determined the proper
motion in right ascension, — 07113 per year while the value

PARALLAXES OF 260 STARS

o LEONIS (9° 35"; +10° 21’)
This star of magnitude 3.76, and of type F5p has been found

from Boss is — 0145.

TABLE 1

PLATES OF 014 LEONIS

 

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
794 1915 Jan. 14 —06 M 0.7
807 Jan. 19 —0.4 Ol 0.9
1166 Apr. 8 +0.7 A 1.0
1188 Apr. 13 +0.3 M 0.8
1189 Apr. 13 +0.8 M 0.9
1227 Apr. 19 +0.3 Ol 0.8
2038 Nov. 17 —0.6 A 1.0
2039 Nov. 17 —0.1 A 0.9
2060 Nov. 24 +0.2 G 0.7
2218 Dec. 23 —0.3 A 1.0
ComPaRISON STars
No. ‘Diameter. a aa Y (Declination). Dependence.
1 0.16 —52.7 +20.8 +0.3488
2 .14 + 6.8 —35.7 .2518
3 .14 +45.9 +14.9 +0.3994
Parallax star | 0.16 + 1.7 + 4.2 |

 

 

 

275
276 S. A, MITCHELL

ri

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR 014 LEONIS
i i Parall: Time i idual ‘p-
Bie. | Bye | Mee | ee cl ae | oe | eae
mm. mm.
794 +0.0138 0.7 +0.435 —163 +0.0005 | +0°01
807 + .0149 0.9 + .360 —158 — .0008 | — .02
1166 + .0108 1.0 — .788 — 79 + .0005 | + .01
1188 + .0135 0.8 — .831 — 74 — .0023 .| — .04
1189 + .0108 0.9 — .831 ~— 74 + .0004 | + .01
1227 + .0094 0.8 — .875 — 68 + .0016 | + .03
2038 + .0102. 1.0 + .934 +144 + .0002 00
2039 + .0080 0.9 + .984 +144 + .0024 | + .05
2060 + .0116 0.7 + .917 +151 — .0013 — .02
2218 +0.0109 1.0 +0.718 +180 —0.0013 | —0.03

 

The normal equations are

8.7¢ + 0.438u + 0.86237
+ 14.8074u + 5.95287
+ 5.41817:

from which:

c = + 0.01124 mm.
= — 0.00149 mm. =
w = + 0.00140 mm. =

Probable error of plate of unit weight

+ 0.0983 mm.
— 0.0088 mm.
+ 0.0084 mm.

~ 070311, or — 07118 per year.
+ 07029 + 07012.

+ 0.00101 mm. = + 07021.

¢ 386 LEONIS (105 11™; +23° 54’)

This star is of magnitude 3.65, of type F, and of small proper
motion 0702 per year. No parallax value has been published
except the spectroscopic result of Mt. Wilson -- 0”014. The
series of plates is the same as for 35 Leonis, Table I, with the
exception there noted. The proper motion in right ascension
from Boss is + 07022 per year, while the value from the McCor-

mick photographs is + 0%013 per year.

measured by Mr. Mitchell.

The plates were
PARALLAXES OF 260 STARS

.

Comparison Stars ror ¢ LEONIS

‘27

 

 

 

 

 

 

 

 

 

No. Diameter. e iy Y (Declination). Dependence.

1 0.15 —59.3 +18.0 +0.133

2 .16 — 6.1 —26.0 -228

3 .13 +11.1 +11.2 .194

4 .16 +19.3 +34.4 171

5 .30 +35.0 —37.6 +0.274

Parallax star 0.21 + 5.7 — 5.8
TABLE 2
Repvuctions ror ¢ 36 LEONIS

Solution Weight | Parallax Time in Residual Vp-o

Plate. (m). (p). | Factor (P). | Days (t). (). in Are.
mm, mm.

752 —0.0249 0.7 +0.639 —320 —0.0016 —0°03
753 — .0246 0.8 + .689 —320 — .0019 — .04
1137 — .0256 0.9 — .592 —237 — .0010 — .02
1152 — .0289 0.9 — .664 —231 + .0022 + .04
1158 — .0268 0.8 — .664 —231 + .0001 .00
1197 — .0271 0.9 — .749 —223 + .0004 + .01
1271 — .0282 0.7 — .899 —203 + .0015 + .03
2141 — .0259 0.8 + .884 + 16 .0000 -00
2142 — .0255 0.9 + .884 + 16 — .0004 — .01
2170 — .0245 | 0.8 | + .8381 | + 25 | — .0014 | — .03
2171 — .0266 0.8 + .831 + 25 + .0007 + .01
2309 — .0270 0.8 + .569 + 51 + .0011 + .02
3457 — .0286 0.9 + .913 +373 + .0033 + .06
3458 — .0226 0.9 + .913 +373 — .0027 —. .05
3459 — .0287 0.6 + .913 +3873 + .0034 | + .05
8493 — .0253 0.6 + .894 +379 -0000 .00
3851 — .0260 1.0 — .681 +501 + .0006 + .01
3852 — .0243 1.0 — .681 +501 — .0011 — .02
- 8862 — .0250 0.9 — .703 +503 — .0004 — .01
3863 —0.0237 0.9 —0.703 +503 —0.0017 —0.03

 

 

 

 

 

 

 
278° S. A. MITCHELL

The normal equations are:

16.6c + 17.092u + 1.38137 = — 0.4305 mm.
+ 174.9497 + 1.40637 = — 0.4169 mm.
+ 9.73777 = — 0.0337 mm.

from which:

c = — 0.02612 mm.
pw = +.0.00017 mm. = + 0%00385, or + 07013 per year.
am = + 0.00022 mm. = + 07005 + 07007. —
Probable error of plate of unit weight
+ 0.00107 mm. = + 07022.

35 LEONIS (10 11"; +24° 0’)

This star is of 5.91 magnitude, and of G type. It has a total
proper motion of 0724 per year. It is situated 320” distant
from ¢ 36 Leonis, and the same series of plates was utilized for
the measures of both stars, with the exception of the first four
plates in Table I below, which were used for the measurement of
35 Leonis only. Allegheny by photography finds the relative
parallax + 0”038 + 0007, while Adams and Joy derive the
absolute result + 07030. The proper motion in right ascension
from the photographsis — 07181 per year, while the value given
by Boss is — 07208. Mr. Mitchell measured the series of
plates.
 

 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 279
TABLE 1
PLatTEs or 35 Lronis

No. Date. Hour Angle. Observers. Weight.

2 1914 May 6 +151 M 1.0

3 May 9 +0.8 M 1.0

4 May 9 +1.4 M 0.6*
688 Dec. 17 —0.4 M 0.8
752 1915 Jan. 7 —1.2 M 0.7
753 Jan. 7 —0.7 M 0.8
1137 Mar. 31 +0.4 G 0.9
1152 Apr. 6 +0.3 M 0.9
1153 Apr. 6 +0.8 M 0.8
1197 Apr. 14 —0.2 G 0.9
1271 May 4 +0.6 M 0.7
2141 Dec. 9 —0.6 A 0.8
2142 Dec. 9 —0.1 A 0.9
2170 Dec. 18 —0.3 M 0.8
2171 Dec. 18 +0.1 M 0.8
2309 1916 Jan. 13 | —0.9 M 0.8
8457 Nov. 30 —0.5 M 0.9
8458 Nov. 30 —0.2 M 0.9
3459 Nov. 30 +0.2 M 0.6*
3493 Dec. 6 —0.8 A 0.6*
3851 1917 Apr. 7 +0.1 A 1.0
8852 Apr. 7 +0.4 A 1.0
3862 Apr. 9 0.0 A 0.7
3863 Apr. 9 +0.1 A 0.7

* One exposure.
Comparison STaRs
No. Diameter. s vie etebe Y (Declination). Dependence.
mm. mm. mm.

1 0.15 —60.8 +11.4 +0.255

3 13 + 9.6 + 4.7 -255

4 .16 +17.7 +27.9 .276

5 .30 +33.5 —44.0 +0.214

Parallax star 0.09 — 1.0 + 2.4

 

 

 

 

 
280 S. A. MITCHELL

TABLE 2
REDUCTIONS FoR 35 LEONIS

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual iv pev
Plate. (m). (p). Factor (P). | Days (t). (). in Are.
mm. mm.
2 —0.0018 1.0 —0.912 —566 —0.0007 ~—0701
3 + .0002 1.0- | — .922 —563 — .0027 — .06
4 — .0039 0.6 — .922 — 563 + .0014 + .02
688 — .0074 0.8 + .836 —341 .0000 00
752 — .0104 0.7 + .639 —3820 + .0024 + .04
753 -— .0074 0.8 + .639 —320 — .0006 — .01
1137 — .0124 0.9 — .592 —237 + .0022 + .04
1152 — .0098 0.9 — .664 | —231 — .0006 — .01
1153 — .0098 0.8 — .664 —231 — .0006 — .01
1197 — .0128 0.9 — .749 —223 + .0022 + .04
1271 — .0118 0.7 — .899 —203 + .0007 + .01
2141 — .0173 0.8 + .884 + 16 + .0014 + .03
2142 — .0126 0.9 + .884 + 16 — .0033 — .06
2170 — .0190 0.8 + .831 + 25 + .0029 + .05
2171 — .0142 0.8 + .831 + 25 — .0019 — .04
2309 — .0156 0.8 + .569 + 51 — .0012 — .02
3457 — .0244 0.9 + .913 +373 -0000 -00
8458 — .0248 0.9 + .913 +373 + .0004 + .01
3459 — .0212 0.6 + .9138 +373 — .0032 — .05
3493 — .0278 0.6 + .894 +379 + .0033 + .05
3851 — .0272 1.0 — .681 +501 — .0006 — .O1
3852 — .0272 1.0 — .681 +501 — .0006 — .01
3862 ~ .0311 0.7 — .703 +503 + .0033 + .06
3863 —0.0252 0.7 —0.703 +503 —0.0026 —0.05
The normal equations are:
19.6c — 2.316u — 0.05597 = — 0.3024 mm.
+ 256.8824u + 14.0075¢ = — 0.5716 mm.
froma which: + 12.29107 = — 0.0297 mm.
e = — 0.01571 mm.
B= — 0.00238 mm. = — 070495, or — 07181 per year.

x = + 0.00023 mm. = + 07005 + 07008.
Probable error of plate of unit weight
+ 0.00124 mm. = + 0"026.
PARALLAXES OF 260 STARS 281

40 LEONIS (10 14"; +19° 58’)

This is a star with a total proper motion of 0734 per year.
It is of F5 type, and of magnitude 4.97. The spectroscopic
parallax of Adams and Joy is + 07058. The proper motion in
right ascension from the photographs is — 0%218 per year while
the value from Boss is — 07234. The plates were measured by
Mr. Olivier.

 

 

 

TABLE 1
Puatres or 40 LEoNIs
No. Date. Hour Angle. Observers. Weight.
811 1915 Jan. 20 +045 G 0.8
827 Jan. 28 0.0 M 0.7
2124 Dec. 6 —0.1 Ol 0.6*
2125 Dec. 6 +0.5 Ol 0.6
2275 1916 Jan. 38 —0.8 ol 0.9
2276 Jan. 3 —0.3 ol 0.9
2331 Jan. 17 —0.3 Ol 0.6*
2332 Jan. 17 +0.2 Ol 0.7
2527 Mar. 30 —0.1 ol 0.8
2528 Mar. 30 +0.5 Ol 0.8
2541 Mar. 31 0.0 G 0.7
2638 May 3 +0.6 Ol 0.8
8514 Dec. 9 —0.8 ol 0.9
8515 Dec. 9 0.0 ol 0.9
8573 1917 Jan. 11 —0.8 ol 0.8
3574 Jan. 11 —0.2 Ol 0.6*
3740 Mar. 9 +0.2 Ol 0.9
3741 Mar. 9 +0.8 Ol 0.9
3831 Mar. 30 +0.4 Ol 0.8
8892 Apr. 18 +0.3 Ol 0.9
3954 May 14 +1.1 M 0.9
3967 a May 15 +1.1 M 0.7*

 

 

 

 

 

* One exposure.
282 S. A. MITCHELL

ComMPARISON STARS

 

 

 

 

 

 

 

No. Diameter. Pe ae Y (Declination). Dependence.
1 0.23 —65.5 +39.4 +0.2544
2 14 +11.1 —32.4 -8053
3 17 +14.3 —15.6 i - 2643
4 37 +40.1 + 8.6 +0.1760
Parallax star 0.20 — 2.4 — 2.5
TABLE 2

RepuctTions For 40 LEonIs

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual VP on
Plate. (m). (p). | Factor (P). | Days (¢). (). in Arc,

mm. mm.
811 +0.0202 0.8 +0.481 —524 +0.0006 | +0701
827 + .0230 | 0.7 + .367 | —516 — .0027 | — .05
2124 + .0150 0.6 + .899 — 204 — .0024 | — .04
2125 + .0103 0.6 + .899 —204 |} + .0023 | + .04
2275 + .0117 | 0.9 + .706 | —177 | — .0004 | — .01
2276 + .0116 0.9 + .706 —-177 — .0002 -00
2331 + .0100 0.6 + .526 —162 + .0005 | + .01
2332 + .0142 0.7 + .526 —162 — .0037 | — .06
2527 + .0051 0.8 — .578 | — 89 | + .0008 | + .01
2528 + .0033 | 0.8 — .578 | — 89 | + .0026 | + .05
2541 + .0015 | 0.7 — .590 | — 88 | + .0044 | + .08
2638 + .0047 | 0.8 — .888 | — 56 — .0004 | — .01
3514 + .0015 0.9 + .883 +165 + .0004 |-+ .01
3515 + .0006 0.9 + .883 +165 + .0013 | + .02
3573 + .0007 | 0.8 + .594 | +198 — .0004 | — .01
3574 — .0026 | 0.6 + .594 | +198 | + .0029 | + .05
3740 — .0027 0.9 — .274 +255 — .0006 | — .O1
3741 — .0026 | 0.9 — .274 | +255 — .0007 | — .01
3831 — .0053 | 0.8 — .574 | +276 | + .0007 | + .O1
3892 — .0027 0.9 — .783 +295 — .0029 | — .06
3954 — .0060 | 0.9 — .9385 | +321 — .0007 | — .O1
3967 —0.0061 | 0.7 —0.937 | +322 —0.0006 | —0.01

 
PARALLAXES OF 260 STARS 283

The normal equations are:

17.2¢ + 2.306 + 0.89347 = + 0.0757 mm.
+ 109.2606 — 12.4635¢ = — 0.3317 mm.
+ 8.16447 = + 0.0584 mm.

from which:
c = + 0.00467 mm.
uw = — 0.00288 mm. = — 070598, or — 07218 per year.
x = + 0.00226 mm. = + 07047 + 07009.
Probable error of plate of unit weight
+ 0.00117 mm. = + 07024.

y LEONIS (105 14"; +20° 20’)

The components of this well-known double, 2 1424, are each
of K type, and of magnitudes 2.61 and 3.80 respectively.
According to Burnham, their relative motion is best explained
by their having a slight difference in proper motion, and thus
resembling the system of 61 Cygni.. The proper motion for
each is approximately 0734 per year. Two measured parallaxes
have been published, a value due to Flint with the meridian
circle of + 07105 + 07040, and a determination with the Yale
heliometer by Smith with the very different value of — 0”046
+ 07013. Assuming the correctness of Doberck’s orbit with a
period of 402.62 years, Belopolsky from measures of radial
velocity, which give a difference for the two components of
2.2 km. (Astronomische Nachrichten, 147, 93, 1898), derives a
parallax between 07015 and 07025. The Lick Observatory
observations’ have a difference of only 0.1 km. for the two
components (Lick Observatory Bulletin, 6,25, 1910). Adams and
Joy find the absolute parallaxes + 07032 and + 0"026 for
brighter and fainter star, respectively.

On account of the fact that these stars are so bright, and that
they are separated by only 375, it was very difficult to obtain a
satisfactory series of photographs for measurement. The plates
were measured by Mr. Mitchell. The weighted mean of the
values of the two components gives the parallax of the system:

— 07007 + 07009.
284 S. A. MITCHELL

TABLE 1

Puatres or y LEONIS

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1208 1915 Apr. 15 0+0 Ol 1.0
1209 Apr. 15 +0.5 Ol 0.8
1241 Apr. 24 —0.5 A 0.9
1242 Apr. 24 +0.1 A 0.7
1251 Apr. 25 —0.2 M 0.9
1252 Apr. 25 +0.3 M 0.7
2191 Dec. 21 —0.8 M 0.7
2192 Dec. 21 —0.5 M 0.5*
2193 Dec. 21 0.0 M 0.8
2299 1916 Jan. 8 —0.4 M 0.4*
2334 Jan. 18 —0.8 M 0.8
2334 Jan. 18 —0.4 M 0.8
2557 Apr. 6 —0.3 M 0.8
2642" May 7 +0.6 M 0.8
2643 May 7 +1.0 M 0.7
2644 May 7 +1.5 M 0.7
2653 May 9 +0.6 M 1.0
3504 Dec. 7 —1.1 M 0.9
3505 Dec. 7 —0.7 M 0.8
3506 Dec. 7 —0.2 M 0.7
3507 Dec. 7 +0.2 M 0.8

 

 

* One exposure.

CoMPARISON STARS

 

 

 

 

 

No. | Diameter. iF roe eas Y (Declination). Dependence.
mm. mm. mom.
1 0.18 —64.7 -17.2 +0.138
2 215 — 8.4 +14.1 -210
3 19 — 6.3 + 9.9 .207
4 -13 +38.4 +40.4 .271
5 .28 +41.0 —47.2 +0.174
Principal star .22 + 5.5 + 5.3
Companion 0.14 + 5.5 + 5.3

 
 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 28
TABLE 2

ReEpuctions For y LEoNIS—PRINCcIPAL STAR

Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p). | Factor (P). | Days (#). (0). in Are.

mm. ; mm.
1208 —0.1224 1.0 —0.750 —297 +0.0010 +0/02
1209 — .1229 0.8 — .750 —297 + .0015 + .03
1241 — .1216 0.9 — .829 —288 + .0007 + .01
1242 — .1177 0.7 — .829 —288 — .0032 — .06
1251 — .1198 0.9 — .836 —287 — .0011 — .02
1252 — .1170 0.7 — .836 —287 — .0039 — .07
2191 — .1090 0.7 + .814 — 47 — .0001 -00
2192 — .1110 0.5 + .814 — 47 + .0019 + .03
2193 — .1115 0.8 + .814 — 47 + .0024 + .04
2299 — .1065 0.4 + .640 — 29 — .0017 — .02
2334 — .1101 0.8 + .514 — 19 + .0024 + .04
2335 — .1075 0.8 + .514 — 19 — .0002 .00
2557 — .1022 | 0.8 | — .662 | +60 | — .0015 | — 03
2642 — .1034 0.8 — .912 +91 |° + .0013 + .02
2643 — .1041 0.7 — .912 + 91 + .0020 + .03
2644. — .1026 0.7 — .912 + 91 + .0005 + .01
2653 - - 10380 1.0 — .920 + 93 + .0010 + .02
3504 — .0916 0.9 + .892 +305 — .0001 -00
3505 — .0884 0.8 + .892 +305 — .0033 — .06
3506 — .0900 0.7 + .892 +305 — .0017 — .03
3507 —0.0925 0.8 + .892 +305 +0.0008 +0.01
The normal equations are:

16.2¢c — 2.7344 — 1.90927 = — 1.7423 mm.
+ 75.6036u + 16.37957 = + 0.6650 mm.

from which:
= — 0.10672 mm.

c

be
T

Probable error of plate of unit weight

+ 10.71507 = + 0.2840 mm.

= — 0.00009 mm. = — 07002 + 07009.

= + 0.00043 mm. = + 07009.

+ 0.00496 mm. = + 071031, or + 07376 per year.
286 S. A. MITCHELL

TABLE 2

Repuctions ror y Lreonis—ComPaNnion

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual vp “ov
Plate. (m). (p). | Factor (P). | Days (t). (). in Are.

Tm. mm. =
1208 +0.0371 1.0 —0.750 —297 0.0000 0700
1209 + .0383 0.8 — .750 —297 — .0012 — .02
1241 + .0432 0.9 — .829 —288 — .0056 — .11
1242 + .0398 0.7 — .829 — 288 — .0022 — .04
1251 + .0371 0.9 — .836 —287 + .0006 + .01
1252 + .0384 0.7 — .836 —287 — .0007 — .01
2191 + .0474 0.7 + .814 — 47 + .0008 + .01
2192 + .0450 0.5 + .814 — 47 + .0032 + .05
2193 + .0452 0.8 + .814 — 47 + .0030 + .06
2334 + .0472 0.8 + .514 — 19 + .0027 + .05
2335 + .0466 0.8 + .514 — 19 + .0033 + .06
2642 + .0564 0.8 — .912 + 91 + .0006 + .01
2643 + .0568 0.7 — .912 + 91 + .0002 .00
2644 + .0558 0.7 — .912 + 91 + .0012 + .02
2653 + .0526 1.0 — .920 + 93 + .0045 + .09
3504 + .0676 0.9 + .892 +305 — .0016 — .03
3505 + .0701 0.8 + .892 +305 — .0041 — .08
3506 + .0650 0.7 + .892 +305 + .0010 + .02
3507 +0.0706 0.8 +0.892 +305 —0.0046 —0.09

 

The normal equations are:

15.0¢ — 3.0984 — 1.63567 = +.0.7571 mm.
+ 75.2820u + 16.7715 = + 0.2056 mm.
+ 10.20067 = — 0.0094 mm.
from which:
ec = + 0.05141 mm.
# = + 0.00507 mm. = + 071055, or + 07385 per year.

a = — 0.00101 mm. = — 0021 + 0015.
Probable error of plate of unit weight
+ 0.00072 mm. = + 07015.
PARALLAXES OF 260 STARS

from Boss is — 07122.

TABLE 1

6 LEONIS MINORIS (10° 22™; +37° 13’)

Although of small total proper motion 07164, Abetti by mer-
idian circle has found a rather large parallax for this star amount-
ing to + 07230 + 07043, the star being of magnitude 4.41
and type K. Adams and Joy find the spectroscopic value
+ 07020. Thirteen of the McCormick plates were measured
by Mr. Alden, the remaining eight by Mr. Mitchell.
parallax of + 07008 + 07009 was found, and a proper motion
in right ascension of — 07128 while the corresponding value

Puates or 6 Leonis Minoris

287

A relative

 

 

 

No. Date. Hour Angle. Observers. Weight.
2291 | 1916 Jan. 7 —on2 Ol 0.4*
2351 Jan. 23 —0.6 G 0.4
2367 Feb. 3 —0.3 A 0.8
2582 Apr. 20 —0.3 G 0.6
2590 Apr. 24 —0.5 M 0.6
2591 Apr. 24 —0.2 M 0.6
4808 1917 Nov. 22 —0.8 B 1.0
4809 Nov. 22 —0.3 B 1.0
4932 1918 Jan. 13 —0.5 Ol 0.6*
5026 Feb. 7 —0.1 ol 0.6*
5294 Apr. 15 —0.4 A. 1.0
5344 May 2 0.0 ' A 1.0
5354 May 5 0.0 A 0.7*
6181 1919 Jan. 6 —1.2 F 0.8
6349 Jan. 26 —0.9 H 1.0
6350 Jan. 26 —0.3 H 0.8
6391 Jan, 29 —0.7 M 0.8
6770 Mar. 28 —0.7 F 0.6
6917 Apr. 21 —0.5 F 0.9
6927 ‘ Apr. 23 —0.2 Ol 0.7*
6936 Apr. 25 —0.4 F 1.0f

 

 

 

 

 

* One exposure.

{ Three exposures.
8. A. MITCHELL

Comparison STARS

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. be ce gia Y (Declination). Dependence.
1 0.11 —62.4 +21.3 +0.2616
2 .20 —26.5 —44.6 . 1828
3 .16 +381.4 +15.0 .2787
4 .14 +57.5 + 8.3 +0.2769
Parallax star 0.18 + 3.5 + 3.9
TABLE 2
Repuctions ror 8 Leonis MInoris
Solution | Weight | Parallax | Time in Residual Vp-0
Plate. (m). (p). Factor (P). | Days (é). (2). in Are.
mm. mm.
2291 —0.0218 0.4 +0.672 —713 +0.0020 | +0°03
2351 — .0208 0.4 + .472 —697 + .0007 | + .01
2367 — .0218 0.8 + .311 —686 + .0014 | + .03
2582 — .0267 0.6 — .783 —609 + .0046 + .07
2590 — .0190 0.6 — .817 —605 — .0032 — .05
2591 — .0202 0.6 — .817 —605 — .0020 ; — .03
4808 — .0306 1.0 + .918 — 28 — .0007 — .01
4809 —. .0308 1.0 + .918 — 28 — .0005 — .01
4932 — .0340 0.6 + .596 + 24 + .0017 | + .03
5026 — .0285 0.6 + .241 + 49 — .0044 — .07
5294 — .0337 1.0 — .730 +116 — .0006 — .o1
5344 — .0841 1.0 — .871 +133 — .0006 — .01
5354 — .0325 0.7 — .888 +136 — .0022 | — .04
6181 — .0351 0.8 + .680 +382 — .0032 — .06
6349 — .0402 1.0 + .426 +402 + .0014 | + .08
6350 — .0407 0.8 + .426 +402 + .0019 + .04
6391 — .0390 0.8 + .382 +405 + .0002 .00
6770 — .0414 0.6 — .518 +463 + .0012 + .02
6917 — .0422 | 0.9 — .785 +487 + .0016 + .03
6927 — .0400 0.7 — .802 +489 — .0007 — .01
6936 —0.0422 1.0 —0.818 +491 +0.0015 | +0.03

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS 289

The normal equations are:
15.9¢ + 10.304y — 1.4055r = — 0.5285 mm.

+ 277.2739n — 4.58397 = — 0.8020 mm.
+ 7.93817 = + 0.0559 mm.
from which:
c = — 0.03211 mm.
w= — 0.00169 mm. = — 070352, or — 07128 per year.
a = + 0.00038 mm. = + 07008 = 07009.

Probable error of plate of unit weight
+ 0.00125 mm. = + 07026.

46 LEONIS MINORIS (108 47"; +34° 45’)

This is a Ko type star, of magnitude 3.92, and of total annual
proper motion 07304. Its parallax has been twice determined,
the relative value from the meridian circle by Abetti gives the
result + 07085 + 07049, and the absolute value by Adams’
spectroscopic method is +-0”019. Twenty of the McCormick
plates were measured by Mr. Mitchell, the balance by Mr. Lamb.
The photographic proper motion in right ascension was found
to be + 07076 while the corresponding value from Boss is
+ 07091.

CoMPARISON STARS

 

 

 

 

No. Diameter. x aor a Y (Declination). Dependence.
1 0.14 —53.9 — 0.7 +0.174
2 14 —20.2 +24.3 554
3 -12 +74.1 —23.6 +0.272
Parallax star 0.15. — 0.5 + 6.9

 

 

 

 

20
290

S. A. MITCHELL

TABLE 1

Puatres oF 46 Leo MInoris

 

 

Observers. | Weight.

 

 

No. Date. Hour Angle. .

795 1915 Jan. 14 —140 M 0.8
1260 2 Apr. 30 —0.6 G 0.4*
1261 Apr. 30 —0.2 G 0.7
2154 Dec. 10 —0.6 G 0.5
2241 “Dec. 29 —-1.2 G 0.8
2242 Dec. 29 —0.9 G 0.7
2257 1916 Jan. 2 —1.2 G 0.7
2258 Jan. 2 —0.7 G 0.7
2569 Apr. 17 —0.6 G 0.7
2612 Apr. 29 —0.6 A 0.8
2613 Apr. 29 —0.3 A 0.8
2623 - May 1 —0.6 G 0.5
2624 May 1 —0.2 G 0.5
3533 Dec. 17 —0.6 L 0.8
3534 Dec. 17 —0.3 L 0.8
3571 1917 Jan. 9 —1.4 L 0.9
8572 Jan. 9 —1.0 L 0.9
3933 May 2 —0.5 Ol 0.9
8934 May 2 —0.2 Ol 1.0
3935 May 2 —0.2 M 0.8
4833 Dec. 1 —0.2 B 0.8
4834 Dec. 1 —1.0 B 0.8
5280 1918 Apr. 14 —0.2 M 0.8
5332 May 1 —0.5 Ol 0.8
5333 May 1° —0.2 Ol 0.6
5345 May 2 0.0 A 1.2f
6042 Noy. 30 —0.6 M 0.7
6043 Nov. 30 —0.3 M 0.7
6057 Dec. 2 —0.2 H 0.9
6095 Dec. 17 —0.3 . D 0.9
6162 Dec. 29 —0.5 M 1.0
6163 Dec. 29 —0.2 M 1.0

 

 

 

 

* One exposure.

t Three exposures.
PARALLAXES OF 260 STARS 291

TABLE 2

Repuctions ror 46 Leo Minoris :

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp-0
Plate. (m). (p). Factor (P). | Days (t). (v). in Arc.

mm. mm.
795 —0.0544 0.8 +0.662 —786 +0.0022 +0704
1260 — 0593 0.4 — .798 —680 + .0048 + .06*
1261 — .0579 0.7 — .798 —680 + .0034 + .06
2154 — .0497 0.5 + .903 —456 + .0013 + .02
2241 — .0506 0.8 + .812 —487 + .0022 + .04
2242 — .0449 0.7 + .812 —437 — .0035 — .06
2257 — .0490 0.7 + .781 —433 + .0006 | + .01
2258 — .0489 0.7 + .781 —433 + .0005 + .01
2569 — .0472 0.7 — .680 —327 — .0035 — .06
2612 — .0488 0.8 — .796 —3815 — .0020 — .04
26138 — .0508 0.8 — .796 —315 .0000 .00
2623 — .0450 0.5 — .813 —313 — .0058 — .09
2624 — .0470 | 0.5 — .813 —313 — .0038 — .06
3533 — .0495 0.8 + .877 — 88 + .0048 + .09
3534 | =F .0449 | 0.8 + .877 — 838 + .0002 .00
8571 — .0398 0.9 + .709 — 60 — .0050 — .10
3572 — .0414 0.9 + .709 — 60 — .0034 — .07
3933 — .0466 0.9 — .819 + 53 — .0006 — .01
3934 = .0486 1.0 _ 819 + 53 + .0014 + .03
3935 — .0469 0.8 — .819 + 53 — .0003 .00
4833 — .0398 0.8 + .912 +266 — :0013 — .02
4834 — .0444 0.8 + .912 +266 + .0033 + .06
5280 — .0471 0.8 — .640 +400 + .0038 + .07
5332 — .0419 0.8 — .809 +417 — .0016 — .03
5333 — .0476 0.6 — .809 +417 + .0041 + .07
53845 — .0436 1.2 — .817 +418 + .0001 .00
6042 — .0334 0.7 + .912 +630 — .0040 — .07
6043 — .0332 | 0.7 | + .912 | +630 | — .0042 | — .07
6057 — .0370 0.9 + .912 +632 — .0004 — .01
6095 — . 0406 0.9 + .880 +647 + .0033 + .06
6162 — .0379 1.0 + .810 +659 + .0005 + .01
6163 —0.03891 1.0 +0.810 +659 +0.0017 +0.04
292 S. A. MITCHELL

The normal equations are:

24.9¢ + 11.720u + 3.66400 = — 1.1213 mm.
+ 486.7224u + 16.74497 = — 0.0105 mm.
+ 16.54467 = — 0.11385 mm.
from which:
c = — 0.04584 mm.

« &=+0.00100 mm. = + 070209, or + 07076 per year.
x = + 0.00227 mm. = + 07047 + 07009.
Probable error of plate of unit weight

+ 0.00175 mm. = + 07036.

x LEONIS (112 0"; +7° 53’)

This star has a total proper motion of 0735, it is magnitude
4.66, and of type F. Adams has found the parallax from

TABLE 1

PLaTEs oF x LEONIS

 

 

 

No. Date. Hour Angle. Obgervers. Weight.
669 1914 Dec. 14 —048 M 1.0
670 Dec. 14 —0.3 M 0.9
682 Dec. 16 —0.3 G 0.8
724 Dec. 27 —1.0 G 0.4
1190 1915 Apr. 13 +0.3 M 1.0
1191 Apr. 13 +0.8 M 0.9
1805 May 13 +0.8 Ol 0.9
2143 Dec. 9 —0.9 A 0.7*
2144 Dec. 9 —0.4 A 0.7*
2277 1916 Jan. 3 —0.3 ol 1.0
2278 Jan. 3 +0.2 Ol 0.9
2333 Jan. 17 +0.2 Ol 0.9
2558 Apr. 6 —0.3 M 0.8
2559 Apr. 6 +0.2 M 0.9
2566 Apr. 15 —0.9 Ol 0.6*
2604 Apr. 27 +0.5 Ol 0.9
2605 Apr. 27 +1.2 Ol 0.8

 

 

 

 

 

* One exposure.
PARALLAXES OF 260 STARS

Comparison Stars

29%

 

 

 

 

 

 

 

 

 

No. Diameter. . oe ial Y (Declination). Dependence.
mm. mm. mm.

1 0.18 —22.8 —27.5 +0.3208

2 -10 —19.0 +26.9 -4240

3 16 +41.8 + 0.6 +0.2552

Parallax star 0.15 — 4.7 + 2.7
TABLE 2
REDUCTIONS FoR x LEONIS
, Soluti Weigh me Time i idual pe
Pee! |) aT ee eee | ee | | eae
. mm,

669 +0.0098 1.0 +0.898 —279 +0.0006 | +0701
670 + .0058 0.9 + .898 —279 + .0046 | + .09
682 + .0125 0.8 + .892 —277 — .0022 | — .04
724 + .0109 0.4 + .842 —266 — .0010 | — .O1
1190 + .0072 1.0 — .585 —159 — .0021 — .04
1191 + .0053 0.9 — .585 —159 — .0002 .00
1305 | + .0042 | 0.9 | — .s67 | -129 | — .0003 | — .o1
2143 — .0011 0.7 + .907 + 81 — .0028 | — .05
2144 — .0019 0.7 + .907 + 81 — .0020 | — .03
2277 — .0060 1.0 + .797 +106 + .0010 | + .02
2278 — .0035 0.9 + .797 +106 — .0014 — .03
2333 — .0066 0.9 + .663 +120 + .0010 | + .02
2558 — .0094 0.8 — .505 +200 + .0003 .00
2559 — .0131 0.9 — .505 +200 + .0040 | + .08
2566 — .0076 0.6 — .618 +209 — .0019 | — .03
2604 — .0090 0.9 — .748 +221 — .0010 | — .02
2605 —0.0111 0.8 —0.748 +221 +0.0011 +0.02

 

 

 

 

 

 

 
294 S. A. MITCHELL

spectroscopic measures to be + 07009. There is no other
published parallax. Mr. Olivier measured the series of plates,
and determined the proper motion in right ascension to be
— 0"302 while the value from Boss is — 07345.

The normal equations are:

14.1¢c — 0.124 + 1.74477 = — 0.0129 mm.
+ 52.1326u — 6.8115r = — 0.2093 mm.
+ 8.14717 = + 0.0279 mm.
from which:
c = — 0.00099 mm.
ph = — 0.00398 mm. = — 070827, or — 07302 per year.
x = + 0.00032 mm. = + 07007 + 07010.

Probable error of plate of unit weight
+ 0.00138 mm. = + 07029.

LALANDE 21258 (115 07; +44° 2’)

This star of 8.9 magnitude, and of Ma, type has a very large
proper motion of 4°47 per year. It has many times been investi-
gated for parallax and with the following results:

 

 

 

 

 

 

Parallax. Authority. : Method.
+07262+407011_ Auwers | Heliometer

.260+ .020 Krueger Heliometer

.87 + .110 | Flint Meridian Circle

-168+ .027 | Kapteyn ~ Meridian Circle

-163+ .018 Russell Photography
+0.202 Adams Spectrograph

Mr. Mitchell measured the McCormick plates and derived the
proper motion in right ascension of — 4"398, while the value of
Boss is — 47334.
PARALLAXES OF 260 STARS

TABLE 1

Puates oF LALANDE 21258

295

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
689 1914 Dec. 17 —052 M 0.5*
770 1915 Jan. 9 —0.1 M 1.0
881 Feb. 10 —0.2 M 1.0
1273 May 8 -0.1 A 1.0
1283. May 9 —0.1 M 1.0
1296 May 10 —0.2 Ol 0.7
2160 Dec. 14 —0.8 M 1.0
2161 Dec. 14 —0.5 M 1.0
2300 1916 Jan. 8 —0.5 M 0.9
2310 Janz 13 —0.9 M 1.0
3508. Dec. 7 —0.1 M 0.8
3524 Dec. 12 —0.8 M 0.7
3525 _ Dee. 12 —0.4 M _ 1.0
3613 1917 Jan. 25 —0.4 M 1.0
-3914 Apr. 23 —0.2 A - 1.0
3917 Apr. 26 -—0.1 A 0.8
* One exposure.
ComPaRISON STARS
No. Diameter, |* (Right Ascen-| y (Declination). | | Dependence.
mm. mm. mm.
ae 0.18 —67.5 — 6.8 +0.218
2 a2 —14.3 + 3.9 .201
3 .12 + 5.8 +45.0 177
4 .18 +22.8 —56.5 .222
5 -15 +53 .2 +14.4 +0.182
Parallax star 0.19 — 1.9 — 2.6

 

 

 

 

 
296 S. A. MITCHELL

TABLE 2

RepuctTions FoR LALANDE 21258

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p). Factor (P). | Days (é). (). in Are.

mm. mm.
689 —0.0658 0.5 +0.890 —396 —(.0046 —0"07
770 — .0858 1.0 + .745 —373 + .0008 + .02
881 — .1085 1.0 + .352 —341 + .0017 + .04
1273 — .1664 1.0 — .831 —254 — .0009 — .02
1283 — .1662 1.0 — .838 —253 — .0017 — .04
1296 — .1672 0.7 — .845 —252 — .0014 — .02
2160 | — .2811 | 1.0 | + .899 | — 34 | + .oo11 | + .02
2161 — .2824 1.0 + .899 — 34 + .0024 | + .05
2300 — .2985 0.9 + .756 - 9 + .0028 | + .05
2310 — .38001 1.0 + .709 — 4 + .0011 + .02
3508 — .4838 0.8 + .908 +325 — .0041 — .08
3524 — .4861 0.7 + .902 +330 — .0048 — .08
3525 — .4909 1.0 + .902 +330 -0000 -00
3613 — .5194 1.0 + .564 +374 + .0002 -00
3914 — .5809 1.0 — .701 +462 — .0001 -00
3917 —0.5866 0.8 —0.732 +465 +0.0036 | +0.07

 

 

The normal equations are:
14.4c¢ + 3.5354 + 4.00617 = — 4.5969 mm.
+ 180.5127 + 2.84797 = — 8.6230 mm.
+ 8.88197 = — 1.3208 mm.
from which:
— 0.30737 mm.
— 0.05793 mm. = — 172050, or — 47398 per year.
+ 0.00851 mm. = + 07177 + 0"012.
Probable error of plate of unit weight

+ 0.00161 mm. = + 07033.

c

“
T

LALANDE 21565 (11" 13"; —4° 31’)

This star of total proper motion 0781 is of magnitude 7.2 and
of K type. Chase with the Yale heliometer determined the
PARALLAXES OF 260 STARS 297

relative parallax 07000 + 07021, while Mt. Wilson with the
spectrograph derived the absolute value + 0”069. Miss Darkow
measured the McCormick plates except four measured by Mr.
Mitchell, and derived a parallax + 0”043 + 07012 with a
proper motion in right ascension + 07818 per year where the
corresponding value from Boss is + 0795.

TABLE 1

Puates oF LaLANDE 21565

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
4898 1917 Dec. 22 | +042 B 1.0
5376 1918 May 17 +0.3 Ol 1.0
5377 May 17 +0.7 Ol 1.0
6096 Dec. 17 +0.2 D 0.8
6097 Dec. 17 +0.7 D 0.7
6313 1919 Jan. 21 —1.1 F 1.0
6314 Jan. 21 —0.8 F 1.0
6828 Apr. 5 +0.1 F 0.8
6869 Apr. 12 +0.7 H 0.9
6870 Apr. 12 +1.0 H 0.9
6988 May 12 0.0 D 1.0
6989 May 12 +0.4 D 0.9
8315 Dec. 20 —0.7 F 1.0
8316 Dec. 20 —0.2 F 1.0
8413 - 1920 Jan. 5 —0.6 F 1.0

 

Comparison STARrs

 

 

 

 

 

 

No. Diameter. x ee ee Y (Declination). Dependence.
mm. mm. mm. ei
1 0.15 —78.5 + 9.2 +0.242
2 .13 — 2.6 —24.2° . 283
3 .08 +29.0 +28.8 - 209
4 -10 +52.1 —13.8 +0.266
Parallax star 0.14 + 0.2 = 23.

 
298 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

‘TABLE 2
Repucrions ror LALANDE 21565
Solution Weight | Parallax Time in Residual Vp-0
Plate. (m). (p). | Factor (P). | Days (2). (2). in Are.
mm. mm.

4898 +0.0011 1.0 +0.881 —429 —0.0014 —0'03
5376 + .0098 1.0 — .868 —283 + .0020 | + .04
5377 + .0110 1.0 — .868 —283 + .0008 | + .02
6096 + .0352 0.8 + .897 — 69 + .0033 | + .06
6097 + .0364 0.7 + .897 — 69 + .0021 | + .04
6313 + .0430 1.0 + .656 — 34 — .0012 | — .02
6314 + .0462 1.0 + .656 — 34 — .0044 — .09.
6828 + .0487 0.8 — .429 + 40 — .0012 — .02
6869 + .0447 0.9 — .525 + 47 + .0034 | + .07
6870 + .0468 0.9 — .525 + 47 + .0013 | + .02
6988 |. + .0536 1.0 — .834 + 77 — .0029 | — .06
6989 + .0529 0.9 — .834 + 77 — .0022 — .04
8315 + .0781 1.0 + .889 +299 | + .0001 .00
8316 | + .0778 1.0 + .889 +299 + .0004 | + .01
8413 +0.0785 1.0 +0.805 | +815 +0.0012 | +0.02

The normal equations are:

14.0c + 0.094 + 1.51277 = + 0.6217 mm.
+ 64.8221n + 5.80937 = + 0.7147 mm..
+ 8.54427 = + 0.1470 mm.

from which:

ce = + 0.04411 mm.
w= + 0.01078 mm. = + 072242, or + 07818 per year.
a = + 0.00207 mm. = + 07043 + 0'012.

Probable error of plate of unit weight

+ 0.00159 mm. = + 07033.

: »} DRACONIS (11 25"; +69° 52’)

This star, of magnitude 4.06, of type Ma, has a small proper
motion of 0705 per year. The spectroscopic parallax of Adams
PARALLAXES OF 260 STARS 299

and Joy is + 07010. Mr. Olivier measured the series of plates,
and determined the proper motion in right ascension — 0”048
per year, while the corresponding value from Boss is — 07034.

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Puates oF \ DRACONIS
No. Date. Hour Angle. Observers. Weight.
2336 1916 Jan. 18 —046 M 0.7
2352 Jan. 23 —0.9 G 0.8
2353 Jan. 23 —0.5 G 0.7
2378 Feb. 7 -1.0 G 0.8
2379 Feb. 7 —0.5 G 0.9
2579 Apr. 19 —0.9 Ol 0.9
2640 May 5 —0.5 G 1.0
2641 May 5 —0.1 G 12.0
2655 May 12 —0.4 Ol 0.6
3573 1917 Jan. 9 —1.0 L 1.0
3574 Jan. 9 —0.6 L 1.0
3633 Jan. 29 —0.9 Ol 1 1a?
3634 Jan. 29 —0.3 Ol , 0.9
3945 May 10 —0.5 ol 0.9
3946 May 10 0.0 ol 0.9
8947 May 10 +0.4 ol 0.9
3951 May 13 —0.2 M 0.8
8952 May 13 +0.1 M 1.0
* Three exposures.
ComMPaARISON STARS
No. Diameter. | |X ca ia Y (Declination). | Dependence.
slon). ”
mm. mm. mm.

1 0.07 —33.6 +34.2 +0.1797

2 13 —23.0 —18.7 .3025

3 .08 —20.5 — 2.4 - 2627

4 .16 +77.1 —13.1 +0.2551

Parallax star 0.17 + 1.3 — 8.5 :

 

 

 

 
300 S. A. MITCHELL

TABLE 2
REDUCTIONS FOR } DRACONIS

 

 

 

 

 

 

 

 

 

Solution Weight | Parallax Time in Residual vVp-o
Plate. (m). (p). | Factor (P). | Days (). (). in Are.

mm. mm.
2336 +0.0011 0.7 +0.720 —241 +0.0005 +0701
2352 .0000 0.8 + .669 —236 + .0016 + .03
2353 + .0022 0.7 + .669 —236 — .0006 — .01
2378 + .0031 | 0.8 | + .490 | —221 | — .0018 | — .03
2379 + .0014 0.9 + .490 —221 — .0001 .00
2579 — .0006 0.9 — .578 —149 + .0008 + .02
2640 + .0010 1.0 — .753 —133 — .0010 — .02
2641 — .0010 1.0 — .753 —133 + .0010 + .02
2655 + .0006 0.6 — .813 —126 — .0007 — .01
3573 — .0005 1.0 + .793 +116 — .0001 -00
3574 + .0005 1.0 + .793 +116 — .0011 — .02
3633 — .0010 1.1 + .595 +136 + .0001 .00
3634 — .0023 0.9 + .595 +136 + .0014 -03
3945 — .0014 0.9 — .795 +237 — .0010 — .02
3946 — .0036 0.9 — .795 +237 + .0012 + .02
3947 — .0024 0.9 — .795 +237 -0000 .00
3951 — .0022 0.8 — .818 +240 — .0002 .00
3952 —0.0022 1.0 —0.818 +240 —0.0002 0.00

 

The normal equations are:

15.9¢ + 2.0184 — 1.01647 = — 0.0079 mm.
+ 59.1355u — 7.19397 = — 0.0430 mm.
+ 8.15037 = + 0.0101 mm.
from which:
ce = — 0.00038 mm.
w= — 0.00064 mm. = — 070133, or — 07048 per year.
a = + 0.00063 mm. = + 07013 + 07005.
Probable error of plate of unit weight
+ 0.00063 mm. = + 0/018.

ll

93 LEONIS (115 42™; +20° 46’)
This star is of magnitude 4.54, and of type F8. It has a proper
motion of 0717 which is common to an eighth magnitude star
PARALLAXES OF 260 STARS

at a distance of 75’.

Campbell and Wright (Astrophysical
Journal, 12, 255, 1900) found 93 Leonis to be a spectroscopic
binary. The only parallax published is that of Adams who finds
the value + 07032. Mr. Graham measured the series of plates

TABLE 1

PLatTes oF 93 LEONIS

301

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

‘No. Date. Hour Angle. Observers. Weight.
690 1914 Dec. 17 —O1 M 1.0
691 Dec. 17 +0.4 M 0.7
703 Dec. 22 0.0 ol 1.0
787 1915 Jan. 13 —0.8 G 0.7
898 Feb. 18 —0.6 G 0.7

1262 Apr. 30 —0.5 G 1.0

1314 May 14 —0.4 G 0.7

1317 May 16 +0.6 M 0.7

1320 May 21 +0.2 A 1.0

13831 June 4 +1.5 G 1.0

2156 Dec. 10 —0.6 G 0.7

2209 Dec. 22 —0.6 G 0.6

2210 Dec. 22 —0.1 G 0.7

2243 Dec. 29 —1.0 G 0.7

2244 Dec. 29 —0.5 G 1.0

8953 1917 May 13 +0.3 M 0.9

8955 May 14 +0.1 M 0.8

8972 May 18 +0.1 A 1.0

3979 May 19 +0.2 Ol 0.8

ComPaRISON STARS
No. Diameter. |~ Se ce iad Y (Declination). Dependence.
mm. mm. mm.
1 0.09 —65.4 —10.1 +0.1982
2 .12 —13.7 —27.0 - 2385
3 .09 +37.9 —14.8 - 2796
4 14 +41.2 +51.9 +0.2837
Parallax star 0.14 + 6.0 + 2.2
302 S. A. MITCHELL

with the exception of the last four plates which were measured
by Mr. Mitchell. The proper motion in right ascension as
determined from the photographs is — 07123 per year, while
the value from Boss is — 07156.

 

 

 

 

 

 

 

 

 

 

TABLE 2
ReEpucTiIons ror 93 LEONIS
Solution Weight Parallax Time in Residual Vp+
Plate. (m). ‘p). Factor (P). | Days (t). (2). in Arc.
mm. mm.
690 —0.0087 1.0 +0.903 —370 0.0000 0700
691 — .0083 0.7 + .908 —370 — .0004 — .01
703 — .0106 1.0 + .899 —365 + .0018 | + .04
787 — .0090 0.7 + .801 —343 — .0002 .00
898 — .0134 0.7 + .398 —307 + .0031 | + .05
1262 — .0114 1.0 — .643 —236 — .0012 | — .02
1314 — .0130 0.7 — .783 —222 .0000 .00
1317 — .0104 0.7 — .800 —220 — .0027 | — .05
1320 — .0152 1.0 — .807 —219 + .0021 | + .04
1331 — .0124 1.0 — .910 —201 — .0011 — .02
2156 — .0124 0.7 + .896 — 12 — .0021 — .04
2209 — .0151 0.6 + .900 0 + .0004 | + .01
2210 — .0163 0.7 + .900 0 + .0016 | + .03
2243 — .0096 0.7 + .883 + 7 — .0052 — .09
2244 — .0155 1.0 + .883 + 7 + .0007 | + .01
3953 — .0245 0.9 — .779 +508 — .0003 — .01
3955 — .0253 0.8 — .787 +509 + .0005 | + .01
3972 — .0237 1.0 — .819 +513 — .0012 | — .02
3979 —0.0282 0.8 —0.827 +514 +0.00382 | +0.06
The normal equations are:
15.7c — 6.223u + 0.29237 = — 0.2361 mm.
+ 164.0953u — 18.51567 = — 0.1890 mm.
dian whee: + 10.72447 = + 0.0378 mm.
c = — 0.01570 mm.
w= — 0.00162 mm. = — 0°0337, or — 07123 per year.
a~ = + 0.00116 mm. = + 07024 + 0”009.

Probable error of plate of unit weight
+ 0.00127 mm. = + 07026.
PARALLAXES OF 260 STARS

6 VIRGINIS (115 45"; +2° 20’)

This star, of magnitude 3.80, and of type F8 has a consider-
able proper motion of 0°79 per year. Its parallax has been
determined by the Yale heliometer by Chase to be + 0711

303

 

 

 

 

 

 

 

 

 

 

 

+ 07047. The Allegheny result by photography is + 07096
TABLE 1
Z PuLates oF £8 VIRGINIS
No. Date. Hour Angle. Observers. Weight.
20 1914 May 17 +051 M 0.6*
21 May 17 +0.8 M 0.6*
26 ‘May 18 0.0 M 0.7
27 ’ “May 19 +0.2 M 0.7
671 © Dec. 14 —0.2 M 0.8
683 - Dec. 16 © —0.2 G 0.8
725 | Dec. 27 -1.0 G 0.7
1274 1915 May 8 —0.2 A 0.8
1286 ° ' May 9 +0.7 M 1.0
1338 ‘June 5° +1.4 A 0.8
2175 Dec. 18 +0.5 M 0.8
2211 Dec. 22 © +0.4 G 0.7
2292 1916 Jan. 7 —0.7 Ol 0.8
2293 | ' “Jan. 7 —0.3 Ol 0.8
3988 1917 “May 21 +0.4 M 1.0
3989 May 23 +0.2 Ol 1.0
3990 May 23 +0.7 ol 1.0
4008 May 25 +0.3 M 1.0
* One exposure.
ComPaARISON STARS
No. Diameter. a (Bight, asia Y (Declination). Dependence.
mm. mm. mm.
1 0.13 —36.0 —32.4 +0.255
2 14 —10.2 +61.2 266
3 .20 +22.5 + 3.9 243
4 .12 +23.7 —32.7 +0.236
Parallax star 0.18 — 0.8 + 1.3

 

 

 

 

 
304 S. A. MITCHELL

+ 07006. Adams by means of the spectroscope finds the value
of + 07132. Mr. Mitchell measured the series of plates and
determined the proper motion in right ascension of + 07744 per
year, while the value from Boss is + 07750.

 

 

 

 

TABLE 2
REDUCTIONS FOR @ VIRGINIS
Solution Weight Parallax Time in Residual Vp+o
Plate. (m). (p). | Factor (P). | Days (f). (2). in Are.
mm. mm.

20 —0.0516 0.6 —0.804 — 430 +0.0006 | +0701
21 — .0502 0.6 — .804 —430 — .0008 | — .01
26 — .0486 0.7 — .8i1 —429 — .0023 — .04
27 — .0486 0.7 — .819 —428 — .0023 — .04
671 — .0199 0.8 + .901 —219 — .0024 | — .05
683 — .0225 0.8 + .903 —217 + .0004 | + .01
725 — .0229 , “0.7 + .890 —206 + .0018 | + .03
1274 — .0166 0.8 — .720 — 74 + .0011 | + .02
1286 — .0170 1.0 — .731 — 73 + .0016 | + .08
1338 — .0172 0.8 — .9l1 — 46 + .0037 | + .07
2175 + .0128 0.8 + .908 +150 + .0013 | + .02
2211 + .0124 0.7 + .900 +154 + .0021 | + .04
2292 + .0178 0.8 + .846 +170 — .0020 | — .04
2293 + .0167 0.8 + .846 +170 — .0009 | — .02
8988 + .0590 1.0 — .836 +670 — .0016 | — .03
3989 + .0586 1.0 — .849 +672 — .0010 | — .02
3990 + .0592 1.0 — .849 +672 — .0016 | — .03
4008 +0.0554 1.0 —0.862 +674 +0.0023 | +0.05

 

 

 

 

 

 

The normal equations are:

14.6c + 14.0994 — 2.76547 = + 0.0553 mm.
+ 248.3270u — 12.563382 = + 2.3252 mm.
+ 10.42297 = — 0.0627 mm.

from which:
c = — 0.00487 mm.
uw = + 0.00987 mm. = + 072056, or + 07751 per year.
7 = + 0.00459 mm. = + 07096 + 0”008.
Probable error of plate of unit weight
+ 0.00122 mm. = + 07025.
PARALLAXES OF 260 STARS 305

GROOMBRIDGE 1830 (115 47"; +38° 26’)

Only two star are known to have a proper motion greater than
Groombridge 18380. These are Cordoba Z. 55243 with an
annual proper motion of 8”7, and the star in Ophiuchus found
by Barnard to have a proper motion of 1074 per year. The
first of these stars has a parallax of + 032, while Barnard’s
star has a greater parallax of + 0753. Groombridge 1830 has a
proper motion of 7704, it is of G5 type, and of magnitude 6.46.
One might expect a rather large parallax. It has been very
extensively investigated for parallax. With the heliometer,
Schluter, Wichmann and Déllen obtained the value of + 07141
+ 0"013. Also with the heliometer, Johnson and Auwers found
the parallax + 07023 + 07033, and with the Yale heliometer,
Smith and Chase found the intermediate result of + 07073
+ 07009. Three determinations with the meridian circle have
been made: Kapteyn deriving the value + 07139 + 07026,
Flint the value — 0701 + 07055 and Jost the result + 07085
++ 07024. In addition, measures have been made by the equa-
torial by means of the micrometer. Russell by photography
finds the value + 07100 + 07029, and Adams with the spectro-
graph finds the value + 07083. The present series of plates
were measured by Mr. Mitchell who finds the parallax of + 07106
+ 0"008. He derives the proper motion in right ascension of
+ 4"053 while the value from Boss is + 47004.

ComPaRISON STARS

 

 

 

 

 

 

 

No. Diameter. < oe daa Y (Declination). Dependence.
mm. mm. mm.
1 0.16 —82.0 + 5.5 +0.178
2 .10 +19.8 — 0.5 . 267
3 17 +27.1 —62.3 .3806
4 .12 +35.1 +47.3 +0.249
Parallax star 0.15 + 7.8 — 3.4

 

21
306 S. A. MITCHELL

TABLE 1

PuaTEs oF GROOMBRIDGE 1830

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
756 1915 Jan. 7 —01 M 1.0
797 Jan. 14 —0.3 M 1.0
829 Jan. 28 -—0.1 M 0.8
841 Feb. 6 —0.3 M 0.7
1272 May 4 —0.4 M 0.7
1284 May 9 —0.4 M 0.7
1285 May 9 —0.1 M 1.0
1297 May 10 —0.6 Ol 1.0
1316 May 16 —0.2 M 1.0
2162 Dec. 14 —0.5 M 0.7
2163 Dec. 14 —0.1 M 0.7
2172 Dec. 18 —0.9 M 1.0
2173 Dec. 18 —0.5 M 1.0
2182 Dec. 19 —1.0 A 1.0
3526 1916 Dec. 12 —0.5 M 0.9
3613 1917 Jan. 25 —0.6 M 0.7
3657 Feb. 12 —1.0 ol 0.6
3658 Feb. 12 —0.5 Ol 1.0
3675 Feb. 16 —0.9 A 1.0
3917 Apr. 26 —0.4 A 0.8
3922 May 1 -0.9 M 1.0
3923 May 1 —0.5 M 1.0
3936 May 9 —0.5 A 1.0
3937 May 9 +0.1 A 1.0

 

 

 
PARALLAXES OF 260 STARS 30

TABLE 2
REDUCTIONS FOR GROOMBRIDGE 1830

 

 

 

 

 

 

 

 

 

Solution Weight | _ Parallax Time in Residual Vp+0
Plate. (m). (p). | Factor (P). | Days (t). (v). in Arc.
756 +0.0384 1.0 +0.847 —495 +0.0027 +0°06
797 + .0451 1.0 + .802 —488 — .0005 — .01
829 + .0520 0.8 + .676 —476 | — .0016 — .03
841 + .0560 0.7 + .574 —465 — .0003 .00
1272 + .0966 0.7 — .673 —378 — .0008 — .01
1284 + .0949 0.7 — .725 —373 + .0033 + .06
1285 + .0999 1.0 — .725 —373 — .0017 — .04
1297 + .0988 1.0 — .735 —3872 — .0001 -00
1316 + .1018 1.0 — .789 —366 — .0002 .00
2162 + .2253 0.7 + .903 —154 — .0019 | — .08
2163 + .2276 0.7 + .903 —154 — .0042 — .07
2172 + .2230 1.0 + .903 —150 + .0026 + .05
2173 + .2244 1.0 + .903 —150 + .0012 + .02
2182 + .2266 1.0 + .903 —149 — .0005°| — .01
3526 + .4148 0.9 + .899 +210 + .0029 + .06
3613 + .4415 0.7 + .702 +254 — .0013 — .02
8657 + .4519 0.6 + .491 +272 — .0032 — .05
3658 + .4474 1.0 + «2491 +272 + .0013 + .03
3675 + .4522 1.0 + .487 +276 — .0016 — .03
3917 + .4839 0.8 — .587 +3845 — .0017 — .03
3922 + .4841 1.0 — .646 +350 + .0005 + .01
3923 + .4848 1.0 — .646 +350 — .0002 .00
3936 + .4891 1.0 — .730 +358 — .0007 — .01
3937 +0.4857 1.0 —0.730 +358 +0.0027 +0.06

 

The normal equations are:
21.3¢ — 12.206u + 2.63877 = + 5.7738 mm.
+ 240.1018u — 11.62917 = + 9.0844 mm.

from which: + 11.74317 = + 0.2334 mm.
c = +. 0.30103 mm.
w= + 0.05339 mm. = + 171104, or + 4053 per year.

a = + 0.00510 mm. = + 07106 + 07008.
Probable error of plate of unit weight
+ 0.00126 mm. = + 07026.
308

y URSZ MAJORIS (115 48"; +54° 15’)

S. A. MITCHELL

According to Hertzsprung (Astrophysical Journal, 30, 134,
1909), the absolute parallax of this star as a member of the

Ursa Major group has been calculated to be 07042.

It is of

A-type, and of magnitude 2.54 with total proper motion 07094.
Pritchard by photography gave the values of the parallax,

TABLE 1

Puates oF y Ursa Masoris

 

 

 

No. Date. Hour Angle. Observers. Weight.
1218 1915 Apr. 17 —140 A 0.9
1233 Apr. 23 —0.6 G 1.0
1315 May 15 sia A 0.7*
2220 Dec. 23 -1.1 A -0.9
2221 Dec. 23 —0.7 A 1.0
2354 1916 Jan. 23 —0.2 G 0.6*
2368 Feb. 3 -1.1 A 1.0
2369 Feb. 3 —0.7 A 1.0
2584 Apr. 20 —0.5 G 1.0
2595 Apr. 26 —0.8 G 0.8
2625 May 1 —0.5 G 1.0
2656 May 14 0.0 M 0.7
3558 1917 Jan. 3 —0.4 A 0.9
3559 Jan. 3 0.0 A 1.0
3587 Jan. 16 —0.3 L 1.0
3588 Jan. 16 0.0 L 0.7*
5281 1918 Apr. 14 —0.8 M 0.7
5282 Apr. 14 —0.4 M 0.8
5355 May 5 —1.0 A 1.0
5356 May 5 —0.6 A 0.6*
5362 _ May 14 —0.2 A 0.9
6164 Dec. 29 —0.8 M. 0.8
6165 Dec. 29 —0.4 M 0.8
6374 1919 Jan. 28 —1.4 F 1.0
6375 Jan. 28 —0.9 F 0.8

 

 

 

 

 

* One exposure.
PARALLAXES OF 260 STARS . 309

TABLE 2

Repvuctions ror y Urs# Masoris

 

 

 

 

 

 

 

 

 

ution — ight | _Parall: Time i id Dp:
vie. | PS GO |e, |Deren | we | ae
mm. mm.
1218 —0.0212 0.9 —0.458 — 658 +0.0013 | +0703
1233 — .0176 1.0 — .538 —652 — .0022 | — .05
1315 — .0220 0.7 — .778 —630 + .0026 | + .05
2220 — .0145 0.9 + .900 | —408 — .0012 | — .02
2221 — .0157 1.0 + .900 —408 -0000 -00
2354 — .0147 0.6 + .732 —377 — .0004 | — .01
2368 — .0170 1.0 + .617 —366 + .0021 | + .04
2369 — .0122 1.0 + .617 —366 — .0027 | — .06
2584 — .0150 1.0 — .509 —289 + .0015 | + .03
2595 — .0119 0.8 — .585 — 283 — .0015 | — .03
2625 — .0132 1.0 — .644 —279 — .0001 -00
2656 —. .0128 0.7 — .716 —265 — .0002 -00
3558 — .0116 0.9 + .866 — 81 + .0024 | + .05
3559 — .0088 1.0 + .866 — 31 — .0004 | — .01
3587 — .0104 1.0 + .785 — 18 + .0015 | + .03
3588 — .0065 0.7 + .785 — 18 — .0024 | — .04
5281 — .0031 0.7 — .421 +435 + .0021 | + .04
5282 + .0008 0.8 — 421 +435 — .0018 | — .03
5355 — .0006 1.0 — .683 | +456 .0000 00
5356 — .0011 0.6 — .683 +456 + .0005 | + .01
5362 + .0009 0.9 — .772 | +465 — .0013 | — .03
6164 + .0004 0.8 + .886 | +694 + .0030 | + .06 -
6165 + .0066 0.8 + .886 | +694 — .0032 | — .06
6374 + .0045 1.0 + .680 | +724 — .0006 | — .01
6375 +0.0026 0.8 +0.680 | +724 +0.0013 | +0.02

 
310 ‘ S. A. MITCHELL

+ 07099 + 07030 while the meridian circle value by Flint is
+ 07043 + 07058. No other parallax values have been pub-
lished. The McCormick plates were measured by Mr. Alden
with the exception of eight plates that were measured by Mr.
Mitchell. The relative parallax from the plates is — 07002
+ 0°007, while the proper motion in right ascension was measured
as + 07131 while the corresponding value from Boss is + 0”093.

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. |< ge at Y (Declination). | Dependence.
mm. mm. mm,

1 0.12 —41.3 + 2.8 +0.2013

2 .13 —36.9 +19.2 .2176

3 .09 + 7.1 +13.9 . 2138

4 -10 +11.4 —52.8 - 1488

5 .08 +59.7 +16.9 +0.2185

Parallax star 0.15 — 0.1 + 3.6 |
The normal equations are:

21.6¢ — 2.738u + 2.92667 = — 0.1895 mm.
+ 456.4312u + 9.52237 = + 0.8121 mm.
+ 11.00247 = - 0.0096 mm.

from which:
c = — 0.00854 mm.
wu = + 0.00173 mm. = + 070360, or + 07131 per year.
a = — 0.00010 mm. = — 07002 + 0007.
Probable error of plate of unit weight
+ 0.00115 mm. = + 07024.

ll

BOSS 3137 (115 55"; —9° 52’)

This star, of total proper motion 0”491 of type G, and of
magnitude 5.63, has had its parallax twice determined. The
Yale heliometer gives the relative parallax, + 07111 + 0"015
while the spectroscopic parallax of Adams is + 0”040. Miss
Darkow measured the McCormick plates and determined a
relative parallax of + 0"087 - 0”012.
PARALLAXES OF 260 STARS 311

TABLE 1

Puates or Boss 3137

 

 

 

No. Date. Hour Angle. Observers. Weight.
5084 1918 Feb. 13 —04 Ds 0.8
5085 Feb. 13 +0.2 Ds 0.7
5102 Feb. 17 —0.3 Ds 0.4
5103 Feb. 17 +0.2 Ds 0.8
5160 |- Mar. 3 0.0 Ol 0.8
5349 May 3 +0.1 ol 0.7
5350 May 3 +0.7 Ol 0.6
5398 May 31 +1.2 Ol 0.7
6236 1919 Jan. 12 —0.6 D 1.0
6273 Jan. 19 —1.2 D 0.9
6274 Jan, 19 —0.6 D 0.9
6462 Feb. 5 —1.3 M 0.9
6463 Feb. 5 —0.7 M 0.6
6912 Apr. 20 —0.2 D 0.7
6913 Apr. 20 +0.6 D 0.5
6950 Apr. 26 +1.2 H 0.9
7001 May 14 +1.2 H 1.0
7023 May 16 +0.6 D 0.7
7025 May 17 +0.2 D 0.9

 

 

 

 

 

ComPARISON STARS.

 

 

 

 

 

 

No. Diameter. F Se aac Y (Declination). Dependence.
mm. mm. mm.

1 0.15 —43.9 + 4.2 +0.212

2 18 — 4.8 — 8.9 + .238

3 -09 — 4.1 — 7.9 + .240

4 12 | +52.8 +12.6 + .310
Parallax star 0.16 + 4.9 + 0.8

 
312

S. A. MITCHELL

Repuctions ror Boss 3137

TABLE 2

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual v D- v
Plate. (m). (p). Factor (P). | Days (2). (v). in Are.
mm. mm.

5084 —0.0190 0.8 +0.510 —247 +0.0027 +0705
5085 — .0159 0.7 + .510 —247 — .0004 — .01
5102 — .0128 0.4 + .457 —243 — .0037 — .05
5103 — .0181 0.8 + .457 —243 + .0016 + .03
5160 — .0162 0.8 + .254 —229 — .0011 — .02
5349 — .0219 0:7 — .640 —168 + .0013 + .02
5350 — .0170 0.6 — .640 —168 — .0036 — .06
5398 — .0221 0.7 — .878 —140 + .0007 + .01
6236 — .0090 1.0 +: .830 + 86 — .0036 — .07
6273 — .0148 0.9 + ,781 + 93 + .0020 + .04
6274 — .0152 0.9 + .781 + 93 + .0024 + .05
6462 — .0137 0.9 + .613 +110 + .0003 | + .01
6463 — .0108 0.6 + .613 +110 — .0026 — .04
6912 — .0169 0.7 — .474 +184 | — .0005 — .01
6913 — .0225 0.5 — .474 +184 + .0051 + .07
6950 — .0160 0.9 — .553 +190 — .0017 — .03
7001 — .0182 1.0 ‘|| — .752 +208 — .0002 .00
7023 — .0166 0.7 — .770 +210 — .0018 — .03
7025 —0.0202 0.9 —0.778 +211 +0.0017 +0.04
The normal equations are:

14.5¢ + 1.934 + 0.16767 = — 0.2402 mm.

+ 48.3174 — 4.56247 = — 0.0171 mm.

+ 6.18517 = + 0.0198-mm.

from which:
= — 0.01671 mm.
# = + 0.00071 mm. = + 070148, or 070540 per year.
a = + 0.00418 mm. = + 07087 =. 07012.

Probable error of plate of unit weight
+ 0.00142 mm. = + 070305.
PARALLAXES OF 260 STARS 313

e CORVI (125 5"; —22° 3’)

Miss France measured the plates of this star of magnitude
3.21 and type K. A relative parallax + 07021 + 0”009 was
determined, and a proper motion in right ascension — 0”023
where the corresponding value from Boss is — 07063. The abso-
lute parallax by Adams and Joy is + 0022.

 

 

 

TABLE 1
Puates or e Corvi
No. Date. Hour Angle. Observers. Weight.
772 | 1915 Jan. 9°|  —O88 M 0.7
899 Feb. 18 —0.3 G 0.7
900 ‘ Feb. 18 +0.3 G 0.7
1234 Apr. 23 —0.2 G 0.9
1298 May 10 0.0 Ol 0.6*
1299 May 10 +0.5 Ol 0.7
2279 1916 Jan. 3 0.0 ol 0.8
2280 Jan. 3 +0.5 Ol 0.8
2644 May 7 +0.3 M 0.8
2645 May 7 +0.8 M 0.8
6444 1919 Feb. 1 —0.6 M 0.8
6445 i Feb. 1 —0.2 M 0.9
6464 Feb. 5 —0.3 M 1.0
6465 Feb. 5 0.0 M 1.0
6880 Apr. 13 +0.2 F 0.9
6881 Apr. 13 +0.6 a F 0.9
6922 Apr. 21 +0.8 F 1.0
7085 May 26 +0.3 F 1.0
7086 May 26 +0.7 F 1.0
8333 Dec. 22 —1.0 F 0.8
8414 1920 Jan. 5 —0.8 F 1.0
8415 Jan. 5 —0.3 F 1.0
8531 Jan. 31 —-1.0 ol 0.8
8588 Feb. 13 —0.7 M 1.0

 

 

 

 

 

(

* One exposure.
314

S. A. MITCHELL

TABLE 2

ReEpuctTions FoR ¢ Corvi

 

 

 

 

 

 

 

 

 

Solution Weight | Parallax Time in Residual vVp-0
Plate- (m). (p). Factor (P). | Days (t). 2). in Are.

mm. mm.
772 +0.0376 0.7 +0.860 —1045 +0.0025 +0'04
899 + .0433 0.7 + .481 —1005 — .0037 — .06
900 + .0368 0.7 + .481 —1005 + .0028 +.°.05
1234 + .0382 0.9 — .479 — 941 + .0002 -00
1298 + .0355 0.6 — .685 — 924 + .0027 + .04
1299 + .0410 0.7 — .685 — 924 — .0028 — .05
2279 + .0386 0.8 + .885 — 486 + .0005 + .01
2280 + .0403 0.8 + .885 — 686 — .0012 — .02
2644 + .0389 0.8 — .661 — 561 — .0018 — .03
2645 + .0354 0.8 — .661 — 561 + .0017 + .03
6444 + .0376 0.8 + .684 + 439 — .0021 — .04
6445 + .0385 0.9 + .684 + 489 — .0030 — .06
6464 + .0354 1.0 + .641 + 443 -0000 .00
6465 + .0332 1.0 + .641 + 443 + .0022 + .05
6880 + .0368 0.9 — .338 + 510 — .0026 — .05
6881 + .0357 0.9 — .338 + 510 — .0015 — .03
6922 + .0304 1.0 — .452 + 518 + .0037 + .08
7085 + .0320 1.0 — .829 + 553 + .0016 + .03
7086 + .0348 1.0 — .829 + 553 — .0012 — .02
8333 + .0354 0.8 + .902 + 763 — .0007 — .01
8414 + .0335 1.0 + .878 + 777 + .0012 + .02
8415 + .0339 1.0 + .878 + 777 + .0008 + .02
8531 + .0337 0.8 + .696 + 803 + .0007 + .01
8588 +0.0345 1.0 +0.549 + 816 —0.0003 —0.01

 
PARALLAXES OF 260 STARS 315

Comparison STARS

 

 

 

 

No. | Diameter. | x a Y (Declination). Dependence.
mm. | mm. mm.
1 0.16 —57.6 +22.5 +0.245
2 -10 —45.1 —38.7 .167
3 .10 — 4.8 +35.7 -245
4 -10 425.5 —45.7 .137
5 .12 +82.0 +26.2 +0.206
Parallax star 0.15 — 2.4 + 6.9 .

 

The normal equations are:

20.6¢ + 16.1534 + 3.62207 = + 0.7423 mm.
+ 1026.4944y + 19.71767 = + 0.2950 mm.
+ 9.89357 = + 0.1350 mm.

from which:
c = + 0.03609 mm.
uw = — 0.00030 mm. = — 070062, or — 07023 per year.

a = + 0.00103 mm. = + 07021 + 07009.
Probable error of plate of unit weight
+ 0.00132 mm. = + 07027.

6 CANUM VENATICORUM (12 29"; +41° 54’)

This star of magnitude 4.32, of type G and of total proper
motion 0”758 has had its parallax determined as follows: Elkin
and Chase by the Yale heliometer found the result + 07089
+ 0"038, Flint with the meridian circle + 07084 + 07036,
Allegheny Observatory by photography + 07109 + 07006, while
Adams by the spectrograph derived the absolute parallax
+ 0”’120. Miss Hawes measured the photographs, and found a
parallax of + 07102 + 07009, with a proper motion in right
ascension of — 0%671 per year, while the corresponding value
from Boss is — 0"701.
316 S. A. MITCHELL

 

 

 

TABLE 1
Piates or 6 Canum VENATICORUM
No. Date. | Hour Angle. Observers. Weight.
2223 1915 Dec. 23 —054 A 1.0
2224 Dec. 23 0.0 A 0.8
2261 1916 Jan. 2 —0.9 G 0.4
2262 Jan. 2 —0.2 G 0.4
2611 Apr. 28 —0.4 M 0.6
3742 1917 Mar. 9 —0.6 Ol 1.0
4899 Dec. 22 . —0.5 B 1.0
4900 Dec. 22 0.0 B. 1.0
5334 1918 May 1 —0.1 Ol 1.0
5363 May 14 —0.4 A 1.0
5364 May 14 0.0 A 0.7*
5381 May 18 —0.5 A 1.0
53882 May 18 —0.1 A 1.0
6109 Dec. 18 -1.1 F 1.0
6110 Dec. 18 —0.7 F 1.0
6166 Dec. 29 —0.5 M 1.0
6167 Dec. 29 —0.1 M 1.0
6948 1919 Apr. 26 -—0.3 H 1.0
6949 Apr. 26 0.0 H 1.0
6990 May 12 —0.1 D 1.0
7011 May 15 —0.8 H 1.0
7012 May 15 —0.1 H 1.0

 

 

 

 

 

* One exposure.

CoMPaRISON STARS

 

 

 

 

No. Diameter. P een Y (Declination). Dependence.
mm. mm. mm.
1 0.08 —72.5 — 7.0 +0.277
2 -08 —11.6 — 8.8 .252
3 12 +18.1 +57.5 .259
4 .08 +66.0 —41.7 +0.212
Parallax star 0.12 — 4.3 + 1.9

 

 

 
PARALLAXES OF 260 STARS

TABLE 2

REDUCTIONS FOR 6 CANUM VENATICORUM

31

 

 

 

 

 

 

 

 

 

 

1 : . hi P. Ti : . —
Bee | | ek (ee. | Gare. | | eke
mm. mm.

2223 +0.1276 1.0 +0.898 —770 +0.0013 +0°03
2224 + .1327 0.8 + .898 —770 — .0038 — .07
2261 + .1274 0.4 + .902 —760 + .0006 + .01
2262 + .1260 0.4 + .902 —760 + .0020 + .03
2611 + .1089 0.6 — .467 —643 + .0021 + .03
3742 + .0860 1.0 + .298 —328 + .0009 + .02
4899 + .0674 1.0 + .897 — 40 — .0030 — .06
4900 + .0608 1.0 + .897 — 40 + .0036 + .07
5334 + .0487 1.0 — .501 + 90 — .0027 — .06
5363 + .0456 1.0 — .660 +103 — .0015 — .03
5864 + .0439 0.7 — .660 +103 + .0002 .00
5381 + .0430 1.0 — .703 +107 + .0005 | + .01
5382" + .0436 1.0 — .703 +107 — .0001 -00
6109 + .0336 1.0 + .886 +321 — .0012 — .02
6110 + .0316 1.0 + .886 +821 + .0008 | + .02
6166 + .0304 1.0 + .904 +332 + .0011 + .02
6167 + .0321 1.0 + .904 +332 — .0006 — .01
6948 + .0140 | 1.0 — .430 +450 + .0006 + .01
6949 + .0174 1.0 — .430 +450 — .0028 — .06
6990 + .0106 1.0 — .635 +466 + .0015 + .03
7011 + .0099 1.0 — .668 +469 + .0018 + .04
7012 +0.0112 1.0 —0.668 +469 +0.0005 +0.01

The normal equations are:
19.9¢ + 13.0134 + 1.86987 = + 1.0171 mm.
+ 342.5794u — 22.33007 = — 2.4022 mm.
+ 10.78117 = + 0.3557 mm.
from which:
c = + 0.05643 mm.
w= — 0.00884 mm. = — 071888, or -- 07671 per year.

vis

+ 0.00490 mm. = + 07102 + 07009.
Probable error of plate of unit weight

+ 0.00127 mm. = + 07026.
318 S. A. MITCHELL

6 VIRGINIS (13 4™; —5° 0’)

This star of magnitude 4.44, of spectral type A has a small
total proper motion 07058. It is accompanied by a star of
ninth magnitude at a distance of 7” which shares the motion
of the principal star. Mitchell (Astrophysical Journal, 30, 241,
1909) has found the star to be a spectroscopic binary. Mr.
Mitchell measured the McCormick plates with the exception of
seven plates measured by Mr. Alden. A relative parallax

 

 

 

TABLE 1
PLATES OF @ VIRGINIS
No. Date. Hour Angle. Observers. Weight.
3588 1917 Jan. 16 —054 . L 1.0 ,
3744 Mar. 9 +0.2 A 0.6
3745 Mar. 9 +0.8 A 1.0
3774 Mar. 19 +0.1 A 0.8
3775 Mar. 19 +0.6 A 0.7
3969 May 15 —0.1 M 0.8
4059 June 13 +0.7 A 0.6*
5121 1918 Feb. 22 +0.2 A 0.8
5122 Feb. 22 +0.8 A 0.8
5365 May 14 0.0 A 1.0
5383 May 18 0.0 A 1.0
5384 May 18 +0.4 A 0.7*
5430 June 8 +0.4 A 1.0
5453 June 12 +1.0 A 1.0
6563 1919 Feb. 23 —0.7 M 1.0
6564 Feb. 23 —0.2 M 1.0
6575 Feb. 26 —0.4 M 1.0
6679 Mar. 12 —0.6 H 0.9
6680 Mar. 12 0.0 H 1.0
7013 May 15 +0.4 H 1.0
7014 May 15 —0.9 H 1.0
7037 May 18 —0.5 M 0.9
7038 May 18 0.0 M 0.8

 

 

 

 

 

* One exposure.
PARALLAXES OF 260 STARS

Comparison STARS

ol!

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. x ight Ascen-| y (Declination). Dependence.
mm. mm, mm.
1 0.08 —36.1 +18.3 +0.3062
2 10 —19.4 —29.0 . 2299
3 13 — 7.7 + 2.9 . 2607
4 .12 +63 .2 + 7.8 +0.2032
Parallax star 0.12 — 4.7 + 1.3
TABLE 2
REDUCTIONS FOR @ VIRINIS
Solution Weight Parallax Time in Residual vp-0
Plate. (m). (p). | Factor (P). | Days (t). (v). in Arc.
mm. mm.
3588 —0.0084 1.0 +0.898 | —478 —0.0005 | —0%01
3744 — .0099 0.6 + .440 —426 + .0005 | + .01
3745 — .0092 1.0 + .440 —426 — .0001 .00
3774 — .0096 0.8 + .296 —416 + .0002 .00
3775 — .0082 0.7 + .296 —416 — .0012 — .02
3969 — .0096 0.8 — .560 —359 — .0012 — .02
4059 — .0108 0.6 — .848 —330 + .0008 | + .O1
5121 — .0102 0.8 + .634 — 76 + .0007 | + .OL
5122 — .0098 0.8 + .634 — 76 + .0003 .00
5365 — .0116 | 1.0 — .544 + 5 + .0003 + .01
5383 — .0122.} 1.0 — .595 9 + .0010 | + .02
5384 — .0091 0.7 — .595 + 9 — .0021 — .03
5430 — .0124 1.0 — .809 + 30 + .0011 + .02
5453 — .0112 1.0 — .840 + 34 — .0002 -00
6563 — .0126 1.0 + .626 +290 | -+ .0007 | +. .02
6564 — .0146 1.0 + .626 +290 + .0027 + .06
6575 — .0106 1.0 + .591 +293 — .0013 — .03
6679 — .0108 0.9 + _.406 +307 — .0012 — .02
6680 — .0123 1.0 + .406 +307 + .0003 + .01
7013 — .0124 1.0 — .554 +371 — .0001 .00
7014 — .0126 1.0 — .554 +371 + .0001 -00
7037 — .0127 0.9 — .591 +374 + .0001 .00
7038 —0.0102 0.8 —0.591 +374 —0.0024 —0.04

 

 

 

 

 

 

 
320 S. A. MITCHELL

+ 0”006 + 07006 was determined, with a proper motion in
right ascension — 0029 where the corresponding value from
Boss is — 0039. No other parallax has been determined.

The normal equations are:

20.4¢ + 5.280n — 0.59927 = — 0.2263 mm.
+ 190.45284 — 7.40632 = — 0.1317 mm.

+ 7.48487 = + 0.0115 mm.
from which:
c = — 0.01099 mm.
nw = — 0.00038 mm. = — 070078, or — 07029 per year.
xr = + 0.00028 mm. = + 07006 + 07006.

Probable error of plate of unit weight
+ 0.00074 mm. = + 07015.

8 COM BERENICIS (135 7™; +28° 23’)

The star has considerable proper motion amounting to 1718
per year. Itis of magnitude 4.32 and of spectral type G. Four
determinations of its parallax have been published as follows:

 

 

 

 

 

Authority. Method. Parallax.
Peter Heliometer +0711 +0°021
Flint Meridian circle + .08 + .053
Chase Heliometer + .118+ .052
Adams Spectrograph +0.132

 

Mr. Alden measured the McCormick plates, and derived a
relative parallax of + 07140 + 07013 with a proper motion in
right ascension of — 0"798 while the value from Boss is —
07797.
PARALLAXES OF 260 STARS 321

TABLE 1

Puates oF 6 Coma

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
929 1915 Feb. 20 —045 G 0.7
980 Mar. 2 —0.8 G 1.0

1005 Mar. 8 —0.8 M 0.7

1028 Mar. 10 —0.8 G 0.9

2263 1916 Jan. 2 —0.3 G 0.8

2355 Jan. 23 —0.8 G 0.6

2381 Feb. 7 —0.7 G 0.7

2434 Mar. 3 —0.5 Ol 0.7

2665 May 17 —0.8 Ol 0.8

2666 ‘May 17 —0.4 ol 0.7*

2678 May 26 —0.6 Ol 0.7

2679 May 26 —0.2 Ol 0:77

2698 June 2 —0.1 G 0.7

3701 1917 Feb. 24 —1.5 Ol 1.0

3702 Feb. 24 —0.8 Ol 1.0

3707 Mar. 5 —0.8 Ol 0.5

3720 Mar. 6 -1.1 L 0.5

3743 Mar. 9 —0.6 A 1.0

8938 May 9 —0.7 A 1.0

3939 May 9 —0.3 A 1.0

3956 May 14 —0.4 M 0.5*

 

* One exposure.

Comparison STARS

 

 

 

 

 

 

 

No. | Diameter. F ae aaa Y (Declination). Dependence.
| mm. mm. mm.

1 0.14 —65.7 +12.0 +0.1687

2 18 —15.6 —46.3 1821

3 12 +10.6 +58.4 -2180

4 12 +26.3 —26.1 -2080

5 ll | +44.4 + 2.0 +0 .2232
Parallax star 0.16 + 3.8 + 1.3

22
 

 

 

 

 

 

 

 

 

 

322 S. A. MITCHELL
TABLE 2
RepvuctTions For 6 Comm
: . ie és =
Piste | Raman) | ee eae | ee | ee || ee
mm. mm.
929 +0.0033 0.7 +0.667 —449 —0.0001 0700
980 — .0006 1.0 + .550 —489 + .0020 + .04
1005 + .0030 0.7 + .471 —483 — .0028 — .05
1028 + .0017 0.9 + .443 —431 — .0019 — .04
2263 — .0304 0.8 + .903 —133 + .0020 + .04
2355 — .0305 0.6 + .881 —112 — .0002 .00
2381 — .0320 0.7 + .792 — 97 = .0009 — .02
2434 — .0400 0.7 + .527 — 72 + .0027 + .05
2665 — .0545 0.8 — .580 + 3 + .0018 + .04
2666 — .0507 0.7 — .580 + 3 — .0020 — .03
-2678 — .0562 0.7 — .685 + 12 + .0019 + .03
2679 — .0522 0.7 — .685 + 12 — .0021 — .04
2698 — .0562 | 0.7 — .756 + 19 + .0007 + .01
3701 — .0718 1.0 + .617 +286 — .0025 — .05
3702 — .0741 1.0 + .617 +286 — .0002 -00
3707 — .0812 0.5 + .504 +295 + .0052 + .07
3720 — .0812 0.5 + .491 +296 + .0050 + .07
3743 — .0730 1.0 + .450 +299 — .0038 — .08
3938 — .0880 1.0 — .473 +360 — .0014 — .03
3939 — .0906 1.0 — .473 +360 + .0012 + .02
3956 —0.0909 0.5 —0.539 +365 +0.0005 +0.01
The normal equations are:
16.2c + 3.674 + 2.52747 -= — 0.8061 mm.
+ 133.07554 — 8.299387 = — 1.6320 mm.
+ 6.06317 = + 0.0056 mm.
from which:
c = — 0.04843 mm.
& = — 0.01051 mm. = — 072185, or — 0"798 per year.
a = + 0.00673 mm. = + 07140 + 0013.

Probable error of plate of unit weight

+ 0.00145 mm. = + 0”030.
PARALLAXES OF 260 STARS 323

61 VIRGINIS (135 13"; —17° 45’)

This star of considerable proper motion 1.51 per year, is of
magnitude 4.80, and of spectral type K. The only trigonometric
parallax is that of Flint with the meridian circle who determines
the relative parallax + 0714 + 07033. The absolute parallax
of Adams and Joy is + 07105. The majority of the McCormick
plates were measured by Mr. Lamb, though some were measured

 

 

 

TABLE 1
Puates oF 61 VircINIs

No. : Date. Hour Angle. Observers. ‘Weight.
969 1915 Mar. 1 +022 “M 0.7
1041 Mar. 12 —0.6 G 0.4
1063 Mar. 14 —0.5 G 0.4*
to99 | ° Mar. 22 0.0 G 0.8
2646 1916 May 7 +0.4 M 1.0
2647 | * May 7 +0.9 M 0.8
2734 June 19 +0.9 Ol, L 0.8
3680 1917 Feb. 20 —1.0 L 1.0
3681 Feb. 20 —0.7 L 1.0
3720 Mar. 6 —0.6_ L 0.8
3721 Mar. 6 —0.2 L 0.9
8958 May 14 +0.5 M 0.7
3959 May 14 +0.9 M 0.7
4055 June 11 +0.6 ol 1.0
4056 June 11 +0.8 M =1.0
4058 June 13 +0.4 A 1.0
5086 1918 Feb. 13 —0.4 Ds 0.9
5087 Feb. 13 +0.1 Ds 1.0
5104 Feb. 17 —0.5 Ds 0.9
5105 Feb. 17 0.0 Ds 0.9
5412 June 4 —0.2 L 1.0
5413 June 4 +0.4 L 1.0
5440 June 9 +0.1 L 0.8
5441 June 9 +0.6 L 1.0

 

 

 

 

 

* One exposure.
324 S. A. MITCHELL

TABLE 2

REpDucTIoNS FoR 61 ViRGINIS

 

 

 

 

 

 

 

 

 

: ae ae
Baia) Sete) eee | eae | ee | ee) | ee
mm. mm.

969 —0.0048 0.7 +0.583 —730 +0.0046 +0°08
1041 — .0028 0.4 + .439 —719 + .0002 -00
1063 — .0052 0.4 + .411 —717 + .0022 + .03
1099 — .0012 0.8 + .294 —709 — .0036 — .07
2646 — .0638 1.0 — .426 —297 — .0003 — .01
2647 — .0639 0.8 — .426 —297 — .0002 .00
2734 — .0706 0.8 — .874 —254 — .0021 — .04
3680 — .0986 1.0 + .680 - 8 + .0029 + .06
3681 — .0990 1.0 + .680 — 8 + .0033 + .07
3720 — .0961 0.8 + .513 + 6 — .0025 — .05
3721 — .0932 0.9 + .513 + 6 — .0054 — .1l
3958 — .1152 0.7 — .519 + 75 + .0009 + .02
38959 — .1118 0.7 — .519 + 75 — .00380 — .05
4055 — .1188 1.0 — .818 +103 — .0010 — .02
4056 — .1204 1.0 — .818 +103 + .0006 + .01
4058 — .1232 1.0 — .8383 +105 + .0030 + .06
5086 — .1430 0.9 + .751 +350 -0000 .00
5087 .| — .1408 1.0 + .751 +350 — .0022 — .05
5104 — .1438 0.9 + .714 +354 + .0001 .00
5105 — .1446 0.9 + .714 +354 + .0009 + .02
5412 — .1681 1.0 — .755 +461 + .0010 + .02
5413 — .1656 1.0 — .755 +461 — .0015 — .03
5440 — .1685 0.8 — .800 +466 + .0004 + .01
5441 —0.1700 | 1.0 —0.800 +466 +0.0019 +0.04

 
PARALLAXES OF 260 STARS 325

by- Mr. Mitchell and also by Mr. Briggs. A parallax + 07130
+ 0011 resulted, and a proper motion in right ascension — 1"011
while the corresponding value from Boss is — 17077.

CoMPARISON STARS

 

 

 

 

No. Diameter. 7 ee eee Y (Declination). Dependence.
mm. mm. mm.

1 0.09 —32.8 + 5.1 +0.2661

2 15 —14.9 — 9.1 .2760

3 .09 — 3.6 +36.7 . 1926

4 -10 +51.3 —32.7 +0.2653
Parallax star 0.12 + 0.1 — 2.8

 

 

 

The normal equations are:
20.5¢ + 10.8284 — 1.68417 = — 2.2258 mm.

+ 271.2583 — 10.3235¢ = — 4.7702 mm.
+ 9.45227 = + 0.3665 mm.
from which:
c = — 0.10103 mm.
uw = — 0.01332 mm. = ~— 072770, or — 17011 per year.
a = + 0.00623 mm. = + 07130 + 0’011.

Probable error of plate of unit weight
+ 0.00155 mm. = + 07032.

y HYDR& (13> 13"; —22° 38’)

The only parallax determined is the absolute value from the
spectroscope at Mt. Wilson + 07022. The star is of magnitude
3.33, of type G5, and of total proper motion 07084. Mr. Olivier
measured the plates and derived a relative parallax + 07007
£ 07010, with a proper motion in right ascension + 07176
where the corresponding value from Boss is + 07067.
326 S. A. MITCHELL

 

 

 

TABLE 1
Piates oF y HypRa
No. Date, Hour Angle. Observers. Weight.
1357 1915 June 10 +052 Ol 1.0
1358 June 10 +0.7 ol 0.9
2281 1916 Jan. 3 0.0 Ol 0.9
2294 Jan. 7 +0.2 |. Ol 0.6
2660 . May 14 . +0.6 M 0.9
2672 May 19 —0.7 Ol 0.8
2673 May 19 —0.2 Ol 1.0
3693 1917 Feb. 22 +0.6 M 1.0
3694 Feb. 22 +0.9 M 0.6*
3703 Feb. 24 —0.1 Ol 0.9
3704 Feb. 24 +0.3 Ol 0.9
3991 May 23 +0.4 Ol 1.0
3092 May 23 +0.8 * ol 0.9
4009 May 25 +0.2 M 1.0
4010 May 25 +0.6 M 0.9
4027 June 4 —0.3 Ol 0.9
4028 June 4 +0.1 Ol 0.9
4915 Dec. 27 —0.4 Ol 0.9
5029 1918 Feb. 7 —0.2 Ol 0.7
5030 Feb. 7 +0.5 Ol 0.7
5163 Mar. 3 +1.0 Ol 0.9
5164 Mar. 3 +1.5 Ol 0.8
7217 1919 June 22 +1.2 F 0.9
7218 June 22 +1.8 F 0.9
7228 June 28 +1.8 Ol 0.9

 

 

 

 

 

* One exposure.

CoMPARISON STARS

 

 

 

 

 

 

 

No. Diameter. ee re Y (Declination). Dependence.
mm. mm, mm.

1 0.19 —54.4 + 8.9 +0.3001

2 12 +16.0 +24.0 .38156

3 .14 +38.4 —32.9 +0.3833
Parallax star 0.18 + 3.4 — 2.4

 
PARALLAXES OF 260 STARS

TABLE 2

ReEDucTIONS ror y HypRa

027

 

 

 

 

 

 

 

 

 

luti . . . . =.
inte: || Reagsea | WEP" snore. |aeee, | a | ae.
1357 —0.0014 1.0 —0.806 —702 +0.0034 | +0°07
1358 + .0004 0.9 — .806 —702 + .0016 | + .03
2281 + .0084 0.9 + .903 —495 — .0010 | — .02
2294 + .0098 0.6 + .909 —491 — .0023 | — .04
2660 + .0104 0.9 |. — .522 —363 — .0004 | — .Ol
2672 + .0128 0.8 — .585 —358 — -.0028 |; — .05
2673 + .0084 1.0 — .585 —358 + .0016 | + .03
3693 + .0150 1.0 + .658 = 79 + .0019 | + .04
3694 + .0147 0.6 + .658 — 79 + .0022 | + .04
3703 + .0175 0.9 + .636 — 77 — .0005 | — .0O1
3704 + .0136 0.9 + .636 — 77 + .0034 | + .07
3991 + .0168 1.0 — .631 + 11 + .0018 | + .04
3992 + .0220 0.9 — .631 + 11 — .0034 | — .07
4009 + .0223 1.0 — .652 + 13 — .0037 | — .08
4010 + .0233 0.9 — .652 + 13 — .0047 | — .09
4027 + .0190 0.9 — .757 + 23 — .0002 -00
4028 + .0194 0.9 — .757 + 23 — .0006 | — .0O1
4915 + .0227 0.9 + .884 +229 + .0014 | + .03
5029 + .0286 0.7 + .801 +271 — .0035 | — .06
5030 + .0287 0.7 + .801 +271 — .0036 | — .06
5163 + .0252 0.9 + .554 +295 + .0003 | + .01
5164 + .0227 0.8 + .554 +295 + .0028 | + .05
7217 + .0346 0.9 — .887 +771 + .0015 | + .03
7218 + .0358 0.9 — .887 +771 + .0003 .00
7228 +0.0338 0.9 —0.914 +777 +0.0024 | +0.05

 
328 S. A. MITCHELL

The normal equations are:
21.8 — 0.4894 — 2.85927 = + 0.4018 mm.
+ 358.4254u — 3.85697 = + 0.8184 mm.
+ 11.63317 = — 0.0580 mm.
from which:
c = + 0.01853 mm.
uw = + 0.00231 mm. = + 070481, or + 07176 per year.
x = + 0.00034 mm. = + 07007 + 07010.
Probable error of plate of unit weight
+ 0.00161 mm. = + 07033.

¢ URSZ MAJORIS (13 19™; +55° 26’)

Mizar and Alcor in the “Big Dipper” are well known. The
former is a visual double of 2.40 and 3.96 magnitudes, and of
types Ap and A2, respectively, and separated by an angular
distance of 14”. The brighter of these has the distinction of
being the first star discovered as a spectroscopic binary. This
was accomplished by Pickering (Amer. Jour. Sci., 39, 46, 1890).
The fainter of the two stars is likewise a spectroscopic binary,
and was discovered by Frost and Lee (Astronomische Nach-
richten, 177, 171, 1908). Mizar and its visual companion have a
nearly common proper motion, which is also shared by Alcor.
These three stars ¢1, ¢? and g Urse Majoris belong to the Ursa
Major group. The parallaxes of all three were measured by
Mr. Mitchell. They unquestionably form a physical system,
and must have the same value of the parallax. The mean
value of the parallax of the three stars (7, ¢? and g Urs Majoris is:

+ 07031 + 07005.

Flint with the meridian circle finds the result for Mizar,
+ 07076 + 07033, and Smith with the Yale heliometer, the
value, + 07007 + 07011. For the companion Adams and Joy
find the spectroscopic parallax + 0"028. According to Hertz-
sprung (Astrophysical Journal, 30, 134, 1909), the theoretical value
of the absolute parallax of ¢ Ursa Majoris should be + 07043.
The annual proper motion in right ascension from the photographs
for Mizar and companion amounts to -+ 07108 and + 0°108,
respectively. Boss gives the values + 07126 and + 07132. —
PARALLAXES OF 260 STARS 32

 

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Puates oF ¢ Urs# Masoris
No. Date. Hour Angle. ; Observers. Weight.
757 1915 Jan. 7 —048 M 0.9
758 Jan. 7 —0.2 M 0.8
798 Jan. 14 —0.5 M 0.9
842 Feb. 6 —1.2 M 0.9
2658 1916 May 14 -0.9 M 0.7
2659 May 14 —0.4 M 0.7
2674 May 21 —1.6 M 0.7
2675 May 21 —1.2 M 0.9
2700 June 3 —0.6 A 0.8
2701 June 3 —0.1 A 0.9
8615 1917 Jan. 25 —0.8 M 1.0
3691 Feb. 22 —0.6 M 0.8
3692 Feb, 22 —0.1 M 1.0
3799 Mar. 24 ~ =0.5 L, Ol 0.8
3800 Mar. 24 —0.1 Ol 1.0
4003 May 24 —1.4 M 1.0
4004 May 24 —1.0 M 1.0
4039 June 7 -—0.2 A 1.0
5041 1918 Feb. 9 —0.9 M 0.7
5161 Mar. 3 —0.6 Ol 0.7
5162 Mar. 3 0.0 Ol 0.8
5175 Mar. 5 —0.4 A 1.0
Comparison STaRs
Dependence.
; : lina oi
Ne: Dismeter. Aeon 7 ta ol Bteei pall ‘
Star. Companion
.mm. mm. mm.
1 0.10 —44.9 — 9.8 +0.309 | +0.306
2 .17 —13.7: +39.0 -270 - 265
3 .18 + 1.3 —38.6 -161 -165
4 .14 +26.7 —39.0 -094 -100
5 15 +30.0 +48.4 +0.166 | +0.164
Principal star 20 — 9.7 + 5.6
Companion 0.11 — 9.4 + 5.0

 

 
330

S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 2
Repuctions ror ¢ Urs# Majsoris, PRincipaL STAR
Solution Weight | Parallax Time in Residual Vp+o
Plate. (m). (p). | Factor (P). | Days (t). ®). in Are.
mm. mm,
757 —0.0025 0.9 +0.909 —645 —0.0015 —0'03
758 — .0060 0.8 + .909 —645 + .0020 + .04
798 — .0064 0.9 + .912 —638 + .0025 + .05
342 | — .0010 | 0.9 | + .825 | —615 | — .0027 | — .05
2658 + .0010 0.7 — .498 —150 — .0010 — .02
2659 + .0013 0.7 — .498 —150 — .0013 — .02
2674 — .0022 0.7 — .588 —143 + .0021 + .04
2675 — .0001 0.9 — .588 —143 -0000 .00
2700 + .0002 0.8 — .734 —132 — .0005 — .01
2701 + .0022 0.9 — .734 —132 — .0025 — .05
3615 + .0041 1.0 + .886 +104 + .0026 -05
3691 + .0080 0.8 + .679 +132 — .0014 — .03
3692 + .0073 1.0 + .679 +132 — .0007 — 01
3799 + .0037 0.8 + .283 +162 + .0024 + .05
3800 + .0070 1.0- + .283 +162 — .0008 — .02
4003 + .0034 1.0 — .622 +223 + .0016 + .03
4004 + .0040 1.0 — .622 +223 + .0010 + .02
4039 + .0044 1.0 — .770 +237 + .0005 + .01
5041 + .0132 0.7 + .801 +484 — .0013 — .02
5161 + .0168 0.7 + .578 +506 — .0051 — .09
5162 + .0088 0.8 + .578 +506 + .0029 + .05
5175 +0.0118 1.0 +0.553 +508 —0.0001 0.00
The normal equations are:
19.0¢ + 0.346u + 2.80717 = + 0.0678 mm.
+ 255.89664 — 7.06107 = + 0.3501 mm.
fom whiohs + 8.96387 = + 0.0187 mm.
c = + 0.00322 mm.
# = + 0.00142 mm. = + 070296, or + 07108 per year.
aw = + 0.00220 mm. = + 07046 + 0’010.

Probable error of plate of unit weight
+ 0.00132 mm. = + 0027.
PARALLAXES OF 260 STARS 331

TABLE 3

Repvuctions ror ¢ Urs# Majsoris, Companion

 

 

 

 

 

 

 

 

 

Solution Weight | Parallax Time in Residual Vp-o
Plate. (m). (p). Factor (P). | Days (#). (). in Arc.
757 | +0.0287 | 0.9-| +0.909 | —645 | —0.0022 | —0%04
758 + .0248 0.8 + .909 —645 + .0017 + .03
798 + .0240 0.9 + .912 —638 + .0026 + .05
842 + .0285 0.9 + .825 —615 — .0016 — .03
2658 + .0313 0.7 — .498 —150 + .0008 + .01
2659 + .0335 0.7 — .498 —150 — .0014 — .02
2674 |. + 0279 0.7 — .588 —143 + .0042 + .07
2675 + .0338 0.9 — .588 —143 — .0017 — .03
2700 + .0326 0.8 - 734 —182 — .0004 — .01
2701 + .0335 0.9 — .734 —132 — .0013 — .03
3615 + .0383 1.0 + .886 +104 — .0017 — .04
3691 + .0373 0.8 + .679 +132 — .0004 — .01
3692 |. + .0372 1.0 + .679 +132 — .0003 — .01
3799 + .0352 0.8 + .283 +162 + .0018 + .03
3800 + .0354 1.0 + .283 +162 + .0016 + .03
4003 + .0366 1.0 — .622 +223 + .0005 + .01
4004 + .0368 1.0 — .622 +223 + .0003 + .01
4039 + .0382 1.0 — .770 +237 — .0011 — .02
5041 + .0430 0.7 + .801 +484 — .0013 — .02
5161 + .0408 0.7 + .578 +506 + .0010 + .02
5162 + .0379 0.8 + .578 +506 +. .0040 + .07
5175 +0.0449 1.0 +0.553 +508 —0.0030 —0.06

 

The normal equations are:

19.0c + 0.3464 + 2.80717 = + 0.6588 mm.
+ 255.8966 — 7.06107 = + 0.3534 mm.
+ 8.96387 = + 0.0945 mm.
332 S. A. MITCHELL

from which:

c = + 0.03453 mm.
pw = + 0.00136 mm. = + 070282, or + 07103 per year. -
a = + 0.00079 mm. = + 07017 + 07009.

Probable error of plate of unit weight
+ 0.00126 mm. = + 07026.

g URSZ MAJORIS (135 21™; +55° 30’)

Like both of the components of Mizar, Alcor or ‘‘The Rider’’
is a spectroscopic binary which was discovered by Frost (Astro-
nomische Nachrichten, 177, 172, 1908). The only value of
the parallax published is that of the Allegheny Observatory
with a result of + 07035 + 07005. The star is of 4.02 magnitude
and A5 type. The McCormick plates give a proper motion in
right ascension of + 07123 while the value from Boss is + 07122.
The plates were measured by Mr. Mitchell. As a member of
the Ursa Major Group, this star should have the theoretical
parallax of + 07042. Table I for g Urse Majoris containing a
list of the plates measured is identical with Table I of ¢ Urse
Majoris (gq. v.).

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. x eee Y (Declination). Dependence.
mm. mm. mm.
2 0.17 —37.1 +27.4 +0.238
3 .18 —22.6 —50.1 .179
4 .14 + 2.8 —50.4 . 166
5 15 + 6.1 +36.9 .221
6 15 +50.8 +36.2 +0.196
Parallax star 0.14 — 1.1 + 4.4

 
PARALLAXES OF 260 STARS

TABLE 2

Repuctions ror g Urs# Majsoris

33

 

 

 

 

 

 

 

 

 

Soluti Wei me Time i i .
Plate. || ee ees Dae a || ek
mm. mm.
757 +0.0109 0.9 +0.909 | .-645 +0.0011 | +0%02
758 + .0095 0.8 } + .909 —645 + .0025 | + .05
798 + .0118 0.9 + .912 — 638 + .0003 | + .01
842 + .0110 0.9 + .825 —615 + .0013 | + .03
2658 + .0214 0.7 — .498 —150 — .0034 | — .06
2659 + .0168 0.7 — .498 —150 + .0012 / + .02
2674 + .0187 0.7 — .588 —143 — .0007 | — .01
2675 + .0208 0.9 — .588 —148 — .0028 | — .06
2700 + .0212 0.8 — .734 —132 — .0032 | — .06
2701 + .0166 0.9 — .734 —132 + .0014 | + .08
3615 + .0281 1.0 + .886 +104 — .0040 | — .08
3691 + .0256 0.8 + .679 | +132 — .0014 | — .02
3692 + .0252 1.0 + .679 +132 — .0010 | — .02
3799 + .0245 0.8 + .283 +162 — .0003 | — .01
3800 + .0252 1.0 + .283 +162 — .0010 | — .02
4003 + .0210 1.0 — .622 | +223 + .0029 | + .06
4004 + .0230 1.0 — 622 +223 + .0009 | + .02
4039 + .0218 1.0 — .770 | +237 + .0021 | + .04
5041 + .0294 0.7 + .801 +484 + .0007 | + .01
5161 + .0298 0.7 + .578 | +6506 + .0004 | + .01
5162 + .0293 0.8 + .578 | +6506 + .0009 | + .02
5175 +0.0286 1.0 +0 553 +508 +0.0016 | +0.03

 

The normal equations are:

19.0c + 0.346n + 2.80717
+ 255.8966 — 7.06107
+ 8.96387

from which:

ec = + 0.02114 mm.
uw = + 0.00162 mm.
a = + 0.00142 mm.

Probable error of plate of unit weight

= + 0.4062 mm.
= + 0.4123 mm.
= + 0.0606 mm.

= + 07029 + 07009.

+ 0.00130 mm. = + 07027.

+ 070337, or + 07123 per year.
334 S. A. MITCHELL

70 VIRGINIS (135 23"; +14° 19’)

This is a star of G5 type, of magnitude 5.16, and of total
proper motion 0763 per year. Three values have been found for

 

 

 

TABLE 1
Puates oF 70 VIRGINIS

No. Date. Hour Angle. Observers. Weight.
773 | 1915 Jan. 9 “920 M 0.9
774 Jan. 9 +0.3 M 0.7*
813 Jan. 20 —0.8 G 0.9
1321 May 21 —0.9 A 1.0
1322 May 21 —0.5 A 1.0
1407 June 28 +1.2 A 1.0
2314 1916 Jan. 13 —0.8 M 0.7
2315. Jan. 13 —0.4 M 0.8
2431 Feb. 29 —1.2 M 0.8
2462 Mar. 11 -1.1 M 1.0
3659 1917 Feb. 12 —-1.2 ol 0.8
3660 Feb. 12 —0.8 ol 0.8
3708 Mar. 5 —0.4 Ol 1.0
3709 Mar. 5 +0.3 Ol 0.9
3746 Mar. 9 +1.2 A 1.0
3970 May 15 +0.1 M 0.9
3971 May 15 +0.5 M 1.0
3981 May 19 —0.3 Ol 1.0
3982 May 19 +0.1 Ol 1.0

 

 

 

 

 

* One exposure.

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. zs hight Asten: Y (Declination). Dependence.
mm. mm. mm.

1 0.14 —18.4 +28.9 +0. 2641

2 18 —17.9 —42.9 . 2406

3 125 + 9.3 — 9.2 2447

4 .14 +27.0 +23.2 +0.2506
Parallax star 0.19 — 0.1 + 0.9

 
PARALLAXES OF 260 STARS 335

the parallax, the heliometer value by Elkin of Yale + 07136
+ 0049, the Allegheny result + 07032 + 07008 and the spectro-
scopic value of Adams + 0”050. The plates of the series were
measured by Mr. Alden who found the annual proper motion in
right ascension to be — 07250 while Boss gives the result — 0243.

TABLE 2

Repvuctions ror 70 VIRGINIS

 

 

 

 

 

 

 

 

 

pate | PS | MEE | asc e,| Boe oe | ee | anes
mm. mm.

773 +0.0091 0.9 +0.911 —491 —0.0005 —0%01
774 + .0063 0.7 + .911 —491 + .0023 | + .04
813 + .0082 0.9 + .906 —480 -0000 00
1321 — .0008 1.0 — .567 —359 + .0018 | + .04
1322 + .0032 1.0 — .567 —359 — .0022 | — .05
1407 — .0010 1.0 — .907 —321 .0000 -00
2314 — .0043 0.7 + .913 —122 + .0007 | + .01
2315 — .0046 0.8 + .918 —122 + .0010 | + .02
2431 — .0036 0.8 + .621 — 75 — .0022 | — .04
2462 — .0052 1.0 + .482 — 64 — .0012 | — .02
3659 — .0187 0.8 + .784 | +274 + .0018 | + .03
3660 — .0166 0.8 + .784 +274 — .0003 | — .01
3708 — .0156 1.0 + .563 +295 — .0025 | — .05
3709 — .0200 0.9 + .563 +295 + .0019 | + .04
3746 — .0172 1.0 + .511 +299 — ..0011 — .02
3970 — .0238 0.9 — .495 +366 + .0011 | + .02
3971 ‘“— .0246 1.0 — .495 +366 + .0019 | + .04
3981 — .0229 1.0 — .548 +370 -0000 .00
3982 —0.0216 1.0 —0.548 +370 —0.0013 | —0.03

 

The normal equations are:

17.2¢ + 1.697p + 3.37897 = — 0.1630 mm.
+ 188.8001n — 5.81697 = — 0.6501 mm.
+ 8.23642 + 0.0046 mm.

ll
336 S. A. MITCHELL

from which:
c = — 0.00957 mm.
pw = — 0.00329 mm: = — 070684, or — 07250 per year.
a = + 0.00217 mm. = + 0/045 + 07008.

Probable error corresponding to unit weight
+ 0.00104 mm. = + 07022.

o 78 VIRGINIS (135 29"; +4° 10’)

According to Bottlinger (Astronomische Nachrichten, 4738)
this star forms one of the Ursa Major group with a theoretical
parallax of + 07014. Mitchell (Astrophysical Journal, 30, 241,
1909) has found it to be a spectroscopic binary. It is of Ap
type, and of magnitude 4.93, with a total proper motion of
0”05 per year. Mr. Alden measured the series of plates and
derived the annual proper motion in right ascension of + 07052,
while Boss obtained the value + 07042.

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. e en ania Y (Declination). Dependence.
mm. mm. min.
1 * 0.10 —29.9 —17.5 +0.2257
2 25 — 5.4 +46.0 .2575
3 .09 +15.1 —27.7 - 2535
4 11 +20.2 — 0.8 +0. 2633
Parallax star 0.17 + 1.0 + 0.7

 
PARALLAXES OF 260 STARS

337

 

 

 

 

 

 

 

 

TABLE 1
Puates OF o 78 VIRGINIS
No. Date. Hour Angle. Observers. Weight.
1029 1915 Mar. 10 —054 G 1.0
1042 Mar. 12 0.0 -G 0.8
1064 Mar. 14 —0.1 G 0.7
1323 May 22 +0.6 -G 0.7*
1332 June 4 +0.4 G 1.0
1347 June 9 0.0 G 1.0
1348 June 9 +0.6 G 0.9
1384 - June 23 +1.1 G. 0.9
2357 1916 Jan. 23 +0.2 G 0.7
2358 Jan. 23 +0.9 G 0.6
2383 Feb. 7 +0.5 G 0.7
2502 Mar. 17 —0.4 G 0.8
2503 Mar. 17 +0.3 G 0.7
3782 1917 Mar. 21 —0.4 L 0.8
3783 Mar. 21 +0.1 L 0.8
3813 Mar. 25 0.4 M, L 0.7
3814 Mar. 25 0.0 L 0.8
4040 June 7 +0.2 A 1.0
4074 June 17 +0.5 M,B 0.9
4075 June 17 +0.9 M, B 1.0
4085 June 18 +0.5 A,B 0.8
4098 June 22 ‘41.0 Ol, B 0.8
* One exposure.
ee.

23

y
338 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR v 78 VIRGINIS

Solution Weight Parallax Time in Residual Vp+o
Plate. (m). D Factor (P). | Days (). (v). in Are.

mm. mm.
1029 +0.0024 1.0 +0.526 —422 +0.0004 | +0701
1042 .0000 0.8 + .499 —420 + .0027 | + .05
1064 + .0061 0.7 + .472 —418 — .0034 | — .06
1323 + .0040 0.7 — .562 —349 — .0020 — .04
1332 + .0022 1.0 — .712 —336 — .0002 -00
1347 + .0032 1.0 — .762 —331 — .0013 — .03
1348 — .0008 0.9 — .762 —331 + .0027 | + .05
1384 + .0030 0.9 — .871 —317 — .0011 — .02
2357 + .0016 0.7 + .905 —103 + .0038 | + .07
2358 + .0032 0.6 + .905 —103 + .0022 | + .03
2383 + .0094 0.7 + .838 — 88 — .0040 — .07
2502 + .0039 0.8 + .420 — 49 + .0013 | + .02
2503 + .0050 0.7 + .420 — 49 + .0002 .00
3782 + .0108 0.8 + .366 +320 — .0032 — .06
3783 + .0072 0.8 + .366 +320 + .0004 | + .01
3813 + .0072 0.7 + .307 +3824 + .0004 | + .01
3814 + .0094 0.8 + .307 +324 — .0018 | — .03
4040 + .0042 1.0 — .748 +398 + .0027 | + .06
4074 + .0036 0.9 — .834 +408 + .00383 | + .06
4075 + ..0088 1.0 — .834 | +408 — .0019 — .04
4085 + .0057 0.8 — .841 | +409 + .0012 | + .02
4098 +0.0101 0.8 —0.868 +413 —0.00382 —0.06

 

The normal equations are:

18.1¢ + 0.1474 — 2.342197 = + 0.0889 mm.
+ 202.73574 — 7.96767 = + 0.1306 mm.
+ 8.37217 = — 0.0080 mm.

from which:
c = + 0.00505 mm.
w= + 0.00068 mm. = + 070142, or + 07052 per year.
aw = + 0.00111 mm. = + 07023 + 0°010.
Probable error of plate of unit weight
= + 0.00134 mm. = + 07028.

ll
PARALLAXES OF 260 STARS 339

LALANDE 25224 (13> 34™; +11° 15’)

This is best known as a visual binary in rapid motion, 6 612.
It is a close and difficult double, discovered by Burnham in 1878,
and whose components are less than 074 distant. With the
observations to 1892, Glasenapp finds a period of 30.0 years.
With measures up to 1912, Aitken (Lick Observatory Publications,
12, 85), derives the period of 23.05 years. The components are
nearly of the same brightness, each being of 6.5 magnitude.
Four values of the parallax have been determined, that of Flint
by means of the meridian circle who gives the value + 0725
+ 07098, — 07016 + 07012 from measures by Miss Steele
of photographs taken at Swarthmore, — 0”001 + 07008 and
+ 07019 + 07008 from photographs at Allegheny and Yerkes
respectively. The rotating sector was utilized to diminish the
brightness of the parallax star, and on account of the equal bright-
ness of the components, the value of the proper motion below must
refer to the center of brightness. The plates were measured by
Mr. Lamb. Boss gives the value of the proper motion in right
ascension of the center of gravity of the system to be — 07112,
while the McCormick value is — 07054. From Aitken’s orbit,
it is found that the McCormick value of the proper motion is for
a time when the companion was at position angle 204°0, and at a
distance 0730. The difference between the two values of the
. proper motion is due to orbital motion, but the present measures
do not permit us to determine the relative masses of the com-
ponents. Using Aitken’s orbit, and the McCormick value of the
parallax, the mass of the system is found to be 0.88 times that of
the sun.
340 S. A. MITCHELL

TABLE 1

Puatres oF LALANDE 25224

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
995 1915 Mar. 3 —06 M 0.7
996 Mar. 3 0.0 M 0.8
1089 Mar. 20 —0.4 M 0.8
2473 1916 Mar. 12 —0.6 A 0.8
2492 Mar. 16 —0.6 M 0.8
2514 Mar. 19 —0.1 A 1.0
2702 June 3 +0.3 M,A 1.0
2708 June 3 +0.7 A 1.0
2713 June 10 +0.5 A 0.9
2722 June 18 +0.4 M, L 0.8
2723 June 18 +0.8 M,L 0.7
3589 1917 Jan. 16 —0.3 L 0.7
3590 Jan. 16 +0.1 L 0.9
3651 Feb. 10 0.0 Ol 0.8
3652 Feb. 10 +0.4 Ol 0.7
3682 Feb. 20 —0.4 L 0.9
3683 Feb. 20 0.0 L 0.9
8923 May 1 —0.6 M 0.9
3924 ‘May 1 —0.2 M 0.8
3983 May 19 +0.6 ol 0.7
3984 May 19 +1.0 Ol 0.9
Comparison Stars
No. Diameter. pg ae aa Y (Declination). Dependence.
mm. mm. mm.

1 0.10 . —53.6 +21.4 +0.168

2 .12 —49.4 +10.6 .274

3 15 +47.3 —22.9 .366

4 .13 +55.7 - 9.1 +0.192

Parallax star 0.21 + 5.4 — 3.6

 

 

 

 
PARALLAXES OF 260 STARS

34

 

 

 

 

 

 

 

 

 

TABLE 2
Repuctions FoR LALANDE 25224

Solution Parallax Time in Residual Vp+v
Plate. ‘m). Factor (P). | Days t). (). in Arc.

mm. ~ mm.
995 —0.0012 0.7 +0.631 —440 —0.0009 —0'02
996 — .0022 0.8 + .631 —440 + .0001 -00
1089 — .0005 0.8 + .410 —423 — .0020 — .04
2473 — .0078 0.8 + .510 — 65 + .0029 | + .05
2492 — .0065 0.8 + .456 — 61 + .0015 | + .03
2514 — .0051 1.0 + .413 — 58 .0000 .00
2702 — .0062 1.0 — .695 + 18 — .0007 | — .OL
2703 — .0090 1.0 — .695 + 18 + .0021 + .04
2713 — .0062 0.9 — .766 + 25 — .0008 — .02
2722 — .0071 0.8 — .833 + 33 — .0001 -00
2723 — .0075 0.7 — .833 + 33 .0003 | + .01
3589 — .0059 0.7 + .916 +245 — .0008 — .01
3590 — .0067 0.9 + .916 +245 .0000 -00
3651 — .0057 0.8 + .824 +270 — .0012 | — .02
3652 — .0055 0.7 + .824 +270 — .0014 | — .02
3682 — .0081 0.9 + .742 +280 + .0010 | + .02
8683 — .0076 0.9 + .742-| +280 + .0005 | + .01
3923 — .0094 0.9 — .249 +350 + .0006 | + .01
3924 -— .0097 0.8 — .249 +350 + .0010 | + .02
3983 — .0072 0.7 — .510 +368 — .0020 — .04
3984 —0.0080 |: 0.9 —0.510 +368. —0.0012 | —0.02

 

The normal equations are:
17.5¢ + 14.3564 + 1.92937 = — 0.1124 mm.

+ 121.7546u — 0.93107 = — 0.1734 mm.
+ 7.68527 = — 0.0020 mm.
from which:
c = — 0.00597 mm.
ph = — 0.00071 mm. = — 070148, or — 07054 per year.

x = + 0.00116 mm. = + 07024 + 07006.
Probable error of plate of unit weight
= + 0.00031 mm. = + 07006.
342 S. A. MITCHELL

LALANDE 25372 (135 40™; +15° 25’)

This star of 8.7 magnitude and K type has a considerable
proper motion 2”31 per year. Mr. Olivier measured the plates
and found a relative parallax + 07224 + 07016 and a proper
motion in right ascension + 17728 per yéar where the cor-
responding value from Porter is + 17780. The parallax has
been several times determined as follows:

 

 

 

 

 

 

 

 

 

Parallax. 5 Authority. Method.
+0743 +0”065 Flint Meridian circle
+ .1744 .048 Elkin Heliometer
+ .221+ .019 Russell Photography
+ .152+ .007 Schlesinger Photography
+0.200 Adams Spectrograph

TABLE 1
Puates oF LALANDE 25372
No. Date. Hour Angle. Observers. Weight.
4029 1917 June 4 +043 Ol 1.0
4030 June 4 +0.7 Ol 0.9
4109 June 23 +0.7 M,B 0.9
4110 June 23 +1.1 M, B 0.9
5180 1918 Mar. 7 —0.3 Ol 0.7
5181 Mar. 7 +0.3 Ol 0.7
5221 Mar. 26 —0.2 A 0.9
5407 June 1 +0.5 L 0.9
5414 June 4 +0.6 L 1.0
5455 June 15 +0.6 Ol 1.0
6298 1919 Jan. 20 —0.5 H 1.0
6299 Jan. 20 +0.1 H 1.0
6414 Jan. 30 —1.1 D 1.0
6415 Jan. 30 —0.6 D 1.0
6693 Mar. 18 —0.9 D 0.7
7138 May 31 +0.6 Ol 1.0
7139 May 31 +1.0 Ol 0.8
7259 July 1 +1.5 -Ol 1.0

 

 

 

 

 
PARALLAXES OF 260 STARS 34.

Comparison STARS

 

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. x Se acai Y (Declination). Dependence.
1 0.09 —21.4 —27.0 +0.2915
2 .07 —24.7 — 4.2 .2519
3 .06 —16.0 +44.2 .1714
4 .14 +62.1 —13.0 +0.2852
Parallax star 0.14 + 2.5 — 5.1
: TABLE 2
ReEpuctTions FoR LALANDE 25372
Solution Weight Parallax Time in Residual Vp-0
Plate. (m). (p). | Factor (P): | Days (t). (0). "in Arc.
mm. mm.
4029 —0.0798 1.0 —0.687 —407 —0.0018 —0"04
4030 — .0780 0.9 — .687 —407 — .0036 — .07
4109 — .0806 0.9 — .857 —384 + .0024 + .05
4110 — .0817 0.9 — .857 —384 + .00385 + .07
5180 + .0018 0.7 + .601 —127 — .0059 — .10
5181 — .0024 0.7 + .601 —127 — .0017 — .03
5221 — .0033 0.9 + .348 — 98 + .0031 + .06
5407 — .0014 0.9 — .650 — 41 + .0034 + .07
5414 — .0003 1.0 — .684 — 38 + .0027 + .06
5455 + .0070 1.0 — .793 — 27 — .0033 — .07
6298 + .0738 1.0 + .917 +192 — .0019 — .04
6299 + ,.0752 1.0 + .917 +192 — .0033 — .07
6414 + -.0680 1.0 + .896 +202 + .0060 + .12
6415 + .0728 1.0 + .896 +202 + .0012 + .02
6693 + .0784 0.7 + .461 +249 + .0016 + .03
7138 + .0880 1.0 — .636 +323 — .0030 — .06
7139 + .0846 0.8 — .636 +3823 + .0004 + .01
7259 +0.0898 1.0 —0.901 +354 —0.0006 —0.01

 

 

 

 

 

 

The normal equations are:
16.4c + 0.653u — 1.85697 = + 0.2961 mm.
+ 112.6909u + 11.63637 = + 2.7015 mm.
+ 9.28337 = + 0.3306 mm.

ll
344 S. A. MITCHELL

from which:
c = + 0.01837 mm.
w= +0.02275 mm. = + 074733, or + 17728 per year.
a = + 0.01076 mm. = + 07224 + 07016.
Probable error of plate of unit weight
+ 0.00218 mm. = -& 07045.

tl

uw VIRGINIS (14" 37™; —5° 13’)

This star is of 3.95 magnitude, of type F5, and of total proper
motion 0”339. The only parallax published is the absolute
value of Adams 07046. Mr. Alden measured the plates and
found a relative parallax + 07048 4- 07010, and a proper motion

TABLE 1
PLATES OF » VIRGINIS

 

 

No. Date. Hour Angle. Observers. Weight.

 

 

 

 

 

982 1915 Mar. 2 —0%8 G 0.6*
983 Mar. 2 —0.6 G 0.7
1030 Mar. 10 —0.4 G 0.8
1173 Apr. 11 —0.2 A 0.8
2714 June 17 —0.5 Ol 0.8
2715 June 17 +0.2 Ol 0.5*
3801 1917 Mar. 24 —0.6 Ol OF
3802 Mar. 24 —0.2 . oO 0.7
5021 1918 Feb. 6 +0.4 Ol 0.7
5088 Feb. 13 —0.6 Ds 0.8
5089 Feb. 13 —0.2 Ds 0.9
5106 Feb. 17 —0.8 Ds 0.8
5107 Feb. 17 —0.4 Ds 0.9
5432 June 8 +0.2 A 0.9
5433 June 8 +0.7 A 1.0
5451 June 11 —0.3 L 0.9
5454 June 12 +0.2 A 0.7*
5461 June 19 —0.3 A] 1.0
5462 June 19 +0.2 A 1.0

 

* One exposure.
PARALLAXES OF 260 STARS

345

in right ascension + 07124, while the corresponding value from
Boss is + 07106. The star was discovered to be a spectroscopic
binary by Burns (Lick Observatory Bulletin, 199, 1910).

ComPaRIson Stars

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. x ee ABCEM Y (Declination). Dependence.
mm. mm. mm.

1 0.18 —86.5 + 2.3 +0.2245

2 .19 —19.4 —53.5 . 1848

3 12 — 7.4 +29.4 -2133

4 -20 +55.4 +16.3 -1911

5 .16 +57.9 + 5.5 +0.1863

Parallax star 0.16 — 3.2 + 1.0
TABLE 2
REDUCTIONS FOR yp VIRGINIS
Solution Weight Parallax Time in Residual vp-0
Plate. (m). (p). | Factor (P). | Days (t). 2). in Arc.
mm. i mm.

982 +0.0051 0.6 +0.821 —794 —0.0019 —0703
983 + .0019 0.7 + .821 —794 + .0013 + .02
1030 + .0028 0.8 + .750 —786 + .0004 + .01
1173 + .0012 0.8 + .840 —754 + .0017 + .03
2714 + .0089 0.8 — .676 —321 — .0010 — .02
2715 + .0121 0.5 — .676 —321 — .0042 — .06
3801 + .0136 0.7 + .586 — 41 + .0015 + .03
3802 | + .0148 0.7 + .586 — 41 + .0003 + .01
5021 + .0243 0.7 + .934 +278 — .0032 — .06
5088 + .0242 0.8 + .917 +285 — .0030 — .06
5089 + .0198 0.9 + .917 +285 + .0014 + .03
5106 + .0186 0.8 + .901 +289 + .0026 + .05
5107 + .0218 0.9 + .901 +289 — .0006 — .01
5432 + .0215 0.9 — .559 +400 — .0015 — .03
5433 + .0183 1.0 — .559 +400 + .0017 + .04
5451 + .0234 0.9 — .597 +403 — .0034 — .07
5454 + .0154 0.7 — .610 +404 + .0046 + .08
5461 + .0196 1.0 — .694 +411 + .0003 + .01
5462 +0.0187 1.0 —0.694 +411 +0.0012 +0.02

 

 

 

 

 

 

 
346 S. A. MITCHELL

The normal equations are:

15.2c + 6.590u + 2.21097 = + 0.2371 mm.
+ 314.1354 — 15.91817 = + 0.5793 mm.
+ 8.05207 = + 0.0226 mm.
from which:

c = + 0.01459 mm.
uw = + 0.00164 mm. = + 070341, or + 07125 per year.
T + 0.00205 mm. = + 0”043 + 0"010.

Probable error of plate of unit weight
+ 0.0138 mm. = + 07027.

€ BOOTIS (14> 46"; +19° 31’)

This forms a well-known double 1888, of magnitudes 4.7
and 6.6, and of types G6 and K8, respectively. Two orbits
have been published, that of Lohse with a period of 159.54
years, and the other by Doberck with the period 179.60 years.
The former represents in a better manner the recent observations
of Aitken (Publications Lick Observatory, 12, 95, 1914). Bott-
linger (Astronomische Nachrichten, 4738), from a discussion of
the proper motion finds that  Bootis is a member of the Ursa
Major group, with a theoretical parallax of + 07044. Adams
by the spectrograph finds the parallax of + 07182, while
Allegheny by photography obtains + 07147 + 07007. Mr.
Olivier measured the McCormick series of plates. He finds
the parallax of + 07200 + 07012, with a proper motion in right
ascension of + 0"150 per year. The value from Boss amounts
to + 07130. While the present series of plates were being taken,
the motion of the companion was almost entirely in declination,
so that this orbital motion would not affect the proper motion
in right ascension. Apparently, the value of the parallax of
& Bootis shows that it is not a member of the Ursa Major group.
Using the McCormick value of the parallax, and the orbit of
Lohse, the mass of the system of £ Bootis is 0.56 that of the
sun.
PARALLAXES OF 260 STARS

TABLE 1

Puates or £ Bootis

347

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
72 1914 June 13 +048 M 0.8
87 June 23 +0.3 M, Ol 0.6
95 June 24 0.0 M, Ol 0.7

845 1915 Feb. 6 —0.4 M 0.5

846 Feb. 6 +0.1 M 0.9

1007 Mar. 8 —0.9 M 0.5

1008 Mar. 8 —0.2 M 0.9

1020 Mar. 9 —0.9 M 0.8

1167 Apr. 8 —0.4 G 0.9

1179 Apr. 12 —0.2 M 0.9

1192 Apr. 13 —0.1 Ol 0.9

1341 June 6 +0.4 M 0.6

1350 June 9 0.0 G 1.0

1379 June 22 +0.2 M,A 0.8

1380 June 22 +0.8 A 1.0

2376 1916 Feb. 3 +0.4 A 0.7
2413 Feb. 19 —0.1 M 0.6
2414 Feb. 19 +0.3 M 0.8
2504 Mar. 17 —0.2 G 0.8
4099 1917 June 22 +0.3 Ol, B 0.7
4100 June 22 +0.4 Ol, B 0.7
4125 June 29 —0.2 Ol, B 0.9
4126 June 29 +0.2 Ol, B 0.9
ComPaRIsON STARS
No. Diameter. |x a ae Y (Declination). Dependence.
1 0.18 —80.3 +384.2 +0.1113
2 14 +25.7 + 3.4 2217
3 16 +28 .4 —11.1 2940
4 .12 +26.2 —26.5 +0.3730
Parallax star 0.17 +14.9 — 8.6

 

 

 

 

 
348

S. A. MITCHELL

TABLE 2

Repuctions For £ Bootis

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual vVp-o
Plate. (m). (p). Factor (P). | Days (é). (v). in Are.
mm. mm.
72 —0.0211 0.8 —0.598 —460 +0.0006 +0°01
87 — .0193 0.6 — .717 —450 — .0022 — .04
95 — .0209 0.7 — .727 —449 — .0006 — .01
845 + .0004 0.5 + .940 222 — .0014'| — .02
846 — .0019 0.9 + .940 —222 + .0009 | + .02
1007 — .0011 0.5 + .790 —192 — .0008,} — .01
1008 ~ .0060 | 0.9 | + .790 | —192 | + .0041:| + .08
1020 — .0013 0.8 + .782 —191 — .0006.} — .O1
1167 — .0014 0.9 + .417 —161 - 0034 — .07
1179 — .0016 0.9 + .858 —157 — .0037 — .07
1192 — .0004 0.9 + .3842 —156 — .0051'} — .10
13841 — .0128 0.6 | — .501 —102 + .0003° .00
1300 | ~ .o180 | 1.0 | — .542 | — 90 | + .dos2 | + 11
1379 — .0161 0.8 — .703 — 86 + .0020 + .04
1380 — .0150 1.0 — .703 — 86 + .0008 + .02
2376 + .0048 0.7 + .941 +140 + .0013 + .02
2413 + .0069 0.6 + .906 +156 — .0008 — .01
2414 + .0043 0.8 + .906 +156 + .0018 + .03
2504 + .0017 0.8 + .692 +183 + .0029 + .05
4099 + .0039 0.7 — .708 +645 — .0037 — .06
4100 — .0012 0.7 — .708 +645 + .0014 + .02
4125 -0000 0.9 — .780 +652 — .0003 — .01
4126 + .0005 0.9 —0.780 +652 —0.0008 —0.02
The normal equations are:
17.9c + 1.181p + 0.61297 = — 0.0936 mm.
+ 210.0668u — 11.11067 = + 0.3008 mm.
+ 9.22467 = + 0.0634 mm.
from which:
c = — 0.00568 mm.
uw = + 0.00197 mm. = + 070410, or + 07150 per, year.

aw = + 0.00963 mm. = + 07200 + 0'012.
Probable error of plate of unit weight

+ 0.00165 mm. = + 07034.
The magnitudes are 8.5 and 10.2, and they are separated by a
distance of 175. The pair has a total proper motion of 0”230
in position angle 350°, which motion is shared by a third star
of 12.5 magnitude at a distance of 974. These stars thus form a
.triple system. Mr. Olivier measured the McCormick series of
plates and finds a prgper motion in right ascension of + 0”007,
while the value due to Porter is — 07022.

PARALLAXES OF 260 STARS

6 31 (14% 48™; +19° 8’)

This double was discovered by Burnham with the six-inch.

349

 

 

 

TABLE 1
Puates or 6 31

No. Date. Hour Angle. Observers. Weight.
96 1914 June 24 +143 M, Ol 0.8
97 June 24 +1.8 M, Ol 0.7
108 June 30 +1.0 M, Ol 1.0
110 July 3 +0.5 M, Ol 0.9
904 1915 Feb. 18 +0.6 G 1.0
905 Feb. 18 +1.1 G 0.6
942 Feb. 22 —1.7 G 0.4
943 Feb. 22 —1.1 G 0.8
1131 Mar. 30 +0.7 Ol 0.7
1144 Apr. 3 —0.6 M 0.7
1360 June 10 +0.6 Ol 0.8
1361 June 10 +1.2 Ol 0.7
1385 June 23 +0.8 G 0.7
8705 1917 Feb. 24 —0.4 Ol 0.9
3706 Feb. 24 —0.1 Ol 0.6
8711 Mar. 5 +0.1 Ol 0.7
3763 Mar. 15 —1.0 M 0.8
3764 Mar. 15 —0.5 M 0.9
3993 May 23 —0.1 Ol 0.6
3994 May- 23 +0.4 = Ol 0.8
8995 May 23 +0.8 Ol 0.9
4018 May 28 +0.6 Ol 1.2*
4019 May 28 +1.0 ol 0.8
4160 July 38 +0.2 Ol 1.0

 

 

 

 

 

* Three exposures.
350

S. A. MITCHELL

ComMPaARISON STARS

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. |* eo Y (Declination). Dependence.
mm. mm. mm,

1 0.23 —49.6 +14.3 +0.2452

2 -ll —33.3 —45.1 . 2434

3 -10 +36.6 +33.9 . 2563

4 -10 +46.3 — 3.1 +0.2551

Parallax star 0.19 + 0.9 +.0.4
TABLE 2
ReEDvUcTIONS FoR 6 31
Solution Weight Parallax Time in Residual vVp-o
Plate. m). (p). | Factor (P). | Days (t). @). in Are.
mm. mm.

96 +0.0141 0.8 —0.723 —582 —0.0002 0”00
97 + .0128 0.7 — .723 —582 + .0011 .02
108 + .0147 1.0 — .784 —576 — .0008 — .02
110 + .0157 0.9 — .811 —573 — .0018 — .04
904 + .0105 1.0 + .912 —343 + .0038 + .08
905 + .0134 0.6 + .912 —343 + .0009 + .01
942 + .0112 0.4 + .894 —339 + .0031 + .04
943 + .0150 0.8 + .894 —339 — .0007 — .O1
1131) |, + .0174 0.7 + .524 —303 — .0031 — .05
1144 + .0191 0.7 + .495 —299 — .0048 — .08
1360 + .0133 0.8 — .550 —231 + .0010 + .02
1361 + .0121 0.7 — .550 —231 + .0022 + .04
1385 + .0134 0.7 — .709 —218 oe 0009 |-+ .01
3705 + .0157 0.9 + .880 +394 — .0007 — .01
3706 + .0136 0.6 + .880 +394 + .0014 + .02
8711 + .0141 0.7 + .816 +403 + .0009 + .02
3763 + .0170 0.8 + .722 +413 — .0020 — .04
3764 + .0148 0.9 + .722 +413 + .0002 .00
3993 + .0133 0.6 — .296 +482 + .0017 + .03
3994 + .0201 0.8 |" — .296 +482 — .0051 — .10
3995 + .0168 0.9 — .296 +482 — .0018 — .04
4018 + .0137 1.2 — .3873 +487 + .0013 + .03
4019 + .0143 0.8 — .3873 +487 + .0007 + .01
4160 +0.0126 1.0 —0.814 +523 +0.0024 +0.05

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS 351

The normal equations are:

19.0¢ + 3.400u + 0.20347 = + 0.2769 mm.
+ 362.0377u + 8.60867 = + 0.0849 mm.
+ 9.10627 = + 0.0047 mm.
from which:

c = + 0.01455 mm.
# = + 0.00010 mm. = + 070020, or + 07007 per year.
az = + 0.00010 mm. = + 07002 + 07010.

Probable error of plate of unit weight
+ 0.00140 mm. = + 07029.

LALANDE 27173 (145 517; —20° 57’)

This is a pair of the 61 Cygni type. According to Boss, the
brighter star has a total motion of 1792 per year in position
angle 150° 17’, while the fainter has a greater motion of 2704
in position angle 149° 31’. The brighter is of 5.8 magnitude
and K5 type, and the fainter of 8.7 magnitude, and Ma type.
De Sitter, by the heliometer finds the paralJax of the brighter to
be + 07162 + 07011, and for the fainter, + 0”173 + 07012.
Flint with the meridian circle finds the value for the brighter of
+ 0704 + 07065. Adams by means of the spectrograph finds
the parallaxes of + 07200 and + 07190 for brighter and fainter,
respectively. It was a very difficult task to obtain a satisfactory
series of photographs for the present discussion. The plates
at the two epochs were taken in midsummer and during February
and March, and with the great southern declination, the seeing
was generally none too good. In addition, the region required a
relatively long exposure due to the faintness of the comparison
stars. The plates were measured by Mr. Mitchell. Apparently,
the two stars form a physical system. The McCormick value
of the parallax of the system amounts to:

+ 07189 + 0006.
352 S. A. MITCHELL

 

 

 

TABLE 1
Puates or LALANDE 27173
No. Date. Hour Angle. Observers. Weight.
128 1914 July 12 | +149 M 0.5*
133 July 18 +1.0 M 0.5
139 July 19 +1.2 M 1.0
917 1915 Feb. 19 —0.4 M 0.7
930 Feb. 20 —1.2 G 0.5*
931 Feb. 20 —0.5 G 1.0
970 Mar. 1 |- —0.5 M 1.0
971 Mar. 1 +0.1 M 0.9
998 Mar. 3 +0.2 M 0.9
1859 June 10 —0.2 ol 1.0
1477 July 17 +1.4 A 0.7
1488 July 18 +1.5 G 0.7
2466 1916 Mar. 11 0.0 M 0.8
2548 Apr. 4 —0.2 M 0.8
2560 Apr. 6 +0.1 A 1.0
2724 June 18 +0.2 M, L 0.8
2725 June 18 +0.8 M, L 0.8
2770 June 25 +0.2 1.0

 

 

 

 

 

* One exposure.

Comparison STARS

 

 

 

 

 

No. | Diameter. | Pe ro Y (Declination). Dependence.

mm. mm. mm.

1 0.16 —51.7 +25.4 +0.222

2 .16 —48.3 -— 0.6 -191

3 .12 + 0.9 +13.5 217

4 .12 +46.9 + 3.9 -213

5 18 +62.2 —42.2 +0.157
Brighter star 25 — 2.0 + 2.5
Fainter star 0.10 — 2.8 + 2.9

 
PARALLAXES OF 260 STARS 35

 

 

 

TABLE 2
Repuctions ror LALANDE 27173, BricHTer Star
luti * | sé ee .
Pie | SRP 1 VER |akertm. (oer. | Me | see
mm. mm.
917 +0.0200 0.7 +0.914 —202 —0.0016 | —0%03
930 + .0234 0.5 + .910 —201 — .0049 | — .07
931 + .0194 1.0 + .910 —201 — .0009 | — .02
970 + .0185 1.0 + .859 —192 + .0007 | + .01
971 + .0172 0.9 + .859 —192 + .0020 | + .04
998 + .0188 0.9 + .848 —190 + .0006 | + .02
1359 + .0211 1.0 — .536 — 91 — .0002 -00
1477 + .0219 0.7 — .906 — 54 + .0008 | + .01
1488 + .0214 0.7 — .912 — 53 + .0014 | + .02
2466 + .0679 0.8 + 772 +184 — .0001 00
2548 + .0656 0.8 + .486 +208 + /0030 | + .05
2560 + .0686 1.0 + .458 +210 -0000 00
2724 + .0708 0.8 — .648 +283 — .0018 | — .03
2725 + .0684 0.8 — .648 +283 + .0006 | + .01
2770 +0.0706 1.0 —0.729 +290 —0.0013 | —0.03

 

 

 

 

 

 

 

The normal equations are:

12.6¢ + 1.2184 + 2.29017 = + 0.5048 mm.
+ 52.2023u — 9.59257 = + 0.6495 mm.
+ 7.39907 = + 0.0210 mm.

from which:

c = + 0.03729 mm.
w= + 0.01809 mm. = + 02724, or + 07994 per year.
x = + 0.00827 mm. = + 07172 + 07010.

Probable error of plate of unit weight
+ 0.00112 mm. = + 07023.

24
354 8. A. MITCHELL

TABLE 3
Repuctions For LALANDE 27173, Fainter Star

 

 

 

 

 

 

 

 

 

Solution Weight | Parallax | Time in Residual Vp-o
Plate. (m). (p). Factor (P). | Days (t). (v). in Are.

mm. mm.
128 —0.0447 0.5 —0.876 —222 —0.0013 —0%02
133 — .0474 0.5 — .913 —216 + .0017 + .02
139 — .0456 1.0 — .918 —215 — .0001 -00
917 — .0049 0.7 + .914 0 + .0004 | + .01
930 — .0054 0.5 + .910 + 1 + .0010 | + .01
931 — .0024 1.0 + .910 ap aL — .0020 — .04
970 — .0038 1.0 + .859 + 10 — .0002 .00
971 — .0043 1.0 + .859 + 10 + .0003 | + .01
998 — .0051 0.9 + .848 + 12 + .0012 | + .02
1359 — .0070 1.0 — .536 +111 -0000 -00
1477 — .0064 0.5 — .906 +148 — .0003 -00
1488 —0.0067 0.7 —0.912 +149 0.0000 0.00

 

The normal equations are:

9.3¢ — 1.124u + 1.04617 = — 0.1278 mm.
+ 13.3340y + 1.99257 = + 0.1779 mm.
+ 6.87307 = + 0.0754 mm.

from which:

c = — 0.013855 mm.
uw = + 0.01072 mm. = + 072226, or + 07812 per year.
az = + 0.00992 mm. = + 07206 + 07005.

Probable error of plate of unit weight
+ 0.00065 mm. = + 07012.

I

6 BOOTIS (145 58"; +40° 47’) =
The only published values of the parallax of this star of small
proper motion, of G5 type, and of magnitude 3.63 are the spec-
troscopic result of Adams giving an absolute parallax of + 07018,
and the relative value of Allegheny by photography + 07013
+ 07008. Mr. Alden measured the McCormick plates and found
the relative parallax of + 07054 + 07015, with a proper motion
PARALLAXES OF 260 STARS 355

in right ascension of — 0”026, while the corresponding value from
Boss is — 07046.
TABLE 1

Puates or 6 Bootis

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1021 1915 Mar. 9 —054 M 1.0
1043 Mar. 12 —0.8 G 1.0
1139 Mar. 31 —0.2 A 1.0
1147 Apr. 4 —0.5 A 0.9
2515 1916 Mar. 19 —0.4 A 1.0
2516 Mar. 19 —0.1 A 1.0
2530 Mar. 30 —0.3 A 0.8
2531 Mar. 30 0.0 A 0.7
2751 June 22 —0.6 Ol, L 0.8
2752 June 22 —0.2 Ol, L 0.8
2759 June 23 —0.6 M,L 1.0
2769 June 25 —0.5 M 0.9
3776 1917 Mar. 19 —0.4 A 0.9
3777 Mar. 19 0.0 A 0.9
3784 Mar. 21 —0.6 L 0.9
3785 : Mar. 21 —0.2 L 0.9
4060 June 13 —0.3 A 1.0
4061 June 13 0.0 A 0.7*
4120 June 24 —0.3 A 0.9
4139 June 30 —0.3 M 0.7

 

 

 

* One exposure.

CoMPARISON STARS

 

 

 

 

 

No. ™“ Diameter. x a hased Y (Declination). Dependence.

1 0.26 —32.2 —53.5 +0.2097

2 .08 —21.9 +19.4 - 2037

3 .18 — 0.8 +35.8 - 1983

4 .09 +26.5 +36.6 .1924

5 -15 +28.4 —38.3 +0.1959
Parallax star 0.16 — 0.7 — 0.6

 
356

S. A. MITCHELL

TABLE 2

ReEpvuctTions For 8 Bootis

 

 

 

 

 

 

 

 

 

 

: in : - . id: ra
piste, | Sm | Mafe |saacrah.| Daeg | ee | ak
mm. mm,

1021 +0.0053 1.0 +0.812 —488 —0.0022 —0"05
1043 + .0042 1.0 + .786 —485 — .0012 — .02
1139 + .0046 1.0 + .573 —466 — .0022 — .05
1147 — .0018 0.9 + .520 —462 + .0040 + .08
2515 — .0018 1.0 + .708 —112 + .0033 + .07
2516 + .0044 1.0 + .708 —112 — .0029 — .06
2530 — .0009 0.8 + .576 —101 + .0020 + .04
2531 — .0014 0.7 + .576 —101 + .0025 + .04
2751 — .0014 0.8 — .678 — 17 — .0010 — .02
2752 — .0025 0.8 — .678 - 17 + .0001 .00
2759 — .0001 1.0 — .689 — 16 — .0024 — .05
2769 — .0066 0.9 — .712 — 14 + .0041 + .08
3776 — .0020 0.9 + .711 +253 + .0022 + .04
3777 — .0011 0.9 + .711 +253 + .0013 + .03
3784 + .0022 0.9 + .689 +255 — .0020 — .04
8785 + .0028 0.9 + .689 +255 — .0026 — .05
4060 — .0059 1.0 — .562 +339 + .0025 + .05
4061 — .0027 0.7 — .562 +339 — .0007 — .01
4120 + .0009 0.9 — .698 +350 — .0047 — .09
4139 —0.0053 0.7 —0.762 +356 +0.0014 +0.02
The normal equations are:
17.8¢ — 2.3124 + 2.90747 = — 0.0048 mm.
+ 155.0501n — 15.61727 = — 0.0924 mm.
+ 8.1618r = + 0.0244 mm.
from which:
ce = — 0.00074 mm.
uw = — 0.00035 mm. = — 070072, or — 07026 per year.
a = + 0.00259 mm. = + 07054 + 0'015.

Probable error of plate of unit weight

+ 0.00177 mm. = + 07037.
PARALLAXES OF 260 STARS 857

u BOOTIS (155 20"; +37° 43’)
This is a triple system with common proper motion. The
brightest star, A, is of magnitude 4.47, and of type F. »? = BC

 

 

 

TABLE 1
Puates oF » Boots
No. Date. Hour Angle. Observers. Weight.
958 1915 Feb. 26 —046 M 0.5
1009 Mar. 8 —0.2 M 0.6
1031 Mar. 10 —0.8 G 0.9
1032 Mar. 10 —0.4 G 0.8
3724 1917 Mar. 6 —0.6 L 0.9
3725 Mar. 6 —0.2 L 0.8
3816 Mar. 25 —0.5 L 0.9
3817 Mar. 25 —0.1 L 0.9
3853 Apr. 7 —0.8 L 1.0
3854 Apr. 7 —0.5 L 0.9
4111 June 23 -—0.1 M,B 1.0
4140 June 30 —0.2 M 0.8
5123 1918 Feb. 22 —0.6 A 1.0
5124 Feb. 22 —0.2 A 1.0
5139 Feb. 26 —1.4 A 0.8
5140 Feb. 26 —0.9 A 0.9
5498 July 2 —0.3 A 1.0
5499 July 2 0.0 A 0.7*
5522 July 4 —0.2 A 1.0
5526 July 6 —0.1 A 0.8
6396 1919 Jan. 29 —0.5 M 0.9
6418 Jan. 30 —0.7 D 0.8*
6419 Jan. 30 —0.3 D 0.8*
6539 Feb. 17 —0.7 D 1.0
6540 Feb. 17 —0.2 D 1.0
7269 July 2 —0.5 F 0.9
7270 July 2 —0.1 F 0..7*
7283 July 5 —0.1 H 1.0
7300 July 11 +0.1 H 0.6*

 

 

 

 

 

* One exposure.
358 S. A. MITCHELL

is a double of long period, about 250 years, and with an angular
separation of 1”, with a combined magnitude 6.66 and spectral
type K. For BC, Flint has determined a relative parallax of
+ 0030 + 0”026. By photography at Swarthmore, the rela-
tive parallax of the star A was found to be + 07033 + 07018,
while BC gave the result + 0”054 +0%011. Miss Darkow
measured the McCormick plates and found for A and BC the
parallaxes of + 07049 + 07008, and + 07031 + 07009,. re-
spectively, with proper motions in right ascension — 07112 and
— 0"146, respectively, while the corresponding values from
Boss are — 07149 and -—- 07145. By the spectroscopic method,
Adams found the absolute parallax of A and BC to be + 07035
and + 07040.

The McCormick measures give for the parallax of the system
the value + 07040 + 07006.

CoMPARISON STARS

 

 

 

 

 

 

 

: ‘ Dependence.
- X (Right Y (Declina-
No. Diameter. Ascension). tion). A. BC.
mm. mm. mm.
1 0.09 —44.6 —25.7 +0.337 +0.347
2 .14 + 0.9 +45.0 .162 .108
3 .10 +17.3 +18.3 . 200 . 186
4 -15 +26.4 —37.6 .801 .359
A 17 — 3.50 — 9.03
BC 0.10 — 2.71 —14.19

 

The normal equations are:
24.0¢ + 22.800u + 8.42177 = — 0.5826 mm.

+ 521.2848 — 18.50757 = — 1.3557 mm.
+ 16.18337 = — 0.1343 mm.
from which:
c = — 0.02369 mm.
uw = — 0.00148 mm. = — 070308, or — 07112 per year.

a = + 0.00234 mm. = + 0/049 + 07008.
Probable error of plate of unit weight
+ 0.00128 mm. = + 07027.
PARALLAXES OF 260 STARS 359

TABLE 2

Repuctions For » Bootis A

 

 

 

 

 

 

 

 

 

luti igh Paralla: i i i Dp:
Plate. ae | MAR | aesae cPy. | Dawe Ut. oe aoe
mm. mm,
958 —0.0054 | 0.5 | +0.926 | —910 | —0.0026 | ~004
1009 | — .0080 | 0.6 | + .871 | —900 | — .0003 | — .o1
1031 — .0071 | 0.9 | + .857 | —898 | — .0013 | — .02
1032 — .0089 | 0.8 | + .857 | —898 | + .0005 | + .o1
3724 — .0203 | 0.9 | + .881 | —171 | + .0012 | + .02
3725 — .0198 | 0.8 | + .881 | -—171 | + .0007 | + .01
3816 — .0215 | 0.9 | + ..714 | -—152 | + .0017 | + .03
3817 — .0222 | 0.9 | + ..714 | —152 | + .0024 | + .05
3853 — .0223 | 1.0 | + .554 | -139 | + .0020 | + .04
3854 — .0170 | 0.9 | + .554 | -—139 | — .0083 | — .07
A111 — .0224 | 1.0 | — .622 | — 62 | — .0018 | — .04
4140 — .0257 | 0.8 | —..706 | — 55 | + .0012 | + .02
5123 — .o259 | 1.0 | + .939 | +182 | + .0017 | + .04
5124 — .0256 | 1.0 | + .939 | +182 | + .0014 | + .03
5139 — .0205 | 0.8 | + .924 | +186 | — .0088 | — .07
5140 | — .0235 | 0.9 | + .924 | +186 | — .0008 | — .o1
5498 — .0334 | 1.0 | — .726 | +312 | + .0034 | + .07
5499 — .0266 | 0.7 | — .726 | +312 | — .0034 | — .06
5522 — .0308 | 1.0 | — .747 | +814 | + .0007 | + .01
5526 | — .0312 | 0.8 | — .768 | +316 | + .0010 | + .02
6396 — .0293 | 0.9 | + .928 | +523 .0000 .00
6418 — .0321 | 0.8 | + .931 | +524 | + .0028 | + .05
6419 — .0304 | 0.8 | + .9381 | +524 | + .0011 | + .02
6539 — .0278 | 1.0 | + .951 | +542 | — .0017 | — .04
6540 — .0269 | 1.0 | + .951 | +542 | — .0026 | — .05
7270 — .0341 | 0.7 | — .723 | +677 | — .0013 | — .02
7283 — .0344 | 1.0 | — .755 | +680 | — .0011 | — .02
7300 —0.0357 | 0.6 | —0.814 | +686 0.0000 0.00

 
360 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 3
Repvuctions ror « Bootts BC
Solution Weight Parallax Time in Residual Vp-v
Plate. (m). (p). | Factor (P). | Days (t). (0). in Are.
mm. mm.

958 —0.0062 0.5 +0.926 —910 —0.0013 —0702
1009 — .0126 0.6 + .871 —900 + .0048 + .08
1031 — .0070 0.9 + .857 —898 — .0009 | — .02
1032 — .0100 0.8 + .857 —898 + .0021 | + .04
3724 — .0214 0.9 + .881 -171 — .0004 — .01
3725 — .0225 0.8 + .881 —-171 + .0008 + .01
3816 — .0202 0.9 + .714 —152 — .0022 — .04
3817 — .0184 0.9 + .714 —152 — .0040 — .08
3853 — .0197 1.0 + .554 —139 — .0032 — .07
3854 — .0208 0.9 + .554 —139 — .0021 | — .04
4111 — .0266 1.0 — .622 — 62 + .0005 + .01
4140 — .0286 0.8 — .706 — 55 + .0022 + .04
5123 — .0284 1.0 + .989 +182 .0000 .00
5139 — .0297 0.8 + .924 +186 + .0012 + .02
5140 — .0292 | 0.9 + .924 +186 + .0007 + .01
5498 — .0851 1.0 — .726 +312 + .0017 + .04
5499 — .0303 0.7 — .726 +3812 — .0031 — .05
5522 — .0355 1.0 — .747 +314 + .0020 + .04
5526 | — .0333 | 0.8 | — .768 | +316 | — .0002 -00
6396 — .0396 0.9 + .928 +523 + .0046 + .09
6418 — .0356 0.8 + .931 +524 + .0006 | + .01
6419 — .0342 0.8 + .931 +524 — .0008 — .01
6539 — .0372 1.0 + .951 +542 + .0019 + .04
6540 — .0334 1.0 + .951 +542 — .0019 — .04
7269 — .0395 0.9 — .723 +677 — .0009 | — .02
7270 — .0387 1.0 — .723 +677 — .0017 | — .04
7283 — .0393 1.0 — .755 +680 — .0012 | — .02
__7300 —0.0443 0.5 —0.814 +686 +0.0036 | +0.05
PARALLAXES OF 260 STARS

The normal equations are:
24.1¢ + 28.418u + 6.69657

+ 568.2659u — 25.538177

+ 15.86267
from which:
c = — 0.02635 mm.
uw = — 0.00192 mm. =

Tv

361

= — 0.6795 mm.

+ 0.00142 mm. = + 07030.

a CORON BOREALIS (15 30"; + 27° 3’)

— 1.8760 mm.
— 0.1038 mm.

— 00399, or — 07146 per year.
+ 0.00150 mm. = + 07031 + 07009.

Probable error of plate of unit weight

The brightest star in the Northern Crown is of A type, of
magnitude 2.31, and of total proper motion 07157. The older
values of the parallax are two values by Pritchard by photography
with the average — 07038, and the meridian circle result of
Flint + 07054 + 07029. According to Bottlinger, (A. N. 4738)
this star is a member of an extended Ursa Major group and
should have a parallax + 07041.
plates and determined a relative parallax + 07056 + 0"010
and a proper motion in right ascension + 07114 where the
corresponding value from Boss is + 0” 120.

CoMPARISON STARS

Mr. Olivier measured the

 

 

 

 

 

 

 

No. Diameter. ~ ago aaa Y (Declination). Dependence.
mm. mm. mm.
1 0.19 —53.4 +39.8 +0.2229
2 .28 —18.0 —35.8 - 2057
3 -23 + 5.7 +33.6 - 2800
4 -15 +65.7 —37.6 +0.2914
Parallax star 0.24 + 5.2 — 0.1

 
362

S. A. MITCHELL

TABLE a

Puates or a Corona BorEALIs

 

 

 

No. Date. Hour Angle. | Observers. Weight.
1083 1915 Mar. 18 —11 M 0.7
1101 Mar. 22 —0.9 G 1.0
1219 Apr. 17 —0.6 M 0.8
1235 Apr. 23 —0.3 Ol 0.9
2485 1916 Mar. 15 —0.7 Ol 0.8
2735 June 19 —0.2 Ol, L 0.8
2741 June 21 —0.9 M, L 0.9
2742 June 22 —0.3 M,L 0.9
2774 June 26 —0.9 Ol 0.6*
3664 1917 Feb. 12 —0.2 Ol 0.8
3803 Mar. 24 —0.4 ol 0.6
3804 Mar. 24 0.0 Ol 0.8
3834 Mar. 31 —0.8 ol 0.7
3835 Mar. 31 —0.3 Ol 0.8
5031 1918 Feb. 7 —1.0 Ol 0.8
5032 Feb. 7 —0.4 Ol 0.8
5059 Feb. 10 —0.2 Ol 0.8
5183 Mar. 7 —0.4 Ol 0.9
5239 Mar. 28 —0.4 Ol 0.6*
5488 June 28 —0.6 Ol 1.0
5531 July 8 —0.2 A 1.0
6459 1919 Feb. 4 -—0.7 H 1.0
6460 Feb. 4 —0.2 H 1.0
6526 Feb. 16 —0.8 M 0.8
6527 Feb. 16. —0.4 M 1.0
6595 Feb. 27 —0.3 H 1.0
6702 Mar. 20 —1.2 D 1.0
6703 Mar. 20 —0.9 D 0.9
7295 July 7 —0.3 D 1.0
7296 July 8 —0.3 Ol 0.8
7301 July 11 +0.2 H 0.7
7311 July 14 0.0 H 0.7

 

 

 

 

 

* One exposure.
PARALLAXES OF 260 STARS 363

TABLE 2

Repuctions ror a Coron Boreas

 

 

 

 

 

 

 

 

 

rie a eee :
rate. | Sn | | ee foe | ee | atte
mm, , mm.
1083 +0.0282 0.7 +0.815 —940 —0.0039 —0°07
1101 + .0248 1.0 + .778 —936 — .0006 — .01
1219 + .0284 0.8 + .457 —910 — .0046 — .09
1235 + .0236 0.9 + .368 —904 -0000 .00
2485 + .0308 0.8 + .834 —577 — .0010 — .02
2735 + .0250 0.8 — .541 —481 + .0025 + .05
2741 + .0248 0.9 — .568 —479 + .0026 | + .05
2742 + .0229 0.9 — .568 —479 + .0045 + .09
2774 + .0300 0.6 — .633 —474 — .0026 — .04
3664 + .0356 0.8 + .958 —243 — .0005 — .01
3803 + .0304 0.6 + .752 —203 + .0047 + .08
3804 + .0326 0.8 + .752 —203 + .0025 + .05
3834 + .0368 0.7 + .675 —196 — .0018 — .08
8835 + .0317 0.8 + .675 —196 + .0033 + .06
5031 + .04038 0.8 + .952 +117 + .0001 .00
5032 + .0481 0.8 + .952 +117 — .0027 — .05
5059 + .0453 0.8 + .957 +120 — .0048 — .09
5183 + .0396 0.9 + .894 +145 + .0011 + .02
5239 + .0397 0.6 + .712 +166 + .0008 + .01
5488 + .0359 1.0 — .652 +258 + .0023 + .05
5531 + .0379 1.0 — .766 +268 + .0002 .00
6459 + .0452 1.0 + .944 +479 + .0006 + .01
6460 + .0454 1.0 + .944 +479 + .0004 + .01
6526 + .0474 0.8 + .958 +491 — .0014 — .02
6527 + .0420 1.0 + .958 +491 + .0040 | + .08
6595 + .0432 1.0 + .934 +502 + .0029 + .06
6702 + .0476 1.0 + .797 +523 — .0015 — .03
6703 + .0471 0.9 |; + .797 +523 — .0010 — .02
7295 + .0468 1.0 — .7538 +632 — .0033 — .07
7296 + .0456 0.8 — .763 +633 — .0021 — .04
7301 + .0429 0.7 — .793 +636 | + .0006 | + .01
7311 +0.0479 0.7 —0.822 +639 —0.0044 —0.08

 
364 S. A. MITCHELL

The normal equations are:

26.9¢ + 5.0654 + 9.37867 = + 1.0048 mm.
+ 721.5128u — 4.88987¢ = + 1.2477 mm.
+ 16.85787 = + 0.3769 mm.
from which:
c = + 0.03613 mm.
uw = + 0.00149 mm. = + 070311, or + 07114 per year.
x = + 0.00269 mm. = + 07056 + 07010.
Probable error of plate of unit weight

+ 0.00169 mm. = + 07035.

a SERPENTIS (155 39"; +6° 44’)

Two values of the parallax of this star, of 2.75 magnitude,

and Ko type have been published. Flint’s result from meridian

circle is + 0”151 + 07034, while the spectroscopic value of
Adams is + 07019. The proper motion is small, and amounts
to 0714 per year. Mr. Mitchell measured the McCormick
plates and derived the parallax of + 07038 + 07008, with
a proper motion in right ascension of + 07129 while the value
from Boss is + 07135.

ComPARISON STARS

 

 

 

 

 

 

No. Diameter. fe sr aa Y (Declination). Dependence.

1 0.28 —56.1 +55.7 +0.367

2 20 + 3.7 —41.9 -261

3 20 +52.4 —13.8 +0.372
Parallax star 0.23 — 0.1 + 4.4

 
PARALLAXES OF 260 STARS

365

 

 

 

*

*

TABLE 1
PuaTEs OF a@ SERPENTIS
No. Date. , Hour Angle. Observers. Weight.
111 1914 July 3 “ +1140 M 0.6
112 July 5 +0.5 M 0.8
154 July 22 +1.0 M 0.7
919 1915 Feb. 19 +0.2 M 0.8
1022 Mar. 9 —0.4 M 0.7
1023 Mar. 9 +0.1 M 0.7
1092 Mar. 20 —0.7 M 0.7
1158 Apr. 7 —0.7 A 0.7
1168 Apr. 8 -0.6 G 0.8
1180 Apr. 12 —0.6 M 1.0
1381 June 22 +0.4 A 0.7
13882 June 22 +0.9 A 0.8
1389 June 25 +1.0 ‘G 0.5
1390 June 25 +1.4 G 0.8
3685 1917 Feb. 20 —0.8 L 0.9
3686 Feb. 20 —0.4 L 1.0
3695 Feb. 22 —0.9 M 0.9
3696 Feb. 22 —0.5 M 0.7
3786 Mar. 21 —0.3 L 0.9
4149 ‘ July 1 —0.6 M 0.9
4150 July 1 —0.3 M 0.9
4209 July 31 +1.0 A 0.8

 

 

 

 

 

* One exposure.

The normal equations are:
17.3c + 3.402u + 3.06937 = + 0.2348 mm.
+ 275.2416u + 6.55157 = + 0.5234 mm.
+ 10.63977 = + 0.0702 mm.
from which:

e = + 0.01292 mm.
w# = + 0.00170 mm.
a = + 0.00183 mm. = + 07038 + 07008.

Probable error of plate of unit weight
+ 0.00127 mm. = + 07026.

+ 070353, or + 07129 per year.
366 8. A. MITCHELL ‘

 

 

 

 

 

TABLE 2
REDUCTIONS FOR a SERPENTIS

Solution Weight Parallax Time in Residual Vp+v

Plate. (m). (p). | Factor (P). | Days (t). (2). in Are.
: mm. mm.

111 +0.0050 0.6 —0.687 — 533 —0.0024 —0'04
112 + .0021 0.8 — .710 —531 + .0005 + .01
154 + .0033 0.7 — .873 —514 — .0007 — .01
919 + .0090 0.8 + .961 —302 + .0005 + .01
1022 + .0080 0.7 + .901 —284 + .0017 + .03
1023 + .0098 0.7 + .901 —284 — .0001 .00
1092 + .0080 0.7 + .820 —273 + .0018 + .03
1158 + .0123 0.7 + .628 —255 — .0026 — .04
1168 + .0068 0.8 + .614 —254 + .0029 + .05
1180 + .0068 1.0 + .561 —250 + .0029 + .06
1381 + .0073 0.7 — .542 —179 + .0016 + .03
1882 + .0106 .| 0.8 — .542 —179 — .0017 — .03
1389 + .0130 0.5 — .583 —176 — .0041 — .06
1390 + .0108 0.8 — .583 —176 — .0019 — .04
3685 + .0236 0.9 + .960 +430 — .0016 — .03
3686 + .0208 1.0 + .960 +430 + .0012 + .02
3695 + .0238 0.9 + .957 +432 — .0018 — .04
3696 + .0242 0.7 + .957 +432 — .0022 — .04
3786 + .0288 0.9 + .807 +459. — .0016 — .03
4149 + .0192 0.9 — .666 +561 + .0020 + .04
4150 + .0215 |' 0.9 — .666 +561 — .0003 — .01
4209 +0.0182 0.8 — .984 +591 +0.0030 +0.06

 

 

 

 

 

6 SERPENTIS (15% 41™; +15° 44’)

This star of magnitude 3.74, and type A2 has a proper motion
of 0709. According to Bottlinger (Astronomische Nachrichten,
4738) it forms a member of the Ursa Major group, with a the-
oretical parallax of + 07023. Allegheny finds the parallax
+ 07031 + 07008. Mr. Mitchell measured the McCormick
plates, with the exception of plates 159, 1129 and 2506, which were
measured by Mr. Graham, and derived the parallax of + 07029
+ 07008, which is not inconsistent with the theory of Bottlinger.
PARALLAXES OF 260 STARS

367

The proper motion from the plates is + 07045 per year in right
ascension, while the value from Boss is + 0"071.

 

 

 

 

 

 

 

 

 

 

 

~ TABLE 1
PLATES OF B SERPENTIS

No. Date. . Hour Angle. Observers. Weight.
159 1914 July 25 +142 M 0.9
959 1915 Feb. 26 —0.2 M 0.6
1044 Mar. 12 —0.7 G 0.8
1065 Mar. 14 —0.8 G 0.6
1129 Mar. 29 0.0 G 1.0
1403 June 27 +0.7 G 0.9
1404 June 27 +1.1 G 0.9
1431 : July 6 +0.3 Ol 0.9
2384 1916 Feb. 7 —1.0 G 0.7
2385 Feb. 7 —0.6 G 0.8
2506 Mar. 17 —0.2 G 0.8
2532 Mar. 30 —0.2 A 1.0
2717 June 17 +0.5 Ol, L 0.6
2744 June 21 +0.9 M 0.9
2813 July 12 —0.3 M 1.0
2814 July 12 +0.1 M 1.0
4112 1917 June 23 +0.3 M,B 1.0
4113 June 23 +0.6 M,B 1.0
4182 July 28 +0.8 A 1.0
4208 July 31 +0.6 A 0.8

Comparison STARS
No. Diameter. = a adel Y (Declination). Dependence.
mm. mm. mm.
1 0.22 —73.0 +18.4 +0.093
2 .16 —33.0 +27.6 . 234
3 .38 +15.2 22.3 333°
4 .12 +48.4 —27.2 195
5- 12 +47.4 —41.1 +0.145
Parallax star | ° 0.18 + 5.9 + 4.3

 

 

 

 

 
 

 

 

 

 

368 §. A. MITCHELL
TABLE 2
REDUCTIONS FOR 6 SERPENTIS

Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p). Factor (P). | Days (t). (2). in Are.

mm. mm.
159 —0.0018 0.9 |. —0.892 —571 —0.0016 | —0%03
959 — .0008 0.6 + .951 —355 + .0012 | + .02
1044 + .0030 0.8 + .886 ~—341 — .0026 — .05
1065 — .0012 0.6 + .872 —339 + .0016 | + .02
1129 + .0018 1.0 + .738 —324 — .0015 — .03
1403 — .0014 0.9 — .603 —234 + .0004 | + .01
1404 — .0022 0.9 — .603 —234 + .0012 | + .02
1431 — .0001 0.9 — .713 —225 — .0010 | — .02
2384 + .0018 0.7 + .948 - 9 + .0007 | + .01
2385 + .0030 0.8 + .948 —- 9 — .0005 | — .01
2506 + .0019 0.8 + .844 + 30 + .0007 | + .01
2532 + .0014 1.0 + .719 + 48 + .0011 + .02
2717 + .0025 0.6 — .475 +122 — .0012 — .02
2744 — .0021 0.9 — .532 +126 + .0033 | + .06
2813 — .0016 1.0 — .785 +147 + .0026 | + .05
2814 .0000 1.0 — .785 +147 + .0010 | + .02
4112 + .0030 1.0 — .556 +493 + .0004 | + .01
4113 + .0065 1.0 — .556 +493 — .0031 — .06
4182 + .0084 | 1.0 | — .914 | +498 | — .0005 | — .01
4208 +0.0045 0.8 —0.931 +531 —0.0014 | —0.03

 

 

 

 

 

The normal equations are:

17.2¢ + 2.921n — 2.27777 = + 0.0191 mm.
+ 180.8927n — 16.90377 = + 0.0879 mm.
+ 10.20417 = + 0.0014 mm.
from which:
c = + 0.00120 mm.
uw = + 0.00060 mm. = +4 070124, or + 07045 per year.
az = + 0.00139 mm. = + 07029 + 07008.

Probable error of plate of unit weight
+ 0.00112 mm. = + 07023.
proper motion of 1734 per year.
have been found, as follows:

°

PARALLAXES OF 260 STARS 369

y SERPENTIS (155 51"; +15° 59’)
This star of 3.86 magnitude and of F8 type, has a considerable

Several values of the parallax

 

 

 

 

Parallax. Authority. Method.
+07090 +07043 Chase Heliometer
— .0814 .024 Russell Photography
+ .05 + .028 Flint Meridian Circle
+ .053+ .009 Allegheny Photography
+0.182 Adams Spectrograph

 

Mr. AJden measured the McCormick plates, and found a
parallax of + 07098 + 0%008 with a proper motion of + 07278
in right ascension, while the value from Boss is + 07302.

PLATES OF 7 SERPENTIS

TABLE 1

 

 

Observers.

 

 

 

 

 

No. Date. Hour Angle. Weight.
1045 1915 Mar. 12 —0.3 G 0.7
1140 Mar. 31 —0.5 A 1.0
1201 Apr. 14 —0.2 A 1.0
1416 June 30 +0.8 A 0.8
1455 July 13 0.0 Ol 0.9
2533 1916 Mar. 30 +0.1 A 1.0
2534 Mar. 30 +0.6 A 0.9
2561 Apr. 6 —0.1 A 1.0
2562 Apr. 6 +0.5 A 1.0
2573 Apr. 17 —0.6 Ol 0.4*
2574 Apr. 17 —0.1 Ol 0.6
2726 June,18 +0.6 M, L 0.9
2727 June 18 +1.0 M,L 0.8
2787 July 3 +1.3 L 0.7
2826 July 19 +0.1 M 0.9
2827 July 19 +0.6 M 1.0

 

25

* One exposure.
370

S. A. MITCHELL

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. x (Right aa0en- Y (Declination). Dependence.
mm. mm. mm.
1 0.11 —50.3 — 7.3 +0.2377
2 .10 — 7.0 +26.8 . 2635
3 .10 +17.2 +23.7 . 2657
4 .12 +40.1 —43.2 +0.2331
Parallax star 0.10 + 0.1 + 1.6
TABLE 2

REDUCTIONS FOR y SERPENTIS

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual vp-

Plate. (m). (p). Factor (P). | Days (é). (0). in Are.
mm. mm.
1045 —0.0088 0.7 +0.905 —3815 +0.0021 +0704
1140 — .0061 1.0 + .747 —296 — .0006 — .01
1201 — .0066 1.0 + .578 —282 — .0004 — .01
1416 — .0121 0.8 — .610 —205 + .0023 : + .04
1455 — .0076 0.9 — .764 —192 — .0024 — .05
2533 + .0065 1.0 + .744 + 69 + .0001 -00
2534 + .0078 0.9 + .744 + 69 — .0012 — .02
2561 + .0049 1.0 + .670 + 76 + .0016 + .03
2562 + .0065 1.0 +» .670 + 76 -0000 -00
2573 + .0048 0.4 + .527 + 87 + .0014 + .02
2574 + .0092 0.6 + .527 + 87 — .0030 — .05
2726 + .0050 0.9 — .453 +149 — .0011 — .02
2727 + .0038 0.8 — .453 +149 + .0001 -00
2787 + .0018 0.7 — .658 +164 + .0016 | + .03
2826 + .0025 0.9 — .838 +180 + .0007 + .01
2827 +0.0033 1.0 —0.838 +180 —0.0001 0.00
The normal equations are:
13.6¢ — 0.551p + 1.24067 = + 0.0113 mm.
+ 44.9691 — 5.83257 = + 0.1368 mm.

+ 6.50197

+ 0.0099 mm.
PARALLAXES OF 260 STARS 371

from which:
c = + 0.00055 mm.
uw = + 0.00366 mm. = + 070761, or + 07278 per year.
a = + 0.00470 mm. = + 07098 + 07008.
Probable error of plate of unit weight
+ 0.00097 mm. = + 0"020.

p CORONA BOREALIS (155 57"; +33° 36’)

This star of F type, of magnitude 5.43 has a total proper
motion of 081. Its parallax has been determined by the Yale
heliometer with the result + 07023 + 07045. The Allegheny
value is + 07045 + 07005. Adams by the spectroscopic method
obtained the value, + 07040. Miss Hawes measured the plates
and derived the relative parallax of + 07018 + 07012, and a
proper motion in right ascension — 07187, while the correspond-
ing value from Boss is — 07213.

TABLE 1
PLATES oF p CoRONz

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
5304 1918 Apr. 8 7 —140 M 0.8
5307 Apr. 22 |. —0.5 A 1.0
5308 Apr. 22 —0.1 A 1.0
5322 Apr. 27 —0.4 Ol 0.9
5463 June 19 —0.5 A 1.0
5464 June 19 —0.2 A 1.0
5523 July 4 —0.2 A 1.3*
5527 July 6 —0.1 A 1.0
6448 1919 Feb. 1 —0.8 M 1.0
6639 Mar. 6 —0.3 Ol [1%
6683 Mar. 12 +1.0 H 0.7
6684 Mar. 12 —0.6 H 1.0
6841 Apr. 6 —0.4 H 1.0
6842 Apr. 6 —0.1 H 1.0
7284 July 5 —0.1 H 1.0
7302 July 11 +0.1 H 0.9
7307 July 12 0.0 D 0.7
7308 July 13 —0.1 F 0.7f

 

 

 

* Three exposures. ft One exposure.
372

S. A. MITCHELL

Comparison STARS

 

 

 

 

 

 

 

 

 

 

No. Diameter. x Vee, Y (Declination). Dependence.
1 0.11 —71.7 —13.6 +0.202
2 .08 —49.6 + 2.6 .172
3 .08 + 8.9 —17.5 .198
4 .08 +23.4 +29.5 -115
5 -09 +35.4 —15.0 .184
6 .12 +53.6 +14.0 +0.134
Parallax star 0.13 — 4.96 — 3.17
TABLE 2
REDUCTIONS FOR p CORONZ
Solution Weight Parallax Time in Residual Vp-0
Plate. (m). (p). | Factor (P). | Days (t). »). in Are.
mm. mm.
5304 —0.0524 0.8 -+0.589 —225 +0.0007 +0/01
5307 — .0472 1.0 + .483 —221 — .0047 — .10
5308 — .0471 1.0 + .483 —221 — .0048 — .10
5322 — .0528 0.9 + .408 —216 + .0007 + .01
5463 — .0550 1.0 — .442 —163 + .0010 + .02
5464 — .0541 1.0 — .442 —163 + .0001 -00
5523 — .0572 1.3 — .649 —148 + .0026 + .06
5527 — .0582 1.0 — .673 —146 + .0036 + .07
6448 — .0582 1.0 +, .9138 + 64 -0000 .00
6639 — .0607 1.1 + .942 + 97 + .0017 + .04
6683 — .0591 0.7 + .914 +103 . 0000 .00
6684 — .0614 1.0 + .914 +103 + .0023 + .05
6841 — .0590 1.0 + .695 +128 — .0009 — .02
6842 — .0624 1.0 + .695 +128 + .0025 | + .05
7284 — .0634 1.0 — .658 +218 + .0002 .00
7302 — .0585 0.9 — .729 +224 — .0049 — .10
7307 — .0623 0.7 — .740 +225 — .0011 — .02
7308 —0.0624 0.7 —0.751 +226 —0.0010 —0.02

 

 

 

 

 

 

 

5
PARALLAXES OF 260 STARS 373

The normal equations are:
17.1¢ — 1.4374 + 1.89897 = — 0.9779 mm.

+ 51.2224u — 0.51477 = — 0.0380 mm.
+ 8.125307 = — 0.1010 mm.
from which:
c = — 0.05748 mm.
w= — 0.00235 mm. = — 070511, or — 0"187 per year.

a = + 0.00085 mm. = + 07018 + 07012.
Probable error of plate of unit weight
+ 0.0018 mm. = + 07037.

& SCORPIT (15 59"; —11° 5’)

This is a most interesting system discovered by Sir William
Herschel. Since its discovery, the companion has described
two and‘a half revolutions about the primary. The best orbit
is that of Aitken who finds a period of 44.70 years. According
to Aitken, the two components are of 4.8 and 5.1 respectively,
though many of the early observers regarded the companion as
the brighter. Distant 7” from this pair AB is a third star C
forming a physical system with AB, thus making a triple system.
Star C is of magnitude 7.2. The diameters below give the di-
mensions where both parallax stars were visible on the plate.
Many of the plates were taken with the opening in the rotating
sector reduced in size. The diameter of AB was then reduced to
0.22 mm. The plates of the series were measured by Mr.
Mitchell. For the system AB, he found a parallax of + 07019
+ 07010, with an annual proper motion of — 07018 per year
in right ascension. For the star C, the parallax is + 07046
+ 0"012, with the annual proper motion in right ascension of
— 07064 per year. The proper motion of the comparison stars
used caused by the motion of the sun through spaces amounts to
approximately — 0”008 per year in right ascension. Hence,
the proper motions from the photographs of AB and C referred
to the equator should be — 07026 and — 0"072, respectively.
Boss finds the proper motions for AB and C to be equal to
— 0%062 and — 0”075, respectively. The difference in proper
3874 S, A. MITCHELL

motions for AB between the present photographs and Boss
show the effects of orbital motion. The six different seasons
when the system AB was photographed were at the times and
when the position angles and distances of the companion were

as follows:

1914.52 166°0 0787
15.21 168.6 0.91
15.51 169.8 0.93
16.24 171.4 0.96
17.26 173.9 1.01
17.49 174.5 1.03

The only interpretation of the present measures possible is
that the companion has a greater mass than the primary, but
as the orbital motion is so slow, and the proper motion of the
center of gravity uncertain, it is not possible to have very great
confidence in the results.

Combining the results of the measures of the parallax of AB
and C the parallax of the system is:

+ 07030 + 07008.

The only other measure of the parallax is by Lee from photo-
graphs with the 40-inch refractor at Yerkes. Lee obtained the
parallax of the system to be + 07050 + 07005.

The McCormick value of the parallax makes the mass of the
system AB to be 4.36 times that of the sun, while the Yerkes
value makes the mass 1.05 that of the sun.

‘

Comparison STARS

 

 

 

 

 

 

 

 

3 e Dependence.
wo. | iamoer. | S98 | ¥ Peginw | _—_epenien_
mm. mm. mm,
1 0.14 —38.4 — 1.2 +0.228 | +0.220
2 .10 + 3.8 +13.4 .255 .260
3 -25 + 4.4 +13.5 .255 .260
4 woe +30.2 —25.7 +0.262 | +0.260
System AB .30 + 1.3 — 0.1
Companion C 0.14 + 1.6 0.0

 
PARALLAXES OF 260 STARS

Puates oF £ Scorpii

TABLE 1

375

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
114 1914 July 8 +148 M,Ol 0.7
129 July 12 +1.6 M 0.7
135 July 18 +1.4 M 1.0
932 1915 Feb. 20 —0.6 G 0.7
946 Feb. 22 —0.2 G 0.8
999 Mar. 3 —0.2 M 0.7
1046 Mar. 12 +0.3 G 0.7
1047 Mar. 12 +0.8 G 0.9
1181 Apr. 12 —0.4 M 1.0
1182 Apr. 12 —0.1 M 0.7
1423 July 2. +0.6 A 1.0
1424 July 2 +1.0 A 0.9
1425 July 2 48 A 0.9
1453 July 11 +0.4 G 0.7
2415 1916 Feb. 19 —0.2 M 0.5*
2468 Mar. 11 +0.1 M 0.7
2470 Mar. 11 +0.8 M 0.8
2549 Apr. 4 —0.4 M 0.7
2550 Apr. 4 —0.1 M 0.9
2551 Apr. 4 +0.2 M 1.0
2552 Apr. 4 +0.5 M 0.8
3842 1917 Apr. 3 —0.4 M 1.0
3843 Apr. 3 —0.1 M 1.0
8855 Apr. 7 —0.6 L 1.0
3856 Apr. 7 —0.3 L 1.0
4129 June 29 +0.9 B, Ol 1.0

 

 

* One exposure.
376 S. A. MITCHELL

TABLE 2

Repuctions For £ Scorpu, System AB

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual mit vVp-o
Plate. (m). (p). Factor (P). | Days (é). (v). in Are. .
mm. mm.
114 +0.0192 0.7 —0.692 —497 +0.0011 +0702
129 + .0206 0.7.) — .738 —493 — .0003 — .01
135 + .0202 1.0 | — .800 —487 .0000 .00
932 + .0184 0.7. + .969 —270 + 0029 + .05
946 + .0216 0.8 + .969 — 268 — .0003 — .01
1046 + .0180 0.7 + .917 —250 + .0032 + .06
1047 + .0206 0.8 + .917 —250 + .0006 + .01
1181 + .0227 1.0 + .629 —219 — .0018 — .04
1182 + .0185 0.7 | + .629 —219 + .0024 + .04
1423 + .0218 1.0 — .614 —138 — .0022 — .05
1424 + .0176 0.9 — .614 +138 + .0020 + .04
1425 + .0170 0.9 — .614 ~ 188 + .0026 + .05
1453 | + .0219 | 0.7 | — .724 | —129 | — .0025 | — .04'
2415 + .0243 0.5 + .969 + 94 — .0039 — .06
2468 + .0231 0.7 + .919 +115 — .0028 — .05
2470 + .0236 0.8 + .919 +115 — .0033 — .06
2549 + .0216 0.7 + .716 +139 — .0015 — .03
2550 + .0223 0.9 + .716 +139 — .0022 — .04
2551 + .0190 1.0 + .716 +139 + .0011 + .02
2552 + .0220 0.9 + .716 +189 — .0019 — .04
3842 + .0185 1.0 + .730 +503 + .0007 + .01
8843 + .0152 1.0 + .730 +503 + .0040 + .08
8855 + .0169 1.0 + .684 +507 + .0023 + .05
3856 + .0200 1.0 + .684 +507 — .0008 — .02
4129 +0.0187 1.0 —0.581 +590 —0.0008 —0.02 "

 

 

The normal equations are:

21.1¢c + 5.086 + 6.48737 = + 0.4217 mm.
+ 238.9049u + 18.56287 = + 0.0605 mm.
+ 11.99107 = + 0.1345 mm.
PARALLAXES OF 260 STARS 37

from which:
c = + 0.01977 mm.
w= — 0.00024 mm. = — 070049, or — 07018 per year.
a = + 0.00089 mm. = + 07018 + 07010.
Probable error of plate of unit weight
++ 0.00140 mm. = + 07029.

ll

TABLE 3

Repuctions ror £ Scorpu, Companion C

 

 

 

 

 

 

 

uti igh Parall: ime i idual p°
ee | Ee eee. | ares | ee | ae

mm. mm.
114 +0.0462 0.7 —0.692 —278 +0.0013 | +0702
129 + .0501 0.7 — .738 —274 — .0027 | — .05
135 + .0453 1.0 — .800 — 268 + .0019 | + .04
932 + .0473 0.7 + .969 — 51 + .0020 | + .04
999 + .0478 0.7 + .955 — 40 + .0014 | + .02
1046 + .0511 0.7 ++ .917 — 31 — .0021 — .04
1047 + .0506 1.0 + .917 — 31 — .0016 | — .03
1423 + .0462 0.9 — .614 + 81 — .0015 | — .03
1424 + .0425 0.9 — .614 + 81 + .0022 | + .04
1453 + .0469 0.7 — .724 + 90 — .0025 | — .04
2415 + .0476 0.5 + .969 +3813 — .0014 | — .02
2468 + .0467 0.7 | + .919 +3834 — .0008 | — .01
2552 +0.0426 0.8 +0.716 +358 +0.0027 | +0.05

 

 

 

The normal equations are:
10.0¢ + 1.1474 + 1.19337 = + 0.4689 mm.
+ 43.01385u + 8.17397 = + 0.0354 mm.
+ 6.59807 = + 0.0635 mm.
from which:
c = + 0.04672 mm. e
w= — 0.00084 mm. = — 070175, or — 07064 per year.
a = + 0.00221 mm. = + 07046 + 0°012.
Probable error of plate of unit weight
+ 0.00131 mm. = + 07027.
378 S. A. MITCHELL

vy SCORPII (16 6"; —19° 12’)

The brighter star of » Scorpii is of 4.29 magnitude, and of B3
type. It is a double, 6 120, of magnitudes 4.4 and 5.9, respec-
tively, and separated by less than 170. ‘This pair AB does not
show orbital motion. 40” distant from AB is another pair of
magnitude 6.5, which was discovered by Mitchel, of which the
components are separated by about‘2”, and which differ about
one magnitude in brightness. According to Burnham, “the
four components are moving together, and undoubtedly form a
vast quadruple system.” The parallaxes of the system AB and
CD were measured by Mr. Mitchell from one series of plates.
The rotating sector was utilized to reduce the brightness of the
parallax stars. The photographs were taken so that the images
of brighter pair AB should be of the same size on the plates as
the average comparison star. As a result, the fainter star CD
was too faint. To have made this equal in size to the com-
parison stars would have required another series of plates.
More confidence should therefore be placed in the results from

TABLE 1
Puates oF »v ScORPII

 

 

No. Date. Hour Angle. Observers. Weight.

 

141 1914 July 19 +184 M 0.8
146 July 21 +2.0 Ol 0.8
972 1915 Mar, 1 -0.2 M 0.8
973 Mar. 1 +0.3 M 0.8
1000 Mar. 3 +0.3 M 0.7
1033 Mar. 10 -0.5 G 0.7
1220 Apr. 17 -0.4 M 0.8
1253 Apr. 26 —0.4 G 0.9
1506 July 24 +0.5 ol 0.9
1507 July 24 +1.2 ol 0.6
1515 July 25 +0.3 G 0.7
2591 1916 Apr. 25 -0.5 A 1.0
2592 Apr. 25 0.0 A 1.0
2599 Apr. 26 ~0.5 ol 0.7

 

 

 

 

 
PARALLAXES OF 260 STARS 379

AB. Since these stars form a physical system, their combined
parallax has the value:

+ 07021 + 07009.

Comparison STaRs

 

 

 

 

 

 

 

 

Dependence.
i X (Righ ¥ (Decli
No. Diameter. Aeceeapa) ‘ ae : aa Principal 3
Star. Companion.
mm. mm. mm.
1 0.18 —52.4 -— 1.1 +0.273 +0.279
2 -26 + 5.6 +55.8 -087 -107
3 -26 +15.8 —33.9 842 -827
4 26 +381.0 —20.8 +0.298 +0.287
Principal
star AB .25 + 0.8 —13.2
Companion 0.10 + 0.1 —11.4
/ TABLE 2.

‘Repuctions ror v Scorpu, Principat Star AB

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp+o
Plate. (m). (p). | Factor (P). | Days (2). (0). in Are.
141 +0.0365 0.8 —0.794 —317 —0.0041 —0"07
146 + .0298 0.8 — .814 —315 + .0025 + .05
972 + .0324 0.8 + .966 — 92 — .0014 — .03
973 | + .0294 0.8 + .969 — 92 + .0015 + .08
1000 + .0297 0.7 + .962 — 90 + .0012 + .02
1033 + .0298 0.7 + .939 — 83 + .0010 + .02
1220 + .0307 0.8 + .589 — 45 — .0004 — .01
1253 + .0308 0.9 + .463 — 36 — .0007 — .01
1506 + .0268 0.9 — .839 + 53 + .0017 + .03
1507 + .0286 0.6 — .839 + 53 -0000 .00
1515 + .0281 0.7 — .847 + 54 + .0004 + .01
2591 + .0257 1.0 + .466 +829 + .0007 + .01
2592 + .0266 1.0 + .466 | +329 | — .0002 .00
2599 +0.0289 0.7 +0.452 +330 —0.0025 —0.04

 
380 S. A. MITCHELL

The normal equations are:
11.2¢ + 1.640% + 1.87727 = + 0.3299 mm.

+ 48.5559u + 4.25037 = + 0.0011 mm.
+ 6.40307 = + 0.0543 mm.
from which:
c = + 0.02952 mm.
uw = — 0.00102 mm. = — 070212, or — 07077 per year.

a = + 0.00051 mm. = + 07010 + 07010.
Probable error of plate of unit weight
+ 0.00112 mm. = + 07023.

 

 

 

 

 

 

 

 

 

 

TABLE 3
Repuctions For » Scorpu, Companion CD
Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p). Factor (P). | Days (é). (2). in Are.
mm. mm. v
141 +0.0381 0.8 —0.794 | —317 —0.0009 | —0.02
972 + .0354 0.8 + .966 | — 92 + .0036 | + .06
973 + .0418 0.6 + .966 | — 92 — .0028 | — .04
1000 + .0374 0.7 + .962 | — 90 + .0016 | + .03
1033 + .0400 0.7 + .939 | — 88 — .0011 | — .02
1220 + .0393 0.8 + .589 — 45 — .0014 — .03
1253 + .0378 0.9 +: .463 — 36 — .0002 -00
1506 + .0311 0.9 — .839 | + 53 + .0032 | + .06
1515 + .0366 0.7 — .847 + 54 — .0024 — .04
2591 + .0328 1.0 + .466 +329 + .0020 + .04
2592 + .0370 1.0 + .466 +329 — .0022 — .04
2599 +0.0358 0.5 +0.452 +330 —0.0010 —0.01
The normal equations are: :
9.4c + 3.366u + 2.74587 = + 0.3448 mm.
+ 38.1021 + 2.384747 = + 0.0984 mm.
+ 5.21847 = + 0.1086 mm.
from which:
c = + 0.03637 mm.
uw = — 0.00075 mm. = — 0"0157, or — 07057 per year.

_ w= + 0.00201 mm. = + 07042 + 0"015.
Probable error of plate of unit weight
+ 0.00146 mm. = + 00380.
PARALLAXES OF 260 STARS 381

49 SERPENTIS (165 8"; + 13° 47’)

This is a double star, 2 2021, both of A-types, and separated
by a distance of 4”. According to Burnham, they have a large
common proper motion of 0745, and they may form a binary of
very long period, or a system of the 61 Cygni class. Eighteen
of the McCormick series of plates were measured by Mr. Mitchell,
the balance by Mr. Lamb. The proper motions of the two
stars in right ascension were found from the photographs to be
+ 07213 and + 07205, respectively, while the mean proper
motion from Boss is + 0”169. The parallaxes of the two stars
are + 07075 + 07010, and + 07073 + 07011, respectively, from
which there results a mean parallax of the system of

+ 0074 + 07007
The spectroscopic parallax of Adams and Joy is + 07040.

ComPaRISON STARS

 

 

 

 

 

 

 

No. Diameter. eS inlay mec Y (Declination). Dependence.
mm. mm. mm.
1 0.17 —32.0 +82.1 +0.1961
2 12 —26.8 —23.6 -1911
3 12 —23.9 + 9.4 -1954
4 22 + 5.2 —51.8 -1954
5 14 +77.5 +33.9 +0. 2220
Principal star 14 \ :
Companion 0.13 , ae oe

 
382

S. A. MITCHELL

TABLE 1

Puates or 49 SERPENTIS

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.”
1093 1915 Mar. 20 —054 M 0.8
1117 Mar. 27 —0.9 G 0.9
1118 Mar. 27 —0.5 & 1.0
1176 Apr, 1f +0.3 A 1.0
2762 1916 June 23 —0.4 M, L 0.7
3726 1917 Mar. 6 —0.3 L 0.8
3727 Mar. 6 +0.1 L 0.8
3818 Mar, 25 —0.6 L 0.8
3819 Mar. 25 —0.2 L 0.8
4077 June 17 +0.3 M,B 1.0
4078 June 17 +0.7 M,B 0.7
5109 1918 Feb. 17 —0.2 Ds 0.5*
5124 Feb. 22 —0.2 - A 0.7*
5141 Feb. 26 —1.0 A 0.6*
5142 Feb. 26 —0.5 A 0.9
5214 Mar. 19 —0.2 A 1.0
5225 Mar. 26 —0.5 A 1.0
5226 Mar. 26 0.0 A 1.0
* 5490 June 28 -0.1 Ol 0.7
5491 June 28 +0.3 Ol 0.7*
5501 July 2 +0.2 A 1.0
5502 July 2 +0.7 A 1.0
6577 1919 Feb. 26 —1.0 M 1.0
6578 Feb. 26 —0.6 M 1.0
6614 Mar. 3 —0.7 H 0.7*
6615 Mar. 3 —0.3 H 0.7*
* One exposure.
The normal equations are:
~ 21.8¢ — 2.033u + 11.48057 = — 0.3387 mm.
+ 466.8694 — 6.80607 = + 1.3224 mm.
+ 14.388717 = — 0.1633 mm.
 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 38
TABLE 2
Repuctions ror 49 SERPENTIS, PRIncipaL Star
uti i Parall Time i i P-
mae | Fe | Nee eee: (ae. | ee | ane
mm. mm.
1093 —0.0378 0.8 +0.885 —892 —0.0012 —0"02
1117 — .0392 0.9 + .830 —885 + .0002 .0¢
1118 — .0368 1.0 + .830 —885 — .0022 — .05
1176 — .0420 1.0 + .672 —870 + .0028 + .06
2762 — .0298 0.7 | — 467 —431 — .0012 — .02
3726 — .0206 0.8 + .955 —-175 + .0020 + .04
8727 — .0200 0.8 + .955 —175 + .0014 + .02
3818 — .0196 0.8 + .843 —156 + .0011 + .02
3819 — .0196 0.8 + .843 —156 + .0011 + .02
4077 — .0202 1.0 — .874 — 72 — .0003 — .01
4078 — .0166 0.7 — .874 — 72 — .0039 — .07
5109 — .0110 0.5 + .967 +173 + .0022 + .03
5124 — .0100 0.7 + .973 +178 + .0014 + .02
5141 — .0082 0.6 + .972 +182 — .0003 — .01
5142 — .0100 0.9 + .972 +182 + .0015 + .03
5214 — .0060 1.0 + .890 +203 — .0022 — .05
5225 — .0060 1.0 + .836 4-210 — .0022 — .05
5226 — .0070 1.0 + .836 +210 — .0012 — .02
5490 — .0058 0.7 — .582 +304 — .0048 — .08
5491 — .0131 0.7 — .532 +304 + .0025 + .04
5501 — .0152 1.0 — .587 +308 + .0046 + .10
5502 — .0110 1.0 — .587 +3808 + .0004 + .01
6577 — .0010 1.0 + .972 +547 + .0027 + .06
6578 + .0026 1.0 + .972 +547 — .0009 — .02
6614 + .0028 0.7 + .964 +552 — .0010 — .02
6615 +0.0049 0.7 +0.964 +552 —0.0031 —0.05
from which:

c = — 0.01717 mm.

p= +.0.00281 mm. = + 070585, or + 07213 per year.

a = + 0.00362 mm. = + 07075 + 0°010.

Probable error of plate of unit weight
+ 0.00145 mm. = + 07030.
384

S. A. MITCHELL

TABLE 3

Repvuctions ror 49 SERPENTIS, CoMPANION

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp-0
Plate. (m). (p). | Factor (P). | Days (). (»). in Arc.
1093 +0.0382 0.8 +0.885 —892 —0.0036 —007
1117 + .0329 0.9 + .830 —885 + .0017 + .03
1118 + .0368 1.0 + .830 —885 — .0022 — .05
1176 + .0312 1.0 + .672 —870 + .0033 + .07
2762 + .0422 0.7 — .467 —431 + .0002 .00
3726 + .0497 0.8 | + .955 —175 + .0045 + .08
3727 + .0521 0.8 + .955 —175 + .0021 + .04
3818 + .0567 0.8 + .843 —156 — .0024 — .04
3819 + .0548 0.8 + .843 —156 — .0004 — .01
4077 + .0522 1.0 — .374 — 72 + .0002 .00
4078 + .0570 0.7 — .374 — 72 — .0046 — .08
5109 + .0586 0.5 + -967 | +1738 + .0051 + .07
5124 + .0640 0.7 + .973 +178 — .0002 -00
5141 + .0604 0.6 + .972 +182 ny .0035 + .06
5142 + .0659 0.9 + .972 +182 — .0020 — .04
5214 + .0650 1.0 + .890 +203 — .0008 — .02
5225 + .0668 1.0 + .8386 +210 — .0026 — .05
5226 + .0660 1.0 + .836 +210 — .0018 — .04
5490 + .0641 0.7 — .582 +304 — .0021 — .04
5491 + .0611 0.7 — .582 +304 + .0009 + .01
5501 + .0602 1.0 — .587 +308 + .0017 + .04
5502 + .0600 1.0 — .587 +3808 + .0019 + .04
6577 + .0756 1.0 + .972 +547 — .0018 — .04
6578 + .0754 1.0 + .972 +547 — .0016 — .03
6614 + .0719 0.7 + .964 +552 + .0020.|} + .04
6615 +0.0711 0.7 +0.964 +552 +0.0028 +0.05
The normal equations are:

21.8¢ — 2.03834 + 11.48057 = + 1.2468 mm.

+ 466.8694u — 6.80607 = + 1.1233 mm.

+ 14.38717 = + 0.6676 mm.
PARALLAXES OF 260 STARS 385

from which:

c = + 0.05561 mm.
# = + 0.00270 mm. = + 070561, or + 07205 per year.
a = +0.00350 mm. = + 07073 + 07011.

Probable error of plate of unit weight

+ 0.00159 mm. = + 07033.

Il

6 OPHIUCHI (16 9"; —3° 26’)

The only parallax determined for this star of magnitude 3.03,
of type Ma, and of total proper motion 0" 160 is the spectrographic

TABLE 1

PLATES OF 6 OPHIUCHI

 

 

 

 

 

 

No. Date. Hour Angle. Observers. | Weight.
5143 1918 Feb. 26 +041 A | 0.9
5210 Mar. 18 -0.1 A 1.0
5211 Mar. 18 +0.3 A 1.0
5336 May 1 =6.3 A 1.0
5516 July 3 +0.4 A 1.0
5517 July 3 +0.8 A 1.0
5524 July 4 +0.2 A 1.0
5525 July 4 +0.5 A 1.0
6685 1919 Mar. 12 —0.3 H 0.9
6686 Mar. 12 0.0 H 1.0
6698 Mar. 18 +0.3 D 1.0
6790 Mar. 30 —0.2 F 1.0
6791 Mar. 30 +0.2 F 1.0
6802 Apr. 1 —0.9 D 0.8
7271 July 2 -0.3 F 1.0
7272 . July 2 0.0 F 1.0
7273 July 2 +0.4 F 1.0
7274 July 2 +0.7 F 1.0
7411 Aug. 3 +1.5 F | 0.9
7423 Aug. 4 1 H | 0.9

 

 

26
386

S. A. MITCHELL

CoMPARISON STARS

 

 

 

 

 

 

 

 

 

 

No. Diameter. X (Right Ascen-) y (Declination). Dependence.
sion).
mm. mm. mm.
1 0.15 —40.4 + 7.1 +0.4306
2 -20 — 2.1 +28.9 . 1266
3 .14 +42.5 —36.0 +0.4427
Parallax star 0.18 + 1.15 — 9.22
TABLE 2
REDUCTIONS FoR 6 OPHIUCHI
Solution Weight Parallax Time in Residual v Dev
Plate. ‘m). (p). | Factor (P). | Days (t). (0). in Are.
mm. mm.
5143 —0.0382 0.9 +0.972 —298 +0.0013 +0702
5210 — .0353 1.0 + .898 —278 — .0018 — .04
5211 — .0351 1.0 + .898 —278 — .0020 — .04
5336 — .0417 1.0 + .3895 —234 + .0035 + .07
5516 — .0449 1.0 — .599 —171 + .0047 + .10
5517 .| — .0418 1.0 — .599 -—171 + .0016 + .03
5524 — .0362 1.0 — .612 —170 — .0040 — .08
5525 — .0372 1.0 — .612 —170 — .0030 — .06
6685 — .0390 0.9 + .933 + 81 + .0010 | 4+ .02
6686 — .0400 1.0 + .9383 + 81 + .0020 | + .04
6698 — .0872 1.0 + .899 + 87 — .0008 — .02
6790 — .0377 1.0 + .804 + 99 — .0006 — .01
6791 — .0382 1.0 + .804 + 99 — .0001 -00
6802 — .0370 0.8 + .785 +101 — .0013 — .02
7271 — .0404 1.0 — .582 +193 — .0007 — .01
7272 — .0410 1.0 — .582 +193 — .0001 -00
7273 — .0400 1.0 — .582 +193 — .0011 — .02
7274 — .0408 1.0 — .582 |. +193 — .0003 — .O1
7411 — .0434 0.9 — .912 +225 + .0016 | + .03
7423 —0.0424 0.9 —0.918 +226 +0.0005 +0.01

 

 

 

 

 

 

 
result of Adams with the result + 07046. Miss Darkow mea-
sured the photographs and determined a relative parallax

PARALLAXES OF 260 STARS

387

+ 0"040 + 07010 with a proper motion in right ascension
— 07020 while the corresponding value from Boss is — 0048.

The normal equations are:

19.4c¢ — 0.4264 + 1.57657
+ 69.3854u — 8.15750

= — 0.7638 mm.

+ 11.19577
from which:
c = — 0.03953 mm.
uw = — 0.00026 mm. =
7 = + 0.00190 mm. = + 07040 + 07010.

Probable error of plate of unit weight

The only parallax for this star of magnitude 3.34, of spectrum

+ 0.00149 mm. = + 07031.

e OPHIUCHI (16 13"; —4° 27’)

— 0.0166 mm.
— 0.0390 mm.

— 070054, or — 07020 per year.

K and of total proper motion 0"085 is the spectrographic result
of Adams with the. absolute value + 0025.

Miss Hawes
measured the photographs, and determined a relative parallax
of + 07046 + 07012, and a proper motion in right ascension

+ 07102 while the corresponding value from Boss is + 07079.

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. % (ighe. eer Y (Declination). | ° Dependence.

1 0.12 —61.5 +36.5 +0.274

2 .14 + 9.6 +23.1 - 208

3 .09 +18.9 —37.6 .278

4 .04 +33.0 —22.0 +0.240
Parallax star 0.14 — 1.70 — 0.91

 
388 8S. A. MITCHELL

TABLE 1

PLATES oF ¢ OPHIUCHI

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1055 1915 Mar. 13 —042 M 0.4
1075 Mar. 17 —0.1 G 0.8
1108 Mar. 24 —0.4 G 0.9
1109 Mar. 24 +0.1 G 0.5*
1169 Apr. 8 +0.3 G 0.6
3865 1917 Apr. 9 —0.6 M 0.8
3893 Apr. 18 —0.9 A 1.0
3894 Apr. 18 —0.5 A 0.7
4101 June 22 0.0 ol, B 1.0
4102 June 22 +0.6 Ol, B 0.8
4130 June 29 +1.2 ol, B 0.8
5309 1918 Apr. 22 +0.2 A 1.0
5310 Apr. 22 +0.6 A -1.0
5329 Apr. 29 —0.2 A 1.0
5330 Apr. 29 +0.5 A 1.0
5540 July 13 +0.6 A 1.0
5590 Aug. 4 +0.9 A 0.8
5603 - Aug. 6 +0.9 A 1.0
6470 1919 Feb. 5 —0.8 M 0.7*
6489 Feb. 6 —0.7 H 1.0
6579 Feb. 26 —0.3 M 1.0
6580 Feb. 26 +0.2 M 1.0
7275 July 2 +1.1 F 1.0
7276 July 2° +1.5 F 1.0
7285 July 5 +0.4 H 0.8
7286 July 5 +0.8 H 1.0

 

 

 

 

* One exposure.

The normal equations are:

22.6c + 40.4964 + 3.96957 = — 0.6522 mm.
622.42054 — 23.5451r = — 0.4989 mm.
+ 11.60527 = — 0.13815 mm.
PARALLAXES OF 260 STARS

~38

 

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR € OPHIUCHI
Soluti igh Parall: i i esidual Dp
Flate. ee: || eae yc ae | Oe eae
mm. mm.
1055 | —0.0398,| 0.4 | +0.934 | —857 | —0.0013 | —0”02
1075 — .0391 | 0.8 | + .914 | —853 | — .0020 | — .04
1108 — .0407 | 0.9 | + .865 | —846 | ~— .0004 | — .O1
1109 | — .0400 | 0.5 | + .865 | -846 | — .o011 | ~ .02
1169 — .0416 | 0.6 | + .721 | —831 | + .0004 | + .01
3865 — .0804 | 0.8 | + .704 | — 99 | — .0010 | — .02
3893 — .0346 | 1.0 | + .592 | ~ 90 | + .0030 | + .06
3804 | — .0302 | 0.7 | + .592 | ~ 90 | ~— .0014 | — .02
4101 — .0362 | 1.0 | — .484 | ~ 25 | + .0032 | + .07
4102, | — .0840 | 0.8 | — .484 | — 25 ; + .0010 |.+ .02
4130 | — .0351 |} 0.8 | — .536 | — 18 | + .0020 | + .04
5309 | — .0231 | 1.0 | + .540 | +279 | — .0036 | — .07
5310 | — .0241 | 1.0 | + .540 | +279 | — .0026 | — .05
5329 — .9260 | 1.0 | + .489 | +286 | — .0008 | — .02
5330 | — .0244 | 1.0 | + .439 | +286 | — .0024 | ~— .05
5540 | — .0303 | 1.0 | —..712 | +361 | + .0019 | + .04
5590 | — .9282 | 0.8 | — .915 | +383 | — .0003 | — .O1
5603 — .0284 | 1.0 | — .927 | +885 | — .0001 | — .00
6470 | — .0273 | 0.7 | + .919 | +568 | + .0053 | + .09
6489 — .02388 | 1.0 ; + .924 | +569 | + .0018 | + .04
6579 — .0222 | 1.0 | + .974 | +589 | + .0006 | + .01
6580 — .0228 | 1.0 | + .974 | +589 | + .0012 | + .02
7275 { — .0216 | 1.0 | — .571 | +715 | — .0017 | — .04
7276 | — .0206 | 1.0 | — .571 | +715 | — .0027 | — .06
7285 | — .0236 | 0.8 | — .610 | +718 | + .0002 | + .00
7286 —0.0218 | 1.0 | — .610 | +718 | — .0016 | — .03
from which:

c = — 0.03165 mm.

uw = + 0.00134 mm. = + 070279, or +- 07102 per year.

ax = + 0.00222 mm. = + 07046 + 07012.

Probable error of plate of unit weight
+ 0.00170 mm. = + 07035.
390 S. A. MITCHELL

n DRACONIS (16 22™; +61° 44’)

Two values of the parallax of this star have been published, the
meridian circle result of Flint, + 0”080 + 07032, and the
spectroscopic value of Adams + 0”032. ‘This is a double star
O® 312 the principal star of magnitude 2.89, and G5 type, and
the companion of 8.1 magnitude at a distance 5”. The rotating
sector was used to diminish the brightness of the principal star,

 

 

 

 

 

TABLE 1
Puates oF 7 Draconis
No. Date. Hour Angle. Observers. Weight.
1085 1915 Mar. 18 —046 M 0.7*
1130 Mar. 29 0.0 G 0.9
1141 Mar. 31 —0.4 A 1.0
1148 Apr. 4 —0.2 A 1.0
1446 July 9 —0.2 A 1.0
1465 July 16 —0.4 A 1.0
2474 1916 Mar. 12 —0.3 A 0.9
2475 Mar. 12 —0.7 A 0.9
2580 Apr. 19 —1.0 G 0.8
2606 Apr. 27 -0.7 aA. 1.0
2607 Apr. 27 —0.4 A 1.0
2803 July 7 —0.6 L 1.0
2804 July 7 —0.3 L 1.0
2806 July 11 -—0.9 Ol 0.9
2807 July 11 —0.4 Ol °0.8

 

 

 

. * One exposure.

Comparison Stars

 

 

 

 

 

 

No. Diameter. |* aaa Y (Declination). Dependence.
mm. mm. mm.
1 0.13 —21.0 — 2.1 +0.1531
2 30 — 0.7 +42.5 5462
3 13 +21.7 —40.4 +0.3007
Parallax star 0.20 + 2.9 +10.7

 
PARALLAXES OF 260 STARS 391

and the companion was, consequently, invisible. The stars
have a common proper motion 006. Mr. Alden measured the
McCormick series of plates and found a proper motion in right
ascension of — 07022 while Boss has the value — 07018.

TABLE 2

REDUCTIONS FOR 7 DRACONIS

 

 

 

 

 

 

 

 

 

uti Wei 11: Time i i p:
mia) OE ee oe | ae | ae
mim. mm.

1085 —0.0104 0.7 +0.922 —275 —0.0012 | —0%02
1130 — .0106 0.9 + .844 —264 — .0011 — .02
1141 — .0128 1.0 + .827 —262 + .0011 | + .02
1148 — .0137 1.0 + .789 —258 + .0020 | + .04
1446 — .0118 1.0 — .635 —162 — .0003 | — .Ol
1465 | — .O111 1.0 — .719 —155 — .0010 | — .02
2474 — .0116 0.9 + .948 + 85 — .0010 | — .02
2475 — .0130 0.9 + .948 + 85 + .0004 | + .01
2580 — .0156 0.8 + .605 +123 + .0028 | + .05
2606 — .0116 1.0 + .495 +131 — .0012 | — .02
2607 — .0107 1.0 + .495 +131 — .0021 — .04
2803 — .0138 1.0 — .618 +202 + .0007 ) + .01
2804 — .0156 1.0 — .618 +202 + .0025 | + .05
2806 — .0100 0.9 — .669 +206 — .0031 — .06
2807 —0.0146 0.8 —0.669 +206 +0.0015 | +0.03

 

The normal equations are:

13.9¢ + 0.005u + 2.47417 = — 0.1732 mm.
+ 51.4820u — 7.33637 = — 0.0150 mm.
+ 7.38807 = — 0.0283 mm.
from which:
c = — 0.01247 mm.
uw = — 0.00028 mm. = — 070060, or — 07022 per year.
x = + 0.00008 mm. = + 07002 + 07010.

Probable error of plate of unit weight
+ 0.00122 mm. = + 07025.
3892 S. A. MITCHELL

) OPHIUCHI (165 25"; +2° 12’)

According to Burnham’s General Catalogue, this is a binary of
long period which has described an arc of only 90° since
its discovery by Struve. As yet, nothing is known of its real
orbit, though several have been computed in which the periods
range from 89.0 years to 373.5 years. The most probable
period is that due to Lewis of 134 years, or that of Lohse of
123.24 years. To add to the interest connected with this star,
Frost has found (Astronomische Nachrichten, 177, 174, 1908)
that it is a spectroscopic binary. It is of A type, and of mag-
nitude 3.85. Van Biesbroeck (Astronomical Journal, 29, 173,
1916) calls attention to the desirability of investigating the
motions of this star in order to determine the ratios of the masses
of the components. The present series of photographs were
taken while the orbital motion of the companion was almost
entirely in declination so that the measures in right ascension,
should give a proper motion in right ascension equal to the
proper motion of the center of gravity of the system which Boss
gives. His value is — 07048 per year, and the value from the
McCormick series of plates which were measured by Mr. Alden
is — 0"047. Three values of the parallax have been given, the
result of photographic measures. At Yerkes, Lee derives the
value + 07018 + 07003, at Swarthmore Miller obtains — 07004
+ 07005, while at Allegheny the value of — 0”010 + 07008 is
found. Making use of the orbit by Lewis, and the McCormick
parallax, the mass of the system is found to be 19.7 times that
of the sun.
PARALLAXES OF 260 STARS

TABLE 1

Puates oF \ OPHIUCHI

393

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1290 1915 May 9 —043 A 1.0
1300 May 10 —0.2 G 0.8
1489 July 18 +0.6 G 0.9
1490 July 18 +1.0 G -0.7*
1516 July 25 +1.0 G 0.7
1537 Aug. 9 +0.9 G 0.8
2508 1916 Mar. 17 +0.1 G 0.7
2509 Mar. 17 +0.4 G 0.8
2621 Apr. 30 —0.4 A 1.0
2622 Apr. 30 ‘+0.1 A 1.0
2796 July 4 +0.8 M 1.0
2877 Aug. 17 +1.5 A 1.0
2910 Aug. 20 +1.2 A 1.0
3697 1917 Feb. 22 —0.8 M 0.9
3698 Feb. 22 —0.4 M 1.0
3786 Mar. 21 —0.3 L 0.9
3787 . Mar. 21 —0.6 L 0.7*
4114 June 23 +0.4 M,B 1.0
4115 June 23 +0.7 M,B 1.0
4183 July 28 +0.4 A 0.9
4184 July 28 +0.7 A 1.0
* One exposure.
ComPaRISON STARS
No. Diameter. oe ee eee Y (Declination). Dependence.
mm. mm. mm.

1 0A9 —31.9 ~+45.8 +0.2143

2 -20 —28.2. — 5.6 - 2446

3 17 + 8.8 —40.0 - 2754

4 .16 +51.3 — 0.2 +0.2657

Parallax star 0.20 + 2.3 — 2.6

 
394 S. A. MITCHELL

TABLE 2

REDUCTIONS FOR )\ OPHIUCHI

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual vpeo
Plate. (m). (p). Factor (P). | Days (é). (2). in Are.
mm. mm.
1290 +0.0077 1.0 +0.340 —421 +0.0008 +0702
1800 + .0108 0.8 + .324 —420 — .0023 — .04
1489 + .0073 0.9 — .733 —351 + .0004 + .01
1490 + .0122 0.7 — .733 —351 — .0046 — .08
1516 + .0044 0.7 — .807 —344 + .0032 + .06
1537 + .0036 0.8 — .927 —329 + .0038 + .07
2508 + .0054 0.7 + .929 —108 + .0015 + :02
2509 + .0062 0.8 + .929 —108 + .0007 + .01
2621 + .0089 1.0 + .466 — 64 — .0025 — .05
2622 + .0073 1.0 + .466 — 64 — .0009 — .02
2796 + .0044 1.0 — .566 + 1 + .0012 + .02
2877 + .0070 1.0 — .978 + 47 — .0019 — .04
2910 + .0053 1.0 — .981 + 48 — .0002 .00
3697 + .0038 0.9 + .975 +234 + .0010 + .02
3698 + .0056 1.0 + .975 +234 — .0008 — .02
3786 + .0032 0.9 + .908 +261 + .0014 + .03
3787 + .0047 0.7 + .908 +261 — .0001 -00
4114 + .0046 1.0 — .402 +855 — .0012 — .02
4115 + .0009 1.0 — .402 +355 + .0026 + .05
4183 + .0041 0.9 — .840 +390 — .0009 — .02
4184 +0.0026 1.0 —0.840 +390 —0.0004 —0.01
The normal equations are:
18.8¢ + 2.3964 — 1.17487 = + 0.1070 mm.

+ 142.6433y + 2.46882 = — 0.0728 mm.

: + 10.9598¢ = — 0.0036 mm.
from which:
c = + 0.00580 mm.
nw = — 0.00061 mm. = — 070128, or — 0047 per year.
a = + 0.00043 mm. = + 07009 + 07008.

Probable error of plate of unit weight
+ 0.00128 mm. = + 07026.
PARALLAXES OF 260 STARS 395

n HERCULIS (16 39"; +-39° 6’)

The older values of the parallax are very discordant, consisting
as they do of + 0740 + 0072 by meridian circle by Belopolsky,
+ 0715 + 07035 by meridian circle by Flint, and -} 07014

TABLE 1

Puates or 1 HERcULIS

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
2586 1916 Apr. 20 —145 Ol 0.9
2587 Apr. 20 —0.9 Ol 0.9
2616 Apr. 29 —0.8 Ol 0.8
2617 Apr. 29 —0.2 Ol 0.7
2815 July 12 —0.3 M 0.8
3886 1917 Apr. 16 —0.4 A 1.0
3895 Apr. 18 —0.4 A 0.9
3896 Apr. 18 —0.1 A 0.7*
4088 June 18 —0.7 A,B 0.9
4089 June 18 —0.2 A,B 0.9
4151 July 1 —0.3 M 1.0
4152 July 1 0.0 M 0.7*
5240 1918 Mar. 28 —0.8 ol 0.8
5241 Mar. 28 —0.3 Ol 0.9
5270 Apr. 4 —0.2 Ol 0.9
5286 Apr. 14 —1.20 Ol 1.0
5287 Apr. 14 —0.5 Ol 0.7
5563 July 20 —0.1 A 1.0
5574 July 21 0.0 A 1.0
6779 1919 Mar. 29 —1.7 Ol 1.0
6780 Mar. 29 —1.1 Ol 0.9
6781 Mar. 29 —0.4 ol 0.9
7348 July 26 —0.3 D 0.9
7364 July 27 —0.2 H 0.9
7365 July 27 +0.1 H 0.6*
7384 July 29 —0.2 D 1.0

 

 

 

 

* One exposure.
396

S. A. MITCHELL

REDUCTIONS FoR 7 HERCULIS

TABLE 2

 

 

 

 

 

 

 

 

 

=e Solution Weight | Parallax Time in Residual _Vp-o
(m). (p). Factor (P.) | Days (¢). 2). in Arc.
mm. mm.
2586 +0.0051 0.9 +0.649 —619 —0.0006 —0'01
2587 + .0034 0.9 + .649 —619 + .0011 + .02
2616 + .0051 0.8 + .528 —610 — .0008 — .02
2617 + .0064 0.7 + .528 —610 — .0022 — .04
2815 + .0045 0.8 | — .630 —536 — .0023 — .04
3886 + .0057 1.0 + .701. —258 + .0015 + .03
3895 + .0080 0.9 + .677 —256 — .0008 — .02
3896 + .0041 0.7 + .677 —256 + .0031 | + .05
4088 + .0045 0.9 — .273 —197 + .0010 + .02
4089 + .0026 0.9 — .273 —197 + .0029 + .06
4151 + .0070 1.0 — .475 —192 — .0019 — .04
4152 + .0023 0.7 — .475 = 192 + .0028 + .05
5240 + .0101 0.8 + .887 + 88 + .0001 .00
5241 + .0108 0.9 + .887 + 88 — .0006 — .01
5270 + .0075 0.9 + .829 + 95 + .0026 + .05
5286 + .0112 1.0 + .727 +105 — .0012 — .02
5287 + .0136 0.7 + .727 +105 — .0036: | — .06
5563 + .0067 1.0 — .724 +202 + .0007 + .01
5574 + .0084 1.0 — .735 +203 — .0010 — .02
6779 + .0119 1.0 + .881 +454 + .0010 + .02
6780 + .0120 0.9 + .881 +454 + .0009 + .02
6781 + .0156 0.9 + .881 +454 — .0027 — .05
7348 + .0082 0.9 — .786 +573 + .0018 + .04
7364 + .0118 0.9 — .797 +574 — .0018 — .04
7365 + .0125 0.6 — .797 +574 — .0025 — .04
7384 +0.0086 1.0 —0.817 +576 +0.0014 +0.03

 
PARALLAXES OF 260. STARS 397

+ 0066 by photography by Russell. The Allegheny result is
+ 0”053 + 07009, while spectrographic value of Mt. Wilson is
+ 07024. Mr. Olivier measured the plates and found a parallax
+ 0°047 + 0”008 with a proper motion in right ascension
+ 0”056 where the value from Boss is + 07034.

4
Comparison STars

 

 

 

 

 

 

 

No. Diameter. |~ ee ada Y (Declination). Dependence.
mm. mm. mm,

1 0.15 —60.9 —34.0 +0.2508

2 10 —19.3 +27.2 38013

3 16 +19.5 —30.2 1945

4 14 +60.7 +37.0 +0. 2534
Parallax star 0.14 — 1.9 + 3.2

 

The normal equations are:
22.7¢ + 2.359u + 3.71937 = + 0.1818 mm.
+ 360.2277u — 15.46737 = + 0.2486 mm.
+ 11.50487 = + 0.0427 mm.
from which:
ce = + 0.00756 mm.
uw = + 0.00074 mm. = + 070153, or + 07056 per year.
x = + 0.00226 mm. = + 07047 + 07008.
Probable error of plate of unit weight

+ 0.00122 mm. = + 0025.

a HERCULIS (17% 10"; +14° 30’)

The principal star of this well-known double is a variable
with a range in magnitude from 3.1 to 3.9, and of spectral
type Mb. The companion of magnitude 5.4 is at a distance of
4"5, but there has been no change in the relative positions since
the first measures. The parallax of Jacob with the equatorial is
+ 0050 + 0%011, while the Allegheny value is — 07025 + 07009.
The spectroscopic value of Adams and Joy is + 07006. Fifteen
of the later plates were measured by Miss France, while the
398 S. A. MITCHELL

earlier plates were measured by Mr. Olivier. The McCormick
plates gave a parallax of + 07006 + 07008, while the value of the
proper motion in right ascension was found to be — 07028 per
year with the corresponding value from Boss of — 07012.

TABLE 1

Puiates or a Hercuis

 

 

 

 

 

 

 

No. Date. Hour ecice. Observers. Weight.
1508 1915 July 24 +151 Ol 0.6*
1509 July 24 +1.6 Ol 0.6
2552 1916 Apr. 4 —0.2 M 0.6*
2649 | May 7 +0.6 A 0.9
2660 May 14 —0.5 A 0.7
2805 July 7 +0.6 L 1.0f
2817 July 12 | +0.5 M 0.9
2818 July 12 +0.9 M 0.7
3806 1917 Mar. 24 —0.4 Ol 0.7
3837 Mar. 31 —0.6 Ol 0.7
3838 Mar. 31 0.0 Ol 0.7
3906 Apr. 22 —1.2 L 0.9
3907 Apr. 22 —0.8 L 0.9
3925 May 1 e141 i, 0.7
3926 May 1 —0.7 L 0.7
3940 May 9 —0.8 Ol 0.8
4131 June 29 +1.0 ol, B 0.8
4251 Aug. 10 -—0.1 Ol 0.9
5311 | 1918 - Apr. 22 +0.2 A 1.0
5312 Apr. 22 +0.6 A 1.0
5331 Apr. 29 +0.1 A 1.0
5358 May 8 —0.6 A 1.0
5551 July 14 —0.5 A 0.8
5552 July 14 +0.1 A 0.9
5604 Aug. 6 +0.4 A 1.0
5605 Aug. 6 +0.8 A 1.0
5640 Aug. 20 +0.8 A 0.9

 

* One exposure. { Three exposures.
PARALLAXES OF 260 STARS 399

TABLE 2

Repvuctions ror a Hercuuis

 

 

 

 

 

 

 

 

 

Soluti Weigh Parall: Time i id: D-
Pinte | Seguin | Meee | eats | ce | Sa | ake
mm. mm.
1508 —0.0061 0.6 —0.683 —665 +0.0024 | +0704
1509 — .0044 0.6 — .683 —665 | + .0007 + .01
2552 — .0059 0.6 + .892 —410 + .0016 + .03
2649 — .0032 0.9 + .523 —377 — .0013 — .02
2660 — .0051 0.7 + .419 —370 + .0006 + .0I
2805 — .0042 1.0 — .459 —316 — .0008 — .02
2817 — .0050 0.9 — .532 —311 -0000 .00
2818 — .0005 0.7 — .532 —311 — .0045 — .08
3806 — .0072 0.7 + .958 — 56 + .0017 | + .08
3837 — .0048 0.7 | + .921 — 49 — .0008 — .01
3838 — .0090 0.7 + .921 — 49 + .0034 | + .06
3906 — .0040 0.9 + .722 — 27 — .0017 — .03
3907 — .0068 0.9 + .722 — 27 + .0011 + .02
8925 — .0042 0.7 + .610 — 18 — .0016 — .03
8926 — .0060 0.7 + .610 — 18 + .0002 .00
3940 — .0054 0.8 + .498 | — 10 — .0004 | — .O1
4131 — .0054 0.8 — .832 + 41 — .0008 — .02
4251 — .0079 0.9 — .866 + 83 + .0014 | + .03
5311 — .0051 1.0 + .724 +838 — .0020 — .04
5312 — .0078 1.0 + .724 +338 + .0008 + .02
5331 — .0068 1.0 + .639 +845 — .0003 — .01
5358 — .0060 1.0 + .516 +354 — .0012 — .02
5551 — .0127°| 0.8 — .553 +421 + .0050 | + .09
5552 — .0108 0.9 — .553 +421 + .0031 + .06
5604 — .0074 1.0 — .828 +444 — .0004 — .O1
5605 — .0038 1.0 — .828 +444 — .0040 — .08
5640 —0.0084 0.9 —0.938 +458 +0.0005 +0.01

 
400 S. A. MITCHELL

CoMPARISON STARS

 

 

 

No. Diameter. rg aa vanced Y (Declination). Dependence.
1 0.15 —33.9 +80.5 +0:205
2 .16 —14.9 —17.4 .273
3 -08 +18.4 —15.0 .272
4 .08 +30.4 + 1.9 +0.250
Parallax star 0.15 + 1.6 — 2.1

 

 

 

 

 

The normal equations are:

22.4¢ + 8.5294 + 1.79917 = — 0.1370 mm.
+ 248.2031 — 4.06517 = — 0.1433 mm.
+ 10.72647 = — 0.0064 mm.
from which:
c = — 0.00600 mm.
uw = — 0.00037 mm. = — 0"0076, or — 07028 per year.

a = + 0.00027 mm. = + 0°006 + 07008.
Probable error of plate of unit weight
+ 0.00132 mm. = + 07027.

6 HERCULIS (175 10"; +24° 57’)

According to Burnham’s General Catalogue 7922, this is a
system of the 61 Cygni type, of magnitudes 3.1 and 8.1, the
relative change in position being due to the difference in proper
motions of the components. The large star is of A type, and
has a total proper motion of 07155. The smaller star was not
observed in the McCormick series of plates measured by Mr.
Mitchell, being cut out by the use of the rotating sector.
Leavenworth by the micrometer finds the average value from
two determinations to be + 07040 + 07011. Allegheny by pho-
tography derives the parallax -- 07029 +0"007. The proper
motion in right ascension from the plates is — 0%022 while the
corresponding value from Boss amounts to — 0”024.
PARALLAXES OF 260 STARS 401

TABLE 1

Puates oF 6 HERcULIS

 

 

 

No. Date. Hour Angle. Observers. Weight.
3820 1917 Mar. 25 —057 B,L 0.8
3821 Mar. 25 —0.3 L 0.5*
3879 Apr. 13 —0.6 L 0.8
3880 Apr. 13 —0.2 L 0.8
4141 | June 30 —0.2 M 0.8
4153 July 1 —0.1 M 0.9
4220 Aug. 1 —0.2 B 0.6
4221 Aug. 1 +0.2 B 0.4*
5249 1918 Mar. 29 —1.0 A 1.0
5305 Apr. 18 =1.4 M 0.8
5306 Apr. 18 —0.9 M 0.9
5625 Aug. 14 0.0 A 0.7*
5638 Aug. 20 +0.2 A 0.5*
5641 Aug. 22 +0.2 A 0.6*
5643 Aug. 23 +0.2 A 0.6*
6565 1919 Feb. 23 —1.5 M 1.0
6566 Feb. 23 —1.0 M 1.0
6616 Mar. 3 —0.8 H 1.0
6617 Mar. 3 —0.4 H 0.9

 

 

 

 

 

* One exposure.

CoMPARISON STARS

 

 

 

 

 

 

 

No. Diameter. |* eo Y (Declination). Dependence.
mm. mm. mm.
1 0.14 —27.3 +36.0 +0.223
2 13 —16.6 —34.2 .220
3 15 +17.4 —20.6 - 268
4 17 +26.5 +18.8 +0.289
Parallax star 0.17 -+ 2.6 + 0.4

 

27
402

S. A. MITCHELL

Repvuctions ror 6 HERcu.is

TABLE 2

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual vVp-»
Plate. ‘m). (p). | Factor (P). | Days (t). (0). in Are.
mm. mm.
3820 —0.0053 0.8 +0.955 —342 —0.0026 —0"05
3821 — .0089 0.5 + .955 —342 + .0010 + .01
3879 — .0075 0.8 + .820 —323 — .0005 — .01
3880 — .0108 0.8 + .820 —323 + .0028 + .05
4141 — .0074 0.8 — .344 —245 — .0017 — .08
4153 — .0118 0.9 — .359 —244 + .0027 + .05
4220 — .0067 0.6 — .778 —213 — .0029 — .05
4221 — .0111 0.4 — .778 —213 + .0015 + .02
5249 — .0091 1.0 + .936 + 26 + .0001 .00
5305 — .0057 0.8 + .772 + 47 — .0034 — .06
5306 — .0115 0.9 + .772 + 47 + .0024 + .05
5625 — .0117 0.7 — .895 +165 + .0010 + .02
5638 — .0081 0.5 — .936 +171 — .0027 — .04
5641 — .0091 0.6 — .948 +173 — .0017 — .03
5643 — .0141 0.6 — .953 | +174 + .0033 + .05
6565 — .0098 1.0 + .957 +358 — .0001 -00
6566 — .0090 1.0 + .957 +358 — .0009 — .02
616 — .0110 1.0 + .983 +366 + .0011 + .02
6617 —0.0100 0.9 +0.983 +3866 +0.0001 0.00
The normal equations are:
14.6c + 3.365u + 4.97227 = -- 0.1373 mm.
+ 105.1028u + 5.87127 = — 0.0590 mm.
+ 10.71727 = — 0.0412 mm.
from which:
c = — 0.00959 mm.
w= — 0.00029 mm. = — 070061, or — 07022 per year.
aw = + 0.00075 mm. = + 0016 + 0”009.

Probable error of plate of unit weight
+ 0.00126 mm. = + 07026.
PARALLAXES OF 260 STARS

6 DRACONIS (178 28"; +52° 22’)

403

The only parallax which has been published for this star of
magnitude 2.99, of type G and of small proper motion 07016
is the spectroscopic value + 0%014. Mr. Alden measured four-

 

 

 

teen of the photographs, and Mr. Mitchell thirteen. A relative
TABLE 1
Puatres oF 8 Draconis
No. Date. Hour Angle. Observers. Weight.
2535 1916 Mar. 30 —0h2 A 0.7
2563 Apr. 6 —0.6 A 0.8
2564 Apr. 6 —0.2 A 0.8
2683 May 2 1.2 A 0.8
2808 July 11 —0.8 Ol 0.5
2875 Aug. 17 —0.2 A 0.8
2876 Aug. 17 +0.1 A 0.8
2895 Aug. 19 —0.1 A 1.0
3748 1917 Mar. 9 —1.2 A 1.0
3843 Apr. 3 —1.1 M 1.0
3857 Apr. 7 —0.3 i 1.0
3866 Apr. 9 —0.9 M 0.8
3867 Apr. 9 0.4 M 0.8
4210 July 31 —0.3 A 0.9
.4211 July 31 * 0.0 A 0.9
5227 1918 Mar. 26 —0.6 A 0.8
5228 Mar. 26 —0.1 A 1.0
5250 Mar. 29 —0.8 A 1.0
5251 Mar. 29 —0.4 A 1.0
5591 Aug. 5 —0.5 A 0.8
5592 Aug. 5 —0.1 A 0.8
5658 Aug. 26 +0.1 A 0.7
5659 Aug. 27 +0.1 A 0.7
6635 1919 Mar. 5 —1.5 M 0.8
6636 Mar. 5 —-1.1 M 1.0
6858 Apr. 8 -1.2 D 1.0
6859 Apr. 8 —0.8 D 1.0

 

 

 

 

 
404 S. A. MITCHELL

parallax of — 07015 + 07007 was determined, and a proper
motion inright ascension — 0”024 while the corresponding value
from Boss is — 07014.

TABLE 2

ReEpvuctTIoNns FOR § Draconis

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Timein |" Residual : Vp-0
Plate. (m). . | Factor (P). | Days @). (). in Are.

mm. mm.
2535 —0.0133 0.7 +0.951 —523 +0.0012 +0702
2563 — .0074 0.8 + .910 —516 — .0047 — .09
2564 — .0113 0.8 + .910 —516 - -0008 — .01
2633 — .0130 0.8 + .651 —490 + .0010 + .02
2808 — .0147 0.5 — .455 —420 + .0033 + .05
2875 — .0104 0.8 — .892 —383 — .0007 — .01
2876 — .0088 0.8 — .892 —383 — .0023 — .04
2895 — .0118 1.0 — .907 —381 + .0007 + .01
3748 — .0136 1.0 + .990 —179 + .0004 + .01
3843 — .0146 1.0 + .931 —154 + .0014 + .03
3857 - — .0104 1.0 + .905 —150 — .0028 — .06
3866 — .0165 0.8 + .891 —148 + .0033 + .06
3867 — .0133 0.8 + .891 —148 + .0001 .00
4210 — .0160 0.9_ — .722 — 35 + .0036 .07
4211 — .0112 0.9 — .722 — 35 — .0012 — .02
5227 a 0139 0.8 + 973 +203 — .0005 — .01
5228 — .0186 | 1.0 + .973 +203 — .0008 — .02
5250 — .0152 1.0 + .959 +206 + .0008 + .02
§251 — .0164 1.0 + .959 +206 |} + .0020 + .04
5591 — .0145 0.8 — .776 +835 + .0010 + .02
5592 — .0122 0.8 — .776 +335 — .0013 — .02
5658 — .0130 0.7 — .949 +356 — .0004 — .01
5659 — .0120 0.7 — .954 +357 — .0014 — .02
6635 — .0118 0.8 + .981 +547 — .0036 — .07
6636 — .0177 1.0 + .981 +547 + .0022 + .05
6858 — .0136 1.0 + .902 +581 — .0019 — .04
6859 —0.0166 1.0 +0.902 +581 +0.0011 +0.02

 
PARALLAXES OF 260 STARS 405

CoMPARISON STARS

 

 

 

 

 

 

 

No. Diameter. |X yes Ascen-| Y (Declination). Dependence.
mm. Tam. mm.

1 0.10 —27.5 —37.9 - +0.2553

2 .16 —27.6 +25.9 . 2290

3 .08 + 6.1 —36.3 . 2673

4 .18 +49.0 +48.3 +0.2484
Parallax star 0.16 + 0.5 — 1.4

 

The normal equations are:

23.2¢c + 3.888 + 7.69837 = — 0.3086 mm.
+ 312.3368 + 8.8508¢ = — 0.1554 mm.

+ 18.50467 = — 0.1165 mm.
from which:
c = — 0.01301 mm.
uw = — 0.00031 mm. = — 00065, or — 07024 per year.
aw = — 0.00074 mm. = — 07015 + 07007.

Probable error of plate of unit weight
+ 0.00132 mm. = + 0"027.

8 OPHIUCHI (17> 38"; +4° 36’)

By photography, the Allegheny Observatory has measured
the parallax of this star, and found the result + 07018 + 07009.
The spectroscopic value of Mt. Wilson is + 07023. The magni-
tude is 2.94, the type K, and the total proper motion 07158.
Fifteen of the McCormick plates were measured by Mr. Mitchell,
the balance by Mr. Briggs, with a relative parallax found of
+ 07021 + 07010, a result in good agreement with Allegheny
and Mt. Wilson. The proper motion from the plates in right
ascension is — 0"029 while the corresponding value from Boss is
— 07041.
406 S. A. MITCHELL

‘

 

 

 

TABLE 1
PLatEs oF @ OPHIUCHI
No. Date. Hour Angle. Observers. Weight.
1076 1915 Mar. 17 —017 G 0.7
1110 Mar. 24 —0.6 G 0.5
1177 Apr. 9 —0.4 A 0.5
1448 July 9 —0.1 A 0.8
1449 July 9 +0.5 A 0.5
1491 July 18 +0.5 G 0.4*
1492 July 18 +1.0 G 0.4*
3887 1917 Apr. 16 —0.5 A 0.6*
3960 May 14 —0.9 Ol 0.8
3961 May 14 —0.5 ol 0.8
4173 July 13 +0.6 Ol 0.8
4174 July 13 +1.0 Ol 0.8
4239 Aug. 5 0.0 B 0.7
4240 Aug. 5 +0.4 B 0.7
5359 1918 May 9 —0.3 Ol 1.0
5360 May 9 +0.3 Ol 1.0
5366 May 14 —0.8 Ol 0.8
5367 May 14 —0.4 Ol 0.8
5642 Aug. 22 +0.4 A 1.0
5668 Sept. 1 +0.3 A -0.8
5669 Sept. 1 +0.6 A 0.8
6687 1919 Mar. 12 —1.0 H 1.0
6739 Mar. 23 —1.4 D 1.0
6740 Mar. 23 —0.9 D 1.0
6792 Mar. 30 —0.6 F 1.0
6793 Mar. 30 —0.1 F 1.0

 

 

 

 

 

* One exposure.
PARALLAXES OF 260 STARS

REDUCTIONS FOR 6 OPHIUCHI

TABLE 2

407

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p). Factor (P). | Days (¢). (). in Are.
mm. ; mm.
1076 —0.0383 0.7 +0.995 —847 —0.0022 —0°04
1110 — .0379 0.5 + .994 —840 — .0026 — .04
1177 — .0388 0.5 + .938 — 824 — .0019 — .03
1448 — .0434 0.8 — .315 —733 + .0011 + .02
1449 — .0437 0.5 — .315 —733 + .0014 + .02
1491 — .0406 0.4 — .456 —724 — .0018 — .02
1492 — .0397 0.4 — .456 —724 — .0028 — .04
3887 — .0473 0.6 + .887 — 86 + .0039 + .06
3960 — .0477 0.8 + .579 — 58 + .0038 + .07
3961 — .0460 0.8 + .579 — 58 + .0021 + .04
4173 — .0458 0.8 — .387 sf 2 + .0007 + .01
4174 — .0459 0.8 — .387 + 2 + .0008 + .01
4239 — .0478 0.7 — .708 + 25 + .0023 + .04
4240 — .0460 0.7 — .708 + 25 + .0005 + .01
5359 — .0490 1.0 + .648 +302 + .0038 + .08
5360 — .0435 1.0 + .648 +302 — .0017 — .04
5366 — .0473 0.8 + .582 +307 + .0020 + .04
5367 — .0402 0.8 + .582 +307 — .0051 — .10
5642 — .0486 1.0 — .878 +407 + .0014 + .03
5668 — .0430 0.8 — .948 +417 — .0043 — .08
5669 — .0459 0.8 — .948 +417 — .0014 — .02
6687 — .0433 1.0 + .987 +609 — .0027 — .06
6739 — .0480 1.0 + .995 +620 + .0019 + .04
6740. — .0437 1.0 + .995 +620 — .0024 — .05
6792 — .0446 1.0 + .981 +627 — .0015 — .03
6793 —0.0484 1.0 +0.981 +627 +0.0023 +0.05
The normal equations are:

20.2¢ + 22:092u + 5.50782 = — 0.9064 mm.

+ 502.6009u + 17.97367 = — 1.1606 mm.

+ 12.34177 = — 0.2407 mm.
408 S. A. MITCHELL

Comparison STARS

 

 

 

 

 

 

 

 

No. Diameter. x ee Y (Declination). Dependence.
mm. mm. | mm.
1 0.15 —53.9 —29.4 +0.197
2 13 —26.6 +41.8 .170
3 ll +15.4 —40.8 .226
4 -10 +21.2 +41.0 .186
5 .12 +43.9 —12.6 +0.221
Parallax star 0.15 + 1.9 — 3.0
from which:
c = — 0.04473 mm.
uw = — 0.00038 mm. = — 070079, or — 07029 per year.
a = + 0.00101 mm. = + 07021 + 07010.

Probable error of plate of unit weight
+ 0.00159 mm. = + 07033.

uw HERCOULIS (17: 42"; -+27° 47’)

This star, of magnitude 3.48 and type G5 is the brighter star
of the well-known system. It has a total proper motion 0”817
per year, which is shared by the companions BC, so that all
three stars form a physical system. The parallax of the brighter
star has been several times determined, as follows: Chase with
Yale heliometer, + 07122 + 07038; Russell by photography
found the value for the principal star, + 0”024 + 07028, and
for the companions BC the value + 07051 + 07049; Flint by
meridian circle obtained + 07126 + 07022; while Jewdokimov,
also by meridian circle found + 0”093 +0”070. The Allegheny
value by photography is + 07104 + 0”008. Adams by the spec-
trograph found the parallax + 0”132. Mr. Mitchell measured
the McCormick plates and found a parallax of + 07108 + 0"009.
With the: McCormick value of the parallax and Aitken’s orbit
(Lick Observatory Publications, 12, 119), the mass of the system
BC is 0.81 ©.
PARALLAXES OF 260 STARS

TABLE 1

PLatTes oF » HERCULIS

409

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
3927 1917 May 1 —047 L 0.7
3928 May 1 —0.4 L 0.7
3948 May 12 —1.3 Ol 0.7
3949 May 12 —0.9 ol 0.7
4012 May 25 —0.2 Ol 0.7
4237 Aug. 5 —0.9 B 0.7
4238 Aug. 5 —0.6 B 0.7
4258 Aug. 12 —0.5 B 0.5
4259 Aug. 12 —0.2 B 0.4*
5298 1918 Apr. 15 —-1.2 A 1.0
5299 Apr. 15 —0.8 A 1.0
5337 May 1 —-1.3 A 0.9
5338 May 1 —0.9 A 1.0
5629 Aug. 19 +0.1 A 1.0
5645 Aug. 23 +0.2 A 1.0
5660 Aug. 27 +0.2 A 1.0
6669 1919 Mar. 1 —1.2 Ol 1.0
6670 Mar. 1 —0.8 Ol 0.9
6706 Mar. 20 —1.3 D 0.8
6707 Mar. 20 —0.9 D 0.7

* One exposure.
Comparison STARS
No. Diameter. x ee Y (Declination). Dependence.
1 0.14 —43.3 +16.4 +0.232
2 .10 —35.3 +25.2 - 247
3 .10 +31.2 —54.0 -223
4 -13 +47.4 +12.4 +0.298
Parallax star 0.13 + 2.4 + 1.7

 

 

 

 

 
410 S. A. MITCHELL

TABLE 2

REDUCTIONS FOR » HERCULIS

 

 

 

 

 

 

 

 

 

Solution Weight Parallax ~ Time in Residual vp-v
Plate. (m). (p). | Factor (P). | Days (). (v). in Are.

mm. mm,
3927 +0.0022 0.7 +0.711 —301 +0.0001 0°00
3928 + .0020 0.7 + .711 —301 + .0003 -00
3948 + .0014 0.7 + .569 —290 — .0002 -00
3949 — .0019 0.7 + .569 —290 + .0031 + .05
4012 + .0030 0.7 + .875 —277 — .0033 — .06
4237 — .Ol11 0.7 — .739 —205 + .0026 + .05
4238 — .0079 0.7 — .739 —205 — .0006 — .01
4258 — .0090 0.5 — .814 —198 — .0002 -00
4259 — 0117 0.4 — .814 —198 + .0026 | + .03
5298 — .0076 1.0 + .875 + 48 — .0011 — .02
5299 — .0103 1.0 + .875 + 48 + .0016 | + .03
5337 — .0086 0.9 + .714 + 64 — .0015 — .03
5338 — .0077 1.0 + .714 + 64 — .0024 — .05
5629 — .0196 1.0 — .876 +174 — .0025 — .05
5645 — .0236 1.0 — .907 +178 + .0012 + .02
5660 — .0226 1.0 — .934 +182 — .0001 .00
6669 — .0174 | 1.0 + .955 +368 — .0018 — .04
6670 — .0197 0.9 + .955 +368 + .0006 + .01
6706 — .0193 0.8 + .994 +387 — .0003 — .01
6707 —0.0251 0.7 +0.994 +887 +0.0055 +0.10

 

The normal equations are:
16.1c + 5.448y + 3.98247 = — 0.1851 mm.

+ 98.1844 + 6.85527 = — 0.3610 mm.
+ 10.79757 = — 0.0134 mm.
from which:
c = — 0.01163 mm.
# = — 0.00339 mm. = — 070706, or — 07258 per year.
a = + 0.00521 mm. = + 07108 + 07009.

Probable error of plate of unit weight
+ 0.00132 mm. = + 07027.
PARALLAXES OF 260 STARS 411

v OPHIUCHI (17 53"; —9° 45’)

This is a star of K type, of magnitude 3.50, and of small total
proper motion 0712 per year. The spectroscopic parallax of
Adams and Joy is + 07019. The twenty plates of the series
were measured by Mr. Alden, who finds a proper motion in
right ascension of + 07011 per year. The value of Boss is
— 07012 per year.

TABLE 1

Puates oF v OPHIUCHI

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1161 1915 Apr. 7 —045 A 0.7
1291 May 9 —1.1 A 1.0
1292 May 9 —0.5 A 1.0
1469 July 16 +0.3 A 0.8
1480 July 17 +0.4 A 1.0
1481 July 17 +1.0 A 1.0
2634 1916 May 2 —1.0 A 0.9
2849 Aug. 7 +0.7 Ol 0.4*
2977 Sept. 9 +0.6 M 0.7
3898 1917 Apr. 18 +0.2 A 0.9
3899 Apr. 18 +0.4 A 0.7*
3950 May 12 +0.5 Ol 0.8
3962 : May 14 —0.1 Ol 0.5
3973 May 18 —0.8 Ol 0.9
3974 May 18 —0.3 Ol 0.8
4291 Aug. 19 +0.6 A 1.0
4292 Aug. 19 , +1.1 A 1.0
4334 Aug. 25 +0.3 A 0.8
4335 Aug. 25 +0.9 °A 0.8
4363 Aug. 28 +0.3 A 1.0

 

* One exposure.
b12

S. A. MITCHELL

CoMPARISON STARS

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. a (tight Aseenr Y (Declination). Dependence.
mm. mm. mm,
1 0.15 —46.4 — 3.8 +0.2056
2 -10 —38.9 —23.5 . 2051
3 .12 —24.3 +39.4 . 2021
4 .16 +55.6 +44.3 . 1925
5 -10 +54.0 —56.4 +0.1947
Parallax star 0.18 — 1.2 — 0.1
TABLE 2
REDUCTIONS FOR »v OPHIUCHI
Solution Weight Parallax Time in Residual Vp-+o
Plate. (m). (p). | Factor (P). | Days (). 2). in Are.
mm. mm.
1161 +0.0098 0.7 +0.949 — 534 —0.0036 —0706
1291 + .0032 1.0 + .652 —502 + .0028 + .06
1292 + .0060 1.0 + .652 —502 .0000 -00
1469 + .0033 0.8 — .425 —434 + .0015 | + .03
1480 + .0068 1.0 — .441 —433 — .0020 — .04
1481 + .0039 1.0 — .441 —433 + .0009 + .02
2634 + .0068 0.9 + .728 —143 — .0002 -00
2849 + .0048 0.4 — .735 — 46 + .0002 .00
2977 + .0054 0.7 — .985 — 13 — .0006 — .01
3898 + .0026 0.9 + .870 +208 + .0046 + .09
3899 + 0043 0.7 + .870 +208 + .0030 + .05
3950 + .0106 0.8 + .605 +232 — .0036 — .07
3962 + .0105 0.5 + .578 +234 — .0036 — .05
3973 + .0093 0.9 + .522 +238 — .0024 — .05
3974 + .0071 [ 0.8 + .522 +238 — .0002 .00
4291 + .0075 1.0 — .855 +331 — .0021 — .04
4292 + .0051 1.0 — .855 +3831 + .0003 + .01
4334 + .0083 0.8 — .904 +337 + .0021 + .04
4335 + .0039 0.8 — .904 +337 + .0015 + .03
4363 +0.0054 1.0 —0.925 +340 0.0000 0.00

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS 413

The normal equations are:
16.7¢ — 1.6602 — 0.61107 = + 0.0981 mm.
+ 200.1036 — 12.38387 = + 0.0053 mm.
+ 9.14577 = + 0.0052 mm.
from which:
c = + 0.00593 mm.
w= + 0.00015 mm. = + 070081 per year.
a = + 0.00116 mm. = + 07024 + 0’011.
Probable error of plate of unit weight
+ 0:00147 mm. = + 07031.

BARNARD’S STAR OF LARGE PROPER MOTION
(17 54™; +4° 25’)

This star has the distinction of having the largest proper
motion at present known, 1073 per year. It is of magnitude
9.7, and oftype Mb. The plates were measured by Mr. Mitchell,
and a relative parallax, + 07539 + 0”008 resulted, with a proper
motion in right ascension — 0"715 per year. Other photo-
graphic determinations of the parallax published are:

 

 

 

 

 

Observatory. Instrument. Parallax.

Dearborn 1814-in. refractor +07557+0°016
Mt. Wilson 60-in. reflector + .519+ .006
Yerkes 40-in. refractor + .509+ .006

 

The value of the McCormick parallax gives for this star an
absolute visual magnitude 13.38, making it one of the smallest
objects known to astronomy outside of the solar system.

CoMPARISON STARS

 

 

 

 

 

No. Diameter. % a Y (Declination). Dependence.
mm. mm. mm.
1 0.14 —24.2 +22.9 +0.245
2 .16 —10.4 — 5.3 .237
3 .12 — 1.4 —38.7 .250
4 15 +19.0 — 1.6 -145
5 _ ll +17.0 +22.7 +0.123
Parallax star 0.15 — 3.91 — 2.78

 

 

 
414

s. A. MITCHELL

TABLE 1

Piares oF Barnarp’s STAR

 

 

No. Date. Hour Angle. Observers. Weight.
2911 1916 Aug. 20 +053 A 0.9
2912 Aug. 20 +0.9 A 0.9
2916 Aug. 25 —0.2 A 1.0
2917 Aug. 25 +0.5 A 1.0
2951 Sept. 3 +0.5 M 1.0
3794 1917 Mar. 22 —1.2 M 0.9
3807 Mar. 24 —0.6 Ol 0.7
3829 Mar. 29 —0.8 M 0.8
3830 Mar. 29 —0.4 M 0.9.
3844 Apr. 3 LG M 0.8
3845 Apr. 3 —0.5 M 0.6*
3860 Apr. 7 —0.4 L 1.0
3861 Apr. 7 0.0 L 1.0
3896 Apr. 18 —0.8 A 1.0
3897 Apr. 18 —0.5 A 0.8
4212 July 31 +0.2 A 0.8
4213 July 31 +0.6 A 0.9
4301 Aug. 20 —0.2 A 0.9
4302 Aug. 20 +0.3 A 1.0
4355 Aug. 27 +0.3 B 1.0
4356 Aug. 27 +0.7 B 1.0
5212 1918 Mar. 18 —0.9 A 1.0
5252 Mar. 29 —0.2 A 1.0
5290 Apr. 14 +0.2 Ol 1.0
5291 Apr. 14 +0.6 ol 0.7
5301 Apr. 15 +0.2 A 1.0
5594 Aug. 5 +0.7 A 1.0
5646 Aug. 23 +0.5 A 0.8
5647 Aug. 23 +0.9 A 1.0
5670 Sept. 1 +0.9 A 0.8

* One exposure.

 
 

 

 

PARALLAXES OF 260 STARS 415
TABLE 2
RepucTIONsS FOR BARNARD’s STAR
Soluti Weigh Parall: Time i i Dp:
Pinte) eae ae | | ae. | | aie
mm. mm.

2911 —0.0404 0.9 —0.868 —345 +0.0010 +0°02
2912 — .0410 0.9 — .868 —345 + .0016 + .03
2916 — .0418 1.0 — .907 —340 + .0010 + .02
2917 — .0417 1.0 — .907 —340 + .0008 | + .02
2951 — .0458 1.0 — .962 —331 + .0027 | + .06
3794 — .0128 0.9 + .995 —131 + .0016 | + .03
3807 — .0142 0.7 + .998 —129 + .0027 | + .05
3829 — .0112 0.8 + .982 —124 — .0010 — .02
3830 — .0131 0.9 + .982 —124 + .0009 + .02
3844 — .0152 0.8 + .964 —119 + .0020 | + .04
3845 — .0111 0.6 + .964 —119 — .0021 — .03
3860 — .0112 1.0 + .944 —115 — .0029 — .06
3861 — .0120 1.0 + .944 —115 — .0021 — .04
3896 — .0156 1.0 + .869 —104 — .0014 | — .03
8897 — .0156 0.8 + .869 —104 — .0014 | — .03
4212 — .0600 0.8 — .648 - 0 — .0062 11
4213 — .0656 0.9 — .648 -— 0 — .0006 | — .O1
4301 — .0682 0.9 — .866 + 20 — .0055 — .1l
4302 — .0710 1.0 — .866 + 20 — .0027 — .06
4355 — .0778 1.0 — .919 + 27 + .0021 + .04
4356 — .0769 1.0 — .919 + 27 + .0012 | + .02
5212 — .0436 1.0 + .996 +230 — .0016 — .03
5252 — .0522 1.0 + .982 +241 + .0056 + .12
5290 — .0538 1.0 + .901 +257 + .0036 | + .07
5291 — .0492 0.7 + .901 +257 — .0010 | — .02
5301 — .0483 | 1.0 + .894 +258 — .0022 | — .05
5594 — .1026 1.0 — .708 +370 + .0000 .00
5646 — .1072 0.8 — .888 +388 — .0017 | — .03
5647 — .1090 1.0 — .888 +388 . 0001 .00
5670 —0.1156 0.8 —0.949 +397 + .0042 | +0.08

 

 

 

 

 

 

 
416 S. A. MITCHELL

The normal equations are:

27.2c + 0.091u + 0.47657 = — 1.3311 mm.
150.000u + 3.43792 = — 1.3280 mm.
22.19477 = + 0.5194 mm.
from which:
c = — 0.04936 mm.
w= — 0.00941 mm. = — 071959 or, — 07715 per year.

a = + 0.02592 mm. = + 07539 + 07008.
Probable error of plate of unit weight
+ 0.00175 mm. = + 07036.

y DRACONIS (17 54"; +51° 30’)

This is a star of 2.42 magnitude, and of K5 type, with small
annual proper motion amounting to 0703. Its parallax has
been many times investigated, but the earlier results are in
general discordant. Some of the more recent values of the
parallax are as follows:

 

 

 

 

Parallax. Authority. Method.
+0°050-+07028 Pritchard Photography
+ .10 + .02 Kostinsky Photography
+ .002+ .021 Flint Meridian circle
— .022+ .058 Jewdokimov Meridian circle
+ .0114 .008 Allegheny Photography
+0°030 Adams Spectrograph

 

Mr. Olivier measured the McCormick series of plates, and
determined a relative parallax of 07000 + 07006, with a proper
motion in right ascension of + 0”%028 while the value from
Boss is — 07008. ;
PARALLAXES OF 260 STARS

TABLE 1

PLATES oF y DRACONIS

417

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1171 1915 Apr. 8 —054 G 1.0
1195 Apr. 13 —0.6 Ol 0.7*
1246 Apr. 24 —0.6 M 1.0
1523 Aug. 6 —0.2 Ol 0.6
1536 Aug. 7 —1.0 Ol 0.9
2487 1916 Mar. 15 —1.2 Ol 0.6*
2588 Apr. 20 -1.4 Ol. 1.0
2589 Apr. 20 —0.8 Ol 0.9
2847 Aug. 7 —0.8 Ol 0.6*
2848 Aug. 7 —0.4 Ol 1.0
2887 Aug. 18 —0.1 Ol 0.9
2913 Aug. 21 —0.1 Ol 0.9
5288 1918 Apr. 14 —1.0 Ol 1.0
5289 Apr. 14 —0.4 ol 0.9
5324 Apr. 27 —1.3 Ol 1.0
5325 Apr. 27 —0.7 ol 1.0
* One exposure.
ComPaRISON STARS
No. Diameter. |* (Bight peest Y (Declination), Dependence.
mm. mm. mm.

1 0.16 —47.3 — 4.8 +0.3349

2 .09 —25.8 —19.1 . 2509

3 .14 +26.5 — 3.2 . 1863

4 .10 +46.6 +27.1 +0.2279

Parallax star 0.16 — 6.8 — 0.8

 

 

 

 

 

28
418 S. A. MITCHELL

TABLE 2

Repvuctions ror y DRAcoNIs

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual . v R v
Plate. (m). (p). Factor (P). | Days (t). (v). in Arc.

mm. . mm. ;
1171 —0.0056 1.0 +0.943- —485 —0.0015 —0703
1195 — .0040 0.7 + .911 —480 + .0001 .00
1246 — .0018 1.0 + .821 —469 + .0022 + .05
1523 — .0036 0.6 — .714 —365 + .0001 .00
1536 — .0057 0.9 — .725 —364 — .0020 — .04
2487 — .0041 0.6 + .983 —143 — .0012 — .02
2588 — .00384 1.0 + .852 —107 — .0007 — .01
2589 — .0011 0.9 + .852 —107 + .0016 + .03
2847 — .0039 0.6 — .734 + 2 — .0016 — .02
2848 — .0016 1.0 — .734 + 2 + .0007 + .01
2887 — .0017 0.9 — .848 + 13 + .0006 + .01
2913 — .0011 0.9 — .874 + 16 + .0012 + .02
5288 — .0013 1.0 + .903 +617: — .0012 — .02
5289 + .0002 0.9 + .903 +617 + .0003 .00
5324 + .0008 1.0 + .789 +630. + .0008 + .02
5325 —~0.0004 1.0 +0.789 +630 —0.0004 —0.01

 

The normal equations are:

14.0¢ + 3.3594 + 4.06997 = —'0.0315 mm.
+ 236.7168 + 10.19987 = + 0.0790 mm.
+ 9.81577 = — 0.0057 mm.

I

from which:

— 0.00234 mm.
+ 0.00037 mm. = + 070076, or + 07028 per year.
+ 0. 00001 mm. = 07000 + 07006.

Probable error of plate of unit weight :
+ 0.00085 mm. = + 07018. |

c

be
T
PARALLAXES OF 260 STARS 419

70 OPHIUCHI (18" 0"; +2° 31’)

This binary system is of more than usual interest. It is one
of the best known and most frequently observed doubles; it
has a period of 88 years, and has completed one revolution since
its discovery. It has a large proper motion of 1713 per year,
and a rather large parallax. According to Campbell, L. O. B.,
5, 63, 1908, the radial velocity of the center of mass is — 7.4 km.
The components are of 4.1 and 6.0 magnitudes with.a distance
of about 4’. An attempt was made to determine the parallax

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. : eo Y (Declination). Dependence.
mm. mm. mm.
1 0.12 —41.0 —23.2 ~  +0.212
2 .12 —35.2 +35.0 240
3 10 +36.8 —29.5 - 263
4 13 +39.4 +17.7 +0.285
- Principal star 22 + 3.7 + 0.9
Companion 0.12 + 3.8 + 0.7

of both components. The rotating sector was used, and was
opened so that the fainter star could be well seen on the photo-
graphs. This had the result of causing the principal star to be
larger on the photographs than would ordinarily be used for
parallax determinations.

A value of the parallax of this star has been published in the
Astrophysical Journal, 42, 263, 1915, the values being obtained
from plates taken in three seasons only. Plates at two addi-
tional seasons were secured. The whole series of plates were
measured by Mr. Mitchell.
420

Puates or 70 OPHIucHI

S. A. MITCHELL

TABLE 1

 

 

 

 

 

No. Date. Hour Angle. Observers. ” Weight.
1 1914 May 2 +044 M 1.0
6 May 9 —0.4 M 0.9
7 May 9 +0.2 M 1.0
10 May 10 +0.3 M 0.9
13 May 11 —1.5 M 0.9
216 Sept. 6 +1.1 M 0.6
249 Sept. 15 +0.6 M 0.9
353 Sept. 30 . +1.3 M 0.9
365 Oct. 1 +1.3 M, Ol 0.7
1120 1915 Mar. 27 —0.5 G 1.0
1183 Apr. 12 —1.0 M 0.7
1203 Apr. 14 —0.9 A 1.0
1213 Apr. 15 —0.9 M 0.9
3845 1917 Apr. 3 —0.4 M 0.8
3908 Apr. 22 —0.8 L 0.9
3909 Apr. 22 —0.3 L 1.0
3996 May 23 —0.8 M 0.7
3997 May 23 —0.3 M 0.8
4278 Aug. 13 —0.4 B 0.9
4279 Aug. 13 +0.1 B 0.9
4322 Aug. 24 —0.2 ol 0.9
4323 Aug. 24 +0.3 ol 0.8

 

 

 
PARALLAXES OF 260 STARS

TABLE 2

Repvuctions ror 70 Opxrucui, Principay Star

42:

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp+o
Plate. (m). (p). Factor (P). | Days (t)- (v). in Are.
mm. mm.
1 —0.0490 1.0 +0.752 —549 +0.0004 +0701
6 — .0486 0.9 + .670 — 542 — .0006 — .01
7 — .0492 1.0 + .670 — 542 - 0000 -00
10 — .0500 0.9 + .657 —541 + .0007 + .01
13 — .0474 0.9 + .644 —540 — .0020 — .04
216 — .0578 0.6 | — .980 —419 — .0029 | — .05
249 — .0582 0.9 -. 995 —413 — .0025 — .05
353 — .0600 0.9 — .994 —398 — .0004 — .01
365 — .0624 0.7 — .992 —397 + .0020 + .04
1120 — .0442 1.0 + .992 —220 + .0035 + .07
1183 — .0406 0.7 + .930 —204 — .0003 — .01
1203 — .0432 ‘1.0 + .917 —202 + .0022 + .05
1213 — .0418 0.9 + .910 —201 + .0008 + .01
3845 — .0244 0.8 + .922 +518 — .00382 — .06
3908 — .0296 0.9 + .850 +537 -| + .0014 + .03
3909 — .0260 1.0 + .850 +5387. — .0022 — .05
3996 — .0306 0.7 + .473 +568 — .0002 .00
3997 — .0280 0.8 + .473 +568 — .0028 — .05
4278 — .0894 0.9 + .831 +655 — .0007 — .01
4279 — .0416 0.9 — .831 +655 + .0015 + .03
4322 — .0422 0.9 — .883 +661 + .0018 + .04
4323 —0.0425 0.8 —0.883 +661 +0.0021 +0.04
The normal equations are:

19.1le + 0.328u + 3.60767 = — 0.8286 mm.

+ 481.3347 — 14.87587 = + 0.7287 mm.

+ 13.4338¢ = — 0.0775 mm.

from which:

c = — 0.04498 mm.
+ 0.00180 mm. = + 070375, or + 07137 per year.
+ 0.00831 mm. = + 07173 + 0°007.

be
T

Probable error corresponding to unit weight
+ 0.00125 mm. = + 07026.
422

S. A. MITCHELL

 

 

 

 

 

 

 

TABLE 3
Repuctions ror 70 OrHiucHi, CoMPANION
Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p Factor (P). | Days (é). (v). in Are.
mm. mm.

1 +0.0768 1.0 +0.752 —549 0.0000 0700

6 + .0808 0.9 + .670 —542 — .0043 — .09

“ + .0777 1.0 + .670 —542 — .0012 — .02
10 + .0762 0.9 + .657 —541 + .0002 -00
13 + .0772 0.9 + .644 | —540 — .0009 — .02
216 + .0678 0.6 — .980 —419 + .0003 -00
249 + .0682 0.9 — .995 —413 + .0001 .00
353 + .0694 0.9 — .994 —398 — .0003 — .01
865 + .0681 0.7 — .992 —397 + .0010 + .02
1120 + .0928 1.0 + .992 —220 + .0029 + .06
1183 + .0974 0.7 + .930 —204 — .0015 — .02
1203 + .0934 1.0 + .917 —202 + .0025 + .05
12138 + .0925 0.9 + .910 —201 + .0034 + .07
3845 + .1308 0.8 + .972 +518 + .0022 + .04
3908 + .1295 | 0.9 + .850 +537 + .0033 + .07
3909 + .1356 1.0 + .850 +537 — .0028 — .06
3996 + .1338 0.7 + .473 +568 — .0027 — .05
3997 + .1362 0.8 + .473 +568 — .0051 — .10
4278 + .1244 0.9 — .831 +655 — .0004 — .01
4279 + .1244 0.9 — .831 +655 — .0004 — .01
4322 + .1238 0.9 — .883 +661 -0000 -00
4323 +0.1208 0.8 —0.883 +661 +0.0030 +0.06

 

 

 

The normal equations are:

19.1¢ + 0.328u + 3.60767 = + 1.9065 mm.
+ 481.3347 — 14.87587
+ 13.48387

from which:

c

bb
T

Probable error corresponding to unit weight
+ 0.00156 mm. = + 07032.

+ 0.09806 mm.

+ 2.3448 mm.
+ 0.3970 mm.

+ 0.00508 mm. = + 071056, or + 0885 per year.
+ 0.00884 mm. = + 07184 + 0°009.
PARALLAXES OF 260 STARS 423

Since these two components form a physical system, the
“values of the parallaxes should be the same. Combining the two
results obtained above, with weights depending on the probable
errors, the parallax of the system is:

+ 07177 + 07006.

Other determinations of the parallax of this system are:

 

 

 

 

 

 

Authority. Method. ag Star ee —
Krueger Heliometer +0°7156+07010
Schur Heliometer + .2864 .031
Jewdokimov Meridian Circle + .2794 .105
Flint Meridian Circle | +0719 +0029
Slocum Photography . +0.212+0.007
Schlesinger Photography +0.184-+0.009
Miller Photography +0.181+40.009

 

The present series of photographs gives the only value of the
parallax of the fainter component so far published. It is to the
measures of the fainter component that we owe additional
information regarding this interesting system.

The equations for 70 Ophiuchi might have been solved by
allowing for the orbital motion. The photographs, however,
were all taken in a comparatively short interval of time, and in
this period of time, the above reductions assumed that the orbital
motion was linear, or in other words, proportional to the time.
Allowance for the orbital motion would have made no appreciable
difference in the values of the parallax, but would have brought
the two values of the proper motion of the two components into
agreement with the proper motion of the system. It is this
difference of proper motion which permits us to obtain the ratios
of the masses of the two components, A and B. Assuming the
value of the proper motion of the system, ua cos 6 = + 07253
as given by Boss in the Preliminary General Catalogue (resulting
from meridian circle observations which stretch over more than a
424 S. A. MITCHELL

whole period of the system), then we readily find that the ratios
of the masses
B/A = 0.88

In Astronomical Journal 32, 153, 1920, Comstock finds the
proper motion of the center of gravity -++ 07246 in right ascen-
sion. Assuming this value, then the above measures give

B/A = 0.79.

According to Comstock, “eight nearly independent .determina-
tions of the mass ratio of the components of 70 Ophiuchi give
B/A = 0.79.”

Assuming a period of 87.9 years, and semi-major axis of 4”56,
then we find the mass of the system is 1.67 times that of the
sun.

99 HERCULIS (18" 3"; +30° 33’)

This is a visual binary of magnitudes 5.2 and 10.5. The
principal star is of type F8, and the system has a total proper
motion 07135. Four determinations of the parallax have been
made, as follows: Flint by meridian circle, + 07074 + 07022;
Adams by spectrograph + 07105; and two values by photog-
raphy, at Allegheny Observatory, + 07025 + 07006, and at
the Sproul Observatory, + 07043 + 07010. Mr. Lamb mea-
sured the McCormick plates, and found a relative parallax of
+ 07044 + 07010, with a proper motion in right ascension
— 07082, while the corresponding value from Boss is — 07095.

The most satisfactory orbit computed for the star is that of
Lohse (Publ. d. Astrophys. Obs. zu Potsdam, 20, 158, 1908), who
found a period of 53.5 years and a value of a equal 1711. Using
Lohse’s values, and the McCormick parallax, the mass of the
system 99 Herculis is 4.1 times that of the sun.
PARALLAXES OF 260 STARS A25

TABLE 1

Piatres oF 99 HERcULIS

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1221 | 1915 Apr. 17 —13 M 0.8
1256 Apr. 26 —0.7 G 0.8
1257 Apr. 26 —0.2 / G 0.6*
1498 July 21 —0.4 G 0.8
2932 1916 Aug. 27 |- —0.4 A 1.0
2933 Aug. 27 0.0 A 1.0
2948 Aug. 31 —0.1 A 0.9
2949 Aug. 31 0.0 A 0.7*
3822 1917 Mar. 25 —0.7 B 0.8
3858 Apr. 7 -1.3 L 1.0
3859 Apr. 7 —1.0 L 1.0
3881 Apr. 13 -—0.3 L 0.8
4020 May 29 —0.5 Ol 1.0
4276 Aug. 18 —0.5 B 1.0
4277 Aug. 18 —0.2 B 0.9
4289 Aug. 19 —0.6 A 1.0
4290 Aug. 19 —0.3 A 1.0
5378 1918 May 17 —0.6 A 1.0
5379 May 17 —0.1 A 1.0
5388 May 25 —0.4 Ol 0.8
5389 May 25 0.0 ol 0.7*
* One exposure.
Comparison STARS

No. Diameter. x ight Ascen-| Y (Declination). Dependence.

1 0.12 —52.4 — 2.3 +0.3511

2 .14 +14.5 —22.6 +0.1296

3 15 +37.9 +24.9 +0.5193

Parallax star 0.14 + 3.2 + 9.2

 

 

 

 
426 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 2
Repuctions ror 99 Hercu.is
Solution -| Weight | Parallax | Time in Residual _Vp-»
Plate. (m). (p). | Factor (P). | Days (2). (2). in Are.
mm, : : : mm. :
1221 +0.0128 0.8 +0.900 —649 —0.0029 —005
1256 + .0073 0.8 + .824 —640 + .0024 + .04
1257 + .0090 0.6 + .824 —640 + .0007 + .01
1498 + .0078 0.8 — .466 —554 — .0018 — .03
2932 + .0008 1.0 — .903 —151 — .0001 .00
2933 — .0005 1.0 — .903 —151 + .0012 + .02
2948 — .0002 0.9 — .931 —147 + .0008 + .02
2949 + .0018 0.7 — .931 —147 — .0012 — .02
3822 + .0047 0.8 + .995 + 59 — .0022 — .04
3858 + .0007 1.0 + .958 + 72 + .0016 + .08
3859 + .0032 1.0 + .958 + 72 — .0010 — .02
3881 — .0040 0.8 + .924 + 78 + .0061 + .11
4020 + .0026 1.0 + .391 +124 — .0021 — .04
4276 — .0021 1.0 — .824 +205 — .0009 — .02
4277 — .0010 0.9 — .824 +205 — .0020 — .04
4289 |. — .0080 1.0 — .884 +206 + .0050 + .10
4290 — .0016 1.0 — .8384 +206 — .0014 — .03
5378 — .0012 1.0 + .571 +477 — .0018 — .04
5379 — .0013 1.0 + .571 +477 — .0016 — .03
5388 — .0052 0.8 + .456 +485 + .0019 + .04
5389 —0.0031 0.7 +0.456 +485 —0.0002 0.00
The normal equations are:

18.6¢c + 4.650u + 0.63987 = + 0.0147 mm.

+ 224.2121u — 0.04407 = — 0.2378 mm.

+ 11.89857 = + 0.0260 mm.

from which:
c = + 0.00099 mm.
ph = — 0.00108 mm. = — 070225, or — 07082 per year.

x = + 0.00213 mm. = + 07044 + 0°010.
Probable error of plate of unit. weight

+ 0.00158 mm. = + 0”033.
PARALLAXES OF 260 STARS 427

SCHJELLERUP 16 (18 14™; —5° 0’)

This is a double of magnitudes 7.9 and 9.2 with the com-
ponents at a distance 273. No other parallax has been deter-
mined. Miss Hawes measured the plates and found a parallax
— 07004 + 07006 with a proper motion in right ascension
+ 0"094.

TABLE 1

Puates or ScHJELLERUP 16

 

 

 

 

 

 

 

No. ? Date. Hour Angle. Observers. Weight.
4379 1917 Aug. 30 +045 B 0.6*
4386 Sept. 1 +0.1 B 1.0
4387 Sept. 1 +0.4 B 0.7*
5401 1918 May 31 —0.1 A 1.0
5692 Sept. 15 +0.5 M 1.0
5693 Sept. 15 +1.0 M 1.0
6741 1919 Mar. 23 -—0.8 D 0.8
6822 Apr. 2 —0.8 H 1.0
6903 Apr. 18 -0.5 D 1.0
6904 Apr. 18 0.0 D 1.0
7446 Aug. 9 0.0 H 0.8
7539 Aug. 23 1,1 H 1.0
7617 Sept. 3 +0:4 F 0.7
7773 Sept. 24 +0.8 A 1.0

 

* One exposure.

ComPaRISON STARS

 

 

 

 

No. Diameter. ae eon gaa Y (Declination). Dependence.
1 0.15 —16.3 +42.7 +0.279
2 .09 -—17.9 —23.2 .276
3 .10 — 6.0 —19.5 .224
4 -15 +10.9 —17.8 .149
a) -20 +29.3 +17.8 +0.072
Parallax star 0.17 -— 7.1 — 0.2

 

 

 

 
428 S. A. MITCHELL

TABLE 2

REDUCTIONS FOR SCHJELLERUP 16

 

 

 

 

 

 

 

 

 

 

Solution Weight | Parallax Time in Residual Vp-0
Plate. _(m). (p). | Factor (P). | Days (t). (0). in Are.

mm. mm. :
4379 +0.0008 0.6 —0.903 —450 —0.0001 0°00
4386 + .0010 1.0 — .917 —448 — .0002 .00
4387 + .0009 0.7 — .917 —448 — .0001 -00
5401 + .0028 1.0 + .406 —176 + .0011 | + .02
5692 + .0052 1.0 — .986 — 69 + .0003 | + .01
5693 + .0062 1.0 — .986 — 69 — .0007 | — .0O1
6741 + .0074 0.8 + .997 +120 . 0000. .00
6822 + .0088 1.0 + .987 +130 — .0012 — .02
6903 + .0084 1.0 + .912 +146 — .0006 — .01
6904 + .0070 1.0 + .912 +146 + .0008 + .02
7446 + .0076 0.8 — .689 +259 + .0019 | + .04
7539 + .0080 1.0 — .841 +273 + .0017 + .04
7617 + .0092 0.7 — .927 +284 + .0006 | + .01
7773 +0.0128 1.0 —1.001 +305 —0.0027 —0.06

The normal equations are:
7 12.6c + 1.564 — 3.10027 = + 0.0798 mm.

+ 85.1925u + 6.35197 = + 0.1137 mm.
+ 10.15147 = — 0.1310 mm.
from which:
c = + 0.00613 mm.
w= + 0.00124 mm. = + 070257, or + 0°094 per year.
a = — 0.00019 mm. = — 0/004 + 07006.

Probable error of plate of unit weight
+ 0.00085 mm. = + 07018.

x DRACONIS (18 22"; +72° 41’)

This star of 3.69 magnitude and F8 type has a considerable
proper motion of 0764. Its parallax has been determined three
times with the following results: With Yale heliometer, Chase
PARALLAXES OF 260 STARS 429

obtained the parallax + 0711 + 07038; by photography the
Greenwich Observatory derived the value + 0”107 + 0011.
Mr. Olivier measured the McCormick series of plates, and found
the annual proper motion in right ascension to be + 0”435,
while the result from Boss is + 07495. ‘

 

 

 

TABLE 1
Puates oF x Draconis

No. | Date. Hour Angle. Observers. Weight.

22 1914 May 17 —048 M 1.0

23 May 17 —0.2 M 0.9

30 May 19 —0.4 M 1.0
203 Sept. 5 0.0 M 0.7
1143 1915 Mar. 31 —0.9 A 0.9
1550 Aug. 14 —0.7 Ol 0.8
1567 Aug. 23 —0.3 01 0.9
2602 1916 Apr. 26 —0.5 Ol 0.5
2618 Apr. 29 -1.1 Ol 0.7
2619 Apr. 29 —0.6 Ol 0.6*
2630 May 1 —1.2 Ol 0.9
2631 May 1 —0.6 Ol 0.8
2840 Aug. 4 —-0.1 Ol 0.9
2896 Aug. 19 —0.5 Ol 0.8
2897 Aug. 19 0.0 Ol 0.8
2962 Sept. 4 —0.3 Ol 0.6*
3002 Sept. 15 +0.2 ol 0.8

 

 

 

 

 

* One exposure.

ComPARISON STARS

 

 

 

 

No. Diameter. oe eo Y (Declination). Dependence.
NX
mm. mm. mm.
1 0.12 —42.2 +32.6 +0.2455
2 08 —41.8 —14.4 2295
3 18 +36.8 —20.8 2565
4 22 +47.2 + 2.6 -+0.2685
Parallax star 0.23 + 2.2 + 0.1

 

 

 

 
430

8. A. MITCHELL

TABLE 2

REDUCTIONS FOR x DRAcoNIS

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp+0
Plate. ‘m).  * (p). Factor (P). | Days (¢). (v). in Arc.
mm. mm.

22 +0.0058 1.0 +0.617 —583 —0.0029 —0'06
23 + .0025 0.9 + .617 —533 + .0004 + .01
30 + .0022 1.0 + .605 —531 + .0007 + .01
203 + .0012 0.7 — .930 —423 + .0013 + .02
1143 + .0224 0.9 + .994 —217 + .0002 .00
1550 + .0237 0.8 — .728 — 80 — .0007 — .01
1567 + .0206 0.9 — .824 — 71 + .0025 + .05
2602 + .0478 | 0.5 | + .857 | +176 | — .0033 | — .05
2618 + .0471 0.7 + .830 +179 — .0025 — .04
2619 + .04382 0.6 + .830 +179 + .0014 + .02
2630 + .0404 0.9 + .811 +181 + .0042 + .08
2631 + .0438 0.8 + .811 +181 + .0008 + .01
2840 + .0476 0.9 — .612 +276 — .0037 — .07
2896 + .0460 0.8 — .791 +291 — .0020 — .04
2897 + .0416 0.8 — .791 +291 + .0024 + .04
2962 + .0415 0.6 — .927 +3807 + .0028 + .04
3002 | +0.0469 | 0.8 | —0.981 | +318 | —0.0022 | —0.04

The normal equations’ are:

13.6c — 3.8204 + 0.42577 = + 0.3983 mm.

+ 145.3349 — 11.88137 = + 0.6644 mm,

+ 8.623602 = — 0.0178 mm.

from which:

ce = + 0.03076 mm.
+ 0.00573 mm. = + 071192, or + 07435 per year.
+ 0.00432 mm. = + 07090 + 0"011.

Probable error of plate of unit weight
+ 0.00153 mm. = + 07032.

be
T
PARALLAXES OF 260 STARS 431

110 HERCULIS (18 41"; +20° 27’)

Jost has determined with the meridian circle the parallax of
this star to be + 07057 + 07022, and Allegheny by photography
+ 07040 + 07011, while Adams finds the value with the spectro-

TABLE 1

Puates or 110 Hercutis

 

 

 

 

 

 

 

_ No. Date. Hour Angle. / Observers. Weight.
1309 | 1915 May13 | —1%5 M 0.8
1566 Aug. 21 40.2 A 1.0
1592 “Aug. 30 +0.2 A 0.9
1593 Aug. 30 +0.7 A 1.0
1682 Sept. 14 - 0.1 M 0.8
2636 1916 May 2- —0.6 A 0.9
2637 May 2 0.1 A 1.2t
2650 . May 7- —0.4 A + 0.9
2651 May 7- 0.0 A 0.9
2873 - “Aug. 16 0.0 A 1.0
2874 Aug. 16-- 40.6 A 0.9
2878 , Aug. 17 - —0.1 A 0.6
2879 Aug. 17 +0.3 A 0.9
2937 “Aug. 30 - 40.7 A 1.0
2091 ~ Sept. 10: - -0.3 M 1.0
4041 | 1917 June 7 -0.5 o 6| o8
4042 | June 7 =0.4 Ol 0.8
4047 | June 8 | —0.3 A 1.0

|
4190 July 29 —0.5 B 0.8

4191 - July 29 it B 0.8
4234 ; Aug. 4 —0.4 B 1.1f
4235 Aug. 4 0.0 B 0.8
7799 1919 Sept. 26 40.1 Ol 1.0
7800 Sept. 26 +0.7 Ol 1.0
7817 Sept. 27 +0.3 D 1.0
7818 Sept. 27 07 D 1.0

 

} Three exposures.
432 S. A. MITCHELL

scope + 07060. It is of F5 type, of magnitude, 4.26, and of
total proper motion 0734. The plates of the series were measured
by Mr. Alden, who derives the proper motion in right ascension
+ 0002, while the corresponding value from Boss is — 07021.

TABLE 2

Repvuctions ror 110 Hercutis

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp-v
Plate. (m). (p). | Factor (P). | Days (). (). in Arc.

mm. mm. :
1309 —0.0091 0.8 +0.741 —638 —0.0029 —0°705
1566 — .0150 1.0 — .752 — 538 — .0013 — .03
1592 — .0160 0.9 — .843 —529 —~.0006 — .01
1593 — .0203 1.0 — .843 —529 + .0037 + .08
1682 — .0182 0.8 — .951 —514 + .00138 + .02
2636 — .0134 0.9 + .845 —283 + .0018 + .04
2637 — .0110 | 1.2 | + .845 | —283 | — .0006 | — .01
2650 — .0103 0.9 + .797 —278 — .0015 — .03
2651 — .0116 0.9 + .797 —278 — .0002 .00
2873 — .0171 1.0 — .703 —177 + .0010 + .02
2874 — .0165 0.9 — .703 —177 + .0004 + .01
2878 — .0125 | 0.6 — .715 —176 — .0036 — .06
2879 — .0164 0.9 — .715 —176 + .0003 + .01
2937 — .0122 1.0 — .850 —163 — .0043 — .09
2991 — .0173 1.0 — .9382 —152 + .0006 + .01
4041 — .0146 0.8 + .393 +118 + .0018 + .03
4042 — .0140 0.8 + .393 +118 + .0012 + .02
4047 — .0134 1.0 + .377 +119 + .0005 + .01
4190 — .0162 0.8 — 454 +170 + .0009 + .02
4191 — .0170 0.8 — .454 +170 + .0017 + .03
4234 — .0134 1.1 — .542 +176 — .0021 = -05
4235 — .0199 0.8 — .542 +176 + .0044 + .08
7799 — .0157 1.0 — .992 +959 — .0009 — .02
7800 — .0150 1.0 — .992 +959 — .0016 — .03
7817 — .0172 1.0 — .994 +960 + .0006 + .01
7818 —0.0167 1.0 —0.994 +960 +0.0001 | 0.00
PARALLAXES OF 260 STARS 433

Comparison STARS

 

 

 

 

 

 

No. Diameter. , Pe SS Y (Declination). Dependence.
mam. mm. mm.

1 0.12 | —42.6 —29.6 +0.2294

2 .16 —17.2 — 6.3 . 2033

3 .16 —10.4 —21.2 - 2285

4 .12 + 2.9 +383.1 - 1506

5 .16 +67.3 424.0 +0.1882
Parallax star 0.16 — 2.5 — 3.4

 

The normal equations are:

23.9c + 2.7754 — 8.22527 = — 0.3583 mm.
+ 564.5190u — 29.27707 = — 0.1082 mm.
+ 14.23977 = + 0.1556 mm.
from which:
c = — 0.01400 mm.

w= + 0.00003 mm. + 070006, or +0”002 per year.
x = +.0.00290 mm. = + 07060 + 07009.

Probable error of plate of unit weight
+ 0.00132 mm. = + 07027.

y LYRE (18* 55"; +32° 33’)

No parallax has been determined for this interesting star in
Lyra. It is of magnitude 3.30, of type A, and of small proper
motion 07007. Mitchell (Astrophysical Journal, 30, 241, 1909),
has found it to be a spectroscopic binary. Twelve of the McCor-
mick plates were measured by Mr. Alden, and eleven by Mr.
Mitchell. A relative parallax + 07007 + 07009 was found,
with a proper motion in right ascension — 07003 while the
corresponding value from Boss is — 07002.

29
434 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Puates or y Lyrm
No. Date. Hour Angle. Observers. Weight.
2992 1916 Sept.10 . 040 M 0.8
2999 Sept. 12 —0.4 M 1.0
3000 Sept. 12 —0.1 A 1.0
3009 Sept. 17 —0.4 M 1.0
3882 1917 Apr. 13 —0.7 L 0.7
3900 Apr. 19 —1.0 M 1.0
3901 Apr. 19 —0.6 M 1.0
3985 May 19 —0.6 M 0.8
4241 Aug. 5 —0.1 B 0.7
4260 Aug. 12 —0.6 B 0.8
4261 Aug. 12 —0.2 B 1.0
4344 | Aug. 26 —0.8 A 1.0
4345 Aug. 26 —0.4 A 1.0
5313 1918 Apr. 22 —0.6 A 1.0
5314 Apr. 22 —0.1 A 0.7*
5341 May 1’ —0.8 A 1.0
5380 May 17 —0.2 A 0.7*
5402 May 31 -0.2 A 0.9
5630 Aug. 19 —0.6 A 1.0
5631 Aug. 19 —0.1 A 1.0
5676 Sept. 13 —0.4 M 1.0
5679 Sept. 14 —0.4 M 0.9
5680 Sept. 14 —0.1 M 1.0 »
* One exposure.
Comparison STARS

No. Diameter. es a a Y (Declination). Dependence.

1 0.11 —41.4 —26.8 +0.1842

2 .16 —31.6 + 6.1 .1813

3 .08 +10.6 —12.1 . 2088

4 .08 +14.9 +57.5 . 1938

5 13° +47.5 —24.7 +0.2320

Parallax star 0.15 + 2.8 — 0.9

 

 

 

 
PARALLAXES OF 260 STARS

TABLE 2
Repuctions For y Lyra

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vv D- v
Plate. (m). (p). | Factor (P). | Days (). (). in Are.
mm. ; mm.
2992 +0.0156 0.8 —0.908 —402 —0.0030 —0"06
2999 + .0124 1.0 — .922 —400 + .0002 .00
3000 + .0108 1.0 — .922 —400 + .0018 + .04
3009 + .0122 1.0 — .950 —395 + .0004 + .01
3882 + .0084 0.7 + .980 —187 + .0047 + .08
3900 + .0133 1.0 + .957 —181 “ .0002 .00
3901 + .0136 1.0 + .957 —-181 — .0005 — .0O1
3985 + .0106 0.8 + .702 —151 + .0024 + .04
4241 + .0154 0.7 — .508 — 73 — .0028 — .05
4260- + .0116 0.8 — .605 — 66 + .0010 + .02
4261 + .0127 1.0 — .605 — 66 — .0001 -00
4344 + .0142 1.0 — .774 — 52 — .0017 —..04
4345 + .0135 1.0 — .774 — 52 — .0010 — .02
5313 + .0138 1.0 + .943 +187 — .0008 — .02
5314 + .0118 0.7 + .943 +187 + .0017 + .03
5341 “+ .0179 1.0 + .884 +196 — .0050 — .10
5380 + .0131 0.7 + .728 +212 — .0002 .00
5402 + .0108 0.9 + .548 +226 + .0020 + .04
5630 + .0138 1.0 — .692 +306 — .0014 — .03
5631 + .0154 1.0 — 692 +306 — .0030 — .06
5676 + .0078 1.0 — 925 +331 + .0045 + .09
5679 + .0090 0.9 — .931 +332 + .0033 + .07
5680 _+0.0128 1.0 | —0.9381 +3382 —0.0005 —0.01
The normal equations are:
21.0c + 0.353u — 3.938947 = + 0.2660 mm.
+ 141.2080u + 3.99267 = + 0.0012 mm.
+ 14.59277 = — 0.0456 mm.
from which:
c = + 0.01273 mm.
nh = — 0.00003 mm. = — 070007, or — 07003 per year.

wv

+ 0.00032 mm. = + 0”007 + 07009.
Probable error of plate of unit weight

+ 0.00161 mm. = + 0083.

‘
436 ' §. A. MITCHELL

¢ SAGITTARII (18" 56"; —30° 1’)

This well-known and difficult double has components of
magnitudes 3.4 and 3.6, respectively, and the center of gravity
has a small proper motion 07022 per year. On account of its
great southern declination, the star is difficult of access to
northern observatories. Mr. Olivier measured the McCormick
plates with the exception of the four last plates which were
measured by Mr. Mitchell. A relative parallax of + 07018
+ 0"008 was determined with a proper motion in right ascension,
+ 07066 while the corresponding value from Boss is — 07022.
The only determination of the parallax published is the meridian
circle result of Flint, + 07115 + 07037. Aitken (Publications
of the Lick Observatory, 12, 135, 1914), finds the period of revo-

 

 

 

TABLE 1
Puates oF ¢ SAGITTARII
No. Date. 4 Hour Angle. Observers. Weight.
3045 1916 Sept. 20 040 M 0.9
3054 Sept. 21 +2. 4 M 0.8
3089 Sept. 26 0.0 Ol 0.8
3910 1917 Apr. 22 —0.6 L 1.0
3911 Apr. 22 —0.3 L 0.7
4013 May 25 —1.0 Ol 0.7
4418 Sept. 12 —0.5 Ol 0.9
4419 Sept. 12 —0.1 Ol 0.6*
4430 Sept. 13 —0.3 M 1.0
4431 ‘Sept. 13 0.0 A 1.0
4432 Sept. 17 —0.2 M 0.6*
5327 1918 Apr. 27 —0.7 Ol 0.8
5328 Apr. 27 —0.2 Ol 1.2}
5372 May 16 —1.2 Ol 1.0
5373 May 16 —0.7 Ol 1.0
5681 Sept. 14 +0.4 M 0.8
5682 : Sept. 14 +0.8 M 1.0
5707 Sept. 22 +0.8 M 1.0
5708 Sept. 22 +1.2 M 1.0

 

 

 

 

 

* One exposure. { Three exposures.
wf.

PARALLAXES OF 260 STARS

437

lution of the double to be 21.17 years, and the semi-major axis,
a = 0565. With these values and the McCormick parallax,
the mass of the system is 33.1 times that of the sun.

CoMPARISON STARS

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. |* ae aa Y (Declination). Dependence.
mm. mm. mm.
1 0.18 —50.5 +17.3 +0.2918
2 -10 —41.7 —40.8 .1192
3 11 + 7.6 + 1.9 . 1949
4 .19 +34.6 —16.0 .1290
5 17 +50.0 +37.6 +0.2151
Parallax star 0.19 — 5.1 + 4.5
TABLE 2
REDUCTIONS FOR ¢ SAGITTARII
Plate. Solution Weight Parallax Time in Residual Vp-v
‘m). (p). Factor (P). | Days (t). (v). in Are.
mm. mm.
8045 —0.0140 0.9 —0.962 —408 —0.0006 —0701
8054 — .0119 0.8.| — .967 —407 — .0027 — .05
3089 — .0154 0.8 — .983 —402 + .0008 + .01
8910 — .0122 1.0 + .944 —194 + .0011 + .02
8911 — ,0096 0.7 + .944 —194 — .0015 — .03
4013 — .0112 0.7 + .630 —161 + .0001 .00
4418 — .0148 0.9 — .918 — 51 + .0033 +- .07
4419 — .0119 0.6 — .918 — 51 + .0004 + .01
4430 — .0106 1.0 — .924 — 50 — .0009 — .02
4431 — .0111 1.0 — .924 — 50 .0004 — .01
4432 — .0148 0.6 — .947 — 46 + .0033 + .05
5327 — .0054 0.8 + .915 +176 -0025 — .05
5328 — .0070 1.2 + .915 +176 — .0009 — .02
5872 — .0081 1.0 + .743 +195 + .0002 -00
5873 — .0110 1.0 + .748 +195 + .0031 + .06
5681 — .0124 0.8 — .929 +316 + 0041 + .08
5682 — .0086 1.0 — .929 +316 | + .0003 + .01
5707 — .0048 1.0 — .969 +324 — .0034 — .07
5708 | —0.0060 | 1.0 | —0.969 | +324 | —0.0022 | —0.05

 

 

 

 

 

 

 
438 S. A. MITCHELL

The normal equations are:

16.8¢ + 2.9784 — 4.46740 = — 0.1734 mm.
+ 0.0612 mm.
+ 138.86647 = + 0.0597 mm.

+ 103.16124 + 2.46197

from which:
c = — 0.01025 mm.
Lb
a = + 0.00085 mm. = + 07018 + 07008.
Probable error of plate of unit weight
+ 0.00144 mm. = + 07030.

ll

¢ AQUILE (19% 1"; +13° 43’)

This is a star of 3.02 magnitude and A type, with total proper
motion of 0710. The only value of the parallax published is that
of the Allegheny Observatory as the result of photography:
+ 070386 + 07008. The McCormick plates were measured by
Mr. Olivier who found the proper motion in right ascension to be

— 0023 while the value from Boss is — 0%009.

TABLE 1
Puates or ¢ Aquita

+ 0.00087 mm. = + 070181, or + 07066 per year.

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1526 1915 Aug. 6 +057 ol 0.8
1553 Aug. 14 +0.6 Ol 0.7*
1579 Aug. 25 0.0 Ol 0.9
1580 Aug. 25 +0.7 ol 1.0
1731 Sept. 22 0.0 M 0.6*
2667 1916 May 17 —0.3 G 0.8
2668 May 17 0.0 G 1.0
2669 May 17 +0.5 G 0.9
2704 June 3 —1.0 M 1.0
2705 June 3 —0.6 M 1.0
2850 Aug. 7 +0.3 Ol 0.8
2851 Aug. 7 +0.7 ol 0.5*
2914 Aug. 21 —0.5 Ol 0.8
2915 Aug. 21 0.0 Ol 1.0
2916 Aug. 21 +0.2 Ol 0.7*

 

* One exposure.
PARALLAXES OF 260 STARS

ComPaRISON STARS

43

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ne, Diameter. |* (Right Ascen-) y (Hectination). | Dependence.
mm. mm. mm.
1 0.20 —69.9 —32.0 +0.1902
2 17 —33.7 +39.1 .2312
3 .20 +16.9 + 1.7 . 1984
4 .16 +42.7 +19.5 . 2060
5 24 +44.0 —28.3 +0.1742
Parallax star 0.19 — 1.3 + 2.4
TABLE 2
Repvuctions For ¢ AQuILz
Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p). - | Factor (P). | Days (ft). (v). in Are.
mm. mm,
1526 +0.0048 0.8 —0.495 —228 +0.0013 +0°02
1553 + .0079 0.7 — .606 —220 — .0020 — .03
1579 + .0046 0.9 — .741 —207 + .0011 + .02
1580 + .0056 1.0 — .741 —207 + .0001 .00
1731 + .0068 0.6 — .953 —183 — .0014 — .02
2667 + .0080 0.8 + .738 + 57 — .0013 — .02
2668 + .0068 1.0 + .738 + 57 — .0001 .00
2669 + .0045 0.9 + .738 + 57 + .0022 | + .04
2704 + .0050 1.0 + .519 + 74 + .0014 + .03
2705 + .0090 1.0 + .519 + 74 — .0026 — .05
2850 + .0064 0.8 — .520 +139 — .0015 — .03
2851 + .0048 0.5 — .520 +139 + .0001 .00
2914 + .0038 0.8 — .704 +153 + .0008 + .01
2915 + .0054 1.0 — .704 +153 — .0008 | — .02
2916 +0.0023 0.7 —0.704 +153 +0.0023 | +0.04
The normal equations are:
12.5¢ + 0.2564 — 2.20537 = + 0.0720 mm.
+ 28.0338u + 4.068387 = — 0.0025 mm.
+ 5.64117 = — 0.0073 mm.
440 S. A. MITCHELL

from which:
c = + 0.00599 mm. ;
Bw = — 0.00033 mm. = — 070062, or — 0023 per year.

+ 0.00128 mm. = + 07027 + 07010.
Probable error of plate of unit weight
+ 0.00102 mm. = + 07021.

Tv

a SAGITTARII (195 3"; —21° 10’)

The spectroscopic parallax + 07008 has been found for this
star which is of 3.02 magnitude, of F type, and of small proper
motion, 0704. Mr. Olivier measured the McCormick plates
and found a proper motion in right ascension of + 07032 while
the value from Boss is — 07005.

 

 

 

TABLE 1
PLATES OF 7 SaGITTARII
No. Date. Hour Angle. Observers. Weight.
1683 1915 Sept. 14 +051 M 0.9
1684 Sept. 14 +0.5 M 1.0
1693 Sept. 15 —0.1 Ol 0.9
2888 1916 Aug. 18 —0.6 Ol 1.0
2889 Aug. 18 —0.1 Ol 0.9
2890 Aug. 18 +0.3 Ol 0.7
2898 Aug. 19 0.0 Ol 0.9
2899 Aug. 19 +0.3 Ol 0.7
3975 1917 May 18 —0.8 ol 1.0
3976 May 18 —0.4 Ol 0.8
4014 May 25 —0.5 ol 0.9
4015 May 25 0.0 Ol 1.0
4021 May 29 1.1 Ol 1.0
4022 May 29 —0.6 ol 1.0
4263 Aug. 13 —0.4 Ol 0.9 _
4264 Aug. 13 +0.1 Ol 1.0
4323 Aug. 24 +0.3 Ol 0.7
4324 Aug. 24 —0.1 Ol 1.0

 

 

 

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 44
Comparison Stars
No. Diameter. - eo Y (Declination). Dependence.
mm. mm. mm. |
1 0.12 —56.2 —40.6 +0.2142
2 13 —58.6 +14.1 . 1346
3 .12 +22.8 +17.8 . 1923
4 15 +50.8 +34.1 . 1909
5 .09 +41.2 —25.4 +0.2680
Parallax star 0.16 + 5.2 — 3.7
TABLE 2
REDUCTIONS FOR 7 SAGITTARII
Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p). | Factor (P). | Days (2). (0). in Arc
mm. mm.
1683 +0.0099 0.9 —0.914 —457 | —0.0011 —0'02
1684 + .0110 1.0 — .914 —457 — .0022 | — .05
1693 + .0059 0.9 — .920 —456 + .0029 | + .06
2888 + .0081 1.0 — .657 —118 — .0006°| — .O1
2889 + .0032 0.9 — .657 —118 + .0043 | + .09
2890 + .0098 0.7 — .657 —118 — .0023 | — .04
2898 + .0092 0.9 — .670 —117 — .0017 | — .03
2899 + .0061 0.7 — .670 —117 + .0014 | + .02
8975 + .0066 1.0 + .730 +155 + .0006 + .01
3976 + .0098 0.8 + .730 +155 — .0026 | — .05
4014 + .0052 0.9 + .8238 +162 + .0020 + .04
4015 + .0095 1.0 + .823 +162 — .0023 — .05
4021 + .0056 1.0 + .602 +166 | + .0015 | + .03
4022 + .0066 1.0 + .602 +166 + .0005 + .01
4263 + .0072 0.9 — .588 +242 — .0011 — .02
4264 + .0044 1.0 — .588 +242 + .0017 | + .04
4323 + .0058 0.7 — .726 +253 + .0002 .00
4324 +0.0073 1.0 —0.726 +253 —0.0014 | —0.03
The normal equations are:
16.3¢ + 0.360u — 3.6145¢ = + 0.1187 mm.
+ 101.0368 + 15.72427 = — 0.0303 mm.
+ 8.713847 = — 0.0283 mm.
442 S. A. MITCHELL

from which:
ce = + 0.00742 mm.
w= — 0.00042 mm. = — 070087, or — 07032 per year.

a = + 0.00058 mm. = + 07012 + 07012.
Probable error of plate of unit weight
+ 0.00136 mm. = + 07028.

AQUILE 59 (19% 8"; +16° 41’)

The principal star of this wide pair, separated 120’, is
of magnitude 6.44 and type A, and the companion of magni-
tude 7.5. By means of the six-inch telescope, Burnham found
the brighter star to be a double, but with little change. The
brighter star is Lalande 36081, and has a small proper motion
of 0708, while the fainter is Lalande 36074 with a total proper
motion of 0722, and according to Porter, a proper motion in right
ascension of + 07138. Mr. Mitchell measured the McCormick

 

 

 

 

 

TABLE 1
Puates or AQuILe 59

No. Date. Hour Angle. Observers. Weight.
294 1914 Sept.22 | +10 M 0.4*
299 Sept. 23 +0.7 M,G 0.8
1269 1915 May 1 —1.0 M 1.0
1302 May 10 —0.7 G 0.9
1339 June 5 —1.1 M 0.8
1342 June 6 —0.6 A 0.8
1524 Aug. 6 —0.7 Ol 0.8
1568 Aug. 23 —0.4 Ol 0.7*
1569 Aug. 23 0.0 ol 0.9
1600 Sept. 6 -0.6 Ol 0.8
1601 Sept. 6 —0.2 M 0.8
1822 Oct. 12 +0.6 M 0.8
1823 Oct. 12 +0.9 M 1.0
2652 1916 May 7 0.0 A 0.8
2661 May 14 —0.7 A 1.0
2662 May 14 —0.1 A 1.0

 

 

 

* One exposure.
PARALLAXES OF 260 STARS

443

series of photographs. No other parallax measures have been

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

published.
Comparison StTars
Dependences.
No. Diameter. X (Right Y (Declina-
Ascension). tion).
“ Brighter. Fainter.
mm. mm. mm.
1 0.15 —16.4 — 9.6 +0.224 | +0.369
2 .16 —10.8 +43.1 -410 383
3 17 +27.2 —33.5 +0.366 | +0.248
Brighter star 18 + 1.9 + 3.2
Fainter star 0.144 | — 3.4 + 4.6
TABLE 2
Repuctions ror Aquitm 59, BricuTer Srar
Solution Weight Parallax Time in Residual Vpew
Plate. (m). (p). | Factor (P). | Days (®). (v). in Are.
mm. mm.
294 +0.0063 0.4 —0.951 —302 +0.0020 | +0703
299 + .0105 0.8 — .958 —301 — .0021 — .04
1269 + .0094 1.0 + .907 — 81 — .0009 — .02
1302 + .0083 0.9 + .835 — 72 + .0002 .00
1339 + .0088 0.8 + .525 — 46 — .0002 .00
1342 + .0065 0.8 + .511 — 45 + .0021 + .04
1524 + .0098 0.8 — .467 + 16 — .0009 — .02
1568 + .0082 0.7 — .697 + 33 + .0008 |.+ .01
1569 + .0062 0.9 — .697 + 33 + .0028 | + .05
1600 + .0071 0.8 | — .843 + 47 + .0019 | + .04
1601 + .0113 0.8 — .843 + 47 — .0022 — .04
1822 + .0096 0.8 — .990 + 83 — .0004 | — .O1
1823 + .0100 1.0 — .990 + 83 — .0008 — .02
2652 + .0079 0.8 + .854 +291 + .0014 | + .02
2661 + .0086 1.0 | + .788 +298 + .0007 | + .01
2662 +0.0118 1.0 +0.788 +298 —0.0025 —0.05
The normal equations are:
13.8¢ + 5.3884 — 1.01997 = + 0.1183 mm.
+ 38.6736u + 5.94667 = + 0.0543 mm.
+ 8.65387 = — 0.0093 mm.
444 S. A,

from which:
c = + 0.00880 mm.
pw = + 0.00021 mm. =

a = — 0.00018 mm.

Probable error of plate of unit weight

+ 0"0043, or + 07016 per year.

MITCHELL

— 07004 + 07008.

 

 

 

 

 

 

 

 

 

 

+ 0.00109 mm. = + 0022.
TABLE 3
Repuctions ror Aquit# 59, Farnrer Star
Solution Weight Parallax Time in Residual Vpeo
Plate. (m). (p). Factor (P). | Days (t). (2). in Are.
mm. mm.
294 +0.0073 0.4 —0.951 —302 = 0010 | +0701
299 + .0087 0.8 — .958 —301 .0004 | — .O1
1269 + .0110 1.0 + .907 — 81 + .0003 | + .01
1302 + .0118 0.9 + .835 — 72 — .0005 | — .O1
1339 + .0140 0.8 + .525.| — 46 —, .0028 | — .05
1342 + .0090 0.8 + .511 — 45 + .0022 | + .04
1524 + .0125 0.8 — .467 + 16 — .0016 | — .03
1568 + .0101 0.7 — .697 + 33 + .0007 | + .01
1569 + .0088 0.9 — .697 + 33 + .0020 | + .04
1600 + .0064 0.8 — .843 + 47 + .0044 | + .04
1601 + .0110 0.8 — .843 + 47 — .0002 -00
1822 + .0145 0.8 — .990 + 83 — .0035 | — .06
1823 + .0124 1.0 — .990 + 83 — .0014 | — .038
2652 + .0172 0.8 + .854 | +291 — .0033 | — .06
2661 + .0134 1.0 + .788 +298 + .0004 | + .O1
2662 +0.0113 1.0 +0.788 +298 +0.0025 | +0.05
The normal equations are:

13.3¢c + 5.3884 — 1.01997 = + 0.1513 mm.

+ 38.6736 + 5.94667 = + 0.0919 mm.

+ 8.6538¢ = — 0.0004 mm.

from which:
c = + 0.01115 mm.

# = + 0.00070 mm. = + 070147, or + 07054 per year.
a = + 0.00078 mm. = + 0016 + 07011.

Probable error of plate of unit weight

+ 0.00146 mm. =

= 07030.
PARALLAXES OF 260 STARS 445

Z 2481 (195 8™; +38° 37’)

This is a triple system. A and B form the double = 2481, of
magnitudes 8.0 and 8.0, and separated by 378. B and C are
separated by 04, and were discovered by Secchi in 1856. Ac-
cording to Burnham, the proper motion of the triple system is
0°273. The movement of BC with respect to A is rectilinear,
“from which it may be inferred that the double component has a
proper motion differing slightly in direction and amount from
that of A.”’ The parallaxes of these stars have been determined
at Swarthmore by photography with the results: for the star A,
a = + 07016 + 07009, while for the pair BC, r = — 07011
+ 07009. Adams and Joy have found the spectroscopic
parallax + 07036 and + 07050, respectively. Mr. Mitchell
measured the McCormick photographs. Since these stars form
a physical system, they must have a common parallax. The com-
bined value gives the McCormick result for the relative parallax:

+ 07032 + 07007.

 

 

 

 

 

 

TABLE 1
PuaTEs oF = 2481

No. Date. , Hour Angle. Observers. Weight.
171 1914 Aug. 7 —04 Ol 0.8
1310 1915 May 13 -1.3 M 0.9
1326 May 22 —1.0 M 1.0
1362 June 10 —1.5 M 1.0
1363 June 10 —-1.1 M 0.8
1612 Sept. 7 —0.4 A 1.0
1630 Sept. 9 —0.2 Ol 0.9
1639 Sept. 10 —0.8 M 0.8
1640 Sept. 10 —0.4 OLA . 1.0
1663 Sept. 12 —0.7 M 0.9
1664 Sept. 12 —0.3 M 0.8
2683 1916 May 30 —0.9 M 0.8
2684 May 30 —0.6 M 0.8
2692 June 1 —1.3 M 0.7
2693 June 1 —-1.1 M 0.9

 

 
446 S. A. MITCHELL.

An orbit by Russell (Lick Observatory Publications, 12, 1388,
1914), gives the period of BC = Secchi 2 to be 58 years, and
a = 0740. With these values, and the McCormick value of the
parallax, the mass of the system BC is 0.38 times that of the

sun.
Comparison STARS

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. es er Y (Declination). Dependence.
mm, mm. mm.
1 0.19 —24.8 —34.4 +0.277
2 .16 —12.8 +25.0 .409
3 14 +37.6 + 9.4 +0.314
Principal star .19 — 0.4 + 3.6
Companion 0.18 — 0.2 ee
TABLE 2
RepuctTions For 2 2481, Principat Star, A
Solution Weight | Parallax | Time in Residual Vp+o
Plate. (m). (p). Factor (P). | Days (¢). (0). in Are.
mm. mm. 7
171 +0.0324 0.8 —0.487 —448 +0.0001 0”00
1310 + .0254 0.9 + .805 —169 + .0027 | + .05
1326 + .0307 1.0 + .707 —160 — .0030 — .06
1362 + .0261 1.0 + .451 —141 + .0005 |} + .01
1363 + .0266 0.8 + .451 —141 -0000 -00
1612 + .0225 1.0 — .853 — 52 — .0011 — .02
1630 + .0199 0.9 — .870 — 50 + .0014 | + .03
1639 + .0239 0.8 — .878 — 49 — .0026 — .05
1640 + .0208 1.0 — .878 — 49 + .0005 | + .O1
1663 + .0178 0.9 — .873 — 47 | + .0034 | + .06
1664 + .0232 0.8 — .873 — 47 — .0020 — .04
2683 + .0180 0.8 + .596 +214 — .0003 .00
2684 + .0204 0.8 + .596 +214 — .0027 — .05
2692 + .0153 0.7 + .569 +216 + .0023 | + .04
2693 +0.0168 0.9 +0.569 +216 +0.0008 | +0.02

 

 

 

 

 

 

 

The normal equations are:
13.1¢ — 5.014n — 0.98287 = + 0.2983 mm.
+ 40.8608u + 4.55937 = — 0.2056 mm.
+ 6.81737 = — 0.0182 mm.
PARALLAXES OF 260 STARS 44

from which:
c = + 0.02195 mm.
w= — 0.00259 mm. = — 070538, or — 07196 per year.
a = + 0.00223 mm. = + 07046 + 0011.
Probable error of plate of unit weight
+ 0.00136 mm. = + 07028.

 

 

 

 

 

 

 

 

 

TABLE 3
Repuctions ror Z 2481, BC (Seccur 2)
Solution Weight Parallax Time in Residual vVp+o
Plate. (m). (p). Factor (P). | Days (t). (v). in Arc.
mm. mm.

171 +0.1628 0.8 —0.487 —448 +0.0010 +0°02
1310 + .1550 0.9 + .805 —169 | — .0012 — .02
1326 + .1546 1.0 + .707 —160 — .0013 — .03
1362 + .1516 1.0 + .451 —141 + .0007 + .01
1363 + .1508 0.8 + .451 —141 + .0015 + .03
1612 + .1498 1.0 — .853 — 52 — .0022 — .04
1630 + .1474 i 0.9 — .870 — 50 + .0001 .00
1639 + .1513 0.8 — .878 — 49 — .0038 — .07
1640 + .1474 1.0 — .878 — 49 + .0001 .00
1663 + .1444 0.9 — .873 — 47 + .0030 + .06
1664 + .1458 0.8 — .873 — 47 + .0016 + .03
2683 + .1380 0.8 + .596 +214 | + .0002 -00
2684 + .1365 0.8 + .596 +214 + .0017 + .03
2692 + .1380 0.7 + .569 |. +216 + .0001 .00
2693 +0.1392 0.9 +0.569 +216 —0.0010 —0.02

 

The normal equations are:

13.1¢ — 5.014 — 0.9828% = + 1.9356 mm.
+ 40.8608u + 4.559387 = — 0.8929 mm.
+ 6.81737 = — 0.1561 mm.

from which:
c = + 0.14629 mm.
nh = — 0.00400 mm. = — 070832, or — 07304 per year.
a = + 0.00087 mm. = + 07018 + 07010.
Probable error of plate of unit weight
+ 0.00117 mm. = + 07024.
448 S. A. MITCHELL

y 2486 (198 97; +49° 37’)

This star, which is also called Cygni 6, is an interesting example
of the wide discordances of the early values of the parallax.
The McCormick results given below for these stars have already
been published in the Astrophysical Journal, 42, 263, 1915.
Before their publication, the following values of their parallax
had been obtained:

 

 

 

 

 

 

 

Authority. Method. Brighter Star Seale Star as re
‘i é 3
Ball Equatorial |+0"504+0"060
(distance)
Ball Equatorial |+0.383-+0.13
(pos. ang.) .
Ball Equatorial |-+0.482-+0.054
(dist. and
pos. ang.)
A. Hall Equatorial |—0.094+0.025
(A8)
A. Hall Equatorial |—0.137+0.017
: (8)
A. Hall Equatorial |-+0.023-0.009
(Ae)
Chase Heliometer —0.027 40.039
Kostinsky Photography|+0.04 +0.03 |+0.05 +0.03 |+0.04 +0.02
Russell Photography | —0.011 0.049} +0.075+0.063
Flint Meridian +0.045+0.021
Circle
Jewdokimov | Meridian +0.094+0.055
Circle

 

These stars form a system of the 61 Cygni class, with nearly
common proper motion of 0764 per year in position angle 344°.
The stars are of type K, and of magnitudes 6.6 and 6.8. Ac-
cording to Adams and Kohlschiitter (Astrophysical Journal, 39,
346, 1914), these stars, though separated by nearly 10’, un-
doubtedly form a physical system since they have radial velocities
of — 41 and — 39 km. respectively. The values of the parallaxes
below, and their common proper motion confirm this idea. The
f

* PARALLAXES OF 260 STARS

449

rotating sector was used. The plates were measured by Mr.

 

 

 

 

 

 

 

 

 

 

 

Mitchell. ‘
TABLE 1
Puates oF 2 2486

No. Date. Hour Angle. Observers. Weight.
52 1914 May 30 —048 M 0.9
53 May 30 —0.3 M 1.0
58 May 31 -1.1 M 0.7
59 May 31 —0.7 M 1.0
212 Sept. 7 —0.2 M 1.0
237 Sept. 14 —0.1 M,A 1.0
278 Sept. 21 —0.5 M 1.0
279 Sept. 21 0.0 M 1.0
291 Sept. 22 —0.4 M 0.9
292 Sept. 22 0.0 M 1.0
346 Sept. 29 —0.1 M 1.0
1184 1915 Apr. 12 —-1.3 M 0.7
1185 Apr. 12 —1.0 M 1.0
1196 Apr. 13 -1.1 Ol 1.0
1204 Apr. 14 —1.2 A 1.0
1205 Apr. 14 —0.9 A 1.0

ComPaRISON STARS

No. Diameter. Fg so al ¥ (Declination). Dependence.

1 0.15 —55.3 —27.8 +0.192

2 -20 —25.1 +41.2 + .185

3 -10 + 9.6 —32.7 + .209

4 .10 +10.0 +32.6 + .196

5 -21 +60.8 —13.3 +0.218.

Brighter 18 +1.9 — 1.2
Fainter 0.16 + 2.1 — 0.9

 

 

 

 

30
!

450 S. A. MITCHELL

The mean for the two stars gives the parallax of the system,
+ 07043 + 07005.

With the 60-inch reflector at Mt. Wilson, Van Maanen derives
the parallax of the brighter star to be + 07042 + 07004, and

 

 

 

TABLE 2

RepvcTion For 2 2486 (Szq). Bricurzr Srar
Solution Weight Parallax Time in Residual Vp+
Plate. (m). (p). | Factor (P). | Days (f). (0). in-Are.

mm. mm.
52 —0.0032 0.9 +0.608 —137 +0.0007 | +0%01
53 — .0020 1.0 + .608 —137 — .0005 — .01
58 — .0008 0.7 + .595 —136 — .0017 — .03
59 — .0035 1.0 + .595 —136 + .0010 | + .02
212 — .0094 1.0 — .852 — 37 + .0004 + .01
237 — .0082 1.0 — .906 — 380 — .0012 — .02
278 — .0094- 1.0 — .948 — 23 — .0003 — .01
279 — .0103 1.0 — .948 — 23 + .0006 + .01
291 — .0103 0.9 — .952 — 22 + .0006 + .01
292 — .0116 1.0 — .952 — 22 + .0019 + .04
346 — .0081 1.0 — .978 — 15 — .0019 — .04
1184 — .0080 0.7 + .990 +180 — .0030 | — .05
1185 — .0112 1.0 + .990 | +180 + .0002 -00
1196 — .0116 1.0 + .988 +181 + .0006 + .01
1204 — .0115 1.0 + .986 +182 + .0004 + .01
1205 —0.0120 1.0 +0.986 +182 +0.0009 | +0.02

 

 

 

 

 

 

 

The normal equations are:

15.2c + 1.8974 + 0.36897 = — 0.1271 mm.
+ 22.5665u + 7.01627 = — 0.0655 mm.
+ 11.91857 = + 0.0053 mm.
from which:
¢ = — 0.00805 mm.
p# = — 0.00299 mm. = — 00622, or — 0"227 per year.

a = + 0.00245 mm. = + 07051 + 07006.
Probable error corresponding to unit weight
+ 0.00086 mm. = + 07018.
«

PARALLAXES OF 260 STARS 451

for the fainter star + 07044 + 07003, with'a mean of + 0”043
+ 0"003. The spectroscopic parallax for A and B is + 0076
and - 0"069, respectively.

 

 

 

 

TABLE 8
REDUCTION FOR 2 2486 (Pr). FarintTer Star
Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p). | Factor (P). | Days (#). (v). in Are.
_ mm. mm.

52 +0.0541 0.9 +0.608 —1387 +0.0018 +0°04
53 + .0543 1.0 + .608 —137 + .0016 + .03
58 + .0588 0.7 + .595 —136° — .0021 — .05
59 + .0570 1.0 + .595 —136 — .0012 — .02
212 + .0508 1.0 — .852 — 37 — .0012 — .02
237 + .0475 1.0 — .906 — 30 + .0018 + .04
278 + .0499 1.0 — .948 — 23 -— .0009 — .02
279 + .0481 1.0 — .948 — 23 + .0009 + .02
291 + .0482 0.9 — .952 — 22 +: .0007 + .01
292 + .0474 1.0 — .952 — 22 + .0015 + .03
346 + .0513 1.0 + .978 — 15 — .0027 — .06
1184 + .0468 0.7 + .990 +180 — .0020 — .04
1185 + .0452 1.0 + .990 +180 — .0004 — .O1
1196 + .0446 1.0 + .988 +181 + .0002 .00
1204 + .0432 1.0 + .986 +182 + .0015 |. + .03
1205 +0.0446 1.0 +0.986 +182 +0.0001 0.00

 

 

 

 

 

 

The normal equations are:

15.2c + 1.8972 + 0.36897 = + 0.7499 mm.
+ 22.5665 + 7.01627 = + 0.0230 mm.
+ 11.9135r = + 0.0130 mm.

from which:
c = + 0.04975 mm.
pw = — 0.00370 mm. = — 070770, or — 07281 per year.

x = + 0.00173 mm. = + 07036 + 07007.
Probable error corresponding to unit weight
+ 0.00107 mm. = + 07022.
452 S. A. MITCHELL

p SAGITTARII (198 15"; —18° 2’)

The spectroscopic parallax of -+- 07033 has been found for this
star of magnitude 3.95, of type F, and of total proper motion
0"031. Thirteen of the McCormick plates were measured by
Mr. Briggs, and eight by Mr. Mitchell. The relative parallax
determined was + 07044 + 07010, with a proper motion in right
ascension — 0”007 while the corresponding value from Boss is
— 07024.

 

 

 

 

 

 

TABLE 1
PLATES OF p SAGITTARII
No. Date. Hour Angle. Observers. Weight.
1705 1915 Sept. 16 040 A 1.0
1706 . Sept. 16 +0.3 A 1.0
1742 Sept. 23 —0.2 M 1.0
1754 Sept. 24 —0.5 A 1.0
2926 1916 Aug. 26 +0.3 Ol 1.0
2927 Aug. 26 +0.4 Ol 0.6*
2963 Sept. 4 +0.4 Ol 1.0
2964 Sept. 4 0.0 Ol 0.7
4049 1917 June 8 —0.1 A 1.0
4062 June 13 —0.5 Ol 0.8
4063 June 13 —0.2 Ol 0.8
4236 Aug. 4 +0.4 B 1.0
4407 Sept. 11 +0.1 M 1.0
4408 Sept. 11 +0.4 B 1.0
4480 Sept. 29 +0.5 B, M 1.0
5444 1918 June 9 —0.7 A. 1.0
5445 June 9 —0.3 A 1.0
5478 June 23 +0.4 Ol 1.0
5479 June 23 +0.9 Ol 1.0
5774 Oct. 9 +0.3 M, F 0.9
5775 Oct. 9 +0.6 F, D 0.8

 

 

* One observation.
 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 45
Comparison Stars

No. Diameter. = ee as Y (Declination). Dependence.

1 - 0,14 —38.6 — 1.6 +0.3011

2 -12 —38.1 —22.8 1314

3 12 + 5.4 +20.9 -4077

4 .20 +71.3 + 3.5 +0.1598

Parallax star 0.17 — 3.0 + 5.6
TABLE 2
REDUCTIONS FOR p SAGITARII
Soluti Weight | Paral ime i i D
oe eo Ole elt en ee ae
mm. mm.

1705 —0.0106 1.0 —0.905 —593 +0.0009 | +0”02
1706 — .0089 1.0 — .905 —593 — .0008 — .02
1742 — .0073 1.0 — .946 | —586 — .0025 — .05
1754 — .0101 1.0 — .951 —585 + .0003 | + .01
2926 — .0138 1.0 — .717 —248 + .0042 | + .09
2927 — .0076 0.6 — .717 —248 — .0020 | — .03
2963 — .0092 1.0 — .812 —239_ — .0006 | — .01
2964 — .0103 0.7 — .812 —239 + .0005 | + .01
4049 — .0102 1.0 + .502 + 38 + .0029 | + .06
4062 — .0081 0.8 + .428 + 43 + .0006 | + .01
4063 — .0072 0.8 + .428 + 48 —, .0003 -00
4236 — .0090 1.0 — .415 + 95 — .0003 | — .O1
4407 — .0105 1.0 — .872 +133 + .0002 -00
4408 — .0090 1.0 — .872 +133 — .0013 — .03
4480 — .0091 1.0 — .973 +151 — .0014 — .03
5444 — .0056 1.0 + .491 +404 — .0021 — .04
5445 — .0073 1.0 + .491 +404 — .0004 — .01
5478 — .0070 1.0 +: .275 +418 — .0012 — .02
5479 —, .0082 1.0 + .275 +418 .0000 .00
5774 — .0122 0.9 — .989 +526 + .0013 | + .02
5775 —0.0125 0.8 —0.989 +526 +0.0016 | +0.03

 

 

 

 

 

 

 
454

The normal equations are:

S. A. MITCHELL

19.6c — 0.031p — 8.32917 = — 0.1808 mm.
+ 280.2267 + 21.709387 = + 0.0189 mm.
+ 10.86187 = + 0.0901 mm.
from which:
c = — 0.00833 mm.
uw = — 0.00010 mm. = — 070020, or — 07007 per year.
a = + 0.00210 mm. = + 07044 + 07010.

Probable error of plate of unit weight

+ 0.00113 mm. = + 07024.

5 AQUILAE (19% 20"; +2° 54’)

By photography, the Allegheny Observatory has found the
parallax of this star to be +:07062 + 0°007. The spectroscopic
value is + 07044. It is of magnitude 3.44, of type F, and of
total proper motion 07264. Mr. Olivier measured the McCormick

plates and found the relative parallax + 07041 + 07010, with a
proper motion in right ascension + 07270 while the corresponding
value from Boss is + 07253.

Comparison Stars

 

 

 

 

No. Diameter. - ee Y (Declination). Dependence.
mm. mim. mm.

1 0.10 —43.4 + 7.1 +0.2543

2 16 —14.8 —27.3 2297

3 -10 — 3.6 +19.8 - 2645

4 10 +61.8 + 0.4 +0.2515
Parallax star 0.14 + 0.2 + 0.9

 

 

 

 
 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 455
* TABLE 1
Puates oF 6 AQUILA
No. Date. Hour Angle. Observers. Weight.
238 1914 Sept. 14 +042 M,A 0.7
239 Sept. 14 +0.6 M,A 0.7
327 Sept. 27 +0.5 M 0.7
328 Sept. 27 +0.9 M 0.8
372 Oct. 5 +0.7 Ol, M 0.8
375 Oct. 6 +0.5 M 0.7
1214 1915 Apr. 15 —1.7 M 0.7
1215 Apr. 15 —1.3 M 0.9
1224 Apr. 17 —1.2 M 0.7
1336 June 4 +0.2 Ol 0.7 —
1337 June 4 +1.0 Ol 0.7
1372 June 18 —0.7 M 0.6
1828 Oct. 21 +1.0 M 0.9
1837 Oct. 24 +0.9 M 0.9
1852 Oct. 25 +0.8 M 0.8
2620 1916 Apr, 29 —0.7 Ol 1.0t
2632 May 1 —0.8 Ol 0.9
2633 May 1 —0.4 Ol 0.6*
2687 May 31 —1.3 Ol 0.7
4265 1917 Aug. 13 +0.6 Ol 0.5*
4266 Aug. 13 +1.2 Ol 0.5*
4312 Aug. 21 +0.4 B 1.0
4313 Aug. 21 +0.8 B 1.0
4326 Aug. 24 +0.8 Ol 1.1f
4327 Aug. 24 +1.2 Ol 1.0
5319 1918 Apr. 23 —0.8 Ol 0.7
5361 May 9 —0.8 Ol 0.6*
5370 May 14 0.0 Ol 1.0
5426 June 7 —0.7 Ol 0.7
5427 June 7 —0.2 Ol 0.6*
5456 June 15 0.0 A 0.9
5457. June 15 +0.4 A 0.9
5767 Oct. 8 +0.2 M 0.9
5781 Oct. 10 +0.1 F 0.9
5782 Oct. 10 +0.5 H 0.9

 

* One exposure.

{ Three exposures.
456 S. A. MITCHELL

TABLE 2 ,
Repvuctions FoR 6 AQUILE

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual
Plate. (m). (p). | Factor (P). | Days (1). (®).

mm. mm.
238 —0.0142 0.7 —0.884 —728 —0.0015
239 — .0134 0.7 — .884 —728 — .0023
327 — .0160 0.7 — .960 —715 + .0006
328 — .0180 0.8 — .960 —715 + .0026
372 — .0115 0.8 — .983 —707 <= 0037
375 — .0072 0.7 — .984 —706 — .0080
1214 — .0004 0.7 + .988 —515 — .0040
1215 — .0087 0.9 + .988 —515 + .0043
1224 — .0106 0.7 + .984 —513 + .0062
1336 — .0068 0.7 + .579 —465 + .0033
1337 — .0042 0.7 + .579 —465 + .0007°
1372 — .0041 0.6 + .375 —451 + .0007
1828 — .0061 0.9 — .974 —326 + .0045
1837 — .0054 0.9 — .964 —323 + .0039
1852 — .0048 0.8 — .960 —322 + .0034
2620 + .0087 1.0 + .932 —1385 + .0003
2632 + .0117 0.9 + .920 —133 — .0027
2633 + .0102 0.6 + .920 —133 — .0012
2687 + .0141 0.7 + .623 —103 — .0046
4265 + .0287 0.5 — .582 +336 — .0058
4266 + .0208 0.5 — .582 +336 + .0021
4312 + .0224 1.0 — .640 +344 + .0005
4313 + °.0268 1.0 — .640 +344 — .0039
4326 + .0253 1.1 — .678 +347 — .0023
4327 + .0241 1.0 — .678 +347 — .0011
5319 + .0381 0.7 + .964 +589 — .0033
5361 + .0343 0.6 + .865 +605 + .0009
5370 + .0362 1.0 + .821 +610 — .0009
5426 + .0319 0.7 + .5384 +634 + .0037
5427 + .0353 0.6 + .534 +634 + .0003
5456- + .0393 0.9 + .416 +642 — .0036
5457 + .0329 0.9 + .416 +642 + .0028
5767 + .0356 0.9 — .987 +757 + .0014
5781 + .0350 0.9 — .988 +759 + .0020
5782 +0.0344 0.9 —0.988 +759 +0.0026

1 = |

|

b+ +++ 444+ 441

bobs

al

+ |

 

 
PARALLAXES OF 260 STARS 457

The normal equations are:

27.7¢ + 6.608u — 3.05647 = + 0.3485 mm.
+ 786.9724u + 7.83747 = + 2.8976 mm.
+ 18.71507 = + 0.0286 mm.

from which:

ce = + 0.01195 mm.
w= + 0.00356 mm. = + 0.0741, or 0"270 per year.
az = + 0.00199 mm. = + 07041 + 0°010.

Probable error of plate of unit weight
+ 0.00200 mm. = + 01042.

31 b AQUILAE (19> 20"; +11° 43’)

This star of magnitude 5.23, of spectral type G7, has a con-
siderable total proper motion 0796. Several discordant values
of the parallax have been made, as follows:

 

 

 

 

 

Authority. Method. Parallax.
Peter Heliometer +0706 +0015
Flint Meridian circle + .01 + .030
Chase Heliometer + .019+ .037
Schlesinger (Yerkes) Photography + .1014 .022
Jewdokimov Meridian circle + .044+ .097
Allegheny Photography + .055+ .011
Adams and Joy Spectrograph +07110

 

Ten of the McCormick plates were measured by Mr. Briggs,
eight by Mr. Mitchell. The relative parallax + 07074 + 07010
resulted, while the proper motion from the plates in right ascen-
sion is + 0"729 and the corresponding value from Boss + 07725.
According to Adams and Kohlschiitter (Astrophysical Journal,
39, 341, 1914), the radial velocity is — 98 km. per second.
458

S. A. MITCHELL

TABLE 1

Puates or 31 b AquiLz

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
2993 1916 Sept. 11 —054 Ol 1.0
3090 Sept. 26 —0.3 L 1.0
3139 Oct. 6 +0.6 L 1.0
4043 1917 June 7 0.0 Ol 0.8
4044 June 7 +0.3 Ol 0.7
4079 June 17 —0.5 Ol 0.9
4080 June 17 —0.6 Ol 0.7
4262 Aug. 12 +0.7 B 1.0
43,70 Aug. 29 —1.0 A 1.0
4371 Aug. 29 —0.6 A 1.0
4463 Sept. 24 +0.6 B 1.0
5403 1918 May 31 +0.1 A 1.0
5404 May 31 +0.5 A 1.0
5422 June 5 +0.1 L 1.0
5423 June 5 +0.5 L 0.7
5648 Aug. 23 0.0 A 1.0
5649 Aug. 23 +0.4 A 1.0
5819 Oct. 21 +0.7 M 1.0
ComPaRISOoNn STARS
No. Diameter. x ee Y (Declination). Dependence.
mm. mm. mm. .

1 0.10 —22.1 — 2.9 +0.2105

2 11 — 9.9 +15.6 . 2653

3 .13 — 2.3 + 4.1 2545

4 -10 +34.3 —16.8 +0.2697

Parallax star 0.13 + 1.4 + 0.0

 

 

 

 

 
PARALLAXES OF 260 STARS 45

TABLE 2

Repuctions ror 31 b AquiL=

 

 

 

 

 

 

 

 

ee = =
vives | | Balaton || Welet) earalles | Sao | Reade | ee
mm. mm.
2993 —0.0252 1.0 —0.864 —404 —0.0017 —0"04
3090 — .0275 1.0 — .958 —389 + .0017 + .04
3139 — ,0232 1.0 — .985 —379 — .0018 — .04
4043 + .0059 0.8 + .530 —135 — .0020 — .04
4044 + .0010 0.7 + .5380 —1385 + .0029./ + .05
4079 + .0059 0.9 + .382 | —125 — .0016 — .03
4080 — .0002 0.7 + .382 —125 + 0045 + .08
4262 + .0048 1.0 — .518 — 69 + .0017 + .04
4370 + .0064 1.0 — .785 — 52 + .0010 + .02
4371 + .0070 1.0 — .785 — 52 + .0004 + .01
4463 + .0106 1.0 — .948 — 26 — .0015 — .03
5403 + .0410 1.0 + .628 +223 — .0024 — .05
5404 + .0381 1.0 + .628 +223 + .0005 + .01
5422 + .0386 1.0 + .561 +228 + .0002 .00
5423 + .0399 0.7 + .561 +228 — .0010 — .02
5648 + .0482 1.0 — .662 +307 — .0011 — .02
5649 + .0408 1.0 — .662 +307 + .0013 + .03
5819 +0.0462 1.0 —0.973 +366 +0.0005 +0.01

 

 

The normal equations are:

16.8¢ + 0.401u — 4.42419 = + 0.2393 mm.
+ 103.16454 + 7.8308" = + 1.0249 mm.
+ 8.6838 = + 0.0399 mm.

from which:

c= + 0.01495 mm.
uw = + 0.00961 mm. = + 071998, or + 07729 per year.
a = + 0.00354 mm. = + 07074 + 07010.

Probable error of plate of unit weight
+ 0.00123 mm. = + 07026.
460 S. A. MITCHELL

& CYGNI (19" 26"; +27° 45’)

@ Cygni is very well known to all users of telescopes on account
of the great difference in color. Webb in his Celestial Objects for
Common Telescopes says that it is, ““One of the finest in the
heavens.’”’ The brighter star is of yellow color of Kop type, and
magnitude 3.26, while the fainter is of blue color of magnitude
5.36 and B9 type. The distance between the stars is 34’.
Only twice have the stars been investigated for parallax. Chase
by means of the Yale heliometer for brighter and fainter star
found the parallax to be — 07027 + 07039 and — 0028 + 07039,

 

 

 

 

 

 

 

TABLE 1
Piates oF #? Crent
No. , Date. Hour Angle. Observers. Weight.
8 1914 May 9 —0b2 M 0.7
11 May 10 —0.3 M 0.7*
12 May 10 —0.1 M 1.0
16 May 11 —0.4 M 0.6*
17 May 11 0.0 M 0.6*
250 Sept. 15 —0.2 M,G 0.8
268 Sept. 20 —0.3 M 0.8
309 Sept. 25 —0.1 Ol 0.8
312 Sept. 26 —0.5 M 0.7
313 Sept. 26 —0.1 M 1.0
371 Oct. 5 0.0 Ol 0.8
388 Oct. 11 +0.1 M 0.8
1239 1915 Apr. 23 —-1.3 Ol 0.5*
1240 Apr. 23 —0.8 Ol 0.7*
1340 June 5 —0.9 M 0.9
1351 June 9 —-1.1 Ol 0.9
1651 Sept. 11 —0.8 M 1.0
1652 Sept. 11 —0.4 M,A 0.9
1672 Sept. 13 —1.0 Ol 0.8.
1673 Sept. 13 —0.6 Ol 0.8
1704 Sept. 16 —0.9 M 0.8

 

* One exposure.
PARALLAXES OF 260 STARS 461

respectively. Jacoby by means of Rutherfurd photographs at
Columbia University has found a parallax for the brighter star
of + 0761 + 0703. Mr. Olivier measured the parallax of both
stars. For the brighter he found the relative parallax of — 0”006
+ 07010, and for the fainter the result, 07000 + 0”006. For
proper motions in right ascension the plates gave — 0”011 and
— 0"011, while Boss found the results, — 07011 and — 07003,
respectively.

Comparison Stars

 

 

 

 

 

 

 

 

 

‘ X Dependence.
No. Diameter. Aan. au fea
B! Cygni. 8? Cygni.
mm. mm. mm.
1 0.16 —52.1 +17.0 +0.1849 | +0.1830
2 14 —47.7 —26.6 . 2142 . 2027
3 .23 +18.0 —36.3 .2255 -2191
4 10 +31.3 +27.9 . 1838 - 19387
5 14 +50.4 +18.2 +0.1916 | +0.2015
6! Cygni 24 — 0.4 — 2.2
& Cygni 0.13 + 1.0 — 1.2

 

The normal equations are:

13.0c + 2.2884 — 2.74247 = — 0.1663 mm.
+ 44.6775u — 5.36627 = — 0.0342 mm.
+ 9.12017 = + 0.0339 mm.
from which:
c = — 0.01283 mm.
zw = — 0.00014 mm. = — 070030, or — 07011 per year.
x = — 0.00028 mm. = — 07006 + 07010.

Probable error of plate of unit weight
+ 0.00125 mm. = + 07026.
462

S. A. MITCHELL

TABLE 2

Repvuctions ror 6! CyeGnr

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vv By
Plate. (m). (p). | Factor (P). | Days (). (). in Arc.
mam. mm.

8 —0.0133 0.9 +0.876 —247 +0.0006 +0701
11 — .0118 0.7 + .868 —246 — .0009 — .02
12 — .0188 0.7 + .868 —246 + .0011 + .02
250 — .0148 0.8 — .879 —118 + .0024 + .04
268 — .0102 0.5 — .914 —113 — .0022 — .03
309 — .0111 0.5 — .942 —108 — .0013 — .02
312 — .0127 0.4 — .947 —107 + .0003 -00
313 — .0160 0.7 — .947 —107 + .0036 + .06
371 — .0113 0.5 — .978 — 98 — .0011 — .02
388 — .0090 0.8 — .986 — 92 — .0034 — .06

1239 — .0088 0.5 + .992 +102 — .0044 — .06
1240 — .0117 0.7 + .992 +102 — .0014 — .02
1340 — .0136 0.9 + .586 +145 + .0004 + .01
1351 — .0160 0.9 + .530 +149 + .0028 + .06
1651 — .0142 1.0 — .847 +243 + .0013 + .03
1652 — .0120 0.9 — 847 +243 — .0009 — .02
1672 — .0141 | 0.8 — .863 +245 + .0012 + .02
1673 —0.0116 | 0.8 —0.863 +245 —0.0013 — .02
The normal equations are:

16.6c + 1.481u — 3.75327 = + 0.0710 mm.

+ 59.2205u — 8.80217 = — 0.0021 mm.

+ 12.69627 = — 0.0148 mm.

from which:

c = + 0.00429 mm.

uw = — 0.00014 mm. = — 070080, or — 07011 per year.
a = + 0.00000 mm. = 07000 + 0”006.

Probable error of plate of unit weight

+ 0.00096 mm. = + 07020.
PARALLAXES OF 260 STARS 463

 

 

 

 

 

 

 

 

 

TABLE 3
A REDUCTIONS FOR 6? CYGNI
Solution Weight Parallax Time in Residual Vp-v
Plate. (m). (p). | Factor (P). | Days (f). (). in Are.
mm. mm.

8 +0.0027 0.7 +0.876 —235 +0.0019 | +0703
11 + .0036 0.7 + .868 — 234 + .0010 | + .02
12 + .0043 1.0 + .868 —234 + .0003 + .01
16 + .0062 0.6 + .860 —233 = .0016 — .02
17 + .0058 0.6 + .860 —233 — .0012 — .02
250 + .0058 0.8 — .879 —106 — .0014 — .02
268 + .0064 0.8 — .914 —101 — .0020 — .04
309 + .0064 0.8 — .942 — 96 — .0020 — .04
312 + .0028 0.7 — .947 — 95 + .0016 | + .03
313 + .0028 1.0 — .947 — 95 + .0016 | + .03
371 + .0046 0.8 — .978 — 86 — .0002 -00
388 + .0031 0.8 — .986 — 80 + .0013 + .02

1239 +. .0080 0.5 + .992 +114 — .0039 — .06
1240 + .0052 0.7 + .992 +114 — .0011 — .02
1340 + .0019 0.9 + .586 +157 + .0022 | + .04
1851 + .0033 0.9 + .530 +161 + .0008 | + .01
1651 + .0035 1.0 — .847 +255 + .0004 | + .01
1652 + .0037 0.9 — .847 +255 + .0002 .00
1672 + .0051 0.8 — .863 +257 — .0012 — .02
1673 + .0052 0.8 — .863 +257 — .0013 — .02
1704 +0.0024 0.8 —0.887 +260 +0.0015 | +0.03

 

LALANDE 37120 (19% 29"; +32°°59’)

This star of magnitude 6.6, of type G, of proper motion 0752
has a considerable radial velocity amounting to — 162 km. per
second. The parallax values published are: Chase from the
Yale heliometer, + 07048 + 07039, Allegheny by photography
+ 07027 + 07010, while Adams with the spectrograph gives the
value + 0”060. Ten of the plates were measured by Mr. Briggs,
and nine by Mr. Mitchell. The relative parallax + 07042 + 07007
resulted, and a proper motion in right ascension — 07473 while
the corresponding value from Porter is - 07472.
464 S. A. MITCHELL

TABLE 1
Puatres oF LaLuanpE 37120—1

 

 

 

No. Date. Hour Angle. Observers. Weight.
3010 1916 Sept. 17 —03 M 1.0
3023 Sept. 18 —0.3 Ol 1.0
3031 Sept. 19 —0.8 M 1.0
3032 Sept. 19 —0.4 M 0.9
8929 1917 May 1 —1.5 L 0.8
3930 May 1 —1.2 L 1.0
4068 June 16 —0.5 A 1.0
4392 Sept. 10 -0.9 B,A 1.0
4393 Sept. 10 —0.5 A 1.0
444] Sept. 19 —0.6 M 1.0
4442 Sept. 19 —0.3 M 0.8
5385 1918 May 18 —0.7 Ol 0.7
5386 May 18 —0.7 Ol 0.7
5472 June 22 —0.9 A 0.7
5473 June 22 —0.2 Ol 1.0
5728 Sept. 30 —0.5 M 1.0
5729 Sept. 30 —0.1 M 1.0
5750 Oct. 3 —0.3 M 1.0
5751 Oct. 3 0.0 M 1.0

 

 

 

 

 

Comparison Stars

 

 

 

 

 

 

No. Diameter. ; x (ight, Ascen-| y (Declination). Dependence.
mm. mm. mm.
1 0.16 —45.5 —24.9 +0.1702
2: .12 —17.8 +10.6 . 1553
3° 17 . — 4,9 +46.6 . 1859
4 .14 — 0.3 —21.3 . 1800
5 -16 +22.5 —35.6 -1951
6 -09 +46.0 +24.6 +0.1635
Parallax star 0.14 + 0.7 — 3.0

 
PARALLAXES OF 260 STARS

TABLE 2

RepvuctTions FOR LALANDE 37120—1

46

 

 

 

 

 

 

 

 

 

 

ca Sema i eee : =
piste. | Sum | NEO | thor). | Dao. | ae | an hee
mm. mm.
3010 —0.0304 1.0 —0.891 —403 —0.0010 —0702
3023 — .0297 1.0 — .898 —402 — .0018 — .04
8031 — .0324 1.0 — .905 —401 + .0008 | + .02
3032 — .0348 0.9 — .905 —401 + .0032 + .06
3929 — .0404 0.8 + .933 -177 — .0014 — .02
3930 — .0412 1.0 + .933 -177 — .0006 — .01
4068 — .0468 1.0 + .431 —131 + .0011 + .02
4392 — .0524 1.0 — .832 — 45 — .0012 — .02
4393 — .0540 1.0 — .832 — 45 + .0004 + .01
4441 — .0554 1.0 — .903 — 386 + .0011 + .02
4442 — .0524 0.8 — .903 — 36 — .0019 — .04
5385 — .0694 0.7 + .803 +205 + .0035 + .06
5386 — .0650 0.7 + .803 +205 — .0009 — .01
5472 — .0676 0.7 |.+ .343 +240 — .0014 — .02
5473 — .0688 1.0 + .343 +240 — .002 -00
5728 — .0794 1.0 — .960 +340 + .0015 + .03
5729 — .0758 1.0 — .960 +840 — .0021 — .04
5750 — .0793 1.0 — .970 +3843 + .0012 + .02
5751 —0.0776 1.0 —0.970 +343 —0.0005 —0.01
The normal equations are:
17.6c — 1.103 — 6.84027 = — 0.9702 mm.
+ 133.2724u + 2.41457 = — 0.7656 mm.
+ 12.59007 = + 0.3849 mm.
from which:
c = — 0.05472 mm.
ph = — 0.00623 mm. = — 01297, or — 07473 per year.
a = + 0.00203 mm. = + 07042 + 07007.

Probable error of plate of unit weight
+ 0.00109 mm. = + 07023.

31
466

S. A. MITCHELL

6 CYGNI (19 337; +49° 59’)

This star is of 4.64 magnitude, and of type F5, with a proper
It is a double, discovered by
Burnham, 8 1131, but the companion is of 14th magnitude, and
in reach of the largest telescopes only. The parallax has been

motion amounting to 0"25.

five times determined, with the following results:

 

 

 

Parallax. Authority. Method.
+07062+0"025 Chase Heliometer
+ .010+ .026 Flint Meridian Circle
+ .0724+ .026 Abetti Meridian Circle
+ .057+ .008 Allegheny Photography
+0.069 Adams Spectrograph

 

Mr. Olivier measured the McCormick plates.

 

 

 

TABLE 1
Puates or @ Cron

No. Date. Hour Angle. Observers. Weight.

40 1914 May 23 —043 M 0.7

48 May 25 —0.7 M 0.7

49 May 25 —0.2 M 0.9

54 May 30 —0.2 M 1.0

297 Sept. 23 —0.6 M,G 1.0

825 Sept. 27 —0.7 M 1.0

326 Sept. 27 —0.3 M 0.9

374 Oct. 6 —0.2 M 0.7

378 Oct. 7 —0.2 M 1.0

380 Oct. 9 —0.2 M 0.7*
1247 1915 Apr. 24 —1.6 M 1.0
1248 Apr. 24 —1.2 M 0.7
1266 Apr. 30 —1.5 Ol 1.0
1267 Apr. 30 —1.1 Ol 0.4*
1268 Apr. 30 —0.6 Ol 0.7
1278 May 8 -1.9 M 0.7
1279 May 8 —1.5 M 1.0

 

 

 

 

 

* One exposure.
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 46
ComPaRISON STARS
No. Diameter. [* PB ee Y (Declination). Dependénce.
mam. mm. mm.
1 0.14 —48.8 +15.3 +0.2485
2 .09 —22.3 —28.8 .2410
3 ; .10 +21.9 +35.3 - 2605
4 .13 +49.2 —21.8 +0.2500
Parallax star 0.14 + 0.5 + 0.6
TABLE 2
Rupuctions ror @ CycGni
Solution Weight Parallax Time in Residual vp+o
Plate. (m). (p). Factor (P). | Days (é). (0). in Are
mm. mm.
40 +0.0047 0.7 +0.760 —188 —0.0002 0°00
48 + .0003 0.7 + .738 —186 + .0041 | + .07
49 + .0056 0.9 + .738 —186 — .0012 — .02
54 + .0062 1.0 + .680 —181 — .0020 | — .04
297 — .0016 1.0 — .920 — 65 + .0005 | + .01
325 — .00382 1.0 — .942 — 61 + .0020 + .04
326 — .0037 0.9 — .942 — 61 + .0025 | + .05
374 + .0032 0.7 — .974 — 52 — .0044 — .08
378 .0004 1.0 — .977 — 51 — .0009 — .02
380 — .0005 0.7 — .980 — 49 — .0008 — .01
1247 + .0114 1.0 + .971 +148 — .0037 — .08
1248 + .0046 0.7 + .971 +148 + .0031 + .05
1266 + .0051 1.0 + .946 +154 + .0026 + .05
1267 + .0046 0.4 + .946 +154 + .0031 + .04
1268 + .0069 0.7 + .946 +154 + .0008 | + .01
1278 + .0078 0.7 + .897 +162 — .0003 .00
1279 +0.0100 1.0 +0.897 +162 —0.0025 | —0.05
The normal equations are:
14.1le — 0.624u + 2.50047 = + 0.0500 mm.
+ 26.1980u + 6.42427 = + 0.0419 mm.
+ 11.41147 = + 0.0560 mm.
468 S. A. MITCHELL

from which:
c = + 0.00289 mm. 3
pw = + 0.00072 mm. = + 070150, or + 07055 per year.
a = + 0.00387 mm. = + 07080 + 07011.
Probable error of plate of unit weight
+ 0.00161 mm. = + 07034.

a SAGITTZ (19 35"; +17° 47’)

The spectroscopic parallax +-0"016 has been found for this star,
which is of G type, of magnitude 4.37, and of small annual proper

TABLE 1
PLaTes OF @ SAGITTE

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
373 1914 Oct. 5 +049 01, G 1.0
386 Oct. 10 +0.4 M,A 1.0
396 Oct. 12 +0.4 O01, G 0.7
397 Oct. 12 414 | Go 1.0
1258 1915 Apr. 26 —1.2 G 0.7
1259 Apr. 26 —0.8 G 0.5*
1303 May 10 —0.8 G 0.7
1304 May 10 —0.2 G 0.7
1319 May 17 0.0 G 0.8
1397 June 26 —0.2 G 1.0
1398 June 26 +0.2 G 1.0
1719 Sept. 19 -0.6 M 0.8
1814 Oct. 11 +0.2 ol 0.8
1827 Oct. 15 +0.8 G 0.9
3999 1917. May 23 —0.8 M 0.7*
4116 June 23 —0.4 Ol 0.8
4117 June 23 0.0 Ol 1.0
4372 Aug. 29 —0.3 A 0.8
4470 Sept. 26 +0.5 M 1.0
4486 Sept. 30 —0.1 M 1.0
4512 Oct. 3 +0.6 M 0.9
4513 Oct. 3 +1.0 M 0.7*

 

 

 

* One exposure.
PARALLAXES OF 260 STARS 46)

CoMPARISON STARS

 

 

 

 

 

 

 

 

 

No. Diameter. = a a aaa Y (Declination). | Dependence.
mm. mm. mm.

1 0.14 —46.9 + 5.0 +0.1469

2 .23 —35.8 —36.8 .1748

3 12 —29.6 —32.1 .1745

4 -16 +20.0 +388 .5 .1517

5 24 +37.1 — 5.1 . 1830

6 -25 +55.2 +30.5 +0.1691

Parallax star 0.20 + 0.9 — 1.2
TABLE 2
REDUCTIONS FOR @ SAGITTs
Solution Weight Parallax Time in Residual Vpeo
Plate. (m). (p). | Factor (P). | Days (1). (2). in Arc.
mm. mm,

373 +0.0044 1.0 —0.970 —489 +0.0015 | +0703
386 + .0082 1.0 — .980 —484 — .0023 — .05
396 + .0058 0.7 — .983 —482 + .0001 .00
397 + .0054 1.0 — .983 —482 + .0005 + .01
1258 + .0029 0.7 + .965 —289 + .0026 | + .04
1259 + .0046 0.5 + .965 —289 + .0009 + .01
1303. | + .0087 0.7 + .886 —272 — .0032 — .05
1304 | + .0047 0.7 + .886 —272 + .0008 + .01
1319 + .0039 0.8 + .827 —265 + .0017 + .03
1397 + .0060 1.0 + .307 —225 — .0001 -00
1398 + .0063 1.0 + .307 —225 — .0004 — .01
1719 + .0071 0.8 — .888 —140 — .0005 — .01
1814 + .0063 0.8 — .981 —118 + .0004 + .01
1827 + .0080 0.9 — .983 —114 — .0012 — .02
3999 + .0098 0.7 + .792 +472 — .0025 — .04
4116 + .0050 0.8 + .346 +503 + .0026 | + .05
4117 + .0092 1.0 + .346 +503 — .0016 — .03
4372 + .0104 0.8 — .689 +570 — .0022 — .04
4470 + .0108 1.0 — .9385 +588 — .0025 — .05
4486 + .0042 1.0 — .954 +592 + .0042 | + .09
4512 + .0068 0.9 — .965 +605 + .0016 | + .03
4513 +0.0085 0.7 —0.965 +605 —0.0001 0.00

 

 

 

 

 

 

 
470 S. A. MITCHELL

motion 005. Twenty-two plates were measured, of which the
first thirteen were measured by Mr. Graham and the balance by
Mr. Mitchell. The proper motion in right ascension from the
plates is + 0”017 while the value from Boss is + 07016.

The normal equations are:
18.5¢ + 3.488n — 5.13407 = + 0.1246 mm.

+ 342.1209n — 7.26397 = + 0.1047 mm.
+ 13.0751r7 = — 0.0413 mm.
from which:
c = + 0.00656 mm.
uw = + 0.00023 mm. = + 00048, or + 07017 per year.

x = — 0.00045 mm. = — 07009 + 07008.
Probable error of plate of unit weight
+ 0.00126 mm. = + 07026.

16 CYGNI or BOSS 5037-8 (195 39"; +50° 17’)

This is a double star of the type of 61 Cygni. The components
are of nearly equal brightness 6.3 and 6.4, respectively, and
their spectral types are F and F5. The two components are
separated by 38’’, and they have nearly the same proper motion
about 20” per year. Parallax measures have been made on this
pair as follows:

 

 

 

Observer. Method. | Boss 5037. Boss 5038. ! Mean.
Jost Meridian +07153 +0031
Circle
Slocum [Photography +0”043-£0008 | +07028+07009 | + .036+ .006
and
Mitchell

Miller |Photography| + .0837+ .012|} + .018+ .006)-+ .027+ .006
Allegheny|Photography| + .0434 .006/ + .0214 .012/+ .038+4 .006
Adams Spectro- | +0.050 +0.044 +0.052

graph

 

 

 

 

 

The McCormick plates were measured by Mr. Mitchell, and
gave a mean parallax of:

+ 0033 + 07007.
PARALLAXES OF 260 STARS 471

 

 

 

TABLE 1
Puates or 16 Cyenr
No. Date. Hour Angle. Observers. Weight.
3164 1916 Oct. 11 —0h2 M 1.0
3177 Oct. 12 —0.1 M 1.0
3188 Oct. 14 —0.1 M 1.0
3205 Oct. 17 0.0 M 1.0
3902 1917 Apr. 19 —1.3 M 1.0
4103 June 22 —0.4 A 1.0
4104 June 22 —0.1 A 0.7*
4405 Sept. 11 —-1.2 M 1.0
4406 Sept. 11 —0.9 B 1.0
4455 Sept. 20 —0.8 M 1.0
4456 Sept. 20 —0.5 M 1.0
5408 1918 June 3 —0.5 A 1.0
5409 June 3 —0.1 A 1.0
5487 June 27 —0.3 Ol 1.0
5742 Oct. 2 —0.4 M 0.8
5743 Oct. 2 —-0.1 M 1.0
5756 Oct. 4 —0.4 M 1.0
5757 Oct. 4 0.0 M 1.0

 

 

 

 

 

* One exposure.
ComPaRISON STARS

 

 

 

 

 

 

 

 

Dependence.
No. Diameter. X (Right Y (Declina-

Hace); Hen): Boss 5037. | Boss 5038.
mm. mm. mm.

1 0.08 —42.7 +41.4 +0.194 +0.201

2 -10 —38.9 —14.1 -201 . 184

3 .10 + 5.4 —22.5 . 203 -195

4 .12 +26.3 —25.6 .204 .199

5 -08 +49.9 +20.8 +0.198 +0.221
Boss 5037 .12 + 0.3 — 0.5
Boss 5038 0.10 + 1.6 + 0.8

 

 

A combination of the three parallax determinations: by pho-
tography, Yerkes, Swarthmore, Allegheny and McCormick are in
excellent agreement and give the mean parallax of:

+ 07033 + 07003.
472 S. A. MITCHELL

The proper motions determined from the photographic plates
at McCormick Observatory in right ascension were, — 07143
and -- 0"123, while the corresponding values from Boss were
— 07155 and -- 07132, respectively.

 

 

 

TABLE 2
Repuctions ror Boss 5037
: Solution Weight Parallax Time in Residual 7 v ‘peo
Plate. (m). (p). | Factor (P). | Days (f). (0). in Are.
mm. mm.

3164 +0.0212 1.0 —0.980 —377 +0.0017 | +0704
3177. + .0244 1.0 — .981 |. —376 — .0015 | — .03
3188 + .0228 1.0. — .982 —374 + .0001 .00
3205 + .0227 1.0 — .982 —371 + .0001 .00
3902 + .0216 1.0 + .984 —187 + .0012 + .02
4103 + .0168 1.0 + .373 —123 + .0037 + .08
4104 + .0241 0.7 + .373 —123 — .0036 — .06
4405 + .0172 1.0 — .818 — 42 — .0003 — .01
4406 + .0192 1.0 — .818 — 42 — .0023 — .05
4455 + .0152 1.0 — .892 — 33 + .0014 + .03
4456 + .0185 1.0 — .892 — 33 — .0019 — .04
5408 + .0182 1.0 + .646 +223 — .0087 | — .08
5409 + .01438 1.0 + .646 +223 + .0002 .00
5487 + .0117 1.0 + .299 +247 + .0017 + .04
5742 + .0079 0.8 — .956 +344 + .0015 + .03
5743 + .0097 1.0 — .956 +344 — .0008 | — .O1
5756 + .0091 1.0 — .964 +346 + .0003 | + .01
5757 +0.0084 1.0 —0.964 +346 +0.0010 | .+0. 02

 

 

 

 

 

 

 

The normal equations are:

17.5¢ — 0.3994 — 7.78477 = + 0.2942 mm.
+ 124.0820u + 4.38417 = — 0.2323 mm.
+ 12.4135r = — 0.1231 mm.
from which:
c = + 0.01755 mm.
p» = — 0.00188 mm. = — 070391, or — 04148 per year.

a = + 0.00175 mm. = + 07036 + 0"009.
Probable error of plate of unit weight
+ 0.00135 mm. = + 07028.
PARALLAXES OF 260 STARS

473

 

 

 

 

 

 

 

 

 

 

TABLE 3
Repuctions ror Boss 5038
ieee : i ar ; =
inte, | Ae | ee | bee ed mee
4 mm., mm.
3164 +0.0026 1.0 —0.980 —377 +0.0015 +003
3177 | + .0026 | 1:0 | — .981 | —376 | + .0015 | + .03
3188 + .0048 1.0 — .982 —374 — .0008 — .02
8205 + .0029 1.0 — .982 —371 + .0011 + .02
3902 + .0028 1.0 + .984 —187° + .0011 + .02
4103 + .0009 1.0 + .373 —123 + .0011 + .02
4104 + .0035 0.7 + .3873 —123 — .0015 — .03
4405 + .0013 1.0 — .818 — 42 — .0024 — .05
4406 + .0032 1.0 — .818 — 42 — .0043 — .09
4455 -0000 1.0 — .892 — 33 — .0013 — .03
4456 — .0018 1.0 — .892 — 33 + .0005 + .01
5408 — .0008 1.0 + .646 +223 — .0024 — .05
5409 — .0020 1.0 + .646 +223 — .0012 — .02
5487 — .0080 1.0 + .299 +247 + .0039 + .08
5742 — .0126 0.8 — .956 +344 + .0051 + .09
5743 — .0064 1.0 — .956 +344 — .0011 — .02
5756 — .0078 1.0 — .964 +346 + .0002 -00
5757 —0.0073 1.0 —0.964 +346 —0.0003 —0.01
The normal equations are:
17.5¢ — 0.3994 — 7.78477 = — 0.0206 mm.
+ 124.0320u + 4.38417 = — 0.1939 mm.
+ 12.41357 = 4+ 0.0154 mm.
from which:
c = — 0.00057 mm.
w= — 0.00162 mm. = — 070336, or — 07123 per year.
az = + 0.00145 mm. = + 07030 + 07011.

Probable error of plate of unit weight
+ 0.00156 mm. = + 07032.

y AQUILAE (19* 41"; +10° 22’)

Two values of the parallax have been published, the meridian
circle result of Flint giving the parallax — 07009 + 07033, and
474

S. A. MITCHELL

TABLE 1

PLatTes oF y AQUILE

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
376 1914 Oct. 6 +048 M 0.6"
403 Oct. 18 +0.7 M 0.5*
404 Oct. 18 +1.0 M 0.8
466 Nov. 2 +0.9 M 0.8
1295 1915 May 9 —0.5 A 1.0
1343 June 6 —0.6 A 1.0
1391 June 25 —0.5 A 1.0
1392 June 25 —0.1 A 0.7*
1405 June 27 —0.4 A 0.9
1406 June 27 0.0 A 0.9
1615 Sept. 7 +0.5 A 0.9
1616 Sept. 7 +1.0 A 0.8
1622 Sept. 8 +0.3 A 1.0
1623 Sept. 8 +0.7 A 0.7*
4035 1917 June 4 —0.5 A 0.9
4036 June 4 —0.2 A 1.0
4070 June 16 +0.1 A 1.0
4071 June 16 +0.4 A 0.8
4336 Aug. 25 +0.4 A 0.8
4337 Aug. 25 +0.7 A 0.9
4396 Sept. 10 +0.2 A 1.0
4397 Sept. 10 +0.4 A 1.0
* One exposure.
Comparison STARS
No. Diameter. |* ar aaa Y¥ (Declination). Dependence.
mm. mm. mm,

1 0.15 —62.4 +60.8 +0.2744

2 .10 —11.0 37.7 .2497

3 .19 +10.5 —25.0 2445

4 .14 +62.9 + 1.9 +0.2314

Parallax star 0.19 — 2.8 + 1.6

 

 

 

 

 
PARALLAXES OF 260 STARS 475

the spectroscopic parallax of Adams with the value + 0”020.
The star is of K2 type, of magnitude 2.80, and of small proper
motion, 07014. Mr. Alden measured the McCormick plates,
and obtained the proper motion in right ascension of + 0”001
while the value from Boss is + 07013.

 

 

 

 

 

 

 

 

 

 

TABLE 2
RepvUcTIONS FOR y AQUILZ
Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p). | Factor (P). | Days (d). (). in Are.
mm. mm.
376° —0.0108 0.6 —0.967 —503 —0.0010 —0"01
403 — .0108 0.5 — .981 —491 — .0010 — .01
404 — .0122 0.8 — .981 —491 + .0004 + .01
466 — .0086 0.8 — .940 —476 — .0031 — .06
1295 — .0074 1.0 + .902 —288 — .0017 — .04
1343 — .0084 1.0 + .620 —260 — .0011 — .02
1391 — .0123 1.0 + .346 —241 + .0024 + .05
1392 — .0115 0.7 + .346 —241 + .0016 + .03
1405 — .0092 0.9 + .314 —239 — .0007 — .01
1406 — .0090 0.9 + .314 —239 — .0009 — .02
1615 — .0144 0.9 — .761 —167 + .0030 + .06
1616 — .0140 0.8 — .761 —167 + .0026 + .05
1622 — .01386 1.0 — .777 —166 + .0022 + .05
1623 — .0095 0.7 — .777 —166 — .0019 — .03
4035 — .0094 0.9 + .638 +469 .0000 .00
4036 - | ~— .0131 1.0 + .638 +469 + .0037 + .08
4070 — .0064 1.0 + .473 +481 — .0032 — .07
4071 — .0106 0.8° | + .473 +481 + .0010 + .02
4336 — .0110 0.8 — .620 +551 — .0001 .00
4337 — .0062 0.9 — .620 +551 — .0049 — .10
4396 — .0132 1.0 — .802 +567 + .0019 + .04
4397 —0.0111 1.0 —0.802 +567 —0.0002 0.00
The normal equations are:
19.0c + 5.5274 — 3.14117 = — 0.2006 mm.
+ 308.6303u + 5.01297 = — 0.0446 mm.
+ 9.22487 = + 0.0453 mm.
476 S. A. MITCHELL

from which:
c = — 0.01033 mm.
uw = + 0.00002 mm. = + 070004, or + 07001 per year.
x = + 0.00138 mm. = + 07029 + 07011.
Probable error of plate of unit weight
+ 0.00149 mm. = + 0031.

17 CYGNI (195 42™; +33° 29’)

This star is called x Cygni, and should not be confused with
the well known variable. It is a star of 5.03 magnitude, and
of F5 type. It has a fairly large proper motion of 0745, which
motion is almost entirely in declination. This proper motion
is shared by a star of 8.1 magnitude and at a distance of 2577.
The two, known as 2 2580, accordingly, form a physical system.
812” distant from this pair is the double 2 2576, the components
of which are separated by 2”5. This second pair has almost the
same proper motion as = 2580. All four stars thus have the
same proper motion, though so widely separated. This common
proper motion signifies a physical system, and all four should
show the same parallax. The plates were measured by Mr.
Mitchell. The double 2 2576 have components of the same
magnitude. The stars were not separated on the plates, and
the center of the elongated image was measured. This gave
rise to no inaccuracy on account of the equality in the size of the
images. The parallaxes and proper motions in right ascension
determined from the photographs follow:

 

 

 

 

 

Star. Parallax. Proper Meson Right _
= 2580, A +0°057 +07009 —0*007
= 2580, B + .042+ .008 + .007
= 2576, AB + .036+ .008 — .034

 

On the assumption that these four stars form a physical system,
the parallax derived from the above is

+ 07045 + 07004.
PARALLAXES OF 260 STARS 477

The spectroscopic values of the three stars are +0” 042, +0°063
and + 07036, with an average value of + 0”047.

The parallax of the brighter star of 17 Cygni by Chase with
the Yale heliometer gives the result + 0701 + 0”026, while Alle-
gheny finds + 07030 + 07007. With the McCormick value of
the parallax, stars A and B of = 2580 are separated by 570
astronomical units, and this pair from 2 2576 by the enormous
distance of 18,000 times that separating earth from sun!

TABLE 1
Puates or 17 Crenr

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
31 1914 May 19 —055 M 0.9
32 May 19 0.0 M 0.9
35 May 22 —0.5 M 0.8
36 May 22 0.0 M 0.9

269 Sept. 20 —0.1 M 0.5*

2938 Sept. 22 +0.1 M 1.0

337 Sept. 28 -0.1 M,G 1.0

347 Sept. 29 0.2 M,A 1.0

385 Oct. 10 —0.3 M 1.0

402 Oct. 18 0.0 M 0.9

1270 1915 May 1 —0.8 M 0.9

1280 May 8 —1.0 M 0.9

1281 May 8 —0.7 M 0.9

1293 May 9 4,6 A 0.8

1294 - May 9 —1.1 A 1.0

4090 1917 June 18 —0.7 M 0.9
4091 June 18 —0.4 M 0.8
4132 June 29 —0.1 A 0.9
4346 ‘Aug. 26 —0.6 A 0.7
4347 Aug. 26 ts A 0.9
4468 Sept. 26 —0.4 M 0.5*
4469 Sept. 26 —0.1 M 0.5*
4511 Oct. 3 0.0 M 0.7
4514 Oct. 4 —0.1 M 0.7

 

 

* One exposure.
478

S. A. MITCHELL

TABLE 2

ReEDucTIONS FoR Z 2580, A

 

 

 

as é Ti . Resid J As

Plate. | Spon | WEN | aeaotor CP). | Days (- ot ae
31 —0.0007 0.7 +0.821 —553 +0.0015 | ‘+0702 ~
32 + .0046 0.7 + .821 —553 — .0038 | — .07
35 + .0043 0.7 + .792 —550 — .0036 — .06
36 — .0022 0.7 + .792 —550 + .0029 | + .05
269 — .0027 0.5 — .883 —429 — .0013 — .02
293 — .0054 1.0 — .897 —427 + .0013 + .03
» 337 — .0064 1.0 — .933 —421 + .0022 | + .05
347 — .0057 1.0 — .938 —420.} + .0015 | + .03
385 — .0057 1.0 — .975 —409 + .0014 | + .03
402 + .0010 0.7 — .981 —401 — .0053 | — .09
1270 + .0031 0.8 + .950 — 206 — .0023 — .04
1280 + .0017 0.8 + .910 —199 — .0010 — .02
1281 — .0016 0.7 + .910 —199 + .0023 | + .04
1293 + .0031 0.5 + .904 —198 — .0024 | — .04
1294 — .0016 1.0 + .904 —198 + .0022 | + .05
4090 — .0016 0.9 + .448 +573 + .0002 -00
4091 — .0045 0.8 + .448 +573 + .0032 | + .06
4132 — .0023 0.9 + .278 +584 + .0005 | + .0O1
4346 — .0002 0.7 — .629 +642 — .0042 — 07
4347 — .0056 0.8 — .629 +642 + .0012 | + .02
4468 — .0041 0.5 — .923 +673 — .0011 — .02
4469 — .0065 0.5 — .923 +673 + .0013 | + .02
4511 — .0050 0.7 — .956 +680 — .0003 — .01
4514 —0.0038 0.7 —0.960 +681 —0.0015 —0.03

 

 

 

 

 

 

 
PARALLAXES OF STARS 47

Comparison STARS FoR 17 Cyani = 2 2580

 

 

 

 

 

 

: Dependences.
No. Diameter. X (Right Y (Declina- —
Ascension). tion).

= 2580, A. = 2580, B
mm. mm. mm.

3 0.16 —36.3 + 6.8 . +0.190 +0.176

4 .07 + 5.0 — 3.6 - 200° -201

5 .14 +11.0 —43.6 .178 171

6 .16 —19.4 +385.3 .214 .215

7 .13 +39.7 + 5.1 +0.218 +0.237
= 2580, A -27 + 0.6 + 1.4
= 2580, B 0.10 + 1.7 + 1.9

 

ComPARISON STARS FOR = 2576

 

 

 

 

 

 

 

No. Diancien |” Se eee Y (Declination). Dependence.
mm. mm. mm.
1 0.15 —33.5 — 1.3 +0.223
2 21 —30.3 —14.2 234
3 .16 — 8.3 +25.5 181
4 .07 +33.0 +15.0 164
5 14 +89.1 —25.0 +0.198
=z 2576 0.18 — 2.9 — 1.5

 

The normal equations are:
18.3¢ — 3.8834 — 1.32797 = — 0.0402 mm.

+ 449.6218u — 14.65907 = — 0.0766 mm.
+ 12.72197 = + 0.0390 mm.
from. which:
c = — 0.00202 mm.
nw = — 0.00010 mm. = — 070020, or — 0°007 per year.
a = + 0.00274 mm. = + 07057 + 07009.

Probable error of plate of unit weight
+ 0.00147 mm. = + 07031.
480 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 3
REDUCTIONS FoR 2 2580, B
Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p). | Factor (P). | Days (t). (v). in Are.
mm. mm.

31 +0.0043 1.0 +0.821 —553 ~—0.0018 —0%04
32 + .0029 1.0 + .821 — 553 — .0004 — .01
35 + .0025 0.9 + .792 —550 .0000 .00
36 + .0023 1.0 + .792 —550 + .0002 .00
269 + .0016 0.5 — .883 —429 — .0024 | — .04
293 + .0010 1.0 — .897 —427 — .0018 | — .04
337 — .0018 1.0 — .983 —421 + .0009 + .02
347 — .0026 1.0 — .938 —420 + .0017 + .04
385 — .0027 1.0 — .975 —409 + .0017 | + .04
402 + .0011 1.0 — .981 —401 — .0021 — .04
1270 + .0028 1.0 + .950 —206 + .0003 | + .01
1280 + .0058 1.0 + .910 —199 — .0028 | — .06
1281 + .0015 1.0 + .910 —199 + .0016 + .03
1293 + .0022 1.0 + .904 —198 + .0008 + .02
1294 — .0011 1.0 + .904 —198 + .0041 + .09
4090 + .0069 0.9 + .448 +573 — .0040 | — .08
4091 + .0022 0.8 + .448 +573 + .0006 + .01
4132 + .0022 0.9 + .278 +584 + .0003 + .01
4346 + .0001 0.7 — .629 +642 + .0006 + .01
4347 + .0007 1.0 — .629 +642 -0000 -00
4468 + .0018 0.5° | — .928 +673 — .0016 | — .02
4469 — .0038 0.5 — .923 +673 + .0040 + .06
4511 + .0031 0.7 — .956 +680 — .0030 — .05
4514 —0.0027 0.7 —0.960 +681 +0.0028 +0.05

 

The normal equations are:

21.1¢ — 12.267n + 0.23767 = + 0.0288 mm.
+ 500.95174 — 21.38047 = — 0.0126 mm.
+ 14.81097 = + 0.0282 mm.

from which:
c = + 0.00140 mm.
uw = + 0.00010 mm. = + 070020, or + 07007 per year.
a = + 0.00202 mm. = + 07042 + 07008.
Probable error of plate of unit weight
+ 0.00136 mm. = + 07028.
 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 48.
TABLE 4
REDUCTIONS FOR 2 2576
i Wei Parall: ime i 4 Be
Hae: | ee ey. | tare | ee aes
mm. mm.
31 +0.0156 1.0 +0.821 —553 +0.0011 +002
32 + .0182 1.0 + .821 — 553 — .0015 — .03
35 + .0151 0.9 + .792 —550 + .0015 + .03
36 + .0212 1.0 + .792 —550 — .0046 — .10
269 + .0102 0.5 — .883 —429 + .0030 + .04
293 + .0148 1.0 — .897 —427 — .0017 — .04
337 + .0102 1.0 — .9383 —421 + .0028 + .06
347 + .0129 1.0 — .988 —420 + .0001 .00
385 + .0132 1.0 — .975 —409 — .0003 — .01
402 + .0143 1.0 — .981 —401 — .0014 — .03
1270 + .0189 1.0 + .950 — 206 — .0036 — .07
1280 + .0164 1.0 + .910 —199 — .0012 — .02
1281 + .0126 1.0 + .910 —199 + .0026 + .05
1293 + .0125 1.0 + .904 —198.| + .0027 + .06
1294 + .0116 1.0 + .904 —198 + .0036 + .07
4090 + .0108 0.9 + .448 +573 -0000 -00
4091 + .0115 0.8 + .448 +573 — .0007 — .01
4132 + .0107 0.9 + .278°| +584 — .0002 -00
4346 + .0108 0.7 — .629 +642 — .0022 — .04
4347 + .0063 1.0 — .629 +642 + .0024 + .05
4468 + .0071 0.5 — .923 +673 + .0009 + .01
4469 + .0093 0.5 — .923 +673 — .0013 — .02
~ 4511 + .0064 0.7 — .956 +680 + .0015 + .03
4514 +0.0111 0.7 —0.960 +681 —0.0032 —0.06
The normal equations are:
21.1e — 12.2674 + 0.23767 = + 0.2740 mm.
+ 500.9517 — 21.38047 = — 0.4240 mm.
+ 14.81097 = + 0.0383 mm.
from which:
c = + 0.01270 mm.
» = — 0.00046 mm. = — 070096, = — 07034 per year.
a = + 0.00171 mm. = + 07036 + 07008.

Probable error of plate of unit weight
+ 0.00150 mm. = + 07031.

32
482 S. A. MITCHELL

a AQUILE (19 45"; +8° 36’)

Altair, of 0.89 magnitude, of A5 type, and of fairly large
proper motion 0"65, has had its parallax many times observed
with the following results:

 

 

 

Parallax. Authority. Method.
+07232+0'019 Elkin Heliometer

.22 + .047 Flint Meridian Circle

.079+ .033 Flint Meridian Circle
+0.216+ .073 Jewdokimov Meridian Circle

 

 

 

Combining the McCormick result, where a = + 07218
+ 0°007, weighting the values according to their probable errors,
and omitting the second value of Flint, above, then the parallax
of Altair results:

n = + 07220.

The McCormick plates were measured by Mr. Mitchell.
The proper motion in right ascension from the plates is -+ 07536,
while the value from Boss is + 0”544. These results have al-
ready been published in Popular Astronomy, 25, 1, 1917.

CoMPARISON STARS

 

 

No. | Diameter. |* eee eee Y (Declination). Dependence.

 

1 0.12 —44.7 +21.8 +0.182
2° 14 —28.2 —48.4 221
3 12 +11.8 — 4.5 204
4 14 +16.8 +50.7 -176
5 12 +44.3 —19.6 +0.217

 

 

 

 

Parallax star 0.19 + 0.6 — 3.0

 
 

 

 

PARALLAXES OF 260 STARS 483
TABLE 1
Priates or ALTAIR
No. Date. Hour Angle. Observers. Weight.
1417 1915 June 30 040 G 0.8
1418 June 30 +0.4 G 0.7
1426 July 2 +0.3 A 0.7
1427 July 2 +0.8 A 0.9
1653 Sept. 11 —0.2 / A 0.6
1654 Sept. 11 +0.1 A 0.9
1665 Sept. 12 —0.3 M 0.6
1720 Sept. 19 —0.2 M 1.0
1732 Sept. 22 —0.2 A 1.0
1760 Sept. 25 —0.7 M 1.0
1761 Sept. 25 —0.2 M 1.0
2679 1916 May 27 —0.7 M 0.5
2680 May 27 —0.4 M 0.7
2694 June 1 —0.7 M 0.8
2695 June 1 —0.4 M 0.7
2753 June 22 —0.6 M 0.8
3046 Sept. 20 —0.2 M 0.8
3114 Sept. 30 —0.2 A 0.8
3119 Oct. 1 —0.2 M 0.7*
3120 Oct. 1 +0.2 M 0.7*
3178 Oct. 12 +0.2 M 1.0
3250 Oct. 23 +0.1 M 1.0
3251 Oct. 23 +0.4 M 0.8

 

 

 

 

 

* One exposure.
484

S. A. MITCHELL

 

 

 

 

 

TABLE 2
REDUCTIONS FoR ALTAIR

Solution Weight Parallax Time in Residual Vp+o
Plate. (m). (p). | Factor (P). | Days (2). (0). in Arc.

mm. mm.
1417 +0.0240 0.8 +0.283 —240 —0.0029 —0"05
1418 + .0186 0.7 + .283 —240 + .0025 + .04
1426 + .0186 0.7 + .251 —238 + .0023 + .04
1427 + .0214 0.9 + .251 —238 — .0005 — .0l
1653. + .0185 0.6 — .795 —167 — .0035 — .05
1654 "| + .0148 0.9 — .795 —167 + .0002 -00
1665 + .0146 0.6 — .805 —166 + .0004 + .01
1720 + .0170 1.0 — .866 —159 — .0021 — .04
1732 + .0150 1.0 — .888 —156 — .0001 -00
1760 + .0130 1.0 — .908 —153 + .0019 + .04
1761 + .0134 1.0 — .908 —153 + .0015 + .03
2679 + .0494 0.5 + .748 + 92 + .0004 + .01
2680 + .0500 ; 0.7 | + .743 | +92 | — .0002 .00
2694 + .0496 0.8 + .686 + 97 . 0000 -00
2695 + .0500 0.7 + .686 + 97 — .0004 — .01
2753 + .0481 0.8 + .3897 +118 - 0000 .00
3046 + .0420 0.8 — .879 +208 — .0009 — .02
3114 + .0425 0.8 — .940 +218 — .0013 — .02
3119 + .0412 0.7 — .945 +219 -0000 -00
3120 + .0393 0.7 — .945 +219 + .0019 + .03
3178 + .0398 1.0 — .977 +230 + .0019 + .04
3250 + .0422 1.0 — .974 +241 + .0003 + .01
3251 +0.0444 0.8 —0.974 +241 —0.0019 | —0.03

 

 

 

 

 

The normal equations are:

+ 11.47707
from which:
c = + 0.03540 mm.
uw = + 0.00719 mm. =

Tv

18.5¢ — 0.5044 — 7.68967 = + 0.5704 mm.
+ 66.4464u — 3.91927

+ 0.00100 mm. = + 0”021.

= + 0.4187 mm.
= — 0.1797 mm.

+ 071496, or + 07546 per year.
+ 0.10513 mm. = + 07218 + 07007.
Probable error of plate of unit weight
PARALLAXES OF. 260 STARS 485

n AQUILE (19> 47"; +0° 45’)

This is a well-known variable of small proper motion 0”012,
and of Go type. The range of light variation is from 3.7 to
4.4 magnitude. 1 Aquile has been found by Belopolsky to be a
spectroscopic binary (Astrophysical Journal, 6, 393, 1897),

 

 

 

TABLE 1
PLatTes OF 7 AQUILE
No. Date. Hour Angle. Observers. Weight.
381 1914 Oct. 9 +054 G 0.9
1434 1915 July 6 0.0 A 1.0
1743 Sept. 23 —0.3 M,G 0.8
1755 Sept. 24 —0.4 A 0.8
1756 Sept. 24 +0.3 A, Ol 0.6*
1916 Oct. 30 +0.7 M 1.0
1917 Oct. 30 +1.2 M 1.0
2736 1916 June 19 —0.8 M 0.8
2737 June 19 —0.4 M 0.9
2764 June 23 —0.3 Ol 0.7
2765 June 23 +0.2 Ol 0.8
2771 June 25 —0.8 M 0.6*
2939 Aug. 30 +0.6 A 0.6*
8078 Sept. 24 +0.4 M 1.0
3079 Sept. 24 +0.8 M 0.8
3115 Sept. 30 +0.3 A 1.0
3116 Sept. 30 +0.9 A 0.9

 

 

 

 

 

* One exposure.
CoMPARISON STars

 

 

 

 

 

 

No. Diameter. X (Right Ascen-| y (Declination). Dependence.
sion).

mm. mm. mm.

1 0.13 —37.0 —15.4 +0.1751

2 .09 —32.0 — 2.1 .1774

3 -12 . —25.8 + 8.1 .1783

4 -21 — 8.9 — 7.8 .1675

5 .17 +42.6 —14.7 . 1469

6 e22 +61.1 +31.9 +0.1548
Parallax star 0.22 — 2.5 — 0.2

 
486 S. A. MITCHELL

with a period of 7.176 days. It is a Cepheid variable, and ac-
cording to Shapley has a theoretical absolute parallax + 07005.
The only parallax is the spectroscopic value of Adams + 07003.
The McCormick plates were measured by Mr. Alden who finds a
proper motion in right ascension to be + 07018 while the value

from Boss is + 0”008.
TABLE 2:

s
REDUCTIONS FOR 7 AQUILE

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vpeo
Plate. (m). (p). | Factor (P). | Days (t). (). in Are.
mm. [mm.

381 +0.0064 0.9 —0.969 —516 —0.0009 —0"02
1434 + .0064 1.0 + .193 —246 — .0003 — .01
1743 + .0064 0.8 — .892 —167 — .0001 .00
1755 + .0050 | 0.8 — .899 —166 + .0013 + .02
1756 + .0054 0.6 — .899 —166 + .0009 + .01
1916 + .0069 1.0 — .957 —130 — .0005 — .01
1917 | + .0054 | 1.0 | — .957 | —130 | + .0010 | + .02
2736 + .0091 0.8 + .447 |. +103 — .0022 — .04
2737 + .0055 0.9 + .447 +103 + .0014 + .03
2764 + .0095 0.7 + .387 +107 | — .0026 — .04
2765 + .0060 0.8 + .387 +107 + .0009 + .02
2771 + .0035 0.6 + .356 +109 + .0034 + .05
2939 + .0074 0.6 — .667 +175 — .0003 .00
3078 + .0058 1.0 — .904 +200 + .0014 + .03
3079 + .0079 0.8 — .904 +200 — .0007 — .01
_ 8115 + .0076 1.0 — .938 +206 — .0004 — .01
3116 +0.0088 0.9 —0.988 +206 —0.0016 —0.03

 

 

 

 

The normal equations are:
14.2¢ — 0.7904 — 6.82097 = + 0.0947 mm.
+ 60.8177 + 3.80507 = + 0.0091 mm.
+ 8.53207 = — 0.0450 mm.
from which:
c = + 0.00665 mm.
n= + 0.00024 mm. = + 070050, or + 07018 per year.
a = — 0.00007 mm. = — 07001 + 07009.
Probable error of plate of unit weight
+ 0.00093 mm. = + 07019.

ll
The spectroscopic parallax + 0”008 has been found for this
star which is of 4.86 magnitude, of G5 type, and of small proper

PARALLAXES OF 260 STARS

£ AQUILA: (195 49; +8° 12’)

motion 0710 per year.

487

The McCormick plates were measured by
Mr. Olivier. The proper motion in right ascension from the plates

is + 07095 per year, and the value from Boss + 0”095.

 

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Puates or £ AQuILa

No. Date. Hour Angle. Observers. Weight.
1721 | 1915 Sept. 19 +045 M 0.9
1722 Sept. 19 +0.9 M 0.8
1825 Oct. 15 -0.1 Ol 0.7
1826 Oct. 15 +0.3 Ol, G 0.8
2891. 1916 Aug. 18 +0.3 Ol 0.8
3024 Sept. 18 0.0 ol 1.0
3025 Sept. 18 +0.5 ol 0.7*
3977 1917 May 18 —0.4 ol 0.9
4017 May 25 +0.2 Ol 1.0
4023 May 29 —0.8 Ol 0.9
4024 May 29 —0.2 ol 0.8
4420 Sept. 12 —0.4 ol 0.9
4421 Sept. 12 +0.1 Ol 0.9
4488 Oct. 1 +0.4 Ds A 1.0
4489 Oct. 1 +0.8 Ds A 1.0
4498 Oct. 2 —0.5 ol 0.9

* One exposure.

Comparison STARS
No. Diameter. |~ eo eal Y (Declination). | Dependence.
mm. mm. mm.

1 0.15 —33.3 +34.1 +0.2234

2 .16 —20.1 —49.2 .38079

3 -11 — 3.2 +17.7 . 1829

4 10 +11.2 +16.6 1544

5 18 445.4 | 19.2 +0.1314

Parallax star 0.17 — 6.52 — 4.25

 

 

 
488 S. A. MITCHELL

TABLE 2

REDUCTIONS FOR £ AQUILA

 

 

 

 

 

 

 

 

 

Plate, | Season | waght | zames,| Bose. | Regie | he
mm. mm.
1721 —0.0111 0.9 —0.858 —444 +0.0026 | +0705
1722 — .0084 0.8 — .858 —444 — .0001 -00
1825 — .0073 0.7 — .977 | —428 — .0012 | — .02
1826 — .0064 0.8 — .977 —428 — .0021 — .04
2891 — .0025 0.8 — .500 —120 — .0014 | — .02
3024 — .0037 1.0 — .856 — 89 — .0004 | — .01
3025 — .0067 0.7 — .856 | — 89 + .0026 | + .05
3977 + .0032 0.9 + .849 +153 — .0014 | — .03
4017 + .0006 1.0 + .775 +160 + .0011 | + .02
4023 + .0002 0.9 + .732 | +164 + .0015 | + .03
4024 + .00380 0.8 + .732 +164 — .0013 | — .02
4420 + .0003 0.9 — .801 +270 + .0002 00
4421 + .0017 0.9 — .801 +270 — .0012 | — .02
4488 — .0020 1.0 — .939 +289 + .0025 | + .05
4489 + .0017 1.0 — .939 +289 — .0012 | — .02
4498 +0.0015 0.9 —0.943 +290 —0.0010 | —0.02

 

The normal equations are:
14.0c + 2.5744 — 6.16437 = — 0.0284 mm.
+ 110.1236 + 7.19207 = + 0.1453 mm.
+ 10.0078r = + 0.0349 mm.
from which:
c = — 0.00154 mm.
# = + 0.00125 mm. = + 070260, = 07095 per year.
x = + 0.00164 mm. = + 07034 + 07009.
Probable error of plate of unit weight

+ 0.00109 mm. = + 07023.

B AQUILZ: (19> 50™; +6° 9’)

Adams has found the spectroscopic parallax of this star to be
+ 07115. Allegheny and Swarthmore by photography have
PARALLAXES OF 260 STARS 489

found the values + 07078 + 07005 and + 0067 + 07011, each
in close agreement with the McCormick value. The star is of
Ko type, of magnitude 3.90, and of annual proper motion 0”484.
Mr. Mitchell measured the McCormick plates, and found the
proper motion in right ascension to be + 0018 while the value
from Boss is + 07035.

TABLE 1

Puates or 6 AQUILE

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
60 1914 May 31 —048 M 1.0
61 May 31 —0.3 M 0.9
83 June 19 —0.2 M, Ol 0.9
84 June 19 +0.3 M, Ol 0.4

240 Sept. 14 +0.7 M,A 1.0

241 Sept. 14 +1.1 M,A 1.0

261 Sept. 19 +1.2 M,A 0.9

415 Oct. 21 +0.7 M, Ol 0.7

434 Oct. 30 +1.0 A 1,2*

447 Oct. 31 +0.8 M 1.0

460 Nov. 1 +0.7 M 1.0

1312 1915 May 13 —0.7 M 1.0

1313 May 13 —0.3 M 1.0

1328 May 22 —0.8 M 1.0

1344 June 6 —0.2 A 1.0

 

* Three exposures.

ComPaRISON STARS

 

 

 

 

 

 

 

No. Diameter. |* ao ead ¥ (Declination). Dependence.
mm. mm. mm.
1 0.11 —49.3 +23.1 +0.156
2 15 —48.2 —36.1 -181
3 .19 —10.4 +34.8 .152
4 -16 +22.8 —42.0 .184
5 .20 +25.3 +30.3 -155
6 .12 +59.8 —10.1 _ +0.172
Parallax star 0.16 + 0.4 — 2.4

 
490 S. A. MITCHELL

TABLE 2
REDUCTIONS FOR 8 AQUILEZ

 

 

 

 

 

 

 

 

 

Plate Solution | Weight | Parallax | Time in Residual Np+o
[ (m). (p). Factor (P). | Days (t). Q@). in Arc,
mm. mm.

60 —0.0186 1.0 +0.716 —156 +0.0012 | +0702
61 — .0169 0.9 + .716 | —156 — .0005 | — .O1
83 — .0158 0.9 + .465 | —137 — .0023 | — .05
84 — .0184 | 0.4 + .465 | —137 + .0003 .00
240 — .0265 1.0 — .815 — 50 + .0045 | + .09
241 — .0228 1.0 — .815 — 50 + .0008 | + .02
261 —' .0238 0.9 — .858 | — 45 + .0017 | + .03
415 — .0179 0.7 — .977 — 13 — .0045 — .07
434 — .0227 1.2 — .958 - 4 + .0004 | + .O1
447 — .0201 1.0 — .954 - 8 — .0022 — .04
460 — .0209 1.0 — .951 = 2 — .0014 | — .03
1312 — .0150 1.0 + .888 +191 — .0010 | + .02
1313 — .0147 1.0 + .888 +191 — .0013 — .03
1328 — .0182 1.0 + .812 , +200 + .0020 | — .04
1344 —0.0176 1.0 +0. 646 +215 +0.0009 | +0.02

 

The normal equations are:

14.0c + 1.631n — 0.94187 = — 0.2724 mm.
+ 23.6798u + 4.79977 = — 0.0106 mm.
+ 9.48397 = + 0.0492 mm.

ll

from which:
c = — 0.01927 mm.
B= + 0.00024 mm. = + 070050, or + 07018 per year.
aw = + 0.00315 mm. = + 07066 + 0’011.
Probable error of plate of unit weight
+ 0.00150 mm. = + 07031.

LALANDE 38287 (19> 58"; + 15° 20’)

This star 7.19 magnitude and G5 type has a total proper
motion 0761. Its parallax has been twice determined, Chase
with the Yale heliometer finding the value + 07075 + 07038,
and Adams and Joy by the spectograph the result + 07068. Mr.
Oliver measured the McCormick plates.
PARALLAXES OF 260 STARS 491 -

TABLE 1

Puates oF LALANDE 38287

 

 

 

No. Date. Hour Angle. Observers. Weight.
3106 1916 Sept. 27 +041 Ol 0.8
8107 Sept. 27 +0.7 Ol 0.9
3140 Oct. 6 +0.4 L 0.8
3141 Oct. 6 +0.9 Ol 0.6
3309 Oct. 30 +0.5 Ol 0.6
3320 Nov. 1 +0.4 Ol 0.9
3944 1917 May 9 —0.8 Ol 0.7
3965 : May 14 —0.7 Ol 0.8
4025 May 29 0.0 Ol 1.0
4422 Sept. 12 +0.5 Ol 1.0
4423 Sept. 12 +0.8 Ol 1.0
4500 Oct. 2 +0.2 ol 0.9
4561 Oct. 12 —0.3 Ol 1.0
4562 Oct. 12 0.0 Ol 0.9
5374 1918 May 16 -1.1 Ol 0.8
5375 May 16 —0.6 Ol 0.9
5386 May 18 —0.7 Ol 0.8
5387 May 18 —0.3 Ol 0.7
5390 May 25 —1.4 Ol 0.8

 

 

 

 

 

CoMPARISON STARS

 

 

 

 

 

No. Diameter. - ea Y (Declination). Dependence.
mm. mm. mm.

1 0.16 —55.4 +10.1 +0.1392

2 «15 —27.8 —10.8 -1451

3 17 +13.0 — 3.5 -2125

4 12 +27.9 — 23.3 2027

5 17 +42.3 +27.5 +0.3005
Parallax star 0.17 + 9.4 + 2.6

 
492 S. A. MITCHELL

TABLE 2

ReEpucTIONS FOR LALANDE 38287

 

 

 

 

 

 

 

 

 

Plate Solution Weight Parallax Time in Residual ? vp-o

: (m). (p). Factor (P). | Days (t). (2). in Arc.

mm. mm.

3106 +0.0150 0.8 —0.904 —295 +0.0016 +0703
3107 + .0144 0.9 — .904 —295 + .0022 + .04
3140 + .0170 0.8 — .949 — 286 — .0007 — .01
3141 + .0181 0.6 — .949 —286 — .0018 — .03
3309 + .0163 0.6 — .959 — 262 — .0006 — .O1
3320 + .0173 0.9 — .953 —260 — .0016 — .03
3944 + .0177 0.7 + .921 — 71 + .0010 + .02
3965 + .0188 0.8 + .889 — 66 — .0006 — .01
4025 + .0186 1.0 + .753 — 51 — .0010 — .02
4422 + .0081 1.0 — .778 + 55 + .0016 + .03
4423 + .0085 1.0 — .778 + 55 + .0012 + .02
4500 + .0097 0.9 — .930 + 75 — .0010 | — .02
4561 + .0085 1.0 — .967 + 85 — .0002 -00
4562 + .0094 0.9 — .967 + 85 — .0011 — .02
5374 + .0111 0.8 + .876 +301 — .0005 — .01
5375 + .0105 0.9 + .876 +301 | + .0001 .00
5386 + .0110 0.8 + .860 +303 — .0005 — .01
5387 + .0094 0.7 + .860 +303 + .0011 + .02
5390 +0.0100 0.8 +0.798 +310 +0.0001 0.00

 

The normal equations are:

15.9¢ + 1.066u — 3.00237 = + 0.2048 mm.
+ 76.7553u — 18.08477 = — 0.0812 mm.
+ 12.50147 = + 0.0330 mm.

from which:

c = + 0.01373 mm.

w= — 0.00213 mm. = — 070443, or — 07162 per year
+ 0.00374 mm. = + 07078 + 0"006.

Probable error of plate of unit weight

+0.00077 mm. = + 07016.

wT
PARALLAXES OF 260 STARS 493

LALANDE 38383 (19° 59™; +23° 5’)

This is a star of considerable proper motion 1739 per year, of
magnitude 7.2 and spectral type G8. Its parallax has been
measured several times with the following results:

 

 

 

 

 

Observer. Method. Parallax.
Flint Meridian circle —0"02 +0028
Chase Heliometer + .095+ .043

* Jewdokimov Meridian circle + .102+ .068
Allegheny Photography + .038+ .007
Adams Spectrograph +0.126

 

Mr. Alden measured the McCormick series of plates with the
exception of the four last, which were measured by Mr. Mitchell.
A parallax of + 07075 + 0”009 was derived, and a proper

 

 

 

TABLE 1
Piates oF LALANDE 38383
No. Date. Hour Angle. Observers. Weight.
3271 1916 Oct. 25 +046 Ol 0.8
3279 Oct. 26 +0.6 Ol 1.0
3345 Nov. 5 +0.8 M 1.0
4154 1917 July: 1 —0.2 A 0.8
4155 July 1 +0.1 A 0.7
4593 Oct. 17 0.0 M 1.0
4597 Oct. 20 0.0 B 0.9
4598 Oct. 20 +0.4 B 1.0
5410 1918 June 3 +0.1 A 1.0
5411 June 38 +0.6 AS 1.0
5458 June 15 +0.3 A 1.0
5459 June 15 +0.8 A 1.0
5460 June 15 +1.2 A 1.0
5683 Sept. 14 +0.2 M 1.0
5684 Sept. 14 +0.6 M 0.9
5758 Oct. 4 +0.3 M,F 1.0
5759 Oct. 4 +0.7 M, H 1.0

 

 

 

 

 
494 S. A. MITCHELL

motion in right ascension of — 17017 per year while the cor-
responding value from Porter is — 17030. Adams has deter-
mined the radial velocity of — 2 km. per sec., so that the motion
of the star is almost entirely at right angles to the-line of sight.

ComPARISON STARS

 

 

 

 

 

 

 

 

 

 

No. Diameter. % rs Y (Declination). Dependence.
1 0.12 —43.7 —35.5 +0.2230
2 -08 —30.8 +10.1 . 1928
3 -10 + 5.1 +20.1 . 1867
4 .10 +17.2 + 9.5 . 1940
5 -08 +52.2 — 4.2 +0.2035
Parallax star 0.12 — 0.8 — 1.2
TABLE 2
ReEpvuctTions FoR LALANDE 38383
Solution Weight Parallax Time in Residual Vp-0
Plate. (m). (p). | Factor (P). | Days (t). (). in Are.
™mm. mm.
3271 —0.0014 0.8 —0.971 —432 +0.0015 +0703
3279 — .0016 1.0 — .970 —431 + .0015 + .03
3345 — .0018 1.0 — .987 —421 + .0005 + .01
4154 — .0255 0.8 + .3812 —183 — .0032 — .06
4155 — .0246 0.7 + .312 —183 — .0041 — .07
4593 — .0481 1.0 — .996 — 75 + .0003 + .01
4597 — .0462) 0.9 — .975 — 72 — .0020 — .04
4598 — .0488 | .1.0 — .975 — 72 + .0006 + .01
5410 — .0742 1.0 + .704 +154 + .0018 + .04_
5411 — .0720 1.0 + .704 +154 — .C004 — .Ol
5458 — .0759 1.0 + .552 +166 + .0014 + .03
5459 — .0754 1.0 + .552 +166 + .0009 + .02
5460 | — .0756 | 1.0 | + .552 | +166 | + .oo11 | + .02
5683 — .0890 1.0 — .791 +257 — .0025 — .05
5684 — .0910 0.9 — .791 +257 — .0005 — .01
5758 — .0951 1.0 — .937 +277 + .0004 + .01
5759 —0.0957 1.0 —0.937 +277 +0.0010 +0.02

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS

The normal equations are:
16.1ce + 1.644 — 5.387720
+ 98.7060p + 8.56957

from which:
c = — 0.05429 mm.
uw = — 0.01339 mm.
az = + 0.00359 mm.

Probable error of plate of unit weight

from photographs taken by Donner (see page 11).

+ 10.3674r

— 0.9154 mm.
— 1.3802 mm.
+ 0.2144 mm.

495

— 0%2785, or — 17017 per year.
+ 07075 + 07009.

+ 0.00118 mm. = + 07025.

BD + 36°.3883 (205 4™; + 36° 17’)

This star is one of the 248 stars in the region surrounding
BD+35°.4013 whose parallaxes were determined by Kapteyn

The star was

put on the McCormick program on account of the large paral-
lax determined by Kapteyn amounting to + 0718. Mr. Oliver
measured the McCormick plates and found a parallax of — 0009

 

 

 

+ 0"010.
TABLE 1.
Piates or BD + 36° 3883
No. Date. Hour Angle. Observers. Weight.
3156 1916 Oct. 8 —043 M 1.0
3157 Oct. 8 0.0 L 0.9
3229 Oct. 21 —0.2 M 1.0
3230 Oct. 21 0.0 M 1.0
4142 1917 June 30 —0.5 Ol 0.9
4143 June 30 —0.3 ol 0.9
4443 Sept. 19 —0.3 M 0.8
4444 Sept. 19 0.0 M 0.8
4532 Oct. 7 —0.4 M 0.9
4533 Oct. 7 —0.1 M 0.9
5392 1918 May 25 —0.6 Ol 1.0
5393 May 25 —0.3 ol 1.0
5394 May 25 0.0 Ol 0.9
5417 June 4 —0.6 Ol 0.8
5418 June 4 —0.2 Ol 0.7

 

 

 

 

 
496 S. A. MITCHELL

ComPaARISON STARS

 

 

 

 

 

 

 

"No. Diameter. x | Y (Declination). Dependence.
mm. mm. mm.
1 0.12 —16.3 +52.1 +0.3708
2 18 —11.2 —34.0 . 8657
3 .09 +27.5 —18.1 +0. 2635
Parallax star 0.12 — 2.9 + 2.1
TABLE 2

Repvuctions ror BD 36°.3883

 

 

 

 

 

 

 

 

 

 

Plate Solution Weight Parallax Time in Residual z Vp-»
F (m). (p). Factor (P). | Days (é). (2). in Are.
mm. mm.
3156 —0.0022 1.0 —0.950 —331 | —0.0014 —0'03
3157 — .00384 0.9 — .950 —331 — .0002 .00
3229 — .0025 1.0 — .974 —318 — .0010 — .02
3230 — .0050 1.0 — .974 —318 + .0014 + .03
4142 — .0061 0.9 + .343 — 66 + .0023 + ..05
4143 — .0032 0.9 + .343 — 66 — .0006 — .01
44438 | - 0031 0.8 — .829 + 15 .0000 -00
4444 — .0027 0.8 — .829 + 15 — .0004 — .01
4532 — .0038 0.9 — .945 + 33 + .0008 + .01
4533 — .0033 0.9 — .945 + 33 + .0003 + .01
5392 — .0014 1.0 + .809 +263 — .0021 — .04
5393 — .0024 1.0 + .809 +263 — .0011 — .02
5394 — .0052 0.9 + .809 +263 + .0017 + .03
5417 — .0047 0.8 + .704 +273 + .0013 + .02
5418 —0.0025 0.7 +0.704 +4273 —0.0009 —0.02
The normal equations are:

13.5¢ — 1.281 — 2.76097 = — 0.0462 mm.

+ 73.2958u + 20.05457 = + 0.0066 mm.

+ 9.17237 = + 0.0086 mm.

from which:

c = — 0.00350 mm.
w = + 0.00015 mm. = + 070032, or + 07012 per year
a = — 0.00046 mm. = — 0”009 + 0”010.
Probable error of plate of unit weight
+ 0.00090 mm. =+ 0019.
PARALLAXES OF 260 STARS 497

LALANDE 38683 (205 6"; + 15° 53’)

This star has a total proper motion of 0755, and is of spectral
type G5 and magnitude 7.3. The Yale heliometer has found a
relative parallax of + 07067 + 07042, and Adams the absolute
parallax of + 07076. Miss Hawes measured the McCormick
plates and found a relative parallax of + 07054 + 0"013, and a
proper motion in right ascension amounting to — 07390 per year.

 

 

 

 

 

 

 

 

 

 

 

TABLE 1
Puates OF LALANDE 38683
No. Date. Hour Angle. Observers. Weight.
4662 1917 Nov. 1 +046 M 0.9
4663 Nov. 1 +0.8 M 1.0
4675 Nov. 2 +0.5 M 1.0
4676 Nov. 2 +0.7 M 1.0
5503 1918 July 2 —0.9 A 0.9
5504 July 2 —0.7 A 0.8
5505 July 2 —0.6 A 0.7
5820 Oct. 21 +0.4 M 0.8
5821 Oct. 21 +0.6 M 0.9
5837 Oct. 22 +0.6 M,D 1.0
5844 Nov. 1 +0.8 M, H 0.7
7045 | 1919 May 18 ~ 0.8 D 1.0
7046 May 18 —0.6 D 1.0
7070 May 22 —0.5 F 1.0
7071 May 22 —0.2 F 1.0
Comparison STARS
No. Diameter. x aaa Y (Declination). Dependence.
mom. mm. mm.

1 0.18 —59.3 — 1.8 +0.237

2 ll —12.1 + 5.1 .228 .

3 -18 +31.2 —24.8 -347

4 .18 +40.2 +21.5 +0.188

Parallax star 0.15 + 1.5 — 3.8

 

 

 

 

 

33
498

S. A. MITCHELL

TABLE 2

REDUCTIONS FOR LALANDE 38683

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual vp-»
Plate. (m). (p). Factor (P). | Days (t). (). in Are.
mm. mm.
4662- —0.0327 0.9 —0.957 —294 —0.0007 —0'01
4663 — .0343 1.0 — .957 —294 + .0009 + .02
4675 — .0368 1.0 — .954 —293 + .0034 + .07
4676 — .0388 1.0 — .954 —293 + .0004 + .01
5503 — .0408 0.9 + .327 — 51 — .0017 — .038
5504 — .0376 0.8 + .327 — 51 — .0049 — .09
5505 — .0422 : 0.7 + .827 — 51 — .0003 -00
5820 — .0524 0.8 — .972 + 60 + .0008 + .01
5821 — .0510 0.9 — .972 + 60 — .0006 — .01
5837 — .0502 1.0 — .972 + 61 — .0015 — .03
5844 — .0506 0.7 — .958 + 71 — .0015 — .03
7045 — .0592 1.0 + .876 +269 + .0017 + .04
7046 + .0580 1.0 + .876 +269 + .0005 + .01
7070 — .0584 1.0 + .844 +273 + .0006 + .01
7071 —0.0590 1.0 +0.844 +273 +0.0012 +0.02
The normal equations are:
13.7e + 0.297% — 2.79657 = — 0.6387 mm.
+ 64.9318 + 17.79667 = — 0.3009 mm.
+ 9.96977 = + 0.0632 mm.
from which:
c = — 0.04598 mm.
w= — 0.00514 mm. = — 071069, = — 07390 per year.
az = + 0.00262 mm. = + 07054 + 0'013.

Probable error of plate of unit weight
+ 0.00061 mm. = + 07013.
PARALLAXES OF 260 STARS 499

o' CYGNI (205 107; +46° 30’)

Allegheny Observatory finds the parallax — 07011 + 0”010 for
this star 30 Cygni which is of magnitude 4.96 and of A2 type,
and of very small proper motion. Mr. Alden measured the
parallaxes of o' and o? Cygni from the same series of plates. For
o! Cygni, the annual proper motion in right ascension from the
plates was found to be —0"020, while the value from Boss is
+ 07015.

 

 

 

 

 

TABLE 1
ro PLATES OF o! AND o? CYGNI
No. Date. Hour Angle. Observers. Weight.
348 1914 Sept. 29 —041 M,A 1.0
366 Oct. 1 —0.2 M, Ol 0.9
408 Oct. 19 —0.3 M, Ol 0.6*
414 Oct. 21 —0.1 M, Ol 0.7*
1409 1915 June 28 —0.9 G 1.0
1410 : June 28 —0.5 G 0.8
1440 July 8 0.0 G 0.8
1450 July 9 0.0 G 0.8
1602 Sept. 1 —0.7 Ol 0.9
1603 Sept. 1 —0.3 Ol 0.7*
1631 Sept. 9 —0.7 Ol 0.9
1632 Sept. 9 —0.3 Ol 0.7
1773 Oct. 3 -1.0 M 0.8
1774 Oct. 3 —0.7 M 0.8
2706 1916 June 3 -1.2 M 0.8
2707 June 3 —0.9 M 0.8
2708 June 3 —0.5 M 0.9
3064 Sept. 23 —0.3 A 0.9
3065 Sept. 23 0.0 A 0.9
3142 Oct. 7 —0.1 A 0.9
3143 Oct. 7 +0.1 A 0.6*

 

 

 

* One exposure.
500

S. A. MITCHELL

o? CYGNI (205 107; +46° 26’)

Adams by means of the spectrograph has found the absolute
parallax of this star, 31 Cygni to be + 07016, while Allegheny
The star is of

finds the relative parallax — 07013 + 07009.

Kop type, of magnitude 3.95, and of very small annual proper

motion, 0”002. The proper motion in right ascension from the

plates is + 0"001 while the value from Boss is + 07002. Camp-
bell (Lick Observatory Bulletin, 1, 22, 1901) has found the star

to be a spectroscopic binary.

CoMPARISON STARS FOR o! CYGNI

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. cs eee Y (Declination). Dependence.
mm. mm. mm.
1 0.16 —29.7 +39.6 +0.224
2 -13 —24.0 —34.3 .162
3 12 + 9.0 +13.5 .215-
4 .12 +10.9 —15.5 .190
5 -11 +33.8 — 3.3 +0.209
o! Cygni 0.12 + 0.6 +- 2.6
Comparison STaRs FOR o? CyGNni
No. Diameter. a eo Y (Declination). Dependence.
mm. mm. mm.
2 0.13 —31.5 —24.4 +0.242
3 -12 + 1.6 +23.4 .099
4 -12 + 3.5 — 5.6 -3808
5 -11 +26.4 + 6.6 +0.351
o? Cygni 0.17 + 2.9 — 0.5

 

 

 

 

 
 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 50:
TABLE 2
REDUCTIONS FOR o! Cy@ni
Solution: ; Weight Parallax Time in Residual Vp+o
Plate. (m). (p). Factor (P). | Days (). (2). in Are.
mm. mm.
348 +0.0254 1.0 —0.890 | —382 —0.0004 —0701
366 + .0258 0.9 |-— .902 —380 — .0008 | — .02
408 + .0242 0.6 — .969 —362 + .0006 | + .01
414 + .0208 0.7 — .971 —360 + .0040 | + .07
1409 + .0254 1.0 + .406 —110 + .0002 .00
1410 + .0262 0.8 + .406 —110 — .0006 | — .01
1440 + .0291 0.8 + .295 —100 — .0036 | — .C7
1450 + .0240 0.8 + .234 — 99 + .0014 | + .03
1602 + .0257 0.9 — .670 — 40 — .0014 — .03
1603 + .0237 0.7 — .670 — 40 + .0006 | + .01
1631 + .0238 0.9 — .704 — 37 + .0004 | + .01
1632 + .0211 0.7 — .704 — 37 + .0031 | + .05
1773 + .0265 0.8 — .913 — 13 — .0026 — .05
1774 + .0260 0.8 — .913 — 13 — .0020 — .04
2706 + .0228 0.8 + .727 +231 + .0022 | + .04
2707 + .0256 0.8 + .727 +231 — .0006 — .01
2708 + .0248 0.9 + .727 +231 + .0002 .00
3064 + .0258 0.9 — .849 +343 — .0028 | — .05
8065 + .0217 0.9 — .849 +343 + .0014 | + .03
3142 + .0223 0.9 — .937 +357 + .0006 | + .01
3143 +0.0210 0.6 —0.937 +357 +0.0019 | +0.03
The normal equations are:
17.2c + 0.360un — 6.584387 = + 0.4209 mm.
+ 102.4216 + 4.78567 = — 0.0140 mm.
+ 9.93852 = — 0.1545 mm.
from which:
c = + 0.02489 mm.
pz = — 0.00027 mm. = — 070057, or — 07020 per year.

x = + 0.00107 mm. = + 07022 + 07009.

Probable error of plate of unit weight
+ 0.00121 mm. = + 07025.
502

S. A. MITCHELL

TABLE 3

REDUCTIONS FOR o? CYGNI

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual Vp-o
Plate. (m). (p). Factor (P). | Days (). (v). in Arc.
mm, mm.
348 +0.0261 1.0 —0.890 —382 —0.0016 —0"03
366 + .0272 0.9 — .902 —380 — .0027 — .05
408 + .0210 0.6 — .969 —362 + .0035 + .06
414 + .0213 | 0.7 — .971 | —360 | + .0032 | + .06
1409 + .0234 1.0 + .406 —110 + .0012 + .02
1410 + .0290 0.8 + .406 —110 — .0044 — .08
1440 + .0246 0.8 + .295 —100 -0000 |- .00
1450 + .0234 0.8 + .234 — 99 + .0012 + .02
1602 + .0262 0.9 — .670 — 40 — .0014 — .03
1603 + .0184 0.7 — .670 — 40 + .0064 + .11
1631 + .0269 0.9 — .704 — 37 — .0021 — .04
1632 + .0216 0.7 — .704 — 37 + .0032 + .05
1773 + .0253 0.8 — .918 — 13 — .0005 — .01
1774 + .0273 0.8 — .9138 — 18 — .0025 — .05
2706 + .0254 0.8 + .727 +231 — .0006 — .01
2707 + .0229 0.8 + .727 +231 + .0020 + .04
2708 + .0251 0.9 + .727 +231 — .0002 .00
3064 + .0280 0.9 — .849 +343 — .0029 — .06
3065 + .0224 0.9 — .849 +343 + .0027 + .05
3142 + .0253 0.9 — .9387 +357 — .0002 .00
3143 +0.0260 0.6 —0.937 +357 —0.0009 —0.01
The normal equations are: ~
17.2¢ + 0.360n — 6.584387 = + 0.4259 mm.
+ 102.4216u + 4.78567 = + 0.0179 mm.
+ 9.98852 = — 0.1634 mm.
from which:
c = + 0.02472 mm.
B= + 0.00009 mm. = + 070002, or + 07001 per year.
az = — 0.00011 mm. = — 0002 + 0’013.

Probable error of plate of unit weight

+ 0.00164 mm. = + 0034.
a! CAPRICORNI (20° 12™; —12° 49’)

PARALLAXES OF 260 STARS

503

The spectroscopic parallax + 07003 has been found for this
star which is of G type, of magnitude 4.55, and of small proper

motion 0%04 per year in position angle 72°.

Mr. Olivier measured

the parallaxes of a! and a? Capricorni from the same series of
plates. For a! Capricorni, he determined the annual proper
motion in right ascension to be + 07025 while the value from

 

 

 

 

 

 

 

 

 

 

 

Boss is + 07015.
TABLE 1
PLATES OF a! AND a? CAPRICORNI
No. Date. ; Hour Angle. Observers. Weight.
350 1914 Sept. 29 +154 M,A 0.9
422 Oct. 23 +0.8 M, Ol 0.8
525 Nov. 9 +0.6 M, Ol 0.8
1459 1915 July 13 +0.2 A 1.0
1460 July 13 +0.7 A 1.0
1482 July 17 —0.3 A, Ol 0.6
1483 July 17 +0.3 Ol 0.8
1656 Sept. 11 +1.0 A 0.8
1657 Sept.11 . +1.6 A 0.8
1733 Sept. 22 +0.1 A 1.0
1767 Oct. 2 —0.1 M 0.9
1768 Oct. 2 +0.4 A 1.0
2708 1916 June 3 —0.2 M 0.6
2709 June 3 +0.2 M 0.6
2731 June 18 —0.6 Ol 0.6
2819 July 12 +0.6 ol 0.9
'
Comparison Stars, a! CAPRICORNI
No. Diameter. a fad ee Y (Declination). Dependence.
mm. mm. mm.
1 0.06 —17.5 +39.3 +0 :2507
2 .06 —19.0 — 1.1 - 2636
3 .08 —16.6 —15.6 . 2663
4 :11 +53.1 —22.6 +0.2194
a! Capricorni 0.15 — 2.2 + 0.5

 

 

 

 
504 S. A. MITCHELL

 

 

 

 

 

TABLE 2
REDUCTIONS FOR a! CAPRICORNI
Plate Solution Weight Parallax Time in Residual Vpeo
* (m). (p). Factor (P). | Days (£). (v). in Are.
mm. mom.

350 —0.0114 0.9 —0.885 —343 —0.0001 0”00
422 — .0109 0.8 — .970 —319 — .0005 — .01
525 — .0132 0.8 — .931 —312 + .0018. + .03
1459 — .0120 1.0 + .179 — 56° + .0005 + .01
1460 — .0102 | 1.0 + .179 — 56 — .0012 — .02
1482 — .0141 0.6 + .114 — 52 + .0027 + .04
1483 — .0093 0.8 + .114 - 52. — .0021 — .04
1656 — .0112 0.6 — .720 + 4 + .0007 + .01
1657 — .0081 0.8 — .720 + 4 — .0024 — .04
1733 “= .0098 1.0 — .829 + 15 — .0006 — .01
1767 — .0108 0.9 — .903 + 25 + .0005 + .01
1768 — .0112 1.0 — .903 + 25 + ..0009 + .02
2708 — .0103 0.6 + .723 +270 — .0005 — .01
2709 — .0122 0.6 + .733 +270 + .0014 + .02
2731 —. .0106 0.6 + .547 +285 .0000 -00
2819 —0.0109 0.9 +0.505 +288 +0.0003 +0.01

 

 

 

 

 

The normal equations are:

12.9¢ — 1.760n — 3.69017 = — 0.1412 mm.
+ 48.7525u + 11.27347 = + 0.0266 mm.
+ 6.24947 = + 0.0398 mm.
from which:
c = — 0.01113 mm.
Bh = + 0.00033 mm. = + 070068, or + 07025 per year.
7 = — 0.00080 mm. = — 07017 + 07009.

Probable error of plate of unit weight
+ 0.00076 mm. = + 0016.

a? CAPRICORNI (205 12™; —12° 51’)

Adams and Joy find the parallax for this star + 07024. It is
of Ko type, of magnitude 3.77, and of small proper motion
0’014 per year in position angle 328°. This is a triple star, B
PARALLAXES OF 260 STARS

505

and C are separated by 1’, and are of twelfth and thirteenth
magnitudes respectively. BCis distant 7” from A. The annual
proper motion from the plates is + 07032 in right ascension
while the value from Boss is + 07058.

Comparison Stars, a? CAPRICORNI

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. |* a no ala Y (Declination). Dependence.
mm. mm. mm.
1 0.06 —35.5 +39.4 +0.1046
2 -06 —37.0 — 1.0 2334
3 -08 —34.6 —15.5 2772
4 11 +35.1 —22.5 2425
5 14 +72.0 — 0.4 +0.1423
@ Capricorni 0.18 — 3.2 — 5.9
TABLE 3
REDUCTIONS FOR a? CaPRICORNI
Plate. Solution Weight | Parallax Time in Residual Vp-o
(m). (p.) Factor (P). | ‘Days (t). (v). in Arc.
mm. mm.
350 +0.0170 0.9 —0.885 —327 —0.0023 —0°04
422 + .0150 0.7 — .970 —305 — .0001 -00
525 + .0154 0.8 — .931 — 296 — .0005 — .01
1459 + .0135 1.0 + .179 — 40 + .0016 | + .03
1460 + .0140 1.0 + .179 — 40 + .0011 + .02
1482 + .0146 0.6 + .114 — 36 + .0005 ; + .01
1656 + .0160 0.9 — .720 + 20 -0000 -00
1657 + .0142 0.8 — .720 + 20 + .0018 | + .03
1733 + .0169 1.0 — .829 + 31 — .0007 — .O1
1767 + .0167 0.9 — .903 + 41 — .0004 — .01
1768 + .0146 1.0 — .903 + 41 + .0017 | + .03
2708 + .0150 0.6 + .738 +286 + .0010 | + .02
2731 + .0165 0.6 + .547 +301 — .0003 -00
2819 +0.0195 0.9 +0.505 +304 —0.0032 —0.06
The normal equations are:
11.7¢ — 0.775 — 4.34017 = + 0.1831 mm.
+ 42.6872 + 9.13457 = — 0.0012 mm.
+ 5.97800 = — 0.0677 mm.
506 S. A. MITCHELL

from which:
c = + 0.01538 mm.
uw = + 0.00042 mm. = + 07008, or + 07032 per year.
a = — 0.00081 mm. = — 0017 + 07013.
Probable error of plate of unit weight
+ 0.00101 mm. = + 07021.

6! and 6? CAPRICORNI (205 15"; —15° 6’)

The spectroscopic parallax + 0”032 has been found for 81 Cap
ricorni a star of magnitude 3.25, and of type Gp, while 6? Capri

TABLE 1

PuLatTEes oF 8 CAPRICORNI

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
295 1914 Sept. 22 +048 M 0.6
301 Sept. 23 +0.8 G 0.5*
356 Sept. 30 +1.0 M,G 0.7
409 Oct. 19 +0.6 Ol, M 0.7
1451 1915 July 9 +0.7 G 0.8
1604 Sept. 1 +0.2 ol 0.6
1694 Sept. 15 —0.7 Ol 0.9
1695 Sept. 15 —0.2 Ol 0.7
1745 Sept. 23 +0.4 G 0.7
2681 1916 May 27 —0.3 M 0.7
2682 May 27 0.0 M 0.5*
2696 June 1 —0.4 M 0.7
2697 June 1 +0.1 M 0.6
3013 Sept. 17 +0.6 M 0.9
3014 Sept. 17 +1.1 M 0.9
3143 Oct. 7 +0.6 A 1.0
3166 Oct. 11 +0.3 L 0.9 |
3167 Oct. 11 +0.7 L 1.0

 

* One exposure.
PARALLAXES OF 260 STARS 507

corni is of magnitude 6.16 and of type A. Both have very small
proper motions which seem to be common to the two stars.
Capricorni is a double, Barnard 12, the companion being 1” dis-
tant. Campbell has found (Astrophysical Journal, 10, 241, 1899)
that 6! Capricorni is a spectroscopic .binary, with a period,
according to Merrill of 1875 days. Mr. Mitchell measured the
parallax of 8! and 6? Capricorni from the same series of plates.
The annual proper motions from the plates were — 0”007 and
+ 0006 respectively, while the values from Boss are + 0%035
and + 07042.

Comparison Stars, 8! CaPRICcORNI

 

 

 

 

 

 

No. Diameter. < Cees Y (Declination). | Dependence.
mm. mm. mm,
2 0.11 —28.0 —12.1 +0.373
3 -10 + 8.1 +47.8 .291
4 -12 +19.9 —35.7 +0.336
6 Capricorni 0.10 — 1.4 — 2.6

 

Comparison Srars, 8? CAPRICORNI

 

 

 

 

 

 

 

No. Diameter. Ps SO Y (Declination). Dependence.
1 0.18 —25.8 + 3.6 +0.280
2 -1l —19.4 —13.3 .291
3 .10 +16.7 +46.6 .172
4 .12 +28.5 —36.9 +0.257
6? Capricorni 0.24 — 2.7 — 4.4

 
508

S. A. MITCHELL

TABLE 2

REDUCTIONS FOR 6! CAPRICORNI

 

 

 

 

 

 

 

 

 

 

Solution Weight | _ Parallax Time in Residual Vv peo
Plate. (m). (p). | Factor (P). | Days @). (v). in Are.
mm. mm.
295 —0.0084 0.6 —0.824 —366 —0.0015 —0%02
356 — .0128 0.7 — .886 —358 + .0028 + .05
409 — .0127 0.7 — .965 —339 + .0026 + .04
1451 — .0077 0.8 + .255 — 76 — .0016 — .03
1604 — .0096 0.6 — .588 — 24 — .0005 — .01
1694 — .0085 0.9 — .754 -— 8 — .0017 — .03
1695 — .0099 0.7 — .754 -— 8 — .0003 — .01
1745 — .0071 0.7 — .830 0 — .0032 — .05
2681 — .0102 0.7 + .811 +247 + .0010 + .02
2682 — .0089 0.5 + .811 +247 — .0003 .00
2696 — .0096, 0.7 + .762 +252 + .0004 + .01
2697 — .0100 0.6 + .762 +252 + .0008 + .01
3013 — .0110 0.8 — .898 +360 + .0003 + .01
8014 — .0122 0.8 — .898 +360 + .0015 + .03
3143 — .0116 1.0 — .973 +380 + .0008 + .01
3166 — .0091 0.8 — .946 +384 — .0017 — .03
3167 —0.0114 1.0 —0.946 +384 +0.0006 +0.01
The normal equations are:
12.6c + 14.757 — 5.87517 = — 0.1275 mm.
+ 102.8549u — 4.16267 = — 0.1554 mm.
+ 8.65207 = + 0.0641 mm.
from which:
c = — 0.00962 mm.
uw = — 0.00010 mm. = — 070020, or — 0”007 per year.
x = + 0.00084 mm. = + 07002 + 07008.

Probable error of plate of unit weight

+ 0.00099 mm. = + 0”021.
 

 

 

 

PARALLAXES OF 260 STARS 50!
TABLE 3
REDUCTIONS FOR 6? CAPRICORNI
Lutio Weigh Parall: Time i si pe
Plate. oe a | oe ee | ae
mm. mm.

295 +0.0018 0.7 —0.824 —366 —0.0006 | —001
301 + .0011 0.5 — .832 —365 + .0001 .00
356 — .0004 0.7 — .886 —358 + .0016 | + .03
409 — ,0007 0.7 — .965 —339 + .0019 | + .03
1451 + .0043 0.8 + .255 — 76 — .0028 | — .05
1604 + .0059 0.6 — .588 — 24 — .0044 | — .08
1694 + :0014 1.0 — .754 | — 8 + .0001 00
1695 — .0004 0.7 — .754 ~ 8 + .0019 | + .03
1745 + .0027 0.7 — .830 0 — .0012 | — .02
2681 — .0010 0.7 |,+ .811 +247 + .0027 | + .05
2682 — .0018 0.5 + .811 +247 + .0035 + .05
2696 + .0027 0.7 + .762 +252 — .0010 | — .02
2697 + .0033 0.6 + .762 +252 ) — .0016 | — .02
3013 + .0037 1.0 — .898 +360 — .0019 | — .04
3014 + .0008 1.0 — .898 +360 + .0010 | + .02
3143 + .0012 1.0 — .973 +380 + .0006 + .01
3166 + .0029 1.0 — .946 +384 — .0011 — .02
3167 +0.0004 1.0 —0.946 +384 +0.0014 | +0.03

 

 

 

 

 

 

The normal equations are:

13.9¢ + 14.7664 — 6.99737 = + 0.0223 mm.
+ 0.0317 mm.
— 0.0111 mm.

+ 118.9894 — 4.35627

from which:

c = + 0.00151 mm.
+ 0.00008 mm. = + 0”0016, or + 07006 per year.
— 0.00001 mm. = 07000 + 07010.

Probable error of plate of unit weight
+ 0.00121 mm. = + 07025.

be
T.

+ 9.62447
510 S. A. MITCHELL

y CYGNI (20' 18"; +39° 56’)

The McCormick parallax differs very materially from the
average of the visual results for this star which is of 2.32
magnitude, of type F8p, and of small annual proper motion,
0"003. The values of the parallax are:

 

 

 

 

 

Authority. Method. : Parallax.
Pritchard Photography +0°102+07021
Chase Heliometer + .099+ .088
Flint Meridian circle + .003+ .024
Allegheny Photography — .022+ .008
Adams Spectrograph +0.010

 

The McCormick value of the relative parallax is — 07003
+0”010. The last sixteen plates of the series were measured
by Miss Hawes, the earlier plates by Mr. Alden. From the
plates, the proper motion in right ascension was found to be
+ 07004 while the corresponding value from Boss is + 0”001.

Comparison STARS

 

 

 

 

 

 

No. Diameter. |* re Y (Declination). Dependence.
mm. mm. mm.

1 0.20 —52.1 +43 .4 +0.1621

2 14 —46.0 — 9.1 . 1890

3 .10 —14.4 —24.7 . 1859

4 ll +20.4 +33.5 . 1403

5 13 +35.9 —19.2 . 1639

6 14 +56.2 —23.8 +0.1588
Parallax star 0.17 — 2.2 — 1.5

 
 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 511
TABLE 2
REpDucTIONS FOR y Cya@nt
Soluti Weigh Parall: ime i i me
Plate. “Onis eet | aes | eee | Regal | ae
mm. mm.

1613 —0.0172 1.0 —0.653 —597 —0.0032 | —0*07
1614 — .0188 1.0 — .653 —597 — .0016 |’ — .03
1784 — .0182 0.7 — .926 —566 — .0021 — .04
1801 — .0240 0.8 — .9385 —564 + .0037 | + .07
1802 — .0258 0.8 — .985 —564 + .0055 | + .10
2685 — .0210 1.0 + .789 —331 + .0006 | + .01
2686 — .0238 1.0 + '.789 —331 + .0034 | + .07
2689 — .0185 0.6 + .779 —330 — .0019 | — .03
2979 — .0198 0.8 — .686 —229 — .0004 — .01
2980 — .0166 0.8 — .686 —229 — .0036 | — .07
3240 — .0170 0.8 — .967 —186 — .0081 — .06
3241 — .0264 0.8 — .967 —186 + .0063 | + .12
3281 — .0174 1.0 — .967 —181 — .0027 | — .06
4050 — .0220 0.9 + .695 + 43 + .0018 | + .04
4051 ~ — .0194 0.9 + .695 + 43 — .0008 — .02
4105 — .0182 0.9 + .515 + 57 — .0020 | — .04
4457 — .0205 1.0 — .800 +147 + .0006 | + .01
4458 — .0203 1.0 — .800 +147 + .0004 | + .01
4515 — .0181 1.0 — .907 +161 — .0018 | — .04
4516 — .0192 0.7 — .907 +161 — .0007 | — .OL
5447 — .0220 1.0 + .686 +409 + .0020 + .04
5448 — .0221 0.7 + .686 +409 + .0021 + .04
5494 — .0146 0.8 + .387 +431 — .0054 | — .10
5495 — .0178 1.0 + .387 +431 — .0022 — .05
5506 — .0206 1.0 + .372 +432 + .0006 + .01
5507 — .0206 0.9 + .372 +432 + .0006 | + .01
5723 — .0188 0.8 — .858 +519 — .0009 | — .02
5790 — 0222 0.8 — .944 +534 + .0025 + .05
5791 —0.0226 0.8 —0.944 +534 +0.0029 | +0.05

 

 

 

* One exposure.

The normal equations are:

25.3¢ + 0.603n — 6.07127 = — 0.5087 mm.
+ 364.1110u + 15.44427

+ 14.77917

{ Three exposures.

ll

tt

+ 0.0044 mm.
+ 0.1209 mm.
512 S. A. MITCHELL

 

 

 

 

 

 

 

 

TABLE 1
PLATES OF y CYGNI
No. Date. Hour Angle. Observers. Weight
1613 1915 Sept. 7 —1*1 A 1.0
1614 Sept. 7 -0.6 A 1.0
1784 Oct. 8 —0.5 01, G 0.7
1801 ‘Oct. 10 —0.7 M 0.8
1802 Oct. 10 —0.4 M 0.8
2685 1916 May 30 —-1.0 M 1.0
2686 May 30 —0.2 M 1.0t
2689 May 31 —1.3 Ol 0.6
2979 Sept. 9 —0.7 A 0.8
2980 Sept. 9 —0.4 A 0.8
3240 Oct. 22 —0.3 M 0.8
3241 Oct. 22 0.0 M 0.8
3281 Oct. 27 —0.2 M 1.0
4050 1917 June 8 —0.6 A 0.9
4051 June 8 —0.3 Poi 0.9
4105 June 22 —0.2 A 0.9
4457 Sept. 20 -0.7 A 1.0
4458 Sept. 20 —0.4 A 1.0
4515 Oct. 4 —0.3 M 1.0
4516 Oct. 4 0.0 M 0.7*
5447 1918 June 9 —0.3 A 1.0
5448 June 9 0.0 A 0.7*
5494 July 1 —0.7 A 0.8
~. 5495 July 1 —0.4 A 1.0
5506 July 2 —0.4 A 1.0
5507 July 2 —0.1 A 0.9
5723 Sept. 27 —0.2 M 0.8
5790 Oct. 12 —0.6 M 0.8
5791 Oct. 12 —0.2 M 0.8
from which:
c = — 0.02014 mm.
uw = + 0.00005 mm. = + 070011, or + 07004 per year.

ll

— 0.00015 mm. = — 07003 + 0°010.
Probable error of plate of unit weight
+ 0.00177 mm. = + 07037.

T
PARALLAXES OF 260 STARS 513

. p CAPRICORNI (20° 23"; —18° 8’)

The spectroscopic parallax + 07011 has been found for this
star of magnitude 4.96, of type F, and of small proper ‘motion

 

 

 

TABLE 1
PLATES OF p CAPRICORNI
INo. Date. Hour Angle. Observers. Weight.
1762 1915 Sept. 25 —042 A 1.0
1763, Sept. 25 —0.2 A 1.0
1777 Oct. 3 +0.2 M 0.8
1778 Oct. 3 +0.7 M 1.0
4081 1917 June 17 —0.6 Ol 0.5
4082 June 17 —0.1 Ol 0.7
4445 Sept. 19 +0.3 M 0.7*
4687 Nov. 3 +0.4 M 0.9
4688 Nov. 3 +0.8 M 0.9
4695 Nov. 4 +0.5 M 0.9
5449 1918 June 9 +0.5 A 1.0
5508 July 2 +0.3 A 1.0
5509 ‘ July 2 +0.6 A 1.0
5696 Sept. 15 +0.2 M 0.8
5697 Sept. 15 +0.7 M 1.0
5717 Sept. 24 +0.1 M 1.0
5718 Sept. 24 +0.5 M 1.0
7096 1919 May 26 —0.7 D 1.0
7097 May 26 —0.2 D 1.0

 

 

 

 

 

* One exposure.

0"026. Mr. Mitchell measured the plates and found a relative
parallax of + 07019 + 07013, and a proper motion in right ascen-
sion + 0”001 while the corresponding value from Boss is — 07014.
p Capricorni is accompanied by a companion of magnitude 7.6,
and at a distance less than 3”. According to Burnham, the two
stars form a physical system. .

34
514 S. A. MITCHELL

CoMPARISON STARS

 

 

 

 

 

 

 

 

No. Diameter. BS oe a ang Y (Declination). Dependence.
mm. mm. mm.

1 0.15 —78.8 + 7.9 +0.277

2 -18 —21.4 —25.6 - 236

3 -08 +45.1 +52.4 _ .278

4 11 +55.1 —34.7 +0.209

Parallax star 0.20 — 2.7 + 3.4
TABLE 2

REDUCTIONS FOR p CAPRICORNI

 

 

 

 

 

 

 

 

 

Plate. Solution Weight Parallax Time in Residual 7 vVp-v
(m). (p). Factor (P). | Days (t). (v). in Arc.
mm. mm.

1762 +0.0060 1.0 —0.828 —756 —0.0019 —0704
1763 + .0060 1.0 — .828 —756 — .0019 — .04
1777 + .0056 0.8 — .888 —748 — .0015 — .03
1778 + .0016 1.0 — .888 —748 + .0025 + .05
4081 + .0032 0.5 +  .598 —125 + .0023 + .03
4082 + .0037 0.7 + .598 —125 + .0018 + .03
4445 + .0027 0.7 — .777 — 31 + .0016 + .03
4687 + .0021 0.9 — .956 + 14 + .0020 + .04
4688 + .0066 0.9 — .956 + 14 — .0025 — .05
4695 + .0022 0.9 — .954 + 15 + .0019 | + .04
5449 + .0080 1.0 — .699 +232 — .0024 — .05
5508 + .0016 1.0 + .390 +255 + .0037 + .08
5509 + .0045 1.0 + .390 +255 + .0008 + .02
5696 + .0064 0.8 — .734 +330 — .0020 — .04
5697 + .0009 1.0 — .734 +3830 + .0034 + .07
5717 + .0031 1.0 — .822 +339 + .0012 + 02
5718 + .0084 1.0 — .822 +3839 — .0041 — .09
7096 + .0078 1.0 + .842 +583 — .0020 — .04
7097 +0.0069 1.0 +0.842 +583 —0.0011 —0.02

 
PARALLAXES OF 260 STARS o1é

The normal equations are:

17.2c + 1.8864 — 5.46237 = + 0.0803 mm.
+ 345.9671u + 26.87267 = + 0.0380 mm.
+ 10.63837r = — 0.0172 mm.

from which:
c = + 0.00495 mm.
Bw = + 0.00001 mm. = + 070003, or + 07001 per year.
x = + 0.00089 mm. = + 07019 + 07013.

Probable error of plate of unit weight
+ 0.00163 mm. = + 07034.

BOSS 5247 (20% 23"; —18° 12’)

This star is of magnitude 7.1, and of proper motion 0”136.
Its parallax was determined from the same plates as that of p
Capricorni, the measures having been made by Mr. Mitchell.
A relative parallax + 07011 + 07010 resulted, and a proper
motion in right ascension + 0”057 while the corresponding value
from Boss is + 07040. No other parallax has been published.

 

 

 

Comparison Stars ror Boss 5247
No. Diameter. x eo aa Y (Declination). Dependence.
1 0.15 —78.8 + 7.9 +0.213
2 .13 —21.4 —25.6 7281
3 .08 +45.1 +52.4 -187
4 -11 +55.1 —34.7 +0.319
Parallax star 0.08 + 3.3 — 6.8

 

 

 

 

 

The normal equations are:

15.3¢ + 3.60384 — 5.63607 = + 0.9629 mm.
+ 344.0248u + 27.60107 = + 0.5005 mm.
+ 9.78667 = — 0.3289 mm.
516 S. A. MITCHELL

TABLE 2

Repuctions For Boss 5247

 

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual : vp-0
Plate. (m). (p). Factor (P). | Days (¢). (2). in Arc.

mm. mm.
1762 |. +0.0580 1.0 —0.828 —756 —0.0012 —0%02
1763 + .0554 1.0 — .828 —756 + .0014 + .038
1777 + .0592 0.8 — .888 —748 — .0024 — .04
1778 + .0566 1.0. — .888 —748 + .0002 .00
4687 + .0622 0.9 — .956 + 14 + .0004 + ..01
4688 + .0620 0.9 — .956 + 14 + .0006 + .01
4695 + .0604 0.9 — .954 + 15 + .0022 + .04
5449 + .0634 1.0 + .699 +232 + .0017 + .04
5508 + .0647 1.0 +. .390 +255 + .0004 + .01
5509 + .0652 1.0 + .390 +255 — .0001 .00
5696 + .0659 0.8 — .734 +330 — .0008 — .02
5697 + .0626 1.0 — 71734 +330 + .0025 + .05
5717 + .0654 1.0 — .822 +339 — .0003 — .0ol
5718 + .0682 1.0 — .822 +3839 — .0031 | — .06
7096 + .0692 1.0 + .842 +583 — .0014 — .03
7097 +0.0680 1.0 +0.842 +583 —0.0002 0.00

from which:
c = + 0.06295 mm.
uw = +.0.00075 mm. = + 070157, or + 07057 per year.

a = + 0.00052 mm. = + 07011 =- 07010.
Probable error of plate of unit weight
+ 0.00109 mm. = + 07023.

41 CYGNI (205 25"; +30° 2’)

This star of magnitude 4.09 and of type F5 has a small proper
motion 07010. Miss Darkow measured the plates and found .a
relative parallax — 07023 + 07006, with a proper motion in
right ascension + 07016 where the corresponding value from
Boss is + 07009. The spectroscopic parallax of Adams and Joy
is 07009.
PARALLAXES OF 260 STARS

TABLE 1

Puates oF 41 Cyani

517

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1641 1915 Sept. 10 —12 A 1.0
1775 Oct. 3 —0.5 M 1.0
1776 Oct. 3 —0.2 M 1.0
3112 1916 Sept. 29 —0.3 L 0.5*
5529 1918 July 6 —0.6 A 0.8
5530 July 6 —0.2 A 0.9
5553 July 14 +0.1 A 0.9
5792 Oct. 12 0.0 M 0.9
5806 Oct. 15 —0.2 M, D 0.9
5835 Oct. 22 —0.3 M 0.8
5836 Oct. 22 0.0 M 0.9
6987 1919 May 7 —1.2 D 1.0
6999 May 12 —1.0 H 1.0
7000 May 12 =.7 H 0.4*
7034 May 17 0.8 M 1.0
7643 Sept. 6 =0,4 H Le
7644 Sept. 6 —0.1 H 1.0
7748 Sept. 17 —0.7 H 0.9
7749 Sept. 17 —08 H 0.9
* One exposure.
CoMPARISON STARS
No. Diameter. & aa aaa Y (Declination). Dependence.
1 0.11 —33.9 —18.9 +0.230
2 .16 —13.8 +11.2 . 266
3 .12 —15.6 —27.5 .161
4 .21 +16.2 +386.2 . 262
5 -10 +47.1 — 1.0 +0.081
Parallax star 0.16 — 5.9 + 3.6

 

 

 

 

 
518 S. A. MITCHELL

TABLE 2 3

Repuctions ror 41 Cya@ni

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual v 5: a,
Plate. (m). | (@). Factor (P). | Days (t). (v). in Ar
: mm. mm.
1641 +0.0114 1.0 —0.667 —923 +0.0001 0700
1775 + .0126 1.0 — .884 —900 — .0008 — .02
1776 + .0110 1.0 — .884 —900 + .0008 + .02
3112 4: 0118 0.5 — .861 —538 +. .0007 + .01
5529 + .0126 0.8 + .336 +107 .0000 .00
5530 + .0146 0.9 + .336 +107 — 0020 — .04
5553 + .0109 0.9 + .210 +115 + .0018 + .04
5792 + .0143 0.9 — .985 +205 — .0001 .00
5806 + .0150 0.9 — .946 +208 — .0008 — .01
5835 | + .0144 | 0.8 | — .962 | +215 | — .0002 .00
5836 + .0148 0.9 — .962 +215 — .0006 — .0l
6987 + .0124 1.0 + .957 +412 + .0002 .00
6999 + .0124 1.0 + .937 +417 |-+ .0002 .00
7000 + .0172 0.4 + .987 +417 — .0046 — .06
7034 + .0111 1.0 + .910 +422 + .0016 + .03
7643 + .0150 1.0 — .619 +534 — .0004 — .01
7644 + .0140 1.0 — .619 +534 + .0006 | + .01
7748 + .0182 0.9 — .746 +545 + .0015 + .03
7749 +0.0152 0.9 —0.746 +545 —0.0005 —0.01

 

 

The normal equations are: 7

16.8¢ + 14.974y — 4.83567 = + 0.2225 mm.
+ 449.9589y + 17.52507 = + 0.2671 mm.
+ 10.51677 = — 0.0694 mm.

from which:
c = + 0.01274 mm.
ph = + 0.00021 mm. = + 070044, or + 07016 per year.

— 0.00109 mm. = — 07023 + 07006.
Probable error of plate of unit weight
+ 0.00080 mm. = + 07017.

wT
PARALLAXES OF 260 STARS 519

8 DELPHINI (20° 32"; +14° 14’)

This is a double, 6 151, discovered by Burnham in 1873 with
the six-inch telescope when separated by a distance of only
0°7, the principal star of magnitude 4.0, and the companion of
magnitude 5.0. The principal star is of type F5. The parallax
has been four times determined with the following results:
Flint with the meridian circle obtaining the value — 0702

TABLE 1

PLatEes OF 8 DELPHINI

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
195 1914 Sept. 2 +056 Ol 0.4*
213 Sept. 7 +0.6 M 0.7
214 Sept. 7 +1.2 M 0.8
218 Sept. 9 +0.6 M 0.8
219 Sept. 9 +1.1 M 0.9
242 Sept. 14 +1.2 M, A 0.8
243 Sept. 14 +1.7 M,A 0.9
538 Nov. 10 +0.5 M 0.9
563 Nov. 12 +0.6 ol 0.8
1346 1915 June 6 +0.1 A 0.5*
1353 June 9 —1.0 ol 0.8
1354 June 9 —0.6 Ol 0.7
1394 June 25+. +0.1 A 0.7
1395 June 25 +0.5 A 0.9
1675 Sept. 13 —0.7 Ol 0.8
1696 Sept. 15 +0.2 ol 0.6*
1697 Sept. 15 +0.6 Ol 0.7*
3282 1916 Oct. 27 +0.1 M 0.8
3283 Oct. 27 +0.4 M 0.9
8299 Oct. 28 +0.2 Ol 0.9
3339 Nov. 3 —0.1 ol 0.9
3340 Nov. 3 +0.4 Ol 0.7*
3417 Nov. 21 +0.9 M 1.0

 

* One exposure.
520 S. A. MITCHELL

+ 0"027; Swarthmore by photography, + 07016 + 07011;
Yerkes by photography, + 07043 + 0”006; and Adams by the
spectrograph, the absolute parallax of + 07032. Several orbits
have been published, the most reliable seeming to be the one of
Aitken (Publications Lick Observatory, 12, 150, 1914), where the
period is 26.79 years, and a = 0748. Mr. Olivier measured the
McCormick plates, and derived the relative parallax of + 07008
+ 07008. The annual proper motion in right ascension from

TABLE 2

Repuctions For 6 DELPHINI

 

 

 

Solution Weight Parallax Time in Residual : vp-o
Plate. (m). Factor (P). | Days (). (2). in Are.

mm. mm.
195 —0.0204 0.4 —0.543 —326 +0.0007 +0701
213 — .0206 0.7 — .609 —321 — .0009 — .02
214 — .0206 0.8 — .609 —321 — .0009 — .02
218 — .0206 0.8 — .634 —319 — .0010 — .02
219 — .0206 0.9 — .634 —3819 — .0010 — .02
242 — .0224 0.8 — .694 —314 + .0008 + .02
243 — .0205 0.9 — .694 —314 — .0010 — .02
5388 — .0228 0.9 — .939 —257 + .0020 + .04
563 — .0217 0.8 — .931 —255 + .0010 + .02
1346 — .0194 0.5 + .759 — 49 + .0026 + .04
1853 — .0170 0.8 + .727 — 46 + .0002 .00
1854 — .0149 0.7 + .727 = 46 — .0019 — .03
1394 — .0170 0.7 + .528 — 380 + .0004 + .01
1395 — .0168 0.9 + .528 — 380 + .0002 -00
1675 — .0148 0.8 — .682 + 50 — .0016 — .03
1696 — .0196 | ,0.6 — .682 + 52 + .0038 + .06
1697 — .0155 0.7 — .682 + 52 — .0003 — .01
3282 — .0075 0.8 — .962 +460 — .0021 — .04
3283 — .0113 0.9 — .962 +460 + .0017 + .03
3299 — .0097 0.9 — .962 | +461 + .0001 .00
3339 — .0105 0.9 — .957 +467 + .0010 + .02
3340 — .0085 0.7 — .957 +467 — .0010 — .02
3417 —0.0082 1.0 —0.879 +485 —0.0010 —0.02

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS 521

.

the plates is -+- 07118, while the value from Boss is + 0”108.
If we assume the value of the relative parallax to be the mean
of the Yerkes, McCormick and Swarthmore values, then the
mass of the system is 3.92 times that of the sun.

Comparison Stars

 

 

 

 

 

 

 

No. Diameter. x a sri Y (Declination). Dependence.
mm. mm. mm.
1 0.27 —41.1 + .1.3 +0.2768
2 -27 ; —34.8 +18.4 . 2054
3 .21 — 4.2 +27.6° -1131
4 .17 +19.1 — 7.0 . 1863
5 19 +61.0 —40.3 +0.2184
Parallax star 0.22 — 2.1 — 2.9

 

The normal equations are:

17.9¢ + 2.7194 — 9.00707 = — 0.2924 mm.
+ 179.5629 — 9.74867 = + 0.2314 mm.
+10.81117 = + 0.1366 mm.

from which:

c = — 0.01637 mm.
w= + 0.00156 mm. = + 070324, or + 07118 per year.
az = + 0.00040 mm. = + 07008 + 07008.

Probable error of plate of unit weight
+ 0.00089 mm. = + 07018.

52 CYGNI (205 41™; +30° 21’)

The spectroscopic parallax + 07015 has been found for this
star which is of 4.34 magnitude, of G5 type, and of small annual
proper motion 0”03. It has a ninth-magnitude companion at a
distance of 6”6, but the pair does not show any relative change.
Mr. Lamb measured the McCormick plates with the exception of
the three last plates and these were measured by Mr. Mitchell.
The annual proper motion in right ascension from the plates is
— 0"028 while the proper motion from Boss is — 07016.
3S

522

S. A. MITCHELL

TABLE 1

Puates oF 52 Cyent

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1655 1915 Sept. 11 —042 A 1.0
1803 Oct. 10 —0.3 M 1.0
1804 Oct. 10 0.0 M 1.0
1815 Oct. 11 —0.2 G 0.8
2755 1916 June 22 —0.7 M 0.5
2772 June 25 —1.2 ol 0.7
2773 June 25 —0.5 Ol 0.4*
2798 July 5 —0.6 L 0.8
8091 Sept. 26 —1.0 L 0.7
38092 Sept. 26 —0.6 L, M 0.8
3134 Oct. 5 —0.3 L 1.0
3231 Oct. 21 —0.2 M 0.8
3251 Oct. 23 0.0 M 1.0
3931 1917 May 1 -1.8. L 0.8
4001 May 23 —1.1 M 0.6*
4002 May 23 —0.8 M 0.8

* One exposure.
Comparison STARS
No. | Diameter. iF st aaa Y (Declination). Dependence.
mm. | mm. mm.
1 0.20 —41.2 ~+19.4 +0.2574
2 .10 — 5.2 — 9.2 - 2005
3 123 + 2.4 — 9.7 -1916
4 .10 + 3.6 —27.4 - 1802
5 .16 +40.4 +26.9 +0.1703
Parallax star 0.18 — 3.7 + 0.9

 

 

 
 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 52
TABLE 2
“Repuctions For 52 Cyent
Soluti Weight | _Parall ime i i ae
Plate. a Ee) ee oe | ee ae:
“mam. mm.
1655 —0.0052 1.0 —0.626 —298 +0.0008 +0702
1803 — .0040 1.0 — .897 —269 — .0006 — .01
1804 — .0036 1.0 — .897 —269 — .0010 — .02
1815 — .0025 0.8 — .902 —268 — .0021 — .04
2755 — .0080 0.5 + .587 — 13 + .0031 + .05
2772 — .0046 0.7 + .547 — 10 — .0003 — .01
2773 — .0050 0.4 + .547 — 10 + .0001 .00
2798 — .0065 0.8 + .405 0 + .0015 + .03
3091 — -.0064 0.7 — .797 + 88 + .0005 | + .01
3092 — .0085 0.8 — .797 + 8&8 + .0026 + .05
3134 — .0073 1.0 — .870 + 92 + .0014 + .03
3231 — .0052 0.8 — .947 +108 — .0008 — .01
3251 — .0051 1.0 — .951 +110 — .0009 — .02
3931 — .0067 0.8 + .972 +300 + .0008 + .02
4001 — .0042 0.6 + .891 +322 — .0018 — .03
4002 —0.0035 0.8 +0.891 +322 —0.0025 —0.05
The normal equations are:
12.7¢c + 0.3584 — 3.67157 = — 0.0677 mm.
+ 54.8566u + 11.21947 = — 0.0170 mm.
: + 8.48347 = + 0.0187 mm.
from which:
¢ = — 0.00519 mm.
zw = — 0.00037 mm. = — 070077, or — 07028 per year.
x = + 0.00045 mm. = + 07009 + 07009.

Probable error of plate of unit weight

+ 0.00100 mm. = + 0"021.
524 S. A. MITCHELL

y DELPHINI (20% 42—; +15° 46’)

This is a wide pair separated 12’, with a common proper
motion of 0720, but with little relative change. The magnitudes
are 4.49 and 5.47, the brighter being of G5 type. Adams by
the spectrograph finds the absolute parallax of + 07015 for the
brighter star and + 0036 for the fainter. Mr. Mitchell meas-
ured the McCormick plates. The parallaxes of the pair found
were + 07038 + 07009, for the brighter star, and + 0046+ 0"008
for the fainter. Their combined values gives the relative par-
allax for the system to be:

+ 07042 + 07006.

By photography Swarthmore finds the parallaxes of + 0”007
+ 07010 and — 07008 + 0"015 for brighter and fainter stars.

CoMPaARISON STARS

 

 

 

 

 

 

 

 

7 7 Dependences.
No. Diameter. | Asesnaoe). | * Yon). a
‘ Brighter. Fainter.
mm. mm. mm.
1 0.14 —66.4 +50.3 +0.194 +0.197
2 .25 —14.8 —36.1 .172 174
3 .22 —14.8 —85.9 -172 174
4 25 +44.5 +21.4 -235 -232
5 .14 +51.5 + 0.3 +0.227 +0.223
Principal star .20 + 4.1 + 2.5 7
Companion 0.15 + 3.6 + 2.5

 
 

 

 

PARALLAXES OF 260 STARS 525
TABLE 1
Puates oF y DELPHINI

No. Date. Hour Angle. Observers. . Weight.
70 1914 June 2 —0>4 M 0.4
71 June 2 0.0 M 0.6
73 June 15 —0.7 M 0.8
74 June 15 —0.3 M 1.0
254 Sept. 15 +0.8 M,G 1.0
262 Sept. 19 +1.0 M,A 1.0
340 Sept. 28 +0.2 M,G 1.0
448 Oct. 31 +0.5 M,A 0.8
461 Nov. 1 +0.2 M 1.0
467 Nov. 2 +0.4 M 0.8
1329 1915 May 22 —-1.2 M 0.7
1330 May 22 —0.8 M 0.7
1365 June 10 —0.6 M 0.7
1366 June 10 —0.2 M 0.8
1367 June 10 +0.2 M 0.7
4094 1917 June 18 —0.3 M 1.0
4095 June 18 0.0 M 1.0
4106 June 22 0.0 A 1.0
4107 June 22 +0.3 A 1.0
4459 Sept. 20 —0.4 A 0.7
4460 Sept. 20 +0.4 A 0.7
4534 Oct. 7 —0.4 M 0.8
4535 Oct. 7 —0.1 M 1.0

 

 

 

 

 
526 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR y DELPHINI, PRINCIPAL STAR
Plate. Solution Weight Parallax Time in Residual Vp-0
(m). (p). Factor (P). | Days (é). (2). in Arc.
mm. mm.
70 —0.0506 0.4 +0.816 —519 —0.0047 | —0*%06
71 — .0559 0.6 + .816 —519 + .0006 | +.
73 — .0523 0.8 + .682 —506 — .00384 | —
74 — .0528 1.0 + .682 —506 — .0029 -.
254 — .0614 1.0 — .675 —414 + .0018 ars
262 — .0624 1.0 — .720 —410 + .0027 +.
340 — .0634 1.0 — .809 —401 + .0084 | +.
448 — .0596 0.8 — .958 —368 — .0011 ee
461 — .0625 1.0 — .958 —367 + .0018 | +
467 — .0584 0.8 — .958 —366 — .0024 =
1329 — .0610 0.7 + .901 —175 + .0010 +
1330 — .0588 0.7 + .901 —175 — .0012 | —
1365 — .0612 0.7 + .740 —146 + .0004 ee
1366 — .0612 0.8 + .740 —146 + .0004 ras
1367 — .0606 0.7 + .740 —146 — .0002
4094 — .0713 1.0 + .642 +593 — .0002
4095 — .0734 1.0 + .642 +593 + .0019 +
4106 — .0746 1.0 + .592 +597 + .00380 +
4107 — .0740 1.0 + .592 +597 + .0024 +.
4459 — .0727 0.7 — .734 +687 — .0027 | —
4460 — .0716 0.7 — .734 +687 — .0038 | —
4534 — .0764 0.8 — .880 +704 + .0005 +.
4535 —0.0729 1.0 —0.880 +704 —0.0030 —0.06
The normal equations are:
19.2c + 4.3384 + 0.09467 = — 1.2389 mm.
+ 463 .9467n — 0.42767 = — 0.9418 mm..
+ 11.538247 = + 0.0159 mm.
from which:
c = — 0.06421 mm.
w= — 0.00143 mm. = — 00297, or — 07108 per year.

a = + 0.00185 mm. = + 07038 + 07009.
Probable error of plate of unit weight
+ 0.00152 mm. = + 07032.
 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 52’
TABLE 3
REDUcTIONS FOR y DELPHINI, COMPANION
Soluti Wei Parall: Time i i Be
Mite. |) Re | OO cece boee | an | ae
mm. mm.
70 +0.0274 0.4 +0.816 —519 —0.0010 —0/01
71 + .0271 0.6 + .816 —519 — .0008 — .01
73 + .0305 0.8 + .682 —506 — .0046 — .09
74 + .0242 1.0 + .682 —506 + .0017 + .04
254 + .0230 1.0 — .675 —414 — .0010 — .02
262 + .0224 1.0 — .720 —410 — .0006 — .0ol
340 + .0181 1.0 — .809 —401 + .0034 + .07
448 “-+- .0206 0.8 — .958 —368 + .0003 .00
461 + .0206 1.0 — .958- —367 + .0002 -00
467 + .0200 0.8 — .958 —366 + .0008 + .02
1829 + .0241 0.7 + .901 —175 — .0011 — .02
1330 + .0244 0.7 + .901 —175 — .0014 — .02
1365 + .0231 0.7 + .740 —146 — .0008 — .01
13866 + .0207 0.8 + .740 —146 + .0016 + .03
1367 + .0208 0.7 + .740 —146 + .0015 + .03
4094 + .0136 1.0 + .642 +593 + .0008 + .02
4095 + .0129 1.0 + .642 +593 + .0016 + .03
4106 + .0126 1.0 + .592 +597 + .0017 + .04
4107 + .0148 1.0 + .592 +597 — .0005 — .01
4459 + .0094 0.7 — .734 +687 + .0010 + .02
4460 + .0157 0.7 — .734 +687 — .0053 — .09
4534 + .0106 0.8 — .880 +704 — .0007 — .01
4535 +0.0101 1.0 —0.880 +704 —0.0002 0.00
The normal equations are:
19.2c + 4.3384 + 0.09467 = + 0.3637 mm.
+ 463.9467 — 0.42767 = — 0.3979 mm.
+ 11.53247 = + 0.0278 mm.
from which:
c = + 0.01917 mm.
zw = — 0.00103 mm. = — 070215, or — 07078 per year.

x = + 0.00221 mm. = + 07046 + 07008.
Probable error of plate of unit weight

+ 0.00124 mm. = + 07026.
528 S. A. MITCHELL

« CYGNI (205 42"; +33° 36’)

This stat has considerable proper motion 07483 per year, is of
spectral type Ko, and of magnitude 2.64. Various discordant
values of the parallax have been determined as follows:

 

 

 

 

 

Authority. Method. Parallax.
Pritchard Photography +07093 +0"031
Pritchard Photography + .1634 .027
Flint: Meridian circle — .19 + .052
Flints Meridian circle — .0164 .024
Jewdokimov Meridian circle — .055+ .071
Allegheny Photography + .054+ .005
Adams Spectrograph +0.044

 

Mr. Mitchell measured seventeen of the McCormick plates,
Mr. Graham measuring ten of the earlier plates. The McCor-
mick parallax is + 07039 + 07008, while the proper motion in
right ascension from the plates is + 07356, while the corre-
sponding value from Boss is + 07360.

ComPaRISON STARS

 

 

 

 

No. Diameter. x cart agate Y (Declination). Dependence.
mm. mm. mm.
1 0.17 —59.9 +30.4 +0.238
2 .10 + 2.8 —22.3 -278
3 .12 +18.4 —30.1 281
4 ll +38.7 +22.0 +0.203
Parallax star 0.15 — 0.3 — 2.9

 

 

 

 
 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 529
TABLE 1
Puates oF ¢ Cyent

No. Date. Hour Angle. Observers. Weight.

50 1914 May 25 —0%5 M 0.5

62 May 31 —0.6 M 1.0

63 May 31 —0.2 M 1.0

69 June 2 —0.9 M 0.7

205 Sept. 5 —0.2 M,G 0.7

253 Sept. 15 -0.1 M,G 0.7

281 Sept. 21 -0.6 M 1.0

282 Sept. 21 —0.2 M 0.7

339 Sept. 28 —0.2 M 0.7*
421 Oct. 23 —0.4 Ol 0.7

517 Nov. 6 —0.1 M 1.0
1368 1915 June 17 —0.8 G 0.8
1369 June 17 —0.4 G 1.0
1373 June 18 —1.3 M 0.8
1874 June 18 —0.6 M 0.7*
4609 1917 Oct. 21 —0.6 M 1.0
4610 Oct. 21 —0.2 M 1.0
4621 Oct. 22 —0.5 M 1.0
4622 Oct. 22 —0.2 M 1.0
5424 1918 June 5 —0.3 L 1.0
5425 June 5 0.0 L 1.0
5437 June 8 —0.8 L 0.7
5438 June 8 —0.4 L 0.6*
5730 Sept. 30 —0.8 M 1.0
5731 Sept. 30 —0.4 M 0.9
5752 Oct. 3 —0.8 M 1.0
5753 Oct. 3 —0.4 M 0.9

The normal equations are:
23.1¢ + 10.3638 — 3.86737
+ 974.9621n — 29.00847

35

+ 15.36557

+-0.0660 mm.
+ 4.5265 mm.
— 0.1111 mm.
530

S. A. MITCHELL

TABLE 2

REDUCTIONS FOR ¢ CYGNI

 

 

 

 

 

 

 

 

 

 

Pte, | Saher) Womet | akdlort®. | Daw. | SES | an'Rre
mm. mm.

50 —0.0343 0.5 +0.880 —730 +0.0028 | +0704

62 — .0280 1.0 + .834 —724 — .0033 — .07

63 — .0326 1.0 + .834 —724 + .0013 | + .03

69 — .0295 0.7 + .816 —722 — .0017 — .03
205 — .0318 0.7 — .549 —627 + .0024 + .04
253 — .0260 0.7 — .675 —617 — .0031 — .05
281 — .0263 1.0 — .741 —611 — .0027 — .06
282 — .0261 0.7 — .7Al —611 — .0029 — .05
339 — .0300 0.7 — .809 — 604 + .0012 | + .02
421 — .0315 0.7 — .950 —579 + .0036 + .06
517 — .0258 1.0 — .953 — 565 — .0014 — .03
1368 — .0156 0.8 + .661 —342 + .0019 + .04
1369 — .0168 1.0 + .661 —342 + .0031 + .06
1373 — .0170 0.8 + .649 —341 + .0033 + .06
1374 — .0124 0.7 + .649 | —341 — .0013 — .02
4609 + .0236 1.0 — .945 +515 — .0002 -00
4610 + .0216 1.0 — .945 +515 + .0018 + .04
4621 + .0247 1.0 — .948 +516 — .0012 — .02
4622 + .0231 1.0 — .948 +516 + .0004 + .01
5424 + .0411 | 1.0 + .788 +742 — .00388 | — .08
5425 + .0390 1.0 + .788 +742 — .0017 | — .04
5437 + .0874 0.7 + .758 +745 .0000 .00
54388 -| + .0346 0.6 + .758 +745 + .0028 | + .05
5730 + .0405 1.0 — .826 +859 — .0007 — .01
5731 + .0399 0.9 — .826 +859 — .0001 -00
5752 + .0387 1.0 — .850 +862 + .0012 | + .02
5753 +0.0386 0.9 —0.850 +862 +0.0013 | +0.02

from which:

ce = + 0.00107 mm.

w= + 0.00469 mm. = + 070975, or + 07356 per year.

+ = + 0.00189 mm. = + 07039 + 07008.

Probable error of plate of unit weight
+ 0.00142 mm. = -: 07030.
PARALLAXES OF 260 STARS 531

n CEPHEI (205 43"; +61° 27’)

Five determinations of the parallax of this star have been
made, as follows: + 07088 -- 07037 from the Yale heliometer
by Smith; + 07241 + 07028 from the meridian circle by
Abetti; + 07066 + 07010 from photography by Slocum and
Mitchell; + 07066 + 07007 by photography at Allegheny; and
the spectroscopic parallax of Adams + 07076. The star has a
considerable proper motion 0782, it is of magnitude 3.59, and of
type Ko. Eleven of the plates were measured by Mr. Briggs, the
balance of nine by Mr. Mitchell. A relative parallax of + 07064

 

 

 

TABLE 1
PLATES oF 7 CEPHEI
No. | Date. Hour Angle. Observers. Weight.
3189 1916 Oct. 14 —047 M 1.0
3190 Oct. 14 —0.3 L 0.8
3343 Nov. 4 0.0 M 0.7
3374 Nov. 10 +0.2 ol 0.8
4092 1917 June 18 —1.0 M 1.0
4093 June 18 | —1.7 M 1.0
4133 June 29 —0.6 A 0.8
4134 June 29 —0.3 A 1.0
4409 Sept. 11 —0.5 M 1.0
4410 Sept. 11 —0.2 B 1.0
4481 Sept. 29 —0.5 B 1.0
4482 Sept. 29 0.0 B 1.0
5518 1918 July 3 —0.6 ol 1.0
5519 July 3 —0.1 Ol 0.9
5542 July 13 —0.1 Ol 0.7*
5543 July 13 +0.2 Ol 0.7
5724 Sept. 27 —0.2 M 1.0
5725 Sept. 27 +0.2 M 0.9
5744 Oct. 2 —0.7 M 1.0
5745 Oct. 2 —0.3 M 1.0

 

 

 

 

 

* One exposure.
132 S, A. MITCHELL

CompPaRIsON STARS

 

 

 

 

 

 

 

 

No. Diameter. cS a de Y (Declination). Dependence.
min. mm. mm.

1 0.11 —66.3 —47.6 +0.2795

2 .16 —11.0 +16.6 . 2145

3 .12 +19.1 +27.1 .1779

4 .14 +24.3 -+14.4 .1707

5 -13 +33.9 —10.5 +0.1574
Parallax star 0.14 — 8.0 — 4.1

TABLE 2

‘REDUCTIONS, FOR 7 CEPHEI

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual vp-o
Plate. (m). (p. Factor (P). | Days (é). (0). in Arc.
mm. mm.

3189 +0.0094 1.0 —0.919 —391 —0.0023 —0"05
3190 + .0044 0.8 — .919 —391 + .0027 + .05
3343 + .0073 0-7 — .955 —370 . 0000 , 00
3374 + .0052 0.8 — .942 —364 + .0022 + .04
4092 + .0159 1.0 + .646 —144 — .0006 — .01
4093 + .0115 1.0 + .646 —144 + .0038 + .08
4133 + .0200 0.8 + .501 —133 — .0050 — .09
4134 + .0140 1.0 + .501 —133 + .0010 + .02
4409 + .0129 1.0 -| — .627 — 59 — .0003 — .01
4410 + .0166 1.0 — .627 — 59 — .0040 — .08
4481 + .0109 1.0 — .817 — 41 + .0013 + .03
4482 + .0128 1.0" — .817 — 41 — .0006 — .O1
5518 + .0223 1.0 + .447 +236 | — .0024 — .05
5519 + .0170 0.9 + .447 +236 + .0029 + .06
5542 + .0193 0.7 + .296 +246 + .0003 + .01
55438 + .0203 0.7 + .296 +246 — .0007 — .01
5724 + .0150 1.0 — .797 +322 + .0023 + .05
5725 + .0185 0.9 — .797 +3822 — .0012 — .02
5744 + .0206 1.0 — .840 +327 — .0034 — .07
__ 5745 +0.0135 1.0 —0.840 | +827 +0.0037 +0.08

 
PARALLAXES OF 260 STARS 533

+ 070138, which is in close agreement with the photographic values
of Yerkes and Allegheny. A proper motion in right ascension
+ 07104 was determined from the plates. The corresponding
value from Boss is + 07097. The star has a large radial velocity
of — 87 km. per second.

The normal equations are:

18.3¢ + 0.7724 — 5.70117 = + 0.2639 mm.
+ 116.2051 + 2.68857 = + 0.1793 mm.
+ 9.39667 = — 0.0547 mm.

from which:
c = + 0.01532 mm.
uw = + 0.00137 mm. = + 070285, or + 07104 per year.
rt = + 0.00309 mm. = + 07064 + 0'013.
Probable error of plate of unit weight
+ 0.00175 mm. = + 07036.

u AQUARII (205 47; —9° 21’)

No parallax has been published for this star of magnitude
4.80, of spectral type F, and of total proper motion 070652.
Mr. Olivier measured the photographs except five plates measured

.

Comparison Strars

 

 

 

 

 

 

No. Diameter. x weer Y (Declination). Dependence.
mm. mm. mm.

1 0.12 —30.5 +22.6 +0.1571

2 .13 —36.5 — 4.7 . 1487

3 .12 — 0.6 +17.8 . 1992

4 -11 +30.4 —45.4 . 2428

5 .10 +37.2 + 9.7 +0.2522
Parallax star 0.12 + 6.4 — 2.1

 

 

by Mr. Mitchell. The relative parallax is small + 07005
+ 0"008, and the proper motion in right ascension from the
plates amounts to + 0”058, while the corresponding value from
Boss is + 07037.
584

S. A. MITCHELL

PLATES OF » AQUARII

TABLE 1

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1624 1915 Sept. 8 +043 A 1.0
1625 Sept. 8 +0.7 A 0.9
‘1642 Sept. 10 —0.1 A 0.7
1643 Sept. 10 +0.3 A 0.7
3080 1916 Sept. 24 +0.6 M 0.7
3081 Sept. 24 +1.0 M 0.7
4045 1917 June 7 —0.3 Ol “0.8
4046 June 7 +0.3 Ol 0.7
4064 June 13 —1.1 Ol 0.9
4065 June 13 —0.5 Ol 0.8
4172 July 10 —0.2 Ol 0.6*
4175 July 13 -1.1 Ol 0.6*
4483 Sept. 29 +0.4 Ds, B 0.8
4484 Sept. 29 +0.9 B, Ds 0.9
4501 Oct. 2 0.0 Ds, Ol 0.9
4502 Oct. 2 +0.4 Ol, Ds 0.8
5468 1918 June 19 —0.5 Ol 1.0
5469 June 19 —0.1 Ol 0.9
5474 June 22 —0.8 Ol 0.8
5475 June 22 —0.2 Ol 0.9
5726 Sept. 28 +0.1 M 1.0
5727 Sept. 28 +0.6 M 0.9
5746 Oct. 2 0.0 M 1.0
5747 Oct. 2 +0.5 M 1.0

 

* One exposure.
 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 535
TABLE 2
. REDUCTIONS FOR p AQUARII
ae ae =
Sol Weight ; _Parall i :
int) SG | ea, eae
mm. mm.
1624 | +0.0004 | 1.0 | —0.567 | —676 | +0.0020 | +0”04
1625 | + .0037 | 0.9 | — .567 | —676 | — .0013 | — .02
1642 | + .0004 | 0.7 | — .592 | —674 | + .0020 | + .04
1643 | + .002 | 0.7 | — .592 | —674 | — .0038 | — .06
3080 | + .0068 | 0.7 |. — .762 | —294 | — .0015 | — .03
3081 | + .0012 | 0.7 | — .762 | —294 | + .0041 | + .07
4045 | + .0081 | 0.8 | + .778 | — 38 | — .0005 | — .01
4046 | + .0064 | 0.7 | + ..778 | — 38 | + .0012 | + .02
4004 | + 0107 | 09 | + 716 | — 32 | — 0081 | — 06
4065 | + .0068 | 0.8 | + .716 | — 32 | + .0008 | + .02
4172 | + .0077 | 0.6 | + .355 | — 5 | + .0001 .00
4i75 | + .0066 | 0.6 | + .310| — 2 | + .0012 | + .02
4483 | + .0087 | 0.8 | — .807 | + 76 | — .0006 | — .O1
4484 | + .0083 | 0.9 | — .807 | +76 | — .0002 .00
4501 | + .0076 | 0.9 | — .832 | +79 | + .0005 | + .01
4502 | + .0102 | 0.8 | — .882 | +79 | — .0021 | — .04
5468 | + .0120 | 1.0 | + .649 | +339 | — .0015 | — .03
5469 | + .o108 | 0.9 | + .649 | +339 | — .0003 | — .O1
5474 | + .0088 | 0.8 | + .611 | +342 | + .0017 | + .03
5475 | + .9086 | 0.9 | + .611 | +342 | + .0019 | + .04
5726 | + .0124 | 1.0 | — .796 | +440 | — .0015 | — .03
5727 | + .ol18 | 0.9 | — .796 | +440 | — .0009 | — .02
5746 | + .o111 | 1.0 | — .830 | +444 | — .0002 .00
5747 | +0.0085 | 1.0 | —0.830 | +444 | +0.0024 | +0.05
The normal equations are:
20.0c + 4.5784 — 3.87667 = +°0.1571 mm.
+ 282.8905u + 6.705387 = + 0.2532 mm.
+ 10.12767 = — 0.0225 mm.
536 S. A. MITCHELL

from which:

c = + 0.00772 mm. ;
» = + 0.00076 mm. = + 070159 or + 07058 per year.
x = + 0.00023 mm. = + 07005 + 07008.

Probable error of plate of unit weight

+ 0.00117 mm. = + 07024.

e EQUULEI (205 54"; +3° 55’)

This forms a triple physical system. The components have a
common proper motion, 0722. The pair 2 2737 are close, and
of nearly equal magnitudes, 5.8 and 6.3, respectively, which
are never separated more than 171. The orbit for this pair
has been found by Russell (Astronomical Journal, 30, 123, 1917),
with a period of 97.4 years, and a = 0761. 10” distant from
this pair AB which is of F5 type, is the star C of magnitude 7.1.
The photographic parallax of Swarthmore is + 07018 + 07012, the
spectroscopic value for AB and C are + 0”021 and + 0”015, re-
spectively. Mr. Mitchell measured the McCormick plates, and
found the parallax of AB to be + 07021 + 07010, and the paral-
lax of C to be + 07002 + 07011. These combined give a relative
parallax of the system:

+ 07011 + 07007.

This gives the absolute value of the parallax to be + 0”016.
Using this value, and Russell’s orbit, then the mass of the system
is equal to 5.8 times that of the sun. The proper motion in
right ascension from the plates is — 07125 for the pair AB,
and — 07135 for the companion C. Boss gives the value
— 07126.
 

 

 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 53
TABLE 1
Puates or ¢ EQUULEI
No. Date. Hour Angle. Observers. Weight.
79 | 1914 June'l7 "+4083 M 0.6
80 June 17 —0.3 M 0.6
85 June 19 0.0 M, Ol 0.6
86 June 19 +0.4 M, Ol 0.6
230 Sept. 13 +0.4 M,G 0.4
272 Sept. 20 +0.9 M 0.8
273 Sept. 20 +1.5 M 0.7
351 Sept. 29 +1.4 A,M 0.7
423 Oct. 23 +0.7 M 0.7
435 Oct. 30 +0.7 G 0.8
548 Nov. 11 +0.1 M 1.0
580 Nov. 17 +0.4 M 0.6
1370 1915 June 17 +0.1 G 1.0
1371 June 17 +0.5 G 0.7
1376 June 19 —0.6 M 0.7
1377 June 19 —0.2 M 0.7
1378 June 19 +0.3 M 2.0.7
4611 1917 Oct. 21 0.0 M 1.0
4612 Oct. 21 +0.2 M 1.0
4623 Oct. 22 +0.1 A 1.0
4624 Oct. 22 +0.3 A 1.0
Comparison STARS
: “ Dependences.
No. Diameter. Pace “i oe —
AB Cc
mm. mm. mm.
1 0.24 —55.1 —15.0 +0.176 +0.171
2 .12 —30.6 +17.0 -218 -217
3 14 +12.0 +26.7 2384 .237
4 .20 +26.7 — 2.0 .200 .202
5 20 +47.0 —26.7 +0.172 | +0.173
Principal
star, AB 20 — 0.1 + 2.3
Companion,C| 0.12 + 0.4 + 2.4

 

 

 

 

 

 
538

S. A. MITCHELL

TABLE 2

Repvuctions ror « Equutel, Principat Star, AB

 

 

 

 

 

 

 

 

 

 

Plate. Solution Weight | Parallax | Time in Residual Vp+o
(m). (p). Factor (P). | Days (t). (ov). in Are.
mm. . mm.
79 +0.0038 0.6 +0.692 —365 +0.0001 0700
80 + .0080 0.6 + .692 —365 — .0041 — .07
85 + .0064 0.6 + .668 —363 | — .0025 — .04
86 + .0072 0.6 + .668 —363 — .0033 — .05
230 + .0022 0.4 — .610 —277 — .0010 — .01
272 + .0027 0.8 — .694 —270 — .0017 — .03
273 — .0008 0.7 — .694 —270 + .0018 | + .03
351 + .0028 0.7 — .786 —261 — .0021 — .04
423 — .0009 0.7 — .937 —237 + .0011 + .02
435 + .0001 0.8 | — .951 —230 — .0001 _ .00
548 — .0027 1.0 — .944 —218 + .0026 + .05
580 — .0014 0.6 — .924 —212 + .0012 + .02
1370 — .0042 1.0 + .694 0 + .0021 + .04
1371 — .0051 0.7 + .694 0 + .0030 + .05
1376 + .0008 0.7 + .671 + 2 — .0029 — .05
1377. | — .0050 | 0.7 | + .671 | + 2 | + .0029 | + .05
178 | = 000 | @7 | + 671 | + 2 | + oes | 4.08
4611 | — .0158 | 1.0 | — .931 | +857 | ~ .0020 | — .04
4612 — .0178 1.0 — .931 +857 .0000 .00
4623 — .0184 1.0 — .934 +858 + .0006 + .01
4624 —0.0172 1.0 —0.934 +858 —0.0006 —0.01
The normal equations are:
15.9¢c + 11.670u — 4.25947 = — 0.0678 mm.
+ 360.3082n — 26.43727 = — 0.6519 mm.
+ 10.39797 = + 0.0659 mm.
from which:
c = — 0.00278 mm.
w= — 0.00164 mm. = — 070342, or — 07125 per year.
aw = + 0.00101 mm. = + 07021 + 07010.

Probable error of plate of unit weight

+ 0.00133 mm. = + 07028.
 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 53
TABLE 3
Repuctions rog € Equute1, Companion, C
Plate. Solution Weight | Parallax Time in Residual Vp+o
(m). (p). Factor (P). | Days (t). (2). in Are.
mm. mm.
79 +0.0599 0.6 +0.692 —365 —0.0030 —0"05
80 + .0582 0.6 + .692 —3865 — .0013 — .02
85 + .0535 0.6 + .668 —363 + .0033 + .05
86 + .0559 0.6 + .668 —363 + .0009 + .01
230 + .0563 0.4 — .610 —277 — .0011 — .01
351 + .0563 0.7 — .786 —261 — .0014 — .02
423 + .0498 0.7 — .9387 —237 + .0046 + .08
435 + .0528 0.8 — .951 — 230 + .0015 + .03
548 + .0557 1.0 — .944 —218 — .0016 — .03
580 + .0567 0.6 — .924 —212 — .0027 — .04
1370 + .0510 1.0 + .694 0 — .0006 — .01
1371 + .0475 0.7 + 694 0 + .0029 + .05
1376 | + 0400 | 0.7 | + .671 | + 2 | + .0013 | + .02
1377 | + .0543 | 0.7 | + .671 | + 2 | — .0040 | — .07
1378 + .0492 0.7 + .671 + 2 + .0011 + .02
4611 + .0364 1.0 — .931 +857 — .0015 — .03
4612 + .0326 1.0 — .931 +857 + .0023 + .05
4623 + .0346 1.0 — .984 +858 + .0003 + .01
4624 +0.0362 1.0 —0.934 +858 —0.0013 —0.03
The normal equations are:
14.4¢ + 15.720u — 3.21847 = + 0.6960 mm.
+ 349.3732u — 29.24797 = + 0.1655 mm.
+ 9.67542 = — 0.1089 mm.
from which:
c = + 0.05030 mm.
uw = — 0.00178 mm. = — 00371, or — 07135 per year.
x = + 0.00008 mm. = + 07002 + 0'011.

Probable error of plate of unit weight
+ 0.00139 mm. = + 07029.
540 S. A. MITCHELL

W, 205 1454 (205 597; +2° 36’)

This star of magnitude 8.0, of type F8 has a total proper
motion 07485. With the heliometer Smith has twice measured
the parallax with the results, — 0”134 + 0"048 and — 0"075
-++ 07013. With the spectrograph Mt. Wilson finds the absolute
parallax + 07015. Mr. Olivier measured the plates and derived
a parallax + 07005 + 07009 with a proper motion in right
ascension — 0289 where the corresponding value from Porter
is — 07297.

 

 

 

TABLE 1
Puates or W, 20° 1454
No. Date. Hour Angle. Observers. Weight.
3346 1916 Nov. 5 +045 M 1.0
3375 Nov. 10 +0.5 Ol 0.9
8376 Nov. 10 +0.9 OL 1.0
3399 Nov. 18 +0.3 M 0.9
3400 Nov. 18 +0.7 M 0.8
4096 1917 June 18 +0.2 M 0.8
4097 June 18 +0.6 M 0.9
4108 June 22 +0.7 A 0.9
4490 Oct. 1 +0.3 Ds, A 0.7
4559 Oct. 11 +0.6 B 0.9
4560 Oct. 11 +0.9 B 0.9
4738 Nov. 8 +0.1 M 0.8
5428 1918 June 7 —1.2 Ol 0.7
5429 June 7 —0.7 Ol 0.7
5470 June 19 +0.4 Ol 0.7*
5471 June 19 +0.8 Ol 0.9
5760 Oct. 4 +0.2 F, H 0.9
5761 Oct. 4 +0.6 F,H 0.8
5778 Oct. 9 +0.4 F,D 0.9
5779 Oct. 9 +0.8 F, D 0.9
7108 1919 May 28 -1.8 Ol 0.8
7109 May 28 —1.4 Ol 0.8
7110 May 28 —1.0 Ol 0.8
7111 May 28 0.6 Ol 0.9

 

 

 

 

 

* One exposure.
PARALLAXES OF 260 STARS 54]

 

 

 

 

 

 

 

 

 

TABLE 2
ReEDucTIONS FoR W, 20> 1454

Plate Solution “Weight Parallax Time in Residual Vp-v

¥ (m). Factor (P). | Days (2). (2). in Are.

mm. mm.

3346 +0.0007 1.0 —0.951 —440 +0.0004 +0°01
8875 + ..0008 0.9 — .945 —435 + .0001 .00
3376 — .0014 1.0 — .945 —435 + .0023 + .05
3399 | + .0005 | 0.9 | — .921 | —427 | + .0001 .00
3400 — .0035 0.8 — .921 —427 + .0041 + .08
, 4096 — .0055 0.8 + .691 —215 — .0016 — .03
4097 — .0078 0.9 + .691 —215 + .0007 + .01
4108 — .0018 0.9 + .643 —211 — .0054 —- .ll
4490 — .0094 0.7 — .793 —110 — .0020 — .04
4559 — .0090 0.9 — .872 —100 — .0028 — .06
4560 — .0128 0.9 — .872 —100 + .0010 | + .02
4738 — .0142 0.8 — .949 — 72 + .0013 + .02
5428 — .01938 | 0.7 + .806 +139 — .0012 — .02
5429 — .0209 0.7 + .806 +1389 + .0004 | + .01
5470 — .0209 0.7 + .682 +151 — .0001 -00
5471 — .0213 0.9 + .682 +151 + .0003 + .01
5760 — .0278 0.9 — .818 +258 + .0023 + .05
5761 — .0227 0.8 “— .818 +258 — .0028 — .05
5778 — .0259 0.9 — .856 +263 + .0002 .00
5779 — .0216 0.9 — .856 +263 — .0041 — .08
7108 .— .0324 0.8 + .886 +394 + .0022 + .04
7109 — .0321 0.8 + .886 +894 + .0019 + .04
7110 — .0312 0.8 + .886 +394 + .0010 + .02
7111 —0.0318 0.9 +0.886 +394 +0.0016 +0.03

 
542 S. A. MITCHELL

CoMPaRISON STARS

 

 

 

 

 

 

 

No. Diameter. 7 | Y (Declination). Dependence.

1 0.13 —26.0 + 0.6 +0.1360

2 .23 —18.5 — 6.8 - 1325

3 .10 — 8.0 . +43.2 -38105

4 .27 +26.0 — 4.7 .2517

5 .24 +26.5 —32.3 +0.1693
Parallax star 0.22 + 2.5 + 5.9 a

 

The normal equations are:
20.3¢ — 2.140 — 3.23077 = — 0.38060 mm.

+ 182.5828u + 24.75647 = — 0.6555 mm.
+ 14.45707 = — 0.0407 mm.
from which:
c = — 0.01543 mm.
Bh = — 0.00381 mm. = — 070791, or — 07289 per year.

az = +0.00025 mm. = + 07005 + 07009.
Probable error of plate of unit weight
° + 0.00145 mm. = + 070380.

61 CYGNI (215 2™; +38° 15’)

No stars in the sky have received more attention than the
pair called 61 Cygni. As is well known, they have a very large
and nearly common proper motion amounting to 516 per year,
they are of 5.6 and 6.3 magnitude, respectively, and both are
of K5 type. Since the parallax was first determined by Bessel
in 1838 by the heliometer, the stars have been many times in-
vestigated to determine their distance. The results are naturally
very discordant, the heliometer values in themselves having a
range from +0718 to + .0%56. Bessel’s parallax was 0”31.
It will not be necessary here to give a complete list of the deter-
minations of parallax, for these have been many times published.
The more recent results are given in Publications of Yerkes
Observatory, 4, 22, 1917. In the Astrophysical Journal, 46, 326,
1917, Adams gives the weighted mean of sixteen of the better
\

PARALLAXES OF 260 STARS 543

class of measures. He finds the values of the absolute parallax:
for 61! Cygni to be + 07313; and for 612 Cygni to be + 0”309.
To change these absolute values so as to find the relative
parallax for the more recent parallax work by large telescopes,
07005 should be subtracted from the absolute parallax. Hence,
the mean value of the relative parallax from sixteen authorities
amounts to + 07308 and + 07304 for 61! and 61? Cygni,
respectively.

On account of the historical interest, the star was placed on the
McCormick observing program. The following values of the
relative parallax have been recently found by photography from
five different telescopes in the United States, each of great focal
length.

 

 

 

 

 

 

Relative Parallax.
. Authority. Telescope.
611 Cygni. 612 Cygni.
+0267 +07004 +0"277+0"006 | Slocum 40-in. Yerkes
refractor
+ .301+ .009 + .2994 .021 | Miller 24-in. Swarthmore
; refractor
+ .325+ .011 + .320+ .008 | Van Maanen | 60-in. Mt. Wilson
: reflector
+ .282+ .009 | + .286+ .007 | Allegheny 30-in. Allegheny
i refractor
+0.306+0.005 +0.308+0.006 | Mitchell 26-in. McCormick
refractor

 

By comparing the results above, it will be noticed that there is
still a considerable range among the values. The absolute
values of the parallaxes, as determined by Adams by the spectro-
graph amount to + 07322, and + 07288 for 611 and 61? Cygni,
respectively.

On account of the special interest attaching to this star, Mr.
Mitchell made a careful selection of the comparison stars with
the idea of testing the relative merits of different combinations.
In accord with the usual practice at the McCormick Observatory,
a group of comparison stars numbering five were selected. In
addition to these, another group of three were selected, and
544 S. A. MITCHELL
these two separate groups were chosen so that they could be
combined and make a system of eight comparison stars. Stars
1, 2, 3, 4 and 5 in the list of Comparison Stars in Table I formed
the five-star combination; while 6, 7 and 8 were the three-star
group. The plates were, of course, measured only once, so that
the parallax stars and the comparison stars to the number of
eight were measured. The results were then reduced entirely
independently, on the basis of: (a) 3-comparison stars, (b) 5-
comparison stars, and (c) 8-comparison stars. Before the solu-
tions were made, it was expected that the five-comparison stars
would show considerably smaller probable errors than the three
comparison stars, but that the increase in accuracy of eight stars
over five would be very little. The results for the three separate
solutions follow:

For 61: Cygni,

3-star. 5-star. 8-star.

a = + 07308 + 07008 + 07300 + 07005 + 07306 + 07005

For 61? Cygni,

3-star. 5-star. 8-star.

aw = + 07315 + 07009 + 07304 +07006 + 07308 + 07006

Comparison STaRs

 

 

 

 

 

Dependences.
No. Diameter. X (Right Y (Declina-|
Ascension). tion).
611. 612.
mm. r mm. mm.
1 0.14 —46.7 —20.6 +0.125 +0.123
2 -11 —16.1 +25.6 .121 -116
3 .12 +15.3 +15.2 .124 .124
4 .14 +21.9 — 3.1 .127 -129
5 .10 +25.0 —18.9 -129 -1384
6 .10 —55.2 +13.9 .120 -113
7 .14 +17.8 —46.1 -131 -189
8 -18 +38.0 +34.0 +0.123 +0.122
61! Cygni .12 + 0.5 — 0.6
61? Cygni 0.10 + 1.3 — 1.3

 

 

 

 

The eight comparison star solutions give naturally the most
reliable results, and those values are adopted as best representing
PARALLAXES OF 260 STARS 545

the McCormick measures. Proper motions from the plates
amounted in right ascension to + 47161 and + 47161, respec-
tively for 61! and 61? Cygni, while the values from Boss are
+ 47148 and + 47134.

Since these stars unquestionably form a physical system, the
combined results of 61! and 61? Cygni give the McCormick value
of the relative parallax of the system to be:

+ 07307 + 07004.

TABLE 1
Puatres or 61 Crenr

 

 

 

No. Date. Hour Angle. Observers. Weight.
1838 1915 Oct. 24 —0h2 M 1.0
1853 Oct. 25 —0.4 M 1.0
1854 Oct. 25 0.0 M 1.0
1974 Nov. 7 —0.1 M 1.0
2720 1916 June 17 —0.4 M 0.7
2721 June 17 —0.1 M 0.7
2739 June 19 —0.5 M 0.7
2740 June 19 —0.2 M 0.7
2757 June 22 —0.3 M 0.7
2777 June 26 —0.8 M 0.7
2778 June 26 —0.4 M 0.7
3258 Oct. 24 —0.2 M 1.0
3351 Nov. 7 —0.1 M 1.0
3366 Nov. 8 —0.4 M 1.0
3367 Nov. 8 —0.1 M 1.0
3378 Nov. 11 —0.1 M 1.0
4038 1917 June 4 —0.4 A 1.0
4052 June 8 —0.5 A 1.0
4053 June 8 —0.2 A 1.0
4072 June 16 —0.5 A 1.0
4073 June 16 —0.1 A 1.0
4471 Sept. 26 —0.5 M 1.0
4472 Sept. 26 —0.2 M 1.0
4557 Oct. 11 —0.4 A 1.0
4558 Oct. 11 —0.1 A,B 1.0

 

 

 

 

 

36
546 S. A. MITCHELL

TABLE 2

Repuctions For 61! Cyan1

 

 

 

 

 

 

 

 

 

: Solution Weight Parallax Time in Residual Vpeo
Plate. (m). (p). | Factor (P). | Days (t). (0). in Arc.
mm. mm.
1838 —0.0214 1.0 —0.929 —375 —0.0010 —0%02
1853 — .0208 1.0 — .9382 —374 — .0011 — .02
1854 — .0214 1.0 — .932 —374 — .0005 — .01
1974 — .0163 1.0 — .949 —361 + .0012 + .02
2720 + .1261 0.7 + .834 —151 + .0003 .00
2721 + .1278 0.7 + .834 —151 — .0014 — .02
2739 + .1291 0.7 + .685 —136 + .0033 + .06
2740 + .1306 0.7 + .685 —136 + .0018 + .03
2757 + .1324 0.7 + .650 —133 + .0011 + .02
2777 + .1367 0.7 + .601 —129 — .0017 — .03
2778 + .1352 0.7 + .601 —129 — .0002 .00
3258 +. 1790 1.0 — .932 - 9 — .0008 — .02
3351 + .1869 1.0 — .949 + 5 — .0012 — .02
3366 + .1840 1.0 — .948 + 6 + .0022 + .05
3367 + .1847 1.0 — .948 + 6 + .0015 _ + .03
3378 + .1889 1.0 — .943 + 9 — .0009 — .02
4038 + .3264 1.0 + .836 +214 + .0C02 .00
4052 + .3285 1.0 + .801 +218 — .0003 — .01
4053 + .3300 1.0 + .801 +218 — .0018 — .04
4072 + .3316 1.0 + .721 +226 —- .0002 .00
4073 + .38314 1.0 + .721 +226 -0000 .00
4471 + .3669 1.0 — .736 +328 — .0010 — .02
4472 + .3651 1.0 — .736 +328 + .0008 + .02
4557 + .3736 1.0 — .865 +343 — .0014 — .03
4558 +0.3702 1.0 —0.865 +343 +0.0020 +0.04

 

The normal equations are:

22.9¢ + 3.015u — 4.36107 = + 4.6098 mm.
+ 1383.7914y + 6.738927 = + 8.0295 mm.
+ 15.9905r = — 0.2536 mm.
 

 

 

PARALLAXES OF 260 STARS 54%
from which:

c = + 0.19689 mm.

p = + 0.05484 mm. = + 171406, or + 47161 per year.

aw = + 0.01473 mm. = + 07306 + 07005.

Probable error corresponding to unit weight
+ 0.00090 mm. = + 07019.
TABLE 3
RepvuctTions For 612 CyGni
uti Weigh u ime i ‘ :
Ba | Se ee eee | ee | ee 8 ae
mm. mm,

1838 +0.0074 1.0 —0.929 —375 +0.0012 +0"02
1853 + .0104 1.0 — .932 —374 — .0012 — .02
1854 + .0104 1.0 — .9382 —3874 — .0012 — .02
1974 + .0154 1.0 — .949 —361 + .0006 + .01
2720 + .1608 0.7 + .834 —151 — .0033 — .06
2721 + .1596 0.7 + .834 —151 — .0021 — .04
2739 + .1602 0.7 | + -.685 —136 + .0033 + .06
2740 + .1589 0.7 + .685 —136 + .0046 + .08
2757 + .1625 0.7 + .650 —133 + .0021 + .04
2777 + .1687 0.7 + .601 —129 — .0026 — .05
2778. + .1663 0.7 + .601 —129 — .0002 .00
3258 + .2087 1.0 — .932 - 9 + .0004 | + .01
3351 + .2171 1.0 — .949 + 5 — .0005 — .01
3366 + .2167 1.0 — .948 + 6 + .0004 + .01
3367 + .2168 1.0 — .948 + 6 + .0003 + .01
3378 + .2196 1.0 — .943 + 9 — .0008 — .02
4038 + .3554 1.0 + .836 +214 + .0021 + .04
4052 + .3584 1.0 + .801 +218 + .0008 + .02
4053 de 3607 1.0 + .801 +218 — .0015 — .03
4072 + .3620 1.0 + .721 +226 + .0004 + .01
4073 + .3652 1.0 + .721 +226 — .0028 — .06
4471 + .3970 1.0 — .736 +328 —_ .0003 — .01
4472 + .3977 1.0 — .736 +328 — .0010 — .02
4557 + .4028 1.0 — .865 +343 + .0002 .00
4558, +0.4016 1.0 —0.865 +343 +0.0014 +0.038

 

 

 

 

 

 

 
548 S. A. MITCHELL

The normal equations are:

22.9¢ + 3.015u — 4.36107 = + 5.3192 mm.
+ 133.7914u + 6.739207 = + 8.1178 mm.
+ 15.9905r = — 0.3878 mm.
from which:
c = + 0.22788 mm.

w= + 0.05479 mm. = + 1.1397, or + 47161 per year.
3 = + 0.01480 mm. = + 07308 + 07006.

Probable error corresponding to unit weight
+ 0.00117 mm. = + 07024.

¢ CYGNI (215 8"; +29° 49’)

The Allegheny Observatory by photography finds the relative
parallax of + 07014 + 0"007, while the spectrographic value of
Adams gives the absolute parallax of + 07013. The star is of
3.40 magnitude, of Ko type, and of small proper motion 0706.
Mr. Alden measured’ the McCormick series of photographs
except the last eight which were measured by Mr. Mitchell.
The proper motion in right ascension from the photographs was
found to be — 0%002 per year, while the value from Boss is
— 0”003. Stebbins and Burns (Lick Observatory Bulletin, 4, 97,
1906), have found the star to be a spectroscopic binary of long
period.

Comparison STARS

 

 

 

 

 

No. Diameter. 7 eal Y (Declination). L Dependence.
1 0.10 —58.2 +28.8 +0. 2383
2 .12 —10.2 +42.0 .1710
3 -20 +10.7 —43.7 .33821
4 .14 +57.7 —27.1 +0. 2586 °
Parallax star 0.14 + 2.9 — 7.5

 

 

 
PARALLAXES OF 260 STARS ‘ 5

TABLE 1

Puates or ¢ CyGni

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
329 1914 Sept. 27 —0*1 M 1.0
387 Oct. 10 —0.2 M 0.7
573 Nov. 13 —0.1 M 1.0
1436 1915 July 6 —0.2 A 1.0
1493 July 18 —0.2 A 1.0
1510 July 24 —0.3 A 0.8
1511 July 24 0.0 A 0.9
1734 Sept. 22 —0.2 A 0.9
1934 Oct. 31 —0.3 M 0.6*
1935 Oct. 31 | _ 0.0 M 1.0
1944 Nov. 2 —0.4 M 1.0
2789 1916 July 3 —1.4 M 1.0
2790 July 3 1.0 M 1.0
2828 July 20 —0.4 L 0.8
5439 1918 June 8 —0.2 L 0.8
5496 July 1 —0.6 A 0.9
5497 July 1 —0.3 A 0.8
5536 July 10 —0.3 A 0.8
5737 Oct. 1 +0.3 M 0.9
5738 Oct. 1 —0.3 M 0.9
5776 Oct. 9 —0.7 F,D 0.9
5777 Oct. 9 —0.4 D,F 0.9
* One exposure.
The normal equations are:
19.6¢ — 2.140n — 3.74797 = + 0.0372 mm.
+ 580.6616u + 11.20367 = — 0.0065 mm.
+ 9.23482 = + 0.0040 mm.
550 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FoR ¢ CYGNI
Solution Weight Parallax Time in Residual : vp-0
Plate. (m). (p). Factor (P). | Days (¢). (2). in Are.
mm. | ' mm.

329 +0.0027 1.0 —0.725 —732 —0.0013 —0°03

387 + .0002 0.7 — .842 —719 + .0010 + .02

573 + .0020 1.0 — .941 —685 — .0009 — .02
1436 + .0036 1.0 + .498 —450 — .0006 — .01
1493 + .0012 1.0 + .823 —438 + .0015 + .03
1510 — .0005 0.8 + .230 —432 + .0031 + .06
1511 + .0078 0.9 + .230 | —432 — .0052 — .10
1734 + .0006 0.9 — .683 —372 + .0007 + .01
1934 + .0001 0.6 — .942 |. —333 + .0009 + .01
1935 + .0018 1.0 — .942 —333 — .0008 — .02
1944 — .0014 1.0 — .944 —331 + .0024 + .05
2789 + .0032 1.0 + .529 — 87 — .0003 — .0O1
2790 + .0027 1.0 + .529 — 87 + .0002 .00
2828 + .0012 0.8 + .281 — 70 + .0014 + .02
5439 + .0002 0.8 + .816 +618 + .0029 + .05
5496 + .0018 0.9 + .562 +641 + .0009 + .02
5497 + .0044 0.8 + .562 +641 — .0017 — .03
5536 + .0046 0.8 + .438 +650 — .0020 — .04
5737 + .0033 0.9 — .765 +733 — .0024 — .05
5738 + .0032 0.9 — .765 +733 — .0023 — .05
5776 — .0004 0.9 — .835 +741 + .0012 + .02
5777 —0.0016 0.9 —0.835 +741 +0.0024 +0705

 

from which:
c = + 0.00215 mm.
Hw = — 0.00003 mm. = — 070006, or — 07002 per year.
ar = + 0.00134 mm. = + 0028 + 07010.
Probable error of plate of unit weight
+ 0.00135 mm. = + 07028.

6 EQUULEI (215 9"; +9° 36’)

According to Aitken (Publications of the Lick Observatory, 12,
158, 1914), ‘the revolution period of 6 Equulei is not only the
PARALLAXES OF 260 STARS 551

shortest known of any visual binary star, but it is the one deter-
mined with greatest accuracy.” The period is 5.7 years, the
semi-major axis, a, is 0727, and the magnitudes of the com-
ponents are 5.3 and 5.4. In view of the short period, the
surest plan of freeing the parallax measures from the effect of
orbital motion seemed to be to allow the photographic plates to
extend in time throughout a whole period of the pair. This was
accordingly done. The two stars of the pair are almost equally
bright. If they are also equally massive, then the center of
mass and center of brightness will coincide. In photographing,
the rotating sector was used. The image on the plate which
was measured was evidently the center of brightness of the pair.
Any uncertainty seemed to be eliminated by allowing the plates
to extend over a considerable period of time. Mr. Olivier
measured the McCormick plates, and determined a relative
parallax of + 07041 + 07007 with a proper motion in right
ascension + 0%029, while the corresponding value from Boss is
+ 07041. Other values of the parallax are + 07017 + 07035
by the use of the equatorial by Leavenworth; + 0”02 + 0041
by Flint with the meridian circle, and the absolute value by
Adams from the spectroscope of + 07060. Hussey obtained an
absolute parallax of + 07071. The system has a considerable
proper motion 07306 per year. Assuming the value of the
parallax from the McCormick plates, the mass of the system is
6.2 times that of the sun.

CoMPARISON STARS

 

 

 

 

 

 

No. Diameter. X (Right Ascen-| y (Declination). | Dependence.
sion).

mm. mm. mm.

1 “0.14 —68.9 —15.7 +0.1296

2 .12 —67.2 +30.4 . 1999

3 .10 +25.6 +12.5 . 1905

4 .14 +34.4 — 2.7 - 1691

5 .16 +36.6 — 9.0 . 1600

. 6 .16 +39.5 | 15.4 +0.1509
Parallax star 0.14 + 0.2 + 2.2

 
552

S. A. MITCHELL

TABLE 1

Puatres or 6 Equuer

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
231 1914 Sept. 13 +140 M,G 0.9
255 Sept. 15 +1.0 M,G 0.9
263 Sept. 19 +1.2 M,A 0.9
284 Sept. 21 +0.6 M 0.8
398 Oct. 12 +0.5 Ol, G 0.6
475 Nov. 3 +0.1 A 1.0
526 Nov. 9 +0.5 ol 1.0
623 Nov. 23 +0.5 ol 0.9
1355 1915 June 9 —0.6 Ol 0.9
1356 June 9 —0.2 Ol 0.7
1484 July 17 +0.3 Ol 0.6
1485 July 17 +1.1 ol 0.6
1805 Oct. 10 +0.1 M 0.7
1816 Oct. 11 —0.1 G 0.7
1817 Oct. 11 +0.4 G 0.8
1984 Nov. 8 +0.3 OL 0.8
2001 Novy. 10 —0.3 Ol 0.4
2029 Nov. 17 +0.2 ol 0.8
3471 1916 Dec. 2 +1.1 M 0.9
3494 Dec. 7 +1.4 M 1.0
4084 1917 June 17 +0.3 ol 0.7
4144 June 30 —0.9 Ol 0.9
4145 June 30 —0.4 Ol 0.8
4715 Nov. 6 +0.3 Ol 0.9
4716 Nov. 6 +0.9 Ol 1.0
4739 Nov. 9 —0.1 Ol 1.0
4740 Nov. 9 +0.4 Ol 1.0
5476 1918 June 22 +0.2 Ol 1.0
5480 June 23 —0.4 Ol 0.9
5481 June 23 +0.2 Ol 0.9

 
PARALLAXES OF 260 STARS 55:

 

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FoR 6 EQUULEI
fits oe ngs oy —
pote. | Sefusion | Weight | Paralles, | dimee | Redual | VRe
mm. mm.
231 —0.0009 0.9 —0.554 —574 +0.0018 +0"04
255 + .0034 0.9 — .582 —572 — .0025 — .05
263 + .0022 0.9 — .632 —568 — .0014 | — .03
284 + .0028 0.8 — .656 —566 — .0020 | — .04
398 — .0008 0.6 — .678 —564 + .0015 | + .02
475 + .0032 1.0 — .945 —523 — .0028 | — .06
526 + .0002 1.0 — .946 —517 + .0002 .00
623 + .0012 0.9 — .908 —503 — .0007 | — .O1
1355 + .0051 0.9 + .811 —305 — .0005 — .0l
1356 + .0012 0.7 + .811 —305 + .00384 | + .06
1484 + .0056 0.6 + .841 —267 — .0018 — .03
1485 + .0012 0.6 + .341 —267 + .0026 | + .05
1805 + .0025 0.7 — .838 —182 — .0006 | — .O1
1816 + .0024 0.7 — .846 —181 — .0005 | — .O1
1817 — .0022 0.8 — .846 —181 + .0041 | + .07
1984 — .0009 0.8 — .947 —153 + .0027 | + .05
2001 + .0028 0.4 — .946 —151 — .0010 | — .O1
2029 + .0026 0.8 — .932 —144 — .0008 | — .O1
3471 + .0011 0.9 — .851 +237 + .0024 | + .04
3494 + .0010 1.0 — .812 +242 + .0026 |} + .05
4084 + .0090 0.7 + .729 +434 — .0017 | — .08
4144 + .0071 0.9 + .575 +447 .0000 .00
4145 + .0070 0.8 + .575 +447 -0000 .00
4715 + .0059 0.9 — .947 +576 — .0013 | — .02
4716 + .0032 1.0 — .947 +576 + .0014 + .03
4739 + .0066 1.0 — .946 +579 — .0020 | — .04
4740 + .0052 1.0 — .946 +579 — .0006 | — .O1
5476 + .0100 1.0 + .676 +804 — .0014 | — .03
5480 + .0094 0.9 + .664 +805 — .0008 | — .02
5481 +0.0077 0.9 +0.664 +805 +0.0009 | +0.02
554 S. A. MITCHELL

The normal equations are:
25.0c + 6.9264 — 9.17167 = + 0.0901 mm.
+ 614.2534u + 25.9574c7 = + 0.3160 mm.
+ 15.6075r = + 0.0017 mm.
from which:
c = + 0.00421 mm.
B= +0.00038 mm. = + 070080, or + 07029 per year.
a = +0.00195 mm. = + 07041 + 07007.

Probable error of plate of unit weight

+ 0.00113 mm. = + 07024.

I

7 CYGNI (215 10"; +37° 37’)

This star is of more than usual interest to the McCormick
Observatory for the reason than in 1874 while testing the 26-inch
objective of the McCormick telescope the star was found to be a
close double by Alvan G. Clark. The star is a difficult one to
measure since the magnitudes are 3.8 and 8.0, and the distance
always small. The best orbit is probably that of Aitken (Publi-
cations of the Lick Observatory, 12, 160). The period is there
given as 47.0 years and the value of a = 0791. The parallax
has been several times determined with rather discordant results,
as follows:

 

 

Parallax. Authority. Method.

 

+0708 +0"06 Wagner-Belopolsky Meridian circle
+ .125+ .042 Jost Meridian circle
+ .029+ .039 Abetti Meridian circle
+ .006+ .016 Slocum and Mitchell Photography
+ .023+ .014 Swarthmore Photography
+ .058+ .010 Allegheny Photography
+0.042 Adams Spectrograph

 
PARALLAXES OF 260 STARS 555

Miss France measured the McCormick plates and determined
the relative parallax + 07046 + 0007, and a proper motion
in right ascension + 07159 where the corresponding value from
Boss is + 07158. The mean of the four values by photography
is + 07033. With this value of the parallax and Aitken’s orbit,
the mass of the system is 6.15 times that of the sun.

*

 

 

 

TABLE 1
Puates oF 7 CyGni
No. Date. Hour Angle. Observers. Weight.
3180 1916 Oct. 12 —043 A 1.0
3214 Oct. 19 —0.1 M 0.9
4594 1917 Oct. 17 —0.8 B 1.0
4595 Oct. 17 —0.5 B 1.0
4677 Nov. 2 —0.1 M 1.0
4726 Nov. 7 —0.2 M 0.9
5554 1918 July 14 —0.3 A. 1.0
5555 July 14 0.0 A 0.9
5565 July 20 —0.5 A 1.0
5566 July 20 —0.2 A 1.0
5732 Sept. 30 —0.6 M 0.9
5733 Sept. 30, —0.2 M 0.8
5754 Oct. 3 —0.5 M,F 1.0
5755 Oct. 3 —0.2 H,F 0.9°
7083 1919 May 25° —-1.3 H 1.0
7084 May 25 —1.0 H 1.0
7104 May 27 —1.0 H 1:2"
7119 May 29 —-1.2 F 1.0
7120 May 29 —0.8 F 1.0
7776 Sept. 24 0.5 A 1.0
7777 Sept. 24 —0.1 A 1.0
7962 Oct. 20 —0.4 F 1.0
7963 Oct. 20 —0.1 F 1.0

 

 

 

 

 

* Three exposures.
356

S, A. MITCHELL

CoMPARISON STARS

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. cd geste Y (Declination). Dependence.

mm. mm. mm. ?

1 0.14 —49.4 +19.3 +0.184

2 .09 —25.9 —32.5 .201

3 14 — 1.7 +27.8 .194

4 ll +35.7 +14.5 -205

5 .14 +41.3 —29.1 +0.216

Parallax star 0.13 + 1.6 — 0.9
TABLE 2
REDUCTIONS FOR 7 CYGNI

Soluti igh 1 Time i id Dp

Hele ee eS eel eee | ee || aes
mm. mm.

3180 —0.0240 1.0 —0.856 —701 +0.0029 +0706
3214 — .0198 0.9 — .898 —694 — .0012 — .02
4594 — .0118 1.0 — .886 —331 — .0016 — .03
4595 — .0130 1.0 — .886 —331 — .0004 — .01
4677 — .0114 1.0 — .943 —315 — .0018 — .04
4726 — .0140 0.9 — .946 —310 + .0010 + .02
5554 — .0030 1.0 + .387 — 61 — .0019 — .04
5555 — .0085 0.9 + .387 — 61 + .0036 + .07
5565 — .0034 1.0 + .296 — 55 — .0015 — .03
5566 | — .0028 | 1.0 | + .296 | — 55 | — .oo21 | — .04
5732 — .0080 0.9 — .750 + 17 + .0022 + .04
5733 — .0070 0.8 — .750 + 17 + .0012 + .02
“5754 — .0036 1.0 — .779 + 20 — .0022 — .05
5755 — .0072 0.9 | — .779 + 20 + .0014 + .08
7083 + .0036 1.0 + .917 +254 — .0007 — .01
7084 + .0028 1.0 + .917 +254 + .0001 .00
7104 + .0023 1.2 + .907 +256 + .0006 + .01
7119 + .0042 1.0 + .895 +258 — .0012 — .02
7120 + .0008 1.0 + .895 +258 + .0022 + .05
7776 + .0026 1.0 — .684 +376 — .0007 — .01
7777 + .0016 1.0 — .684 +376 + .0003 + .01
7962 + .0022 1.0 — .900 +402 — .0002 .00
7963 +0.0016 1.0 —0.900 +402 +0.0004 +0.01

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS 557

The normal equations are:
22.5¢ + 1.466 — 5.11400 = — 0.1082 mm.
+ 229.0845u + 21.48097 = + 0.5220 mm.
+ 14.11897 = + 0.0992 mm.

from which:
¢ = — 0.00444 mm.
w= +.0.00210 mm. = + 070436, or + 07159 per year.
a = + 0.00223 mm. = + 07046 + 0°007.

Probable error of plate of unit weight
+ 0.00116 mm. = + 07024.

a CEPHEI (21> 16"; +62° 9’)

Pritchard has investigated the parallax of this star by photo-
graphy. Using four different comparison stars he determined
parallaxes of + 07073, + 07037, + 07017, and + 07119, re-
spectively, the probable errors averaging + 07027. Flint, by
the meridian circle has found the parallax of + 07084 + 07024.
The star is of magnitude 2.60, of type A5, and of annual proper
motion 0716. Mr. Olivier measured the McCormick plates, and
found a proper motion in right ascension of + 07154 while the
value from Boss is + 07152.

CoMPARISON STARS

 

 

X (Right Ascen-

 

No. Diameter. sion). Y (Declination). Dependence.
1 0.19 — 29.3 —40.9 +0.2830
2 13 —25.7 +29.0 2921
3 lB +19.0 +22.1 2277
4 26 +36.0 —10.2 +0.1972

 

 

 

 

Parallax star 0.27 — 4.4 — 0.1

 
558 S. A. MITCHELL

 

 

 

TABLE 1
PLatTEes OF a CEPHEI
No. Date. Hour Angle. Observers. Weight.
|

283 1914 Sept. 21 —0h2 M 0.9
310 Sept. 25 —0.4 Ol, G 0.7
316 Sept. 26 —0.3 M, A 0.9
490 Nov. 4 0.0 M 1.0
507 Nov. 5 —0.2 M 0.7
518 Nov. 6 —0.2 M 0.9
1399 1915 June 26 —0.9 G 0.7
1411 June 28 —0.9 G 0.6
1412 June 28 —0.5 G 1.0
1881 Oct. 28 —0.8 Ol 1.0
_ 1882 Oct. 28 —0.4 Ol 0.6
1900 Oct. 29 —0.4 Ol 0.8
2691 1916 May 31 —0.9 Ol 0.8
2747 June 21 —1.0 Ol 1.0
2748 June 21 —0.6 Ol 0.9
2766 June 23 —0.7 Ol 0.9
2767 June 23 —0.3 ol 0.7
3066 Sept. 23 —0.6 A 0.9
3067 Sept. 23 —0.2 A 0.9
3158 Oct. 8 —0.7 L 1.0
3159 Oct. 8 —0.3 L 1.0
3321 Nov. 1 —0.3 ol 0.9
4066 1917 June 13 —0.4 ol 0.9
4067 June 13 —0.1 ol 0.9
4118 June 23 —1.0 Ol 0.9
4119 June 23 —0.7 Ol 1.0

 

 

 

 

 

The normal equations are:

22.5¢ + 3.409% — 2.74447 = + 0.2238 mm.
+ 258.41064 + 27.14297 = + 0.6788 mm.
+ 13.60617 = + 0.0867 mm.
PARALLAXES OF 260 STARS

TABLE 2

REDUCTIONS FOR a CEPHEI

55

 

 

 

 

 

 

 

 

 

 

Plate. Solution Weight Parallax Time in Residual vp-0
(m). (p). Factor (P). | Days (t). OF in Are.
- mm. mmm.
283 —0.0025 0.9 —0.635 —504 —0.0004 —0"01
310 — .0030 0.7 — .681 —500 - 0000 -00
316 — .0002 0.9 — .692 —499 — .0028 — .06
490 — .0064 1.0 — 942 —460 + .0031 + .06
507 — .0041 0.7 — .943 —459 + .0008 + .01
518 ~— .0016 0.9 — .944 —458 — .0017 — .03
1399 + .0074 0.7 + .650 —226 + .0010 + .02
1411 + .0055 |, 0.6 + .626 —224 + .0028 + .05
1412 + .0102 1.0 + .626 —224 — .0019 — .04
1881 + .0028 1.0 — .926 —102 + .0013 + .03
1882 + .0058 0.6 — .926 —102 — .0017 — .03
1900 + .0007 0.8 — .933 —101 + .0033 + .06
2691 + .0156 0.8 + .886 +114 + .0008 + .01
2747 + .0175 1.0 + .699 +135 — .0015 — .03
2748 + .0175 0.9 + .699 +185 — .0015 — .03
2766 + .0164 0.9 + .676 +187 — .0005 — .01
2767 + .0145 0.7 + .676 +137 + .0014 .02
3066 + .0118 0.9 — .665 +229 + .0001 .00
3067 + .0154 0.9 — .665 +229 — .0035 — .07
3158 + .0120 1.0 — .814 +244 — .0004 — .01
3159 + .0104 1.0 — .814 +244 + .0012 + .02
3321 + .0123 0.9 — .939 +268 — .0008 — .01
4066 + .0222 0.9 + .784 +492 + .0014 + .03
4067 + .0231 0.9 + .784 | -+492 + .0005 + .01
4118 + .0206 0.9 + .679 +502 + .0028 + .05
4119 +0.0256 1.0 +0.679 +502 —0.0022 —0.05
from which:

c = + 0.01017 mm.

pw = + 0.00203 mm. = + 0704238, or + 07154 per year.

a = + 0.00437 mm. = + 07091 + 07008.

Probable error of plate of unit weight

+ 0.00121 mm. = + 07025.
560 S. A. MITCHELL

6 AQUARII (21 26"; —6° 0’)

This is a G-type star of magnitude 3.07 and of small annual
proper motion, 0”016. Two faint stars are noted in Burnham’s
General Catalogue 11026, which are “not likely to have any
connection with the large star.”’ Mr. Briggs measured the
majority of the McCormick plates, Mr. Mitchell measured a
dozen of the plates, while some of the earlier ones were measured

 

 

 

 

TABLE 1
Puates oF 6 AQUARII
No. Date. Hour Angle. Observers. Weight.
1747 1915 Sept. 23 +046 G 0.5
3135 1916 Oct. 5 —0.2 L 1.0
3159 Oct. 10 +0.2 M 1.0
3160 Oct. 10 +0.6 M 1.0
4123 1917 June 24 —0.2 M 0.7*
4124 June 24 +0.2 'M 0.7*
4176 July 19 —0.5 ol 0.8
4177 July 19 0.0 Ol 0.8
4195 July 29 +0.1 Ol 0.7
4196 July 29 +0.6 ‘Ol 0.7
4485 Sept. 29 +0.9 Ds, B 1.0
4678 Nov. 2 +0.6 B 1.0
4679 Nov. 2 +1.0 B 1.0
4791 Nov. 19 +0.3 M 1.0
4792 Nov. 19 +0.8 M 0.7
5538 1918 July 10 +0.4 A 0.7
5539 July 10 +0.7 A 1.0
5567 July 20 0.0 A 1.0
5568 July 20 +0.6 A 1.0
5740 Oct. 1 +0.6 M 1.0
5741 Oct. 1 +1.0 M 1.0
5748 - Oct. 2 +0.4 M 1.0
5749 Oct. 2 +0.9 M 1.0

 

 

 

 

* One exposure.
PARALLAXES OF 260 STARS 561

TABLE 2

REDUCTIONS FOR 6 AQUARIL

 

 

 

 

 

 

 

 

 

1 : . . a . a
Plate. oe || ee ete ee a ae
mm. mm.
1747 —0.0107 | 0.5 | —0.620 | —760 | 40.0031 | +0%05
3135 — .0058 | 1.0 | — .759 | —382 | — .0015 | — .03
3159 — .0098 | 1.0 | — .804 | —377 } + .0025 | + .05
3160 — .0069 | 1.0 | — .804 | —377 | ~ .0004 | — .O1
4123 — .0087 | 0.7 | + .697 | —120 | + .0014 | + .02
4124 — .0066 | 0.7 | + .697 | —120 | — .0006 | — .O1
4176 — .0056 | 0.8 | + .369 | — 95 | — .0016 | — .03
4177 — .0105 | 0.8 | + .369 | — 95 | + .0033 | + .06
4195 — .0073 | 0.7 | + :215 | — 85 | + .0001 .00
4196 — .0o78 | 0.7 | + .215 | — 85 | + .0006 | + .01
4485 — 0044 | 1.0 | — .695 | — 23 | — .0027 | — .06
4678 — 0040 | 1.0 | — .929 | +11 | — .0031 | — .06
4679 — .0038 | 1.0 | — .929 | +11 | — .0033 | — .07
4791 — .0053 | 1.0 | — .930 | + 28 | — .0018 | — .04
4792 —-.0107 | 0.7 | — .930 | + 28 | + .0036 | + .06
5538 — .0036 } 0.7 | + .500 | +261 | — .0034 | — .06
5539 — .0074 | 1.0 | + .500 | +261 | + .0004 | + .O1
5567. | — .0067 | 1.0 | + .357 | +271 | — .0003 | — .O1
5568 — .0059 | 1.0 | + .357 | +271 | — .0011 | — .02
5740 | — .0088 | 1.0 | — .714 | +344 | + .0019 | + .04
5741 — .0060 | 1.0 | — .714 | +344 | — .0009 | — .02
5748 — .o112 | 1.0 | — .724 | +845 | + .0043 | + .09
5749 —0.0085 | 1.0 | —0.724 | +345 | +0.0016 | +0.03

 

37
562 S. A. MITCHELL

in addition by Mr. Lamb. The proper motion from the plates
is + 0%005 in right ascension, while the corresponding value
from Boss amounts to + 0”014. The only parallax determina-
tions are by Flint with the result — 07068 + 0°032, and the
spectroscopic value + 07018.

ComMPARISON STARS

 

 

 

 

 

 

 

No. Diameter. me a on Y (Declination). Dependence.

1 0.18 —62.7 +17.8 +0. 25382

2 .10 + 0.4 —31.5 .1773

3 .12 + 4.9 —20.0 -1825

4 .12 +23.3 +42.0 .2150

5 .10 +34.1 — 8.3 +0.1720
Parallax star 0.14 — 4.0 + 2.9

 

The normal equations are:
20.3¢ + 4.55384 — 6.255897 = — 0.1440 mm.
+ 150.3210u + 3.08827 = — 0.0225 mm.
+ 9.45117 = + 0.0442 mm.

from which:
¢ = — 0.00713 mm.
w= + 0.00007 mm. = + 070014, or + 07005 per year.
a = — 0.00006 mm. = — 07001 + 07012.
Probable error of plate of unit weight
+ 0.00152 mm. = + 070382.

y CAPRICORNI (21" 34"; —17° 6’)

The spectroscopic parallax for*this star which is of magnitude
3.80 and type Fp, and of annual proper motion 019 is + 0”035.
Mr. Olivier measured the McCormick plates, and found a proper
motion in right ascension of + 0”169 while the proper motion
from Boss is + 0187.
PARALLAXES OF 260 STARS 563

 

 

 

TABLE 1
PLATES OF y CAPRICORNI

No. Date. Hour Angle. Observers. Weight.
357 1914 Sept. 30 +054 M,G 0.8
589 Nov. 10 +0.3 Ol 1.0
1501 1915 July 23 —0.5 G 0.7
1512 July 24 +0.3 A 0.8
1513 July 24 +0.8 A 0.7
2004 Nov. 10 +1.1 ol 0.9
2015 Nov. 16 —0.2 Ol 0.6
2030 Nov. 17 +0.5 Ol 0.8
2031 Nov. 17 +1.2 A 1.0
2732 1916 June 18 —1.2 Ol 0.6
2733 June 18 —0.6 Ol 1d *
2749 June 21 —0.4 Ol 0.7
2750 June 21 +0.1 ol 0.5
2768 June 23 0.0 Ol 0.9
2811 July 11 —0.5 L 0.7

 

 

 

 

 

* Three exposures.

ComMPaRISON STARS

 

 

 

 

 

No. Diameter. ee a aaa Y (Declination). Dependence.
mm. mm. mm.
1 0.16 —26.4 +17.9 +0.2915
2 17 —16.7 +14.3 . 2402
3 st — 2.4 +27.1 .0573
4. | .25 +25.9 —38.3 . 2332
5 16 +19.6 —21.0 +0.1778
Parallax star 0.20 — 2.3 — 2.5

 
564 S. A. MITCHELL

TABLE 2

REDUCTIONS FOR y CAPRICORNI

 

 

 

 

 

 

 

 

 

eae |) ee | EE eee | a) ae
mm. if mm.
357 —0.0147 0.8 —0.676 —425 —0.0002 - 0700
539 — .0134 1.0 — .935 —384 — .0008 — .02
1501 — .0078 0.7 + .349 —129 + .0001 .00
1512 — .0098 0.8 + .333 —128 + .0021 + .04
1513 — .0076 0.7 + .333 —128 — .0001 -00
2004 — .0054 0.9 — .935 — 19 — .0007 — .01
2015 — .0042 0.6 — .936 — 13 — .0018 — .03
2030 — .0081 0.8 — .935 — 12 + .0021 + .04
2031 — .0064 1.0 — .935 — 12 + .0004 + .01
2732 — .0006 0.6 + .777 +202 + .0005 + .01
2733 — .0001 1.1 + .777 +202 -0000 -00
2749 — .0002 0.7 + .748 +205 + .0001 .00
2750 + .0031 0.5 + .748 +205 — .0032 — .04
2768 + .0010 0.9 + .727 +207 — .0010 — .02
2811 —0.0013 0.7 +0.510 +225 +0.0015 +0.03

 

The normal equations are:

11.8¢ — 1.1964 — 0.58837 = — 0.0631 mm.
+ 52.26654 + 12.03517 = + 0.1299 mm.
+ 6.73307 = + 0.0340 mm.

from which:
c = — 0.00509 mm.
w= + 0.00222 mm. = + 070462, or + 07169 per year.
aw = + 0.00064 mm. = + 07013 + 0’009.

Probable error of plate of unit weight
= + 0.00083 mm. = + 0017.

76 CYGNI (21% 37™; +40° 21’)

No parallax has been published for this star which is of A type
and magnitude 6.05, with small proper motion 0” 05, but on the
PARALLAXES OF 260 STARS 565
assumption that it forms a member of an extended Ursa Major
group, Bottlinger (Astronomische Nachrichten, 4738), finds a
theoretical parallax of + 07013. Mr. Alden measured the
McCormick plates, except the last eight plates which were
measured by Mr. Mitchell and found a relative parallax of
+ 07005 with a proper motion in right ascension of — 07030
while the value from Boss is — 0010.

TABLE 1

Puates or 76 Cyrent

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
508 | 1914 Nov. 5 020 M 1.0
549 Nov. 11 —0.1 M 0.6*
1396 1915 June 25 —0.1 A 0.9
1735. Sept. 22 —0.2 A 0.9
1945 Nov. 2 —0.4 M 1.0
1946 Nov. 2 0.0 A 0.7
2791 1916 July 3 —1.0 M 1.0
2792 July 3 —0.6 M 1.0
2793 July 3 —0.3 M 1.0
3144 Oct. 7 —0.3 A 1.0
3145 Oct. 7 0.0 A 0.9
3181 Oct. 12 —0.2 A 0.9
3182 Oct. 12 0.0 A 0.7*
3300 Oct. 28 —0.3° Ol, A 0.8
5510 1918 July 2 —0.1 A 1.0
5532 July 9 —1.3 Ol 0.7
5533 July 9 —0.9 Ol 0.9
5537 July 10 —0.3 A 0.9
5734 Sept. 30 —0.2 M 0.8
5739 Oct. 1 —0.4 M 1.0
5764 Oct. 6 —0.5 M 0.9
5765 Oct. 6 —0.1 M 0.9

 

* One exposure.
566

S. A. MITCHELL

CoMPARISON STARS

 

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. x nian Ascen-| y (Declination). Dependence.

1 0.18 —71.9 ~—26.3 +0. 2026

2 18 —13.3 +45.5 . 2276

3 .17 + 7.1 —45.0 .1740

4 .19 +30.4 +45.8 .2177

5 .12 +47.7 —20.0 +0.1781

Parallax star 0.14 — 1.2 + 3.6
TABLE 2
Repuctions For 76 Crentr
Solution Weight Parallax Time in Residual vp-»
Plate. (m). (p). Factor (P). | Days (t). 2). in Are.
mm. : mm.

508 —0.0016 1.0 —0.925 —802 +0.0010 -| +0702
549 — .0028 0.6 — .9384 —796 + .0022 + .04
1396 — .0030 0.9 + .721 |. —570 + .0019 + .04
1735 — .0046 0.9 — .568 —481 + .0028 + .06
1945 — .0012 1.0 — .915 —471 — .0007 — .01
1946 — .0060 0.7 — .915 —471 + .0041 + .07
2791 — .0026 1.0 + .621 —196 0000 00
2792 — .0002 1.0 + .621 —196 — .0024 — .05
2793 | — -0020 1.0 + .621 —196 — .0006 — .01
3144 — .00385 1.0 — .747 —102 + .0002 00
3145 + .0011 0.9 — .747 —102 — .0044 — .09
3181 — .0011 0.9 — .793 — 95 — .0022 — .04
3182 — .0004 0.7: — .793 — 95 — .0029 — .05
3300 + .0009 0.8 — .898 — 79 — .0043 — .08
5510 — .0043 1.0 + .639 +533 — .0011 — .02
5532 — .0086 0.7 + .552 +540 + .0031 + .05
5533 — .0018 0.9 + .552 +540 — .0037 — .07
5537 — .0090 0.9 + .588 +541 + .0085 + .07
5734 — .0078 0.8 — .668 +623 + .0017 + .03
5739 — .0080 1.0 — .679 +624 + .0019 + .04
5764 — .0087 0.9 — .732 +629 + .0026 + .05
5765 —0.0052 0.9 —0.732 +629 —0.0009 —0.02

 

 

 

 

 

 
PARALLAXES OF 260 STARS 567

The normal equations are:

19.5¢ + 1.1534 — 4.97137 = — 0.0702 mm.
+ 448.1682u + 12.47567 = — 0.1759 mm.
+ 10.36787 = + 0.0151 mm.
from which:
ec = — 0.00351 mm.
w= — 0.00039 mm. = — 070081, or — 07030 per year.

+ 0.00024 mm. = + 07005 + 07012.
Probable error of plate of unit weight
+ 0.00169 mm. = + 07035.

Tv

e PEGASI (21' 39"; +9° 25’)

This is‘ star of Ko type, and of magnitude 2.54, with small
proper motion 07025. Pritchard, by photography, determined
the parallax with the result, + 07080 + 07015, while Flint with
the meridian circle obtained the relative parallax + 07041
+ 07030, and the Allegheny Observatory by photography the
value — 07022 + 0"009. Adams by the spectrograph gives
the absolute parallax + 0"028. The McCormick plates were
measured by Mr. Olivier who obtained the relative parallax of
+ 07017 + 07008, and a proper motion in right ascension of
+ 07022 while the corresponding value from Boss is + 07025.
*

 

 

 

 

 

 

 

 

 

 

 

568 S. A. MITCHELL
TABLE 1
PLATES OF ¢ PEGASI
No. Date. Hour Angle. Observers. Weight.
1452 1915 July 9 +051 G 0.9
1494 July 18 0.0 A 0.8
1495 July 18 +0.5 A 0.7
1518 Aug. 2 —0.2 ol 0.7
1519 Aug. 2 +0.8 Ol, L 0.7
1723 Sept. 19 +0.8 M 0.9:
1976 Nov. 7 +0.4 M 0.6
2799 1916 July 5 —0.7 L 0.6
2800 July 5 —0.2 L 0.6
3136 Oct. 5 +0.1 L 0.8
3137 Oct. 5 +0.6 L 0.8
3191 Oct. 14 —0.5 L 0.8
3192 Oct. 14 0.0 L 0.6
3280 Oct. 26 —0.3 A 0.7
4146 1917 June 30 —0.3 ol 0.7
4147 June 30 +0.1 ol 0.6
4202 July 30 +0.2 A 1.0
4203 July 30 +0.6 A 1.0
4539 Oct. 7 +0.4 M 0.9
4540 Oct. 7 +0.8 M 0.9
4580 Oct. 15 +0.3 D 0.8
4581 Oct. 15 +0.8 D 0.9
ComPaRISON STARS
No. Diameter. |*~ be aay Y¥ (Declination). Dependence.
1 0.11 —30.2 + 7.7 +0.1347
2 24 + 2.6 —42.3 . 2428
3 17 + 9.3 +28.8 - 2984
4 -20 +18.3 + 5.8 +0.3241
Parallax star 0.23 + 5.3 + 1.2

 

 

 

 

 
PARALLAXES OF 260 STARS

 

 

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR ¢ PEGASI
ear ; ; ie : —.
poe | Sane | ge | a ae. | ee | ee,
mm. mm.
1452 +0.0009 0.9 +0.561 —434 +0.0021 | +0”04
1494 + .0032 0.8 + .4388 —425 — .0003 — .01
1495 + 0039 0.7 + .438 —425 — .0010 | — .02
1518 + .0038 0.7 + .213 —410 — .0010 | — .02
1519 + .0059 0.7 + .213 —410 — .0031 | — .05
1723 + .0011 0.9 — .523 —362 + .0012 + .02
1976 + .0009 0.6 — .927 —313 + .0012 + .02
2799 + .0028 0.6 + .602 — 72 + .0013 + .02
2800 + .0008 0.6 + .602 — 72-| + .00383 | + .05
3136 + .0049 0.8 — .722 + 20 — .0016 | — .03
3137 + .0061 0.8 — 7.722 + 20 — .0028 | — .05
3191 + .0036 0.8 — .805 + 29 — .0004 | — .O1
3192 + .0030 0.6 — .805 + 29 + .0002 .00
3280 + .0011 0.7 — .886 + 41 + .0021 + .04
4146 + .0055 0.7 + .665 +288 — .0003 | — .O1
4147 + .0078 0.6 + .665 +288 — .0026 | — .04
4202 + .0046 1.0 + .252 +318 + .0003 + .01
4203 + .0047 1.0 + .252 +318 + .0002 -00
4539 + .0034 0.9 — .740 +387 + .0009 | + .02
4540 + .0044 0.9 — .740 +387 — .0001 .00
4580 + .0035 0.8 — .812 +395 + .0008 | + .01
4581 +0.0045 0.9 —0.812 +395 —0.0002 0.00
The normal equations are:
17.0¢ + 2.777% — 3.09077 = + 0.0625 mm.
+ 170.6636u — 10.60857 = + 0.0511 mm.
+ 6.938042 = — 0.0090 mm.

from which:

c = + 0.00378 mm.
+ 0.00029 mm. = + 070060, or + 07022 per year.
+ 0.00082 mm. = + 0017 + 07008.

Probable error of plate of unit weight

Bb
T

+ 0.00097 mm. = + 07020.
570 S. A. MITCHELL

uw CYGNI (215 39"; +28° 17’)

This is a double star, = 2822, and according to Burnham their
relative motions finds the simplest explanation under the assump-
tion that they form a system of the 61 Cygni class, with slightly
different proper motions. The brighter star is of 4.73 magnitude,
and F5 type, and the fainter of 6.0 magnitude. The rotating
sector. was utilized to reduce the brightness of the parallax star,

 

 

 

 

 

 

TABLE 1
PuatTEes oF p CYGNI
No. Date. Hour Angle. Observers. Weight.
317 1914 Sept. 26 —0h2 M, A 0.7
406 Oct. 18 +0.1 M 1.0
462 Nov. 1 —0.2 M 1.0
468 Nov. 2 —0.1 G 1.0
594 Nov. 20 —0.2 Ol 0.9
598 Nov. 21 0.0 M 1.0
611 Nov. 22 0.0 M 1.0
1383 1915 June 22 —0.6 G 0.9
1401 June 26 —0.4 G 0.7
1402 June 26 0.0 G 0.7
1420 June 30 —0.4 G 1.0
18389 Oct. 24 —0.2 M 0.8
1840 Oct. 24 +0.1 M 1.0
1883 Oct. 28 —0.3 M 1.0
1884 Oct. 28 0.0 M 1.0

 

 

ComPaRIsON STARS

 

 

 

 

 

 

 

No. Diameter. x eh ABOen Y (Declination). Dependence.

1 0.18 —73.2 — 6.0 +0.300

2 .27 + 0.4 + 6.0 .279

3 .15 +22.0 + 3.5 243

4 .17 +50.8 ~ 3.5 +0.178
Parallax star 0.18 — 7.5 + 0.1

 
PARALLAXES OF 260 STARS 571

with the result that the brighter star only was measured. Mr.
Mitchell measured the plates, and found a proper motion in right
ascension to be + 07330 while the value from Boss is + 07283.
The spectroscopic parallax is +07058.

TABLE 2

REDUCTIONS FOR » CYGNI

 

 

 

 

 

 

 

 

 

Pl Solution Weight Parallax Time in Residual Vp+o
ate. (m). (p). | Factor (P). | Days (t). (0). in Are.
317 —0.0645 0.7 —0.613 —269 —0.0001 0°00
406 — .0624 1.0 — .831 —247 — .0017 — .03
462 — .0646 1.0 — .909 —233 + .0010 + .02
468 — .0642 1.0 — .913 —232 + .0006 + .02
594 — .0632 0.9 — .9380 —214 + .00038 + .01
598 — .0626 1.0 — .928 —213 — .0002 — .O01
611 — .0628 1.0 — .926 —212 + .0001 -00
1383 — .0508 | 0.9 + .757 0 + .0005 + .01
1401 — .0528 0.7 + .716:| + 4 + .0019 + .04
1402 | — .0483 | 0.7 | +.716 | + 4 | — .0018 | — .08
1420 — .0491 1.0 + .672 + 8 — .0008 — .02
1839 — .0446 0.8 — .870 +124 - -0029 — .06
1840 — .0460 1.0 — .870 +124 — .0020 — .04
1883 — .0512 1.0 — .891 +128 + .0033 +°.07
1884 —0.0492 1.0 —0.891 +128 +0.0013 +0.03

 

The normal equations are:

13.7c — 10.251 — 6.76547 = — 0.7663 mm.
+ 41.1835 + 9.04507 = + 0.7267 mm.
+ 9.74577 = + 0.4083 mm.

from which:

— 0.05172 mm.
+ 0.00434 mm. = + 070908, or + 07330 per year.
a = + 0.00196 mm. = + 0/041 + 07010.

Probable error of plate of unit weight
+ 0.00123 mm. = + 07026.

Era
ll
572 S. A. MITCHELL

x PEGASI (21' 40™; +25° 11’)

«x Pegasi is a star of more than ordinary interest. It is a visual
binary discovered by Burnham in 1880, and having one of the
shortest known periods of 11.37 years. According to Aitken,
the magnitudes are 5.0 and 5.1. Campbell (Astrophysical
Journal, 12, 257, 1900) found that one of the components was
a spectroscopic binary. « Pegasi is, therefore, a triple system.
In Lick Observatory Bulletin, 9, 120, 1918, Henroteau makes a
careful investigation of the spectroscopic orbit, findng a period
of 5.9175 days. He finds a parallax of + 07025 + 07002, and
the masses of the visual binary to be 10.33 and 4.00 times that
of the sun, while the masses of the spectroscopic binary are
6.62© and 3.710, respectively. The a has been found
by other observers as follows:

 

 

 

 

 

Parallax. Authority. Method.
—0702 +07043 Flint Meridian Circle
+ .084+ .071 Jewdokirov Meridian Circle
+ .021+ .011 Lee ; Photography
+ .073+4 .009 Miller and Steele Photography
+ .021+ .007 Allegheny Photography
+0.036 Adams Spectrograph

 

Mr. Mitchell measured the McCormick series of plates, with
the exception of the first four plates which were measured by
Mr. Graham. He found a relative parallax of + 0”016 + 07008,
with an annual proper motion in right ascension of + 0”010
while the value from Boss is + 07032. The McCormick value
of the absolute parallax is + 0021, is in substantial agree-
ment with the value found by Henroteau. Using this value of
the parallax, and Burnham’s orbit where a = 0”29, the mass of
the system is found to be 20.37 times that of the sun.
 

 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 573
TABLE 1
PLaTEs oF x Precast

No. Date. Hour Angle. Observers. Weight.
330 1914 Sept. 27 —0*1 M 0.9
476 Nov. 3 +0.2 M 1.0
519 Nov. 6 -—0.1 M 1.0
636 Nov. 24 —-0.1 M 0.9
1413 1915 June 28 —0.4 G 0.9
1414 June 28 0.0 G 0.7
1428 July 3 —0.7 G 0.8
1429 July 3 —0.3 G 0.8
1442 July 8 —0.3 G 0.5*
1829 Oct. 21 —0.8 G 0.8
1830 Oct. 21 —0.4 G 0.9
1975 Nov. 7 —0.3 M 0.8
3379 1916 Nov. 11 —0.4 M 1.0
3380 Nov. 11 —0.1 M 1.0
3382 Nov. 16 -0.1 M 1.0
4135 1917 June 29 —0.8 A 0.9
4136 June 29 —0.4 A 0.9
4156 July 1 —1.0 A 0.7
4157 July 1 —0.6 A 0.7
4537 Oct. 7 = —-0.3 M 1.0
4538 Oct. 7 0.0 M 1.0
4642 Oct. 28 0.0 M 1.0
4643 Oct. 28 +0.2 M 1.0

* One exposure.
ComPaRIsON STARS
No. Diameter. |* aa Y (Declination). Dependence.
- mm. mm. mm.

1 0.21 —58.3 —20.4 +0.2490

2 15 —23.4 +17.9 - 2482

3 .13 +17.4 —47.3 .25381

4 .18 +64.3 +49.8 +0.2497

Parallax star 0.18 + 0.1 — 0.2

 

 

 

 

 
574

S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR « PEGASI
a a a . id :
Pine, | ejasin | wile | Ears | meg. | Peat | atlas
mm. mm.
330 —0.0086 0.9 —0.624 —589 —0.0011 —0"02
476 — .0096 1.0 — .916 —552 — .0002 .00
519 = -0084 1.0 — .924 —549 — .0014 — .03
636 — .0090 0.9 — .921 —531 — .0008 — .02
1413 — .0085 0.9 + .696 —315 + .0002 .00
1414 — .0079 0.7 + .696 —315 — .0004 — .01
1428 — .0083 0.8 + .639 —310 .0000 .00
1429 — .0092 0.8 + .639 —310 + .0009 + .02
1442 — .O111 0.5 + .577 —3805 + .0027 + .04
1829 — .0118 0.8 — .850 —200 + .0025 + .05
1830 — .0099 0.9 — .850 —200 + .0006 + .01
1975 — .0087 0.8 — .926 —183 — .0006 — .01
3379 — .0092 1.0 — .933 +187 + .0003 + .01
3380 — .0107 1.0 — .933 +187 + .0018 + .04
3382 — .0090 1.0 — .984 +192 + .0002 -00
4135 — .0067 0.9 + .679 +417 — .0006 — .01
4136 — .0065 0.9 + .679 +417 — .0008 — .02
4156 — .0116 0.7 + .656 +419 + .0043 + .07
4157 — .0024 0.7 + .656 +419 — .0049 — .09
4537 — .0113 1.0 — .737 +517 + .0030 + .06
4538 — .0058 |, 1.0 — .737 +517 — .0025 — .05
4642 — .0076 1.0 — .893 +538 — .0008 — .02
4643 —0.0075 1.0 —0.893 +538 —0.0009 —0.02
The normal equations are:
20.2¢c + 2.6534 — 6.91127 = — 0.1747 mm.
+ 340.4976u + 0.95957 = + 0.0242 mm.

from which:
c = — 0.00840 mm.
w= + 0.00013 mm. = + 070028, or + 07010 per year.
aw = + 0.00076 mm. = + 07016 + 0°008.
Probable error of plate unit weight

+ 18.04277 = + 0.0681 mm.

+ 0.00121 mm. = + 07025.
PARALLAXES OF 260 STARS 575

6 CAPRICORNI (21' 41™; —16° 34’)

‘The McCormick measures give a parallax for this star of
+ 07110 + 07012. No other parallax has been determined.
It is of A5 type, of magnitude 2.98, and of total proper motion
07392. Slipher found it to be a spectroscopic binary (Astro-
physical Journal, 24, 361, 1906). Miss Hawes measured: the
plates, and found a proper motion in right ascension + 07262,
in good agreement with the value of Boss amounting to + 07258.

 

 

 

TABLE 1
Puates oF 6 CAPRICORNI

No. Date. Hour Angle. Observers. Weight.
3095 1916 Sept. 26 +042 M 1.0
3168 Oct. 11 —0.2 L 1.0
3169 Oct. 11 +0.1 L 1.0
3252 ‘Oct. 23 —0.4 L 1.0
3253, Oct. 23 —0.1 L 1.0
4224 1917 Aug. 1 +0.3 Ol 0.7
4225 Aug. 1 +0.6 Ol 0.7
4244 Aug. 5 +0.6 A 0.9 -
4245 Aug. 5 +0.9 A 1.0
4565 Oct. 13 +0.7 Ds 0.9
4741 Nov. 9 +0.4 Ol 1.0
4742 Nov. 9 +0.9 Ds 1.0
4797 Nov. 20 +0.1 Ol 1.0
4798 Nov. 20 +0.5 Ol 1.0
5544 1918 July 13 —0.3 Ol 0.7
5546 July 13 +0.7 Ol 0.8
5575 July 21 —0.5 A 1.0
5735 Sept. 30 +0.1 M 1.0
5736 Sept. 30 +0.5 M 1.0
5771 Oct. 8 —0.2 H, D 0.8
5772 Oct. 8 +0.2 M,D 1.0
7225 June 22 —0.7 Ol 0.9
7280 July 4 —0.1 Ol 0.9
7281 July 4 +0.4 ol 1.0
7282 July 4 +0.9 Ol 1.0
7291 July 5 —0.5 D 1.0

 

 

 

 

 
576 S. A. MITCHELL

TABLE 2
REDUCTIONS FOR 6 CAPRICORNI =

 

 

 

 

 

 

 

 

 

 

Plate Solution | Weight | Parallax | Time in Residual _Vp-0

7 (m). (p). Factor (P). | Days (Z). (z). in Are.

mm. mm.

8095 —0.0632 1.0 —0.613 —395 —0.0052 —0710
3168 — .0664 1.0 — .773 —380 — .0023 — .05
3169 — .0702 1.0 — .773 —380 + .0015 + .03
8252 — .0722 1.0 — .864 —368 + .00384 | + .07
3253 — .0676 “1.0 — .864 —368 — .0012 — .02
4224 — .0517 0.7 + .230 — 86 — .0015 — .03
4225 — .0516 0.7 + .230 — 86 — .0016 — .03
4244 — .0547 0.9 + .168 — 82 + .0013 + .02
4245 — .0524 1.0 + .168 — 82 — .0010 — .02
4565 — .0571 0.9 — .789 — 13 + .0010 + .02
4741 — .0562 1.0 — .930 + 14 + .0003 + .01
4742 — .0576 1.0 — .930 + 14 + .0017 + .04
4797 — .0590 1.0 — .930 + 25 + .0034 + .07
4798 — .0562 1.0 — .930 + 25 + .0006 + .01
5544 — .0410 0.7 + .512 +260 + .0012 + .02
5546 — .0411 0.8 + .512 +260 + .0013 + .02
5575 — .0458 1.0 + .401 +268 + .0056 + .12
5735 — .0407 1.0 — .655 +339 — .0026 — .05
5736 — .0418 1.0 — .655 +339 — .0015 — .03
5771 — .0421 0.8 — .740 +347 — .0014 — .02
5772 — .0430 1.0 — .740 +347 — .0005 — .01
7225 — .0260 0.9 + .762 +604 — .0007 — .01
7280 — .0278 0.9 + .643 +616 + .0009 + .02
7281 — .0264 1.0 + .643 +616 — .0005 — .01
7282 — .0250 1.0 + .643 +616 — .0019 — .04
7291 —0.0261. 1.0 +0.619 +617 —0.0009 —0.02
PARALLAXES OF 260 STARS 577

CoMPaRISON STARS

 

 

 

 

 

 

 

 

No. Diameter. Pe ae aaa Y (Declination). Dependence.
mm. mm. mm.
1 0.08 —38.7 +31.1 +0.211
2 .16 —31.7 +21.1 .210
3 .10 +18.4 —52.0 . 204
4 .08 +22.2 +50.8 .177
5 .10 +29.8 —51.0 +0.198
Parallax star 0.10 — 1.28 — 0.70
The normal equations are:
24.3c + 28.0674 — 5.97947 = — 1.1864 mm.
+ 316.9845u + 26.94007 = — 0.2111 mm.
+ 11.713897 = + 0.4627 mm.
from which:
c = — 0.05150 mm.

uw = + 0.00344 mm. = + 070716, or + 07262 per year.
x = + 0.00529 mm. = + 07110 + 07012.

Probable error of plate of unit weight
+ 0.00145 mm. = + 07030.

a AQUARII (22> 0; —0° 48’)

The only parallax published is the absolute value of Adams
by the spectrograph with the result + 07004. The star is of
3.19 magnitude, of Go type, and of small proper motion 07015.
Mr. Mitchell measured the McCormick plates with the exception
of four photographs measured by Mr. Graham. The proper
motion in right ascension from the plates is + 07002 while the
value from Boss is + 07014.

38
578 S. A. MITCHELL

 

 

 

TABLE 1
PLATES OF a AQUARII
No. Date. Hour Angle. Observers. Weight.
331 1914 Sept. 27 +049 M 0.5
332 Sept. 27 +1.4 M 0.7
527 Nov. 9 +0.5 Ol 0.8
591 Nov. 19 +0.9 A 1.0
1443 1915 July 8 —0.1 G 0.6
1444 July 8 +0.5 G 0.5
1473 July 16 —0.3 G 0.5
1474 July 16 +0.2 G 0.5
1857 Oct. 25 +0.6 G 0.5
1858 Oct. 25 +1.1 G 0.7
2051 Nov. 24 0.0 ol 0.7
2061 Nov. 25 —0.1 M 1.0
2834 1916 July 29 0.0 A 0.8
2835 July 29 +0.6 A 0.8
2843 Aug. 4 +0.9 A 0.9
2844 Aug. 4 +1.4 A 0.7
3170 Oct. 11 +0.4 L 1.0
3171 Oct. 11 +0.8 L 1.0
3329 Nov. 2 -—0.1 L 1.0
3330 Nov. 2 +0.2 L 0.9

 

 

 

 

 

ComMPaARISON STARS

 

 

 

 

 

 

 

No. Diameter. X (Right Ascen-| y (Declination). Dependence.
sion).

mm. mm. mm.

1 0.14 —42.7 +40.9 +0.194

2 .21 —15.7 +23.1 . 202

3 15 +21.1 : —50.7 -882

4 15 +37.3 —13.3 +0.222
Parallax star 0.20 + 4.9 — 9.7

 

The normal equations are:
15.1¢ + 9.371p — 5.78832 = + 0.3256 mm.
+ 122.2508 — 1.37457 = + 0.2053 mm.
+ 7.73947 = — 0.1234 mm.
PARALLAXES OF 260 STARS

 

 

 

579
TABLE 2
REDUCTIONS FOR a AQUARII
Soluti Weigh Parall i i i Ds
Plate. Oe ee eee ae een | eee | ave
mm. mm.

ool +0.0176 0.5 —0.552 —397 +0.0038 +0705
332 + .0191 0.7 — .552 —397 + .0023 + .04
527 + .0227 0.8 — .910 —385 — .0014 — .02
591 + .0228 1.0 — .927 —375 — .0015 — .03
1443 + .0245 0.6 + .641 —113 — .0027 — .04
1444 + .0246 0.5 + .641 —113 — .0028 — .04
1473 + .0193 0.5 + .542 —105 + .0025 + .03
1474 + .0226 0.5 + .542 —105 — .0008 — .0Ol
1857 + .0214 0.5 — .833 — 4 .0000 -00
1858 + .0180 0.7 — .833 — 4 + .0034 + .06
2051 + .0230 0.7 — .923 + 26 — .0016 — .03
2061 + .0226 1.0 — 924 + 27 — .0012 — .02
2834 + .0214 0.8 + .349 +274 + .0004 + .01
2835 + .0205 0.8 + .349 +274 + .0013 + .02
2843 + .0204 0.9 + .258 +280 + .0014 + .03
2844 + .0235 0.7 + .258 +280 — .0017 — .03
3170 + .0194 1.0 — .719 +348 + .0021 + .04
3171 + .0219 1.0 — .719 +348 — .0004 — .01
3329 + .0216 1.0 — .885 +370 — .0001 .00
3330 +0.0237 0.9 —0.885 +370 —0.0022 —0.04

 

 

 

 

 

 

 

from which:
c = + 0.02165 mm.
w = + 0.00002 mm.
a = + 0.00025 mm.

Probable error of plate of unit weight
+ 0.00118 mm. = + 07024.

= + 070005, or + 07002 per year.
= + 07005 + 07010.

vy PEGASI (228 0™; +4° 34’)

The Allegheny parallax by photography is + 07010 + 07009,
while the spectroscopic value is +0”012. The star is of magni-
tude 4.90, of type Kp, and of total proper motion 07138. Miss
Darkow measured the McCormick plates finding a relative
580 S. A. MITCHELL

parallax of + 07012 + 07008, and a proper motion in right
ascension + 0”090, while the corresponding value from Boss is
+ 07103.

 

 

 

TABLE 1
Puatres oF 22 PEGasi
No. Date. Hour Angle. Observers, Weight.
3301 1916 Oct. 28 +051 Ol 1.0
3341 Nov. 3 —0.2 L 0.9
3342 Nov. 3 +0.1 L 1.0
3434 Nov. 24 —0.2 ol 0.6
3435 Nov. 24 +0.2 Ol 0.9
4252 1917 Aug. 10 +0.3 A 1.0
4654 Oct. 31 +0.5 B 0.9
4655 Oct. 31 +0.9 B 0.9
4810 Nov. 26 +0.1 M 1.0
4811 Nov. 26 +0.4 M 0.8
5556 1918 July 14 —0.3 A 1.0
5557 July 14 0.0 A 0.8
5576 July 21 —0.3 A 1.0
5577 July 21 +0.2 A 1.0
5596 Aug. 5 —0.7 A 0.7
5773 Oct. 8 +0.3 H, D 0.9
5780 Oct. 9 +0.2 F 0.8
5817 Oct. 16 +0.4 M 0.8
5818 Oct. 16 +0.8 M 0.7

 

 

 

 

 

Comparison STARS

 

 

 

 

 

 

No. Diameter. Ps ae oe aa Y (Declination). Dependence.

mm. mm. | mm.

1 0.09 —39.6 —27.1 +0.186

2 13 —33.8 +31.4 .161

3 13 + 4.5 +31.9 .188

4 .21 +11.6 —35.3 .225

5 .14 +57.3 — 0.9 +0.240
Parallax star 0.16 + 4.4 — 2.2

 
PARALLAXES OF 260 STARS 58

TABLE 2

RepvuctTions ror 22 Precast

 

 

 

 

 

 

sa 17o me :
Bale | Alen | Se eee, | eee | || ae.
mm. mm.
3301 —0.0331 1.0 —0.858 —415 +0.0011 +0702
3341 — .0308 0.9 — ,890 —409 — .0012 — .02
3342 — .0314 1.0 — .890 —409 — .0006 | — .O1
3434 — .0290 0.6 — .924 — 388 — .0027 | — .04
3435 — .0332 0.9 — .924 —388 + .0015 | + .03
A252 — .0294 1.0 + .168 —129 + .0014 + .03
4654 — .0278 0.9 — .874 — 47 +- .0002 00
4655 — .0285 0.9 — .874 — 47 + .0008 + .02
4810 — .0276 1.0 — .921 — 21 + .0002 .00
4811 — .0259 0.8 — .921-| — 21 — .0015 — .03
5556 — .0234 1.0 + .563 +209 — .0004 | — .O1
5557 — .0238 0.8 + .563 +209 -0000 -00
5576 — .0214 1.0 + .470 +216 — .0023 — .05
5577 — .0236 1.0 + .470 +216 — .0001 -00
5596 — .0265 0.7 + .250 +231 + .0028 | + .05
5773 — .0230 0.9 — .683 +295 — .0005 — .01
5780 — .0234 0.8 — .694 +296 — .0001 -00
5817 — .0232 0.8 — .763 +303 — .0002 -00
5818 —0.0246 0.7 —0.763 +303 +0.0012 | +0.02

 

 

 

 

The normal equations are:
16.7c — 0.9884 — 7.18407 = — 0.4491 mm.
+ 128.2705u + 14.35357 = + 0.1809 mm.
+ 9.18637 = + 0.2133 mm.

from which:
c = — 0.02657 mm.
w= + 0.00119 mm. = + 070247, or + 07090 per year.
x = +.0.00059 mm. = + 0012 + 07008.
Probable error of plate of unit weight
- + 0.00086 mm. = + 07018.
582 S. A. MITCHELL

t PEGASI (22 2™; +24° 51’)

This star is of 3.95 magnitude, of type F5, and of annual
proper motion 0730. Its parallax has recently been determined
by photography; Swarthmore Observatory obtained the relative

TABLE 1
PLATES OF « PEGASI
cy

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
106 1914 June 28 0+0 M, Ol 1.0
119 July 9 —1.1 M 0.9
120 July 9 0.6 M 0.7
130 July 15 | —0.1 Ol 1.0
383 Oct. 9 —0.4 Ol, G 0.7
449 Oct. 31 —0.2 A 0.7
463 Nov. 1 —0.1 M 1.0
469 Nov. 2 0.0 G 0.9
477 Nov. 3 +0.2 M 1.0
564 Nov. 12 —0.3 Ol 0.7
637 Nov. 24 0.0 M 0.8
1437 1915 July 6 —0.6 A 0.9
1438 July 6 —0.1 A 0.9
1538 Aug. 9 —0.3 L 0.9
1539 Aug. 9 +0.1 L 0.6*
8285 1916 Oct. 27 —0.4 L 0.6*
3322 Nov. 1 —0.4 A 1.0
3323 Nov. 1 —0.1 A 1.0
3382 Nov. 16 —0.1 M 0.9
4214 1917 July 31 —0.3 Ol 0.8
4215 July 31 0.0 Ol 1.0
4242 Aug. 5 —0.5 A 0.9
4243 Aug. 5 —0.2 A 0.9
4600 Oct. 20 —0.5 Ds 0.6*
4644 Oct. 30 —0.6 B 0.9
4645 Oct. 30 —0.2 B 0.8
4664 Nov. 1 —0.7 M ~ 0.9
4665 Nov. 1 —0.3 A 1.0

 

 

* One exposure.
 

 

 

PARALLAXES OF 260 STARS 58:
TABLE 2
REDUCTIONS FOR t PEGASI

Soluti Weigh Parall. Ti i i é

Bee | Oe | ae laa eey (Gee ee | ae ee
mm. mm.
106 +0.0122 | 1.0 | +0.750 | —591 | —0.0023 | —0’05
119 + .0123 | 0.9 | + .631 | —580 | — .0025 | — .05
120 + .0107 | 0.7 | + .631 | —580 | — .0009 | — .02
130 + .0092 | 1.0 | + .556 | —574 | + .0005 | + .01
383 + .0066 | 0.7 | — .688 | —488 | + .0007 | + .01
449 + .0062 | 0.7 | — .870 | —466 | + .0011 | + .02
463 + .0090 | 1.0 | — .875 | —465 | — .0016 | — .03
469 + .0054 | 0.9 | — .880 | —464 | + .0020 | + .04
477 + .0064 | 1.0 | — .885 | —463 | + .0010 | + .02
564 + .0042 | 0.7 | — .917 | —454 | + .0034 | + .06
637 + .0092 | 0.8 | — .924 | —442 | — .0012 | — .02
1437 + .0209 | 0.9 | + .668 | —218 | + .0021 | + .04
1438 + .0224 | 0.9 | + .668 | —218 | + .0006 | + .01
1538 + .0204 | 0.9 | + .199 | —184 | + .0018 | + .04
1539 + .0220 | 0.6 | + .199 | —184 | + .0002 .00
3285 + .0338 | 0.6 | — .849 | +256 | — .0004 | — .O1
3322 + .0381 | 1.0 | — .878 | +266 | — .0045 | — .09
3323 + .0349 | 1.0 | — .878 | +266 | — .0013 | — .03
3382 + .0332 | 0.9 | — .924 | +281 | + .0008 | + .01
4214 + .0480 | 0.8 | + .828 | +538 | + .0007 | + .01
4215 + .0455 | 1.0 | + .328 | +538 | + .0032 | + .07
.»

4242 + .0488 | 0.9 | + .253 | +543 | — .0003 .00
4243 + .0508 | 0.9 | + .253 | +543 | — .0023 | — .04
4600 + .0475 | 0.6 | —*.795 | +619 | — .0008 | — .01
4644 + .0460 | 0.9 | — .865 | +629 | + .0007 | + .01
4645 + .0494 | 0.8 | — .865 | +629 | — .0027 | — .05
4664 + .0448 | 0.9 | — .876 | +631 | + .0020 | + .04
4665 +0.0458 | 1.0 | —0.876 | +631 | +0.0010 | +0.02

 

 

 

 

 

 

 
584 S. A. MITCHELL

parallax + 0”063 + 0”011, while Allegheny derived the result
+ 0”067. Adams finds the absolute parallax by the spectro-
graph of + 07087. Mr. Olivier measured the McCormick series
of plates. He derived the proper motion in right ascension
+ 0"273 per year. The value of the proper motion according
to Boss is + 07299.

CoMPARISON STARS

N

 

 

 

 

No. Diameter. ? eo Y (Declination). Dependence.
mm. mm. mm.

1 0.22 —41.6 — 4.0 +0.0456

2 .36 S37 —26.2 . 2265

3 .24 +14.5 —27.5 .33874

4 .26 +34.8 +57.7 +0.3905
Parallax star 0.27 +14.8 + 7.1

 

The normal equations are:

24.0¢ + 0.7774 — 6.870387 = + 0.6422 mm.
+ 555.9585u — 18.80647 = + 1.9387 mm.
+ 12.91067 = — 0.2028 mm.

from which:
c = + 0.02790 mm.
w= + 0.00360 mm. = + 070748, or + 0278 per year.
x = + 0.00488 mm. = + 07091 + 0’008.
Probable error of plate of unit weight
+ 0.00124 mm. = + 07026.

ll

cd

¢ CEPHEI (22> 7™; +57° 42’)

This star of magnitude 3.62, of type K and of total proper
motion 07013 has had its parallax determined by photography
at the Allegheny Observatory with the value + 07023 + 07010,
and by Mt. Wilson by the spectrograph + 0’024. Mr. Olivier
measured the McCormick plates and derived the parallax
+ 07019 + 07010 with the proper motion in right ascension
+ 07011 where the value from Boss is + 0”011.
 

 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 58
TABLE 1
Puates oF ¢ CEPHEI
No. Date. Hour Angle. Observers. Weight.
389 | 1914 Oct. 11 Oh M 1.0
491 Nov. 4 —0.2 G 0.8
581 Nov. 17 —0.1 M 0.9
1936 1915 Nov. 1 —1.5 Ol 0.6
2042 Nov. 19 —0.9 Ol 0.7
2043 Nov. 19 —0.4 Ol 0.5
3431 1916. Nov. 22 —0.3 Ol 0.8
3432 Nov. 22 +0.1 ol 1.0
5520 1918 July 3 —1.0 Ol | 1.0
5521 July 3 —0.6 .Ol 0.9
5534 July 9 —0.8 Ol 1.0
5535 July 9 —0.2 ol 0.8
5816 Oct. 16 0.0 M 0.8
5841 Oct. 31 —0.4 M 1.0
5842 Oct. 31 0.0 M 0.8
5868 Nov. 3 —1.0 M 0.9
5869 Nov. 3 —0.6 M 0.9
7192 1919 June 8 -1.7 Ol 0.6
7193 June 8 —1.2 Ol 1.1*
7194 June 17 —1.8 ol 1.0
7195 June 17 —1.5 Ol 1.0
7196 June 17 = Ol 1.0
7197 June 17 —0.6 Ol 1.0
* Three exposures.
ComPaRISON STARS

No. Diameter. |* sari naked Y (Declination). Dependence.

1 0.15 —40.1 —35.3 +0.3983

2 .16 —26.4 +33.3 . 2624

3 .20 +66.5 + 2.0 +0.3393

Parallax star 0.20 — 0.3 — 4.6

 

 

 

 

 
586

S. A. MITCHELL

 

 

 

 

 

 

; TABLE 2
REDUCTIONS FOR ¢ CrpHEt
Bola | Seaow | Wee) realign | Meee | ee
mm, mm.

389 +0.0036 1.0 —0.694 —1126 —0.0012 —0"02
491 + .0009 0.8 — .882 —1102 + .0014 + -02
581 + .0021 0.9 — .922 —1089 + .0002 .00
1936 + .0031 0.6 — .865 — 740 — .0003 -00
2042 + .0051 0.7 — .923 — 722 — .0023 — .04
2043 + .0052 0.5 — .923 — 722 — .0024 — .04
3431 + .0011 0.8 — .924 — 353 + .0022 + .04
3432 + .0021 1.0 — .924 — 353 + .0012 + .02
5520 + .0051 1.0 + .712 + 235 + .0005 + .01
5521 + .0038 0.9 + .712 + 235 + .0018 + .04
5584 + .0024 1.0 + .645 + 241 + .0032 + .07
.§535 + .0073 0.8 + .645 + 241 — .0017 — .03
5816 + .0043 0.8 — .745 + 340 + .0001 .00
5841 + .0070 1.0 — .861 + 355 | — .0027 — .06
5842 + .0067 0.8 — .861 + 355 - -0024 — .04
5868 + .0023 0.9 — .877 + 358 + .0020 + .04
5869 + .0020 0.9 — .877 + 358 + .0023 + .05
7192 + .0050 0.6 + .906 + 575 + .0013 + .02
7193 + .0098 Lal, + .906 + 575 — .0035 — .08
7194 + .0083 1.0 + .854 + 584 — .0021 — .04
7195 + .0057 1.0 + .854 + 584 + .0005 + .01
7196 + .0081 1.0 + .854 + 584 — .0019 — .04
7197 +0.0030 1.0 +0.854 + 584 +0.0032 +0.07

 

 

 

 

The normal equations are:

20.1e + 8.1574 — 1.77367 = + 0.0925 mm.
+ 717.0905 + 63.93837

from which:
c = + 0.00463 mm.

w= + 0.00014 mm.

I!

= + 0.1972 mm.
+ 14.0647 = + 0.0138 mm.

a = + 0.00093 mm. = + 07019 + 07010.

Probable error of plate of unit weight
+ 0.00138 mm. = + 07029.

+ 070029, or + 07011 per year.
PARALLAXES OF 260 STARS 587

e CEPHEI (225 11™; +56° 32’)

This star of magnitude 4.23 and of A5 type has a total proper
motion 07452. With the heliometer Chase found the parallax
+ 07110 + 07015, by photography with the 40-inch refractor
Slocum and Mitchell found the result + 07060 + 07009, while
at Allegheny by photography the result is + 07027 + 07011.
Miss Hawes measured the plates and found the parallax + 07053
-+ 07008 with a proper motion in right ascension -+- 07462 where
the corresponding value from Boss is + 07450.

 

 

 

 

TABLE 1
Puates or e CEPHEI
No. Date. Hour Angle. Observers. Weight.
8215 1916 Oct. 19 —04 M 1.0
3216 Oct. 19 0.0 M 1.0
3272 Oct. 25 —0.9 L 1.0
3273 Oct. 25 —0.5 L 1.0
4689 1917 Nov. 3 —0.4 A 1.0
4799 Nov. 22 —0.1 Ol 0.9
4818 Nov. 28 -0.1 M 1.0
5582 1918 Aug. 2 0.0 A 1.0
5583 Aug. 2 +0.2 A 0.7*
5597 Aug. 5 —0.4 A 1.0
5598 Aug. 5 -0.1 A 0.9
5810 Oct. 15 —0.2 H, D 1.0
5987 Nov. 23 0.0 D,H 1.0
5998 Nov. 25 —0.1 M 0.9
7158 1919 June 2 —1.8 M 1.0
7159 June 2 —1.5 M 0.8
7246 June 29 —-1.3 Ol 0.9
7247 June 29 —0.9 Ol 1.0
7248 June 29 —0.5 Ol 1.0
7823 Sept. 27 —0.5 D 1.0
7824 Sept. 27 —0.2 D 1.0
7869 Sept. 30 —0.5 D 1.0
7870 Sept. 30 —0.2 D 1.0
7871 Sept. 30 +0.2 D 0.7*

 

 

 

 

* One exposure.
588

S. A. MITCHELL

CoMPARISON STARS

 

 

 

 

 

 

 

 

 

 

No. Diameter. x eo Y (Declination). Dependence.

1 0.11 —39.5 + 7.0 +0.177

2 .14 —21.1 +11.5 . .178

3 .12 + 3.2 —11.5 .215

4 .14 +11.8 —29.0 -240

5 .12 +45.6 +22.0 +0.190
Parallax star 0.15 + 1.4 — 2.0

TABLE 2
REDUCTIONS FOR e¢ CEPHEI
Fite. |) eee | Meee cams | Sere | ae || age
mm. mm.

3215 —0.0412 1.0 —0.766 —679 +0.0026 | +0°05
3216 — .0373 1.0 — .766 —679 = .0013 — .03
* 3272 — .0871 | -1.0 — .815 —673 — .0013 — .03
3273 — .0383 1.0 — .815 —673 — .0001 .00
4689 — .0164 1.0 — .871 —299 + .0007 | + .01
4799 — .0156 | 0.9 — .923 —280 + .0009 + .02
4818 — .0146 1.0 — .918 —274 + .0003 + .01
5582 + .0022 1.0 + .338 — 27 + .0017 + .04
5583 + .0007 0.7 + .338 — 27 + .0032 + .06
5597 + .0031 1.0 + .293 — 24 + .0009 + .02
5598 + .0064 0.9 + .293 — 24 — .0024 — .05
5810 + .0086 1.0 — .723 + 47 — .0029 — .06
5987 + .0084 1.0 — .923 + 86 — .0008 — .02
5998 + .0101 0.9 — .922 + 88 — .0024 — .05
7158 + .0244 1.0 + .932 +277 — .0004 — .01
7159 + .0260 0.8 + .932 +277 — .0020 — .04
7246 + .0249 0.9 + .764 +304 + .0003 ; + .01
7247 + .0254 1.0 + .764 +304 — .0002 .00
7248 + .0256 1.0 + .764 +304 — .0004 — .01
7823 + .0286 1.0 — .510 +394 — .0012 — .02
7824 + .0260 1.0 — .510 +394 + .0014 | + .03
7869 + .0269 1.0 — .549 +397 + .0006 + .01
7870 + .0254 1.0 — .549 +397 + .0021 + .04
7871 +0.0258 0.7 0.549 +397 +0.0017 +0.03

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS 589

The normal equations are:

22.8¢ — 1.682u — 5.73537 = + 0.0823 mm.
+ 822.4020u + 28.14407 = + 2.0280 mm.
+°11.9573r = + 0.1751 mm.

from which:
ce = + 0.00470 mm.
w= + 0.00609 mm. = + 071267, or + 07462 per year.

7 = + 0.00256 mm. = + 07053 + 07008.
Probable error of plate of unit weight
+ 0.00110 mm. = + 07023.

LALANDE 43492 (22 12"; +12° 24’)

This star of magnitude 6.9, of Go type and of total proper
motion 0°85 has had its parallax several times determined, as
follows:

 

 

 

 

 

_Authority. Method. Parallax.
Chase Heliometer +0"140+07065
Russell Photography + .021+ .023
Flint Meridian circle + .019+ .033
Jewdokimov Meridian circle — .024+4 .105
Allegheny Photography + .033+ .009
Adams Spectrograph +0.058

 

Mr. Alden measured the McCormick plates, and found a
relative parallax + 0”052 + 07007, with a proper motion in
right ascension + 0”839 while the corresponding value from
Porter is + 07847.
590

S. A. MITCHELL

TABLE 1

Puates oF Lauanpe 43492

 

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
3347 1916 Nov. 5 +046 M 0.6*
3370 Nov. 8 +0.1 A 0.8
3371 Nov. 8. +0.4 A 0.9
3482 Dec. 6 +1.0 Ol 0.8
4253 1917 Aug. 11 +0.2 B 0.8
4254 Aug. 11 +0.5 B 0.7
4582 Oct. 15 +0.8 Ds 0.6
4755 Nov. 10 +0.9 Ds 0.8
4854 Dec. 9 +0.6 M 0.5*
4878 Dec. 15 +1.1 M 1.0
5558 1918 July 14 +0.3 A 1.0
5559 July 14 +0.5 A 1.0
5578 July 21 +0.5 A 1.0
5579 7 July 21 +0.9 A 0.7*
5607 Aug. 6 —0.9 A 1.0
5608 Aug. 6 —0.7 A 0.9
* One exposure.
CoMPARISON STARS
No. Diameter. 7 ao Y (Declination). Dependence.
1 0.16 —59.0 +15.6 +0.2015
2 -15 —41.0 —17.9 . 1658
3 .14 — 6.1 +35.2 -2417
4 .09 +37.2 —44.3 . 1568
5 oT: +67.9 +11.4 +0. 2342
Parallax star 0.15 + 1.8 + 4.4

 

 

 

 
PARALLAXES OF 260 STARS 59

TABLE 2

‘REDUCTIONS FOR LALANDE 43492

 

 

 

 

 

 

 

 

 

Soluti Weigh Parall: ime i i D-
ais | Ee ae ee | | | es
mm. mm.

3347 —0.0094 0.6 —0.881 —367 —0.0001 0700
3370 — .0087 0.8 — .894 —364 — .0005 — .01
3371 — .0106 0.9 — .894 — 364 + .0014 | + .08
3482 — .0057 0.8 — .896 —336 — .0004 | — .0O1
4253 + .0250 0.8 + .202 — 88 — .0009 — .02
4254 + .0233 0.7 + .202 — 88 + .0008 | + .01
4582 + .0313 0.6 — .142 — 23 — .0009 | — .O1
4755 + .0321 0.8 — .901 + 3 — .0007 — .01
4854 + .0335 0.5 — .884 + 382 + .0011 | + .02
4878 + .0358 1.0 — .851 + 38 — .0004 | — .O1
5558 + .0618 1.0 + .601 +249 + .0005 | + .01
5559 + .0630 1.0 + .601 +249 — .0007 | — .O1
5578 + .0630 1.0 + .511 +256 — .0001 -00
5579 + .0631 0.7 + .511 +256 — .0002 -00
5607 + .0634 1.0 + .283 +272 + .0007 | + .01
5608 +0.0636 0.9 +0.283 +272 +0.0005 | +0.01

 

The normal equations are:

13.le + 2.5284 — 1.95287 = + 0.4592 mm.
+ 78.6253u + 15.82647r = + 0.9928 mm.
+ 5.62287 = + 0.1240 mm.
from which:
c = + 0.03330 mm.
pw = + 0.01105 mm. = + 072299, or + 0839 per year.
x = + 0.00250 mm. = + 0052 + 07007.
Probable error of plate of unit weight

+ 0.00047 mm. = + 07010.
592 S. A. MITCHELL

¢ AQUARII (225 23"; —0° 31’)

This well-known double of magnitudes 4.42 and 4.59 and of
type F5 has a considerable proper motion 0718 per year. Ac-
cording to Burnham’s General Catalogue, “It is evident that
neither by computation nor conjecture can any one at this time
be reasonably certain of naming a period which shall be within
one thousand years of the correct time.” Thirteen of the
McCormick photographs were measured by Mr. Alden, the
balance by Mr. Mitchell. The parallaxes of the brighter and

 

 

 

TABLE 1
Puares oF ¢ AQUARII
No. Date. Hour Angle. Observers. Weight
1886 1915 Oct. 28 +04 M 0.7
2062 Nov. 25 +0.1 M 0.9
2779 1916 June 26 —-1.0 M 0.7
2780 June 26 —0.6 M 0.7
3254 Oct. 23 —0.1 L 1.0
3354 Nov. 7 —0.1 L 1.0
3355 Nov. 7 +0.3 L, M 1.0
3420 Nov. 21 +0.6 L 1.0
4267 1917 Aug. 18 +0.5_ A 1.0
4268 Aug. 13 +1.0 A 1.0
4680 Nov. 2 +0.7 B 0.8
4681 Nov. 2 +1.2 B 1.0
4698 Nov. 4 —0.2 M 1.0
4699 Nov. 4 +0.2 M 1.0
4703 Nov. 5 —0.4 A 1.0
4704 Nov. 5 0.0 A 1.0
5570 1918 July 20 +0.6 A 1.0
5571 July 20 +1.1 A 1.0
5611 Aug. 6 +0.8 A 1.0
5897 : Nov. 6 +0.3 M 0.7
5905 Nov. 7 —0.2 D 0.7
5972 Nov. 14 +0.3 F 1.0
5973 Nov. 14 +0.7 F 1.0

 

 

 

 

 
 

 

 

PARALLAXES OF 260 STARS 593
TABLE 2
Repuctions For ¢' Aquaru, BricuTer Star
Soluti Weight | _Parall ime i i D-
Plate. co | Oe” beers, | ase: ae | ae
mm. mm.
1886 —0.0710 | 0.7 —0.803 | —661 +0.0020 | +0703
2062 — .0668 | 0.9 — .919 | —633 — .0019 | — .04
2779. — .0581 0.7 + .812 | —419 — .0034 | — .06
2780 — .0635 0.7 + .812 | —419 + .0020 | + .04
8254 — .0612 1.0 — .768 —300 — .0004 | — .O1
3354 — .0642 1.0 — .872 | —285 + .0028 | + .06
3355 — .0658 1.0 — .872 | —285 + .0044 | + .09
3420 — .0590 1.0 — .916 —271 — .0022 — .05
4267 — .0531 1.0 + .219 | — 6 — .0008 | — .02
4268 — .0551 1.0 + .219 | — 6 | + .0012 | + .02
4680 — .0512 | 0.8 — .842 | + 75 — .0028 | — .05
4681 — .0492 1.0 — .842 | + 75 — .0048 | — .10
4698 — .0540 1.0 — .854 | + 77 -0000 .00
4699 — .0550 1.0 — .854 ; + 77 | + .0010 | + .02
4703 — .0530 1.0 — .860 | + 78 — .0010 | — .02
4704 — .0538 1.0 — .860 | + 78 — .0002 .00
5570 — .0498 1.0 + .563 | +3835 | + .0084 | + .07
5571 — .0464 1.0 + .563 | +3835 0000 .00
5611 — .0430 1.0 + .328 | +352 — .0034 | — .07
5897 — .0528 | 0.7 — .865 | +444 | + .0064 | + .11
5905 — .0470 | 0.7 — .869 | +445 | + .0006 | + .O1
5972 — .0456 1.0 — .900 | +452 — .0007 | — .O1
5973 —0.0452 1.0 —0.900 +452 —0.0011 —0.02

 

 

 

 

 

 

 

39
594 S. A. MITCHELL

fainter stars are + 0”034 +0013, and + 07029 + 07010,
respectively, so that the parallax of the system is + 070382
+ 07008. Proper motions of + 07156 and + 07166 for ¢! and ¢?
Aquarii resulted from the photographs, while the values from
Boss are + 0172 and + 0%207, respectively. The spectroscopic
parallaxes for ¢1 and % arc + 07028 and + 0029, respectively.

CoMPARISON STARS

 

 

 

 

 

 

 

No. Diameter. |* ee Y (Declination). Dependence.
1 0.13 —43.3 +12.8 +0. 1402
2 .16 —36.0 +45.9 .1879
3 .08 —28.2 —11.5 1251
4 .17 +17.6 -17.7 .1621
5 .12 +35.9 + 6.0 . 2090
6 .10 +54.0 —35.5 +0.1757
Brighter star .12 + 3.5 + 1.1
Fainter star 0.10

 

The normal equations are:

21.2c + 2:2138u — 9.74587 = — 1.1592 mm.
+ 230.5939u + 1.52027 = + 0.3568 mm.
+ 12.80807 = + 0.5516 mm.
from which:
c = — 0.05415 mm.
uw = + 0.00206 mm. = + 070428, or + 07156 per year.
ar = + 0.00162 mm. = + 0034 + 0’013. ,

Probable error of plate of unit weight
+ 0.00175 mm. = + 0036.
PARALLAXES OF 260 STARS

59

 

 

 

 

 

 

 

 

 

 

TABLE 3
Repuctions ror ¢ Aquaril, Fainter Star
Soluti Weight | Paral ime i i Ss
Plate. ‘eae ee oe | oe ae
mm. mm.
1886 -| +0.0388 0.7 —0.803 —661 —0.0016 —0"03
2062 + .0383 |. 0.9 — .919 —633 — .0006 — .01
2779 + .0450 0.7 + .812 —419 — .0003 — .01
2780 + .0483 0.7 + .812 —419 + .0014 + .02
3254 + .0444 1.0 — .768 —300 + .0007 + .01
3354 + .0454 1.0 — .872 —285 — .0001 -00
3355 + .0462 1.0 — .872 —285 — .0009 — .02
3420 + .0461 1.0 — .916 —271 — .0005 — .01
4267 + .0533 1.0 + .219 — 6 — .0004 — .01
4268 + .0535 1.0 + .219 — 6 — .0006 — .01
4680 + .0518 0.8 — °.842 + 75 + .0014 + .03
4681 + .0545 1.0 — .842 + 75 — .0013 — .03
4698 + .0501 1.0 — .854 + 77 + .0032 + .07
4699 + .0524 1.0 - . 854 + 77 + .0008 + ..02
4703 + .0523 1.0 — .860 + 78 + .0010 + .02
4704 + .0520 1.0 — .860 + 78 + .0013 +: .03
5570 + .0584 1.0 + .563 +335 + .0024 + .05
5571 + .0600 1.0 + .563 +3835 + .0008 + .02
5611 + .0652 1.0 + .328 +352 — .0043 — .09
5897 + .0590 0.7 — .865 +444 + .0022 + .04
5905 + .0596 0.7 — .869 +445 + .0017 + .03
5972 + .0666 1.0 — .900 +452 — .0052 — .ll
5973 +0.0612 1.0 —0.900 +452 +0.0002 0.00
The normal equations are:
21.2c + 2.2134 — 9.74587 = + 1.1095 mm.
+ 230.5939u + 1.52027 = + 0.6228 mm.
+ 12.80807 = — 0.4931 mm.
from whieh:
c = + 0.05274 mm.
pn = + 0.00219 mm. = + 0'0455, or + 07166 per year.
x = + 0.00137 mm. = + 07029 + 07010.

Probable error of plate of unit weight
+ 0.00135 mm. = + 07028.
596 S. A. MITCHELL

KRUEGER 60 (22 24™; +57° 11’)

This star has long been noted as an exceptional star on account
of its large proper motion amounting to 0"94 per year, its rapid
orbital motion, and its large parallax. Our knowledge of the
pair has been mainly through the magnificent series of observa-
tions made by Barnard. The preceding star of Krueger’s wide
pair, separated 12”, was discovered by Burnham in 1890 to
be an unequal double, with a distance of 273. As noted by
Barnard (Monthly Notices, May, 1916), Krueger’s two stars
have no physical connection, and their proximity in space is
purely accidental, while the pair discovered by Burnham is a
binary of a very interesting character. The truth of this
remark will be borne out by the parallax measures described
below.

The parallax has been three times determined as follows:
Barnard by micrometric measures obtained + 07249 + 07010,
Russell by photography + 07258 + 07019, and Schlesinger by
photography with the Yerkes refractor + 07252 + 0”006.
These three measures were made of the brighter component, A,
of the pair. According to Aitken, this star has a magnitude
9.3 while the companion, B, is of magnitude 10.8. A is of
spectral type Mb, according to Adams. The distant star, C,
forming with AB the stars of Krueger’s double is of magnitude
10.0, and in consequence of the large proper motion of the pair
AB the distance has now increased to 50’, or as Barnard has
expressed it, ‘‘this star has been left behind in space.” C has
no sensible proper motion. In view of the interest attaching to
this system, it seemed worth while to determine the parallaxes
and the proper motions of all three stars, A, B, and C. The
plates taken for this purpose, and the measures made by Mr.
Mitchell follow:
,

PARALLAXES OF 260 STARS 597

 

 

 

 

TABLE 1
Puates or Krurecer 60
No. Date. Hour Angle. Observers. Weight.
3418 1916 Nov. 21 —054 M 1.0
3419 Nov. 21 —0.1 M 1.0
3437 Nov. 26 —0.3 M 1.0
3438 Nov. 26 0.0 M 1.0
4166 1917 July 4 —0.7 M 1.0
4167 July 4 —0.4 M 1.0
4168 July 4 0.0 M 1.0
4696 Nov. 4 —1.0 M 1.0
4697 Nov. 4 —0.7 M 0.8
4701 Nov. 5 —1.2 M 1.0
4702 Nov. 5 —0.8 M 1.0
4727 Nov. 7 —1.0 M 1.0
4728 Nov. 7 —0.7 M 1.0
5511 1918 July 2 —0.4 A 1.0
5512 July 2 —0.1 A 0.7
5513 July 2 0.0 A 0.5*
5570 July 20 +0.2 A 0.8
5609 Aug. 6 —0.2 A 0.8
5871 Nov. 3 —0.2 M 0.8
5903 Nov. 7 —1.4 M 1.0
5970 Nov. 14 —0.6 M 0.8
5971 Nov. 14 | —0.3 M 1.0

 

 

 

 

* One exposure.
CoMPARISON STARS

 

 

 

 

 

 

 

: sa Dependence.
ne Diameter. | trues | * Gon Fae i
mm. mm. mm.
1 0.14 —30.6 — 7.8 +0.185 +0.154
2 -12 —22.1 422.1 .180 -175
3 11 — 1.3 +82.0 . 168 .187
4 .09 -— 1.1 —32.9 .167 -145
5 .17 +26.6 + 2.5 -151 .175
6 -09 +28.5 —15.9 +0.149 +0.164
A and B .12 and.06; — 1.8 + 0.4
Cc 0.09 + 0.4 + 1.7

 
598 S. A. MITCHELL '

TABLE 2
Repuctions ror Krurcer 60, A

 

 

 

 

 

 

 

 

 

 

‘a ¥ . . : al 7 ale
Biatey || Sataais | | Wale | ecales, | aa | eae | ape
mm. : mm. i
3418 +0.0144 1.0 —0.916 — 393 +0.0016 +0703
3419 + .0148 1.0 — .916 —393 + .0012 + .02
8437 + .0148 1.0 — .919 —388 + .0007 + .01
3438 + .0148 1.0 — .919 —388 + .0007 + .01
4166 + .0204 1.0 + .743 —168 — .0030 — .06
4167 + .0146 1.0 + .743 —168 + .0028 | + .06
4168 + .0176 1.0 + .743 —168 — .0002 -00
4696 — .0159 1.0 — .853 — 45 + .0019 + .04
4697 — .0137 0.8 — .853 — 45 — .0003 .00
4701 — .0088 1.0 — .859 — 44 — .0053 — .11
4702 — .0114 1.0 — .859 — 44 — .0027 — .06
4727 — .0146 1.0 — .870 — 42 + .0001 .00
4728 — .0128 1.0 — .870 — 42 — .0017 — .04
5511 — .0144 1.0 + .764 +195 .0000 .00
5512 — .0097 0.7 + .764 +195 — .0047 — .08
5513 — .0185 0.5 + .764 +195 + .0041 + .06
5570 — .0228 0.8 + .565 +213 + .0042 + .08
5609 — .0210 0.8 + .330 +230 — .0021 — .04
5871 — .0504 0.8 — .846 +319 + .0043 + .08
5903 — .0482 1.0 — .869 +323°> | + .0015 + .03
5970 — .0480 0.8 — .899 +830 + .0003 -00
5971 —0.0462 1.0 —0.899 +330 —0.0015 —0.03
The normal equations are:
20.2¢ — 3.634 — 7.20167 = — 0.2017 mm.
+ 124.9731 + 7.30577 = — 0.9858 mm.
+ 13.7318r = + 0.1622 mm.
from which:
¢ = — 0.00699 mm.
# = — 0.00884 mm. = — 071839, or — 0"671 per year.
w= + 0.01285 mm. = + 0°267 + 0’011.

Probable error of plate of unit weight
+ 0.00173 mm. = + 0°036.
PARALLAXES OF 260 STARS 59$

 

 

 

 

 

 

 

 

 

TABLE 3
Repuctions ror Kruscer 60, B
Soluti Weighi Parall: ime i i Dp:
Elst: Gs (| Factor ). mee | eeaeel: ay
mm. mm.
3418 +0.1088 1.0 —0.916 —393 +0.0020 | +0704
3419 + .1084 1.0 — .916 —393 + .0024 |} + .05
3437 + .1098 1.0 — .919 —388 + .0003 + .01
3438 + .1050 1.0 — .919 —388 + .0051 + .11
4166 + .1064 1.0 + .743 —168 — .0025 — .05
4167 + .1058 1.0 + .743 —168 — .0019 — .04
4168 + .1082 1.0 + .743 —168 — .0043 — .09
4696 f| + .0679 1.0 — .853 — 45 + .0003 + .01
4697 + .0686 0.8 — .853 — 45 — .0004 — .01
4701 + .0724 1.0 — .859 — 44 — .0044 | — .09
4702 + .0706 1.0 — .859 — 44 — .0026 — .05
4727 + .0664 1.0 — .870 — 42 + .0012 | + .02
4728 + .0726 1.0 — .870 — 42 — .0050 — .10
5511 + .0521 1.0 + .764 +195 + .0068 | + .14
5512 + .0600 0.7 + .764 +195 — .0011 — .02
5513 + .0549 0.5 + .764 +195 + .0040 | + .06
5570 + .0527 0.8 + .565 +213 + .0014 | + .02
5871 + .0194 0.8 — .846 +319 + .0035 + .07
5903 + .0210 1.0 — .869 +323 + .0011 + .02
5970 + .0238 0.8 — .899 +330 — .0029 — .05
5971 +0.0220 1.0 —0.899 +330 —0.0011 —0.02

 

The normal equations are:

19.4¢ — 5.474 — 7.46567 = + 1.3984 mm.
+ 120.7411u + 6.69857 = — 1.8222 mm.
+ 13.64467 = — 0.4584 mm.
from which:
c = + 0.07346 mm.
ph = — 0.01247 mm. = — 072593, or — 07946 per year.

ao = +0.01272 mm. = + 07265 + 07014.
Probable error of plate of unit weight

+ 0.00221 mm. = + 07046.
 

 

 

 

 

 

 

 

 

 

600 S. A. MITCHELL
TABLE 4
Repuctions ror Krurcer 60, C
votes | OS™ | Ge | more. | Dace. | ee | ane
mm, mm.
3418 +0.0301 1.0 —0.916 —3893 +0.0023 +0705
8419 + .0306 1.0 — .916 —393 + .0018 + .04
3437 + .0346 1.0 — .919 —388 — .0022 — .05
3438 + .0306 1.0 — .919 —388 + .0018 + .04
4166 + .0358 1.0 + .743 —168 — .0032 — .07
4167 + .0318 1.0 + .743 —168 + .0008 + .02
4168 + “0314 1.0 + .743 —168 + .0012 | + .02
4696 + .0335 1.0 — .853 — 45 — .0008. | — .02
4697 + .0309 0.8 — .853 — 45 + .0018 + .03
4701 + .0326 1.0 — .859-| — 44 + .0001 -00
4702 + .0359 1.0 — .859 — 44 — .0032 — .07
4727 + .0366 1.0 — .870 — 42 — .0039 — .08
4728 + .0326 1.0 — .870 — 42 + .0001 -00
5511 + .0320 1.0 + .764 +195 + .0009 + .02
5512 + .0365 0.7 + .764 +195 — .0036 — .06
5513 + .0275 0.5 + .764 +195 + .0054 + .08
5570 + .0312 0.8 + .565 +213 + .0018 + .03
5609 + .0350 0.8 + .330 +230 — .0020 — .04
5871 + .0343 0.8 — .846 +319 — .0013 — .02
5903 + .0310 1.0 — .869 +323 + .0020 + .04
5970 + .0329 0.8 —. .899 +330 + .0001 -00
5971 +0.0314 1.0 —0.899 +330 +0.0016 +0.03
The normal equations are:

20.2¢c — 3.634u — 7.20167 = + 0.6612 mm.

+ 124.9731u + 7.30577 = — 0.1085 mm.

+ 13.73187 = — 0.2349 mm.

from which:
c = + 0.03276 mm.

w= + 0.00008 mm.

a = + 0.00003 mm. = + 07001 + 0010.

Probable error of plate of unit weight

+ 0.00152 mm. =

07032.

+ 070017, or + 07006 per year.
PARALLAXES OF 260 STARS 601

For the pair AB, the parallaxes derived are, + 07267 + 07011,
and + 07265 + 07014, for brighter and fainter, respectively.
The parallax of the system is, therefore,

+ 07266 + 07009.

The parallax of the star C is + 07001 + 0"010.

The proper motions in right ascension for the three stars,
A, B, and C are — 0°671, — 07946, and + 07006.

From the parallax and proper motion of the star C, it is evident
that its parallax and proper motion are practically the same in
size as those of the comparison stars, and therefore, we must
conclude with Burnham (General Catalogue 11761), that C is
fixed in space. :

The proper motion in right ascension of the pair AB has been
determined by Porter to amount to - 0°797 per year. Un-
fortunately, this proper motion is the results of two meridian
circle measures only, and consequently, for obvious reasons, its
value cannot have a high degree of accuracy. As Russell has
pointed out in Astronomical Journal 30, 131, 1917, little is known
of the proper motion of the center of gravity of the system, or of
the relative masses of the components A and B. The present
measures and Porter’s. proper motion show that the relative
masses of A and B are in the approximate ratio 6 : 5, but in the
present state of our knowledge, this figure is at best but a rough
guess.

The present series of plates have been measured to determine
the position angle and distances of the pairs AB, AC, and BC.
These measures have been compared with the very excellent
series of micrometer measures made by Barnard with the 40-inch
Yerkes refractor. The details of these measures appear else-
where (Astronomical Journal, 32, 177, 1920). The measures in-
dicate that even when a double is as close as 2”, or 0. 1 millimeter
on the McCormick plates, the measures on the photographs have
as high a degree of accuracy as similar measures with the mi-
crometer.

In the Astronomical Journal (loc. cit.), Russell has discussed
the elements of this pair, and has given two possible orbits that
satisfy the observations made up to 1916 equally well. Un-
602 S, A. MITCHELL

published observations by Barnard made by the micrometer,
and the measures of the position angle and distance of the photo-
graphs, referred to above, seem to indicate that the second of the
orbits with a period of 54.9 years represents these later observa-
tions the better. With this assumption, the mass of the system
is 0.40 that of the sun, while the McCormick parallax gives the
absolute magnitudes of A and B to be 11.5 and 13.0, or respec-
tively, 6.5 and 8.0 magnitudes fainter than our own sun. This
gives to B a luminosity about one-two-thousandth that of the
sun, which is about equivalent to the luminosity of Barnard’s
star of large proper motion. These two stars are among the
faintest suns that are as yet known to astronomy.

n PEGASI (225 38"; +29° 42’)

Four values have been found for the parallax of this star
which is of 3.10 magnitude, of Go type, and of small proper
motion 07036. Flint with the meridian circle found the relative
parallax of — 07028 + 07027, the Allegheny Observatory by pho-
tography the relative parallax of — 07002 + 07013, Swarthmore
the photographic parallax — 07004 + 07012, and Adams with
the spectrograph the absolute parallax of + 0”022. Mr. Olivier
measured the plates and found a parallax of — 07008 + 07010,
with a proper motion in right ascension of — 0”058 per year
while the value from Boss is + 0”010.
PARALLAXES OF 260 STARS 603

TABLE 1

PLATES OF 7 PEGASI

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight,
121 1914 July 9 —046 M 0.9
122 July 9 —0.2 M 0.5*
149 = July 21 —1.0 M 0.9
384 Oct. 9 —0.6 G 0.6
464 Nov. 1 —0.3 M 0.8
470 Nov. 2 -0.1 M,G 0.8
478 Nov. 3 0.0 M 0.8
492 Nov. 4 —0.3 G 1.0
509 Nov. 5 —0.5 A 0.9
520 Nov. 6 —0.3 A 1.0
14389 1915 July 6 —0.2 A 0.8
1461 July 13 10 A 1.0
1462 July 13 —0.6 A 1.0
3444 1916 Nov. 27 —0.3 M 0.8
3445 Nov. 27 0.0 M 0.6*
8450 Nov. 30 —0.2 M 0.9
3451 Nov. 30 0.0 M 0.9
3481 Dec. 6 —0.1 Ol 0.9
3516 Dec. 10 0.0 M 0.9
4646 1917 Oct. 30. —0.2 B 0.7
4844 Dec. 5 -0.1 M 0.9

 

* One exposure.

Comparison STARS

 

 

 

 

 

 

 

No. Diameter. |* agg naaeee Y (Declination). Dependence.
mm. mm. mm.

1 0.22 —51.2 +35.4 +0.2381

2 18 —44.6 —26.0 1165

3 .19 +38.6 —18.9 .2758

4 12 +57.2 + 9.5 +0.3696
Parallax star 0.20 +14.4 + 3.7

 
604

S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 2
ReEDUvcTIONS FOR 7 PeGasi
Solution Weight Parallax Time in Residual ‘ vVp-0
Plate. ‘m). (p). | Factor(P). | Days (). 0). in Are.
mm. mm.
121 —0.0238 0.9 +0.732 —458 +0.0002 0700
122 — .0236 0.5 + .732 —458 -0000 .00
149 — .0240 0.9 + .599 —446 + .0003 + .01
384 — .0260 0.6 — .586 —366 + .0022 + .04
464 — .0259 0.8 — .802 —343 + .0020 + .04
470 — .0213 0.8 — .810 —342 — .0026 — .05
478 — .0242 0.8 — .817 —341 + .0003 -00
492 — .0251 1.0 — .824 —340 + .0012 + .02
509 © — .0254 0.9 — .831 —339 + .0015 + .03
520 — .0205 1.0 — .838 —338 — .0034 — .07
1439 — .0273 0.8 + .763 — 96 + .0009 + .02
1461 — .0236 1.0 + .693 — 89 — .0028 — .06
1462 — .0280 1.0 + .693 — 89 + .0016 + .03
3444 — .0296 0.8 — .914 +414 -0000 .00
8445 — .0267 0.6 — .914 +414 — .0029 — .05
3450 — .0327 0.9 — .915 +417 + .0031 + .06
3451 — .0278 0.9 — .915 +417 — .0018 — .04
3481 — .0288 0.9 — .908 +423 — .0009 — .02
3516 — .0310 0.9 — .898 +427 + .0018 + .02
4646 — .0298 0.7 — .789 +751 — .0024 — .04
4844 —0.0347 0.9 —0.910 +787 +0.0023 +0.04
The normal equations are:
17.6¢ + 0.083 — 7.06777 = — 0.4695 mm.
+ 302.0590u — 22.48227 = — 0.2227 mm.
+ 11.60697 = + 0.2021 mm.
from which:
c = — 0.02683 mm.
# = — 0.00076 mm. = — 070158, or — 0058 per year.
aw = — 0.00039 mm. = — 07008 + 0010.

Probable error of plate of unit weight

+ 0.00128 mm. = + 0”027.
PARALLAXES OF 260 STARS 605

& PEGASI (225 41™; +11° 39’)

This star is Lalande 44552, and is of 4.31 magnitude, of F5
type, and of total proper motion 054 per year. Chase has found
the parallax with the Yale heliometer to be + 0”080 + 0047.
The Allegheny parallax by photography is + 07044 + 07009,
and the spectroscopic value of Adams and Joy is + 0”079.
At a distance of 12” there is a companion of 12.8 magnitude
which has the same proper motion as £ Pegasi, so that they
probably form a physical system. The McCormick plates were
measured by Mr. Lamb, who found a proper motion in right
ascension of + 07204 per year while the value from Boss is
+ 07227.

 

 

 

 

 

 

TABLE 1
Puates oF ~ PEGASI
No. Date. Hour Angle. Observers. Weight.
390 1914 Oct. 11 +045 M 0.5*
451 Oct. 31 +0.4 A, M 1.0
692 Dec. 21 +0.8 Ol 0.7
1502 1915 July 23 —0.7 G 0.8
15038 July 23 —0.2 G 1.0
1514 July 24 +0.4 A 0.7
1522 Aug. 5 6.8 G 0.5*
1548 Aug. 13 —0.1 G 0.9
1549 Aug. 13 +0.4 G 0.8
1869 Oct. 27 —0.1 G 1.0
1870 Oct. 27 +0.5 M 1.0
1940 Nov. 1 +0.3 G 1.0
1941 Nov. 1 +0.8 G 1.0
2794 1916 July 3 —0.8 M 0.9
2795 July 3 03 M 0.9
2801 July 5 —0.4 L 0.8
2802 July 5 +0.1 L 1.0
2829 July 20 —1.1 L 0.9
2830 July 20 —0.6 L 0.7

 

 

* One exposure.
306 S, A. MITCHELL

CoMPARISON STARS

 

 

 

 

 

 

 

 

No. Diameter. X (Right Ascen-| y (Declination). Dependence.
sion).

mm. mm. mm.

1 0.15 —37.0 —21.0 +0.281

2 .13 —35.0 +11.8 .3802

3 .18 +32.9 +31.7 .231

4 -15 +39.1 —22.5 +0.186
Parallax star 0.16 — 6.1 + 0.8

TABLE 2

REDUCTIONS FOR £ PEGASI

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual - Vp-o
Plate. (m). (p). | Factor (P). | Days (). (0). in Arc.
390 +0.0222 0.5 —0.580 —360 —0.0018 —0702
451 + .0230 1.0 — .786 —309 — .0025 — .05
692 + .0217 0.7. — .856 —380 -0000 : .00
1502 + .0322 0.8 + .589 — 95 — .0015 — .08
1503 + .0297 1.0 + .589 — 95 + .0010 + .02
1514 + .0281 0.7 + .577 — 94 + .0026 + :04
1522 + .0282 0.5 + .417 — 82 + .0025 + .03
1548 + .0283 0.9 + .301 — 74 + .0023 + .04
1549 + .0309 0.8. + .301 — 74 — .00038 -00
1869 + .0307 1.0 — .750 + 1 — .0004 — .01
1870 + .0298 1.0. — .750 + 1 + .0005 + .01
1940 + .0299 1.0, — .792 + 6 + .0004 + .01
1941 + .0288 1.0 — .792 + 6 + .0015 + .03
2794 “| + .0393 0.9 + .791 +251 + .0012 + .02
2795 + .0415 0.9 + .791 +251 — .0010 — .02
2801 + .0412 0.8 + .773 +253 _ .0007. — .01
2802 + .0444 1.0 + .773 ‘+253 — .0039: | — .08
2829 + .0404 | 0.9 | + .617 | +268 | + .0002 .00
2830 +0.0396 0.7 +0.617 +268 +0.0010. | +0.02

 
PARALLAXES OF 260 STARS 607

The normal equations are:

16.1le + 1.801 + 1.22757 = + 0.5221 mm.
+ 64.7348 + 13.47637 = + 0.2623 mm.
+ 7.58782 = + 0.0925 mm.

from which:
c = + 0.03195 mm.
w= + 0.00270 mm. = + 070562, or + 07205 per year.

a = + 0.00222 mm. = + 07046 + 07011.
Probable error of plate of unit weight
+ 0.00113 mm. = + 07024.

p PEGASI (22 45™; +24° 4’)

The Allegheny parallax published for this star which is of K
type, of 3.67 magnitude, and of total proper motion 0°16
is + 07043 + 07006, while the spectroscopic value is + 07030,
Mr. Alden measured the plates and found a proper motion in
right ascension amounting to + 07167 while the value from
Boss is + 07147.
 

 

 

 

 

 

 

 

 

 

 

 

 

 

‘608 S. A. MITCHELL
TABLE 1
PuaTES OF » PEGASI
No. Date. Hour Angle. Observers. Weight.
575 1914 Nov. 13 —0b4 O1,G 0.8
582 Nov. 17 —0.2 A 1.0
624 Nov. 23 —0.2 Ol 0.8
638 Nov. 24 —0.2 M 0.9
1517 1915 July 31 —0.6 A 0.6*
1528 Aug. 6 —0.8 G 0.7*
1529 Aug. 6 —0.4 G 0.7
1570 Aug. 23 —0.4 A 0.8
1834 Oct. 23 —0.3 A 1.0
1835 Oct. 23 +0.1 A 1.0
1947 Nov. 2 —0.7 A 1.0
1948 Nov. 2 —0.2 M 0.7*
3443 1916 Nov. 27 —0.8 M 0.9
3450 Nov. 30 —0.7 M 1.0
3459 Dec. 1 —0.6 M 1.0
4158 1917 July 1 —1.1 A 1.0
4159 July 1 —0.6 A 1.0
4280 Aug. 18 —0.4 B 0.6*
4281 Aug. 18 0.0 B 0.7*
4630 Oct. 25 —0.1 A 1.0
* One exposure.
CoMPARISON STARS
No. Diameter. |* Right Ascen-| y (Dectination). | Dependence.
mm. mm. mm.
1 0.14 —35.6 +26.7 +0.4047
2 22 —15.2 —38.4 . 2378
3 .16 +50.8 +11.7 +0.3575
Parallax star 0.18 + 0.1 + 5.9

 
PARALLAXES OF 260 STARS 60

TABLE 2

REDUCTIONS FOR » PEGASI

 

 

 

 

 

 

 

 

 

Soluti .| Weight Parall: Time i i Dp:
er || er | Sener es | Dae we me | ae
mm. mm.

575 —0.0043 0.8 —0.865 —488 —0.0046 | —0’09
582 — .0084 1.0 — .883 —484 — .0005 | — .01
624 — .0089 0.8 — .903 —478 + .0002 -00
638 — .0097 0.9 — .905-| —477 + .0010 | + .02
1517 — .0080 0.6 + .499 —228 + .0044 | + .07
1528 — .0026 0.7 + .418 —222 — .0009 | — .O1
1529 — .0062 0.7 + .418 — 222 + .0027 | + .05
1570 + .0014 0.8 + .163 — 205 — .0044 | — .08
1834 + .0001 1.0 — .701 —144 — .0015 | — .08
1835 — .0044 1.0 — .701 —144 + .0030 | + .06
1947 — .0020 1.0 — .792 —134 + .0008 | + .02
1948 — .0039 0.7 — .792 —134 + .0027 | + .05
3443 + .0060 0.9 — .910 +257 + .0015 | + .03
3450 + .0074 1.0 — .914 +260 + .0001 -00
3459 + .0088 1.0 — .914 +261 — .0012 | — .02
4158 + .0115 1.0 + .816 +473 + .0002 .00
4159 + .0131 1.0 + .816 +473 — .0014 | — .08
4280 + .0133 0.6 + .232 +521 — .0004 | — .01
4281 + .0127 0.7 + .232 +521 + .0002 -00
4630 +0.0152 1.0 —0.726 +589 —0.0005 | —0.01

 

The normal equations are:

17.2c + 1.511p — 6.28477 = + 0.0317 mm.
+ 236.05574 + 14.71077 = + 0.5178 mm.
+ 9.57707 = + 0.0199 mm.

from which:

c = + 0.00155 mm.

pw = + 0.00220 mm. = + 070458, or + 07167 per year.
— 0.00029 mm. = — 07006 + 07012.

Probable error of plate of unit weight

+ 0.00141 mm. = + 07029.

I

Tv

40
610 S. A. MITCHELL

. CEPHEI (22> 46"; +65° 40’)

This is a Ko type star, of magnitude 3.68, and of total proper
motion 07139. The Allegheny value of the parallax is + 07027
+ 0”007, while the spectroscopic result of Adams furnishes the
absolute parallax of -+ 07030. Mr. Alden measured the
McCormick plates with the exception of the last six plates

 

 

 

TABLE 1
PuatTes oF « CEPHEI
No. Date. Hour Angle. Observers. _ Weight.
1902 1915 Oct. 29 —042 Ol 0.9
1938 Nov. 1 —0.9 G 0.8
1939 Nov. 1 —0.5 G , 1.0
2010 Nov. 11 —0.2 A 1.0
2101 Dec. 1 —0.5 Ol 0.6
2841 1916 Aug. 4 —0.8 A 0.9
2842 Aug. 4 —0.4 A 1.0
2852 Aug. 7 —0.5 A 1.0
2853 Aug. 7 —0.2 A 0.9
2860 Aug. 12 —0.4 A 1.0
2861 Aug. 12 —0.1 A 1.0
3286 Oct. 27 —0.4 L 1.0
3287 Oct. 27 —0.1 L 1.0
3307 Oct. 29 —0.4 A 0.8
3308 Oct. 29 —0.2 A 1.0.
3324 Nov. 1 —0.4 A 0.9
5599 1918 Aug. 5 —0.2 A 1.0
5600 Aug. 5 +0.1 A 1.0
5619 Aug. 13 —1.1 A 0.9
5620 Aug. 13 —0.8 A 1.0
5872 Nov. 3 —0.2 M 1.0
5873 Nov. 3 +0.1 M 1.0
5929 © Nov. 11 —1.1 H 1.0
5930 Nov. 11 —0.6 D 0.8
5952 Nov. 13 —0.9 H 1.0
5953 Nov. 13 —0.5 D 1.0

 

 

 

 

 
PARALLAXES OF 260 STARS 611

which were measured by Mr. Mitchell. The photographic
proper motion in right ascension is — 0"091 while the corre-
sponding value from Boss is — 07068.

TABLE 2

REDUCTIONS FOR t CEPHEI

 

 

 

 

 

 

 

Soluti Weight | Paral ime ‘ Ba
Plate. ee RGR, (Bege Ce | Pepe a 7c
mm. mm.

1902 +0.0052 0.9 —0.756 —549 +0.0022 +0704
1988 + .0083 0.8 — .782 —546 — .0010 — .02
1939 + .0058 1.0 — .782 —546 + .0015 + .03
2010 + .0078 1.0 — .852 —536 — .0008 — .02
2101 + .0037 0.6 — .912 —516 + .0030 + .05
2841 + .0070 0.9 + .4387 —269 — .0002 .00
2842 + .0072 1.0 + .437 —269 — .0004 — .01
2852 + .0070 1.0 + .394 —266 — .0003 — .01
2853 + .0068 0.9 + .394 —266 — .0001 .00
2860 + .0066 1.0 + .321 —261 — .0002 .00
2861 + .0042 1.0 + .321 —261 «+ .0022 + .05
3286 + .0022 1.0 — .745 —185 + .0009 + .02
3287 + .0058 1.0 — .745 - 185 — .0027 — .06
3307 + .0051 0.8 — .763 —183 — .0021 — .04
3308 + .0050 | 1.0 — .763 —183 — .0020 — .04
3324 + .0043 0.9 — .788 —180 |. — .0014 — .03
5599 — .0002 1.0 + .429 +462 — .0018 — .04
5600 — .0046 1.0 + .429 +462 + .0026 + .05
5619 — .0014 0.9 + .314 +470 — .0010 — .02
5620 — .0015 1.0 + .314 +470 — .0009 — .02
5872 — .0086 1.0 — .800 +552 + .0027 + .06
5873 — .0076 1.0 — .800 +552 + .0017 + .04
5929 — .0070 1.0 — .853 +560 + .0009 + .02
5930 — .0046 0.8 — .853 +560 — .0015 — .03
5952 — .0065 1.0 — .864 +562 + .00038 + .01
5953 —0.0046 1.0 —0.864 +562 —0.0016 +0.03

 

 

 
612 y S.A; MITCHELL

Comparison STaRs

 

 

 

 

 

 

No. | Diemeter. | aero Y (Declination). Dependence.
mm. mm. mm

1 0.14 —30.2 + 5.9 +0.1718

2 .09 —21.4 +19.2 . 1886

3 15 — 7.7 —35.6 .1713

4 .12 +20.5 +42.0 . 2459

5 .14 +38.8 —31.5 +0.2224
Parallax star 0.14 + 3.1 + 1.9

 

 

The normal equations are:

24.5¢ + 3.306u — 8.24777 = + 0.0400 mm.
+ 447.3148u — 0.91657 = — 0.5314 mm.
+ 11.05897 = + 0.0054 mm.

from which:
c = + 0.00257 mm.
# = — 0.00120 mm. = — 070250, or — 07091 per year.
a« = + 0.00230 mm. = + 07048 + 07008.

Probable error of: plate of unit weight
+ 0.00112 mm. = + 07023.

LALANDE 45028 (225 56"; —4° 23’)

Two values have been published for the parallax of this star
which is of 7.8 magnitude, of K type, and of total proper motion
0°54. Smith with the Yale heliometer found a relative parallax
of + 0038 + 07015, and Adams by the spectrograph the
absolute parallax of + 07046. Mr. Olivier measured the plates
and determined the proper motion in right ascension to be

+ 07405 while the value from Porter is + 0”0418.
PARALLAXES OF 260 STARS

 

 

 

 

 

 

 

 

 

 

 

613
TABLE 1
Puates oF LALANDE 45028
No. Date. Hour Angle. Observers. Weight.
1836 1915 Oct. 23 +046 A 1.0
1903 Oct. 29 +0.1 Ol 0.8
1904 Oct. 29 +0.6 Ol 1.0
2017 Nov. 16 —0.4 O1 A 0.8
2018 Nov. 16 +0.1 A 1.0
2823 1916 July 12 —0.4 ol 0.9
2866 Aug. 13 —0.3 Ol 0.4
2867 Aug. 13 +0.1 ol 0.9
2880 Aug. 17 —0.2 ol 0.7
2881 Aug. 17 +0.2 Ol 0.9
2882 Aug. 17 +0.6 Ol 0.9
2883 Aug. 17 +1.1 Ol 0.8
3331 ; Nov. 2° 0.0 L 1.0
3332 Nov. 2 +0.3 L 0.9
3356 Nov. 7 +0.4 M 1.0
3357 Nov. 7 +0.8 M 0.9
3414 Nov. 20 —0.2 Ol, A 0.9
3433 Nov. 22 +0.1 Ol, A 0.6
Comparison STaRS ~~ .
No. Diameter. e a lial Y (Declination). Dependence.
mm, mm. mm.
1 0.13 —49.1 —23.5 +0.2698
2 .16 + 1.9 +61.1 . 1873
3 24 +12.3 — 6.6 - 2579
4 -17 +34.9 —31.0 +0.2850
Parallax star 0.18 + 0.2 — 5.4

 

 

 

 

 
614 S. A. MITCHELL

TABLE 2

Repucrtions ror LALANDE 45028

 

 

 

 

 

 

 

 

 

is . a . R Ge 1 vp-
Bist. | Ba a laneeresy, | Deeg. | Gk | ames
mm. mm.
1836 +0.0086 1.0 —0.666 —226 +0.0005 +0701
1903 + .0088 0.8 — .727 —220 + .0005 + .01
1904 + .0070 1.0 — .727 —220 + .0023 + .05
2017 + .0118 0.8 — .861 —202 — .0019 — .03
2018 + .0118 1.0 — .861 —202 — .0019 — .04
2823 + .0279 0.9 + .745 + 387 — .0012 — .02
2866 + .0292 0.4 + .350 + 69 — .0018 — .02
2867 + .0276 0.9 + .350 + 69 — .0002 .00
2880 + .0255 0.7 + .291 + 73 + .0019 + .03
2881 + .0273 0.9 + .291 + 73 + .0001 -00
2882 + .0257 0.9 + .291 + 73 + .0017 + .03
2883 + .0288 0.8 + .291 + 73 — .0014 — .02
8331 + .0286 1.0 — .770 +150 + .0002 -00
8332 + .0256 0.9 — .770 +150 | + .0032 + .06
3356 + .0308 1.0 — .810 +155 — .0019. | — .04
3357 + .0284 0.9 — .810 +155 + .0005 + .01
3414 + .0282 0.9 — .882 +168 + .0012 + .02
3433 +0.0336 0.6 —0.890 +170 —0.0042 —0.06

 

The normal equations are:

15.4¢ + 2.110u — 5.76840 = + 0.3476 mm.
+ 36.7789u + 1.95647 = + 0.2477 mm.
+ 7.21607 = — 0.1027 mm.

ll

from which:

c = + 0.02281 mm.
& = + 0.00529 mm. = + 071100, or + 07405 per year.
a = + 0.00257 mm. = + 07053 + 0’011.

Probable error of plate of unit weight
+ 0.00119 mm. = + 07025.
circle found the relative parallax

PARALLAXES OF 260 STARS

6 PEGASI (22> 58"; +27° 32’)

Four values of the parallax of 6 Pegasi have been published,
but the results differ very greatly. Flint with the meridian
— 0°047 + 07046, while
Jewdokimov, also with the meridian circle obtained a still

TABLE 1

Puates oF 6 PEGAsSI

615

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
124 1914 July 10 —048 M, Ol 0.5
125 July 10 —0.3 M, Ol 0.6
131 — July 15 —0.2 Ol 0.6
137 July 18 -1.0 M 0.8
143 July 19 —-1.3 M 0.9
465 Nov. 1 0.0 M 1.0
493 Nov. 4 —0.1 M,G 0.8
510 Nov. 5 =0.2 M, A 0.9
§21 Nov. 6 0.0 A 1.0
551 Nov. 11 —0.1 M,G 0.8
600 Nov. 21 —0.2 M,A 1.0
654 Nov. 26 0.0 M 1.0
658 Dec. 12 —0.1 M 0.8
1463 1915 July 13 —0.4 A 0.9
1464 July 13 0.0 A 1.0
1486 July 17 0.0 Ol 0.9
3460 1916 Dec. 1 —0.4 M 1.0
3461 Dec. 1 —0.1 M 0.9
3477 Dec. 5 —0.4 M 1.0
3478 Dec. 5 —0.1 M 1.0
4170 1917 July 9 —0.4 B 0.7
4216 July 31 —0.4 Ol 0.9
4217 July 31 6.1 ol 0.8
4666 Nov. 1 —0.8 A 1.0
4667 Nov. 1 —0.5 A 1.0
4717 Nov. 6 —0.4 Ds 1.0
4718 Nov. 6 —0.1 Ol 0.9

 

 
616 S. A. MITCHELL

TABLE 2

Repvuctions FoR §@ PEGASI

 

 

 

 

 

 

 

 

 

Solution Weight Parallax Time in Residual ; vp-o
Plate. (m). (p). | Factor (P). | Days (d). (0). in Are.

mm. mm.
124 —0.0151 0.5 +0.773 —512 —0.0004 —0701
125 — .0150 0.6 + .773 —§12 — .0005 — .01
131 — .0188 0.6 + .726 —507 + .0034 + .06
137 — .0177 0.8 + .696 |. —504 + .0024 + .04
143 — .0151 0.9 + .685 —503 — .0002 -00
465 — .0091 1.0 — .752 —399 — .0032 — .07
493 — .0110 0.8 — .777 —3895 — .0011 — .02
510 — .0120 0.9 — .785 —394 — .0001 -00
521 — .0116 1.0 — .793 —393 — .0005 — .01
551 — .0126 0.8 — .829 —388 + .0007 + .01
600 — .0110 1.0 — .882 —378 — .0007 — .01
654 — .0115 1.0 — .898 —373 .0000 -00
658 — .0098 0.8 — .903 —357 — .0013 — .02
1463 — .0067 0.9 + .748 —144 + .0007 + .01
1464 — .0064 1.0 + .748. —144 + .0004 + .01
1486 — .0064 0.9 + .708 —140 + .0005 + .01
3460 + .0088 1.0 — .908 +363 — .0013 — .08
3461 + .0052 0.9 — .908 +363 + .0023 + .05
8477 + .0054 1.0 — .910 +3867 + .0022 + .05
8478 + .0061 1.0 — .910 +367 + .0015 + .03
4170 + .0126 0.7 + .779 +583 + .0002 -00
4216 + .0168 0.9 + .540 +605 — .0033 — .07
4217 + .0164 0.8 + .540 +605 — .0029 — .05
4666 + .0170 1.0 — .754 +698 | — .0008 — .02
4667 + .0155 1.0 — .754 +698 + .0007 + .01
4717 + .0162 1.0 — .795 +703 + .0001 .00
4718 +0.0146 0.9 —0.795 +703 +0.0017 +0.03

 
PARALLAXES OF 260 STARS 617

greater negative parallax of — 07190 + 0"076. The Alle-
gheny value by photography is + 07018 + 07010. Adams by
means of the spectrograph found the absolute parallax amounting
to + 070380. The McCormick result from photographs measured
by Mr. Olivier gives a relative parallax of — 07005 + 07006.
8 Pegasi is a star of 2.61 magnitude, of Ma type, and of total
proper motion 07234 per year. In right ascension Boss finds a
proper motion of + 07192 while the value from the photographs
is + 07197.

CoMPARISON STARS

 

 

 

 

 

No. | Diameter. F ae Pie Y (Declination). Dependence.
mm. mm. mm.
1 0.12 —57.1 +24.4 +0.4077
2 22 +13.1 —46.0 .3312
3 32 +44.0 +21.6 +0.2611
Parallax star 0.23 — 7.5 — 0.4

 

The normal equations are:
23.7¢ + 6.5954 — 6.6215¢ = — 0.0306 mm.

+ 530.6446 — 17.56997 = + 1.3649 mm.
+ 14.79707 = — 0.0351 mm.
from which:
c = — 0.00208 mm.
pw = + 0.00259 mm. = + 070539, or ++ 07197 per year.
«+ = — 0.00023 mm. = — 07005 + 0"006.

Probable error of plate of unit weight
+ 0.00107 mm. = + 07022.

7 ANDROMEDZ (235 8"; +48° 51’)

This star is of magnitude 4.62, of type F, and of total proper
motion 0”137. The Allegheny parallax is + 07053 + 07013,
while ‘the spectroscopic value of Mt. Wilson is + 07035. Mr.
Olivier measured the plates and derived a relative parallax
+ 0033 +0”010, with a proper motion in right ascension
+ 0”088, where the corresponding value from Boss is + 07095.
618

S. A. MITCHELL

TABLE 1

Piates oF 7 ANDROMEDZ

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
1920 1915 Oct. 30 —0h2 A 1.0
2071 Nov. 26 —0.4 ol 0.5
2073 Nov. 27 —0.7 Ol 0.7
2145 Dec. 10 -0.4 Ol 0.8
4305 1917 Aug. 20 —0.5 A,B 1.0
4306 Aug. 20 —0.2 B 1.0
4800 Nov. 22 —0.5 Ol 0.9
4801 Nov. 22 —0.1 ol 1.0
5585 1918 Aug. 2 +0.2 A 0.7*
5632 Aug. 19 —0.5 A 1.0
5633 Aug. 19 —0.1 A 1.0
5848 Nov. 2 —0.8 F,M 0.9
5849 Nov. 2 —0.3 F,M 0.9
7332 1919 July 24 —1.6 Ol 0.9
7333 July 24 —1.2 Ol 0.9
7334 July 24 —0.8 Ol 0.7
7358 July 26 —0.8 H 1.0
7359 July 26 —0.4 H 0.9
8136 Nov. 24 —0.7 M 0.9
8137 Nov. 24 —0.4 M,A 1.0
8162 Dec. 1 —0.8 Ol 1.0
8163 Dec. 1 —0.5 Ol 1.0
* One exposure.
CoMPARISON STARS
No. Diameter. & a Need Y (Declination). Dependence.
mm. mm. mm.

1 0.14 —54.6 +39.7 +0.1876

2 .18 —33.9 —16.2 . 2407

3 19 +33.2 —31.8 . 2935

4 .12 +55.3 + 8.3 +0.2782

Parallax star 0.14 + 6.7 — 3.5

 

 

 

 

 
 

 

 

 

PARALLAXES OF 260 STARS 61¢
TABLE 2
REDUCTIONS FoR 7 ANDROMEDZ
Soluti Weigh Parall imein |- i Dp:
Plate. oo. Oe eee | eee | ee | ee
mm. Pa mm.

1920 +0.0105 1.0 —0.705 —952 —0.0035 | —0%07
2071 + .0068 0.5 — .888 —925 + .0003 .00
2073 + .0068 0.7 — .891 —924 + .0003 -00
2145 + .0085 0.8 — .907 —911 — .0013 — .02
4305 + .0182 1.0 + .296 —292 + .0031 + .06
4306 + .0160 1.0 + .296 —292 + .0003 | + .01
4800 + .0116 0.9 — .875 —198 + .0039 ; + .08
4801 + .0136 1.0 — .875 —198 + .0019 | + .04
5585 + .0232 0.7 + .549 + 55 — .0025 — .04
5632 + .0202 1.0 + .314 + 72 + .0003 | + .01
5633 + .0204 1.0 + .314 + 72 + .0001 .00
5848 + .0222 0.9 — .737 +147 — .0024 — .05
5849 + .0168 0.9 — .737 +147 + .0030 | + .06
7332 + .0258 0.9 + .660 +411 — .0008 | — .01
7333 + .0243 0.9 + .660 +411 + .0007 | + .01
7334 + .0288 0.7 + .660 +411 .| — .0088 | — .07
7358 + .0226 1.0 + .637 +413 + .0024 | + .05
7359 + .0258 0.9 + .637 +413 — .0008 | — .01
8136 ‘+ .0267 0.9 — .881 +534 — .0027 | — .05
8137 + .0252 1.0 — .881 +6834 — .0012 — .02
8162 + .0242 1.0 — .901 +541 — .0001 .00
8163 +0.0233 1.0 —0.901 +541 +0.0008 | +0.02

 

 

 

 

 

 

The normal equations are:

19.7¢ + 6.056u — 4.49877
+ 476.5636u + 16.56097
+ 10.07927

from which:
c = + 0.01921 mm.

BM
T

+ 0.001
+ 0.001

16 mm.

57 mm. = + 07033 + 07010.
Probable error of plate of unit weight
+ 0.00142 mm, = + 07030.

+ 0.3784 mm.
+ 0.6968 mm.
— 0.0513 mm.

+ 070242, or + 07088 per year.
620 S. A. MITCHELL

y PISCIUM (235 12”; +2° 44’)

This is a Ko type star, of magnitude 3.85, and of total proper
motion 0"0753. The Yale heliometer by Chase gave the parallax
— 0°05 + 07044, the photographic value of Allegheny is
+ 07018 + 07010, while the spectroscopic result of Adams is
+ 07022. Mr. Olivier measured the McCormick plates finding
a proper motion in right ascension of + 07748 while the corre-
sponding value from Boss is + 07752. The McCormick parallax
is + 07044 + 0”010.

TABLE 1

PLaTEs oF y Piscrum

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
2086 1915 Nov. 29 —049 Ol 0.9
2087 Nov. 29 —0.4 Ol, M 0.9
2111 Dec. 6 —0.6 Ol 0.8
2112 Dec. 6 —0.1 ol 0.7
4275 1917 Aug. 17 —0.2 A 0.9
4296 Aug. 19 +0.7 Ol 0.7
4316 Aug. 21 +0.4 Ol 0.8
4317 Aug. 21 +0.9 Ol 0.9
4338 Aug. 25 +0.6 Ol 0.9
4339 Aug. 25 +1.1 ol 1.0
4812 Nov. 26 “0.0 B 1.0
4813 Nov. 26 +0.6 B 1.0
4855 Dec. 10 +0.3 M 0.8
4856 Dec: 10 +0.8 M,A 0.8
4863 Dec. 14 +0.4 Ol 0.7*
4864 Dec. 14 +0.8 Ol 0.9
5547 1918 July 13 —0.3 Ol 0.9
5548 July 13 +0.2 Ol 0.9
5580 July 21 +0.4 A 0.9
5581 July 21 +0.9 A 0.7*
6074 Dec. 6 +0.4 H 0.8
6173 1919 Jan. 6 +1.7 D 1.0

 

* One exposure.
PARALLAXES OF 260 STARS 621

 

 

 

 

 

 

 

 

 

*
TABLE 2
REDUCTIONS FOR y Piscium
Soluti Wei l ‘ime i i D.
Plate. ‘cue ee | oe | ee) ee
mm. mm.

2086 —0.0589 0.9 —0.893 —651 —0.0020 —0%04
2087 — .0624 0.9 — .893 —651 + .0015 + .03
2111 — .0556 0.8 — .906 —644 — .0046 — .09
2112 — .0623 0.7 — .906 —644 + .0021 + .04
4275 + .0047 0.9 + .357 — 24 — .0012 — ..02
4296 + .0024 0.7 + .3827,| — 22 + .0012 + .02
4316 + .0036 0.8 |-+ .297 — 20 + .0001 .00
4317 -+ .0027 0.9 + .297 — 20 + .0010 + .02
4338 + .0041 0.9 + .237 — 16 — .0001 .00
4339 + .0026 1.0 + .237 — 16 + .0014 + .03
4812 + .0121 1.0 — .885 + 77 — .0013 — .03
4813 + .0078 | 1.0 — .885 + 77 + .0030 + .06
4855 + .0106 0.8 — .907 + 91 + ~.0015 + .038
4856 + .0118 0.8 — .907 + 91 + .0008 + .01
4863 + .0108 0.7 — .903 + 95 + .0017 + .03
4364 | + .0113 | 0.9 | — .903 | +95 | + .0012 | + .02
5547 + .0348 0.9 + .777 +306 + .0020 + .04
5548 + .0389 0.9 + .777 +306 — .0021 — .04
5580 + .0396 0.9 + .701 +314 — .0022 — .04
5581 + .0363 0.7 + .701 +314 + .0011 + .02
6074 + .0487 0.8 — .906 +452 — .0010 — .02
6173 +0.0540 1.0 —0.797 +483 —0.0031 —0.06

 
622 S. A. MITCHELL

CoMPARISON STARS

 

 

 

 

 

 

 

No. Diameter. x eka Y (Declination). Dependence.

1 0.13 —36.4 —12.4 +0.1847

2 15 —23.8 —11.5 . 1904

3 .14 —20.2 — 9.3 .1919

4 .12 + 2.6 +39.1 - 1950

5 .23 +77.8 — 5.9 +0. 2380
Parallax star 0.14 + 3.9 0.0

 

The normal equations are:

18.9¢ + 1.1024 — 5.12867 = + 0.0957 mm.
+ 214.9548u + 15.53557 = + 2.1542 mm.
+ 10.46517 = + 0.1489 mm.
from which:

c = + 0.00506 mm. ‘
w= + 0.00984 mm. = + 072048, or + 07748 per year.
xr = + 0.00209 mm. = + 07044 + 07010.

Probable error of plate of unit weight
+ 0.00130 mm. = + 07027.

LALANDE 45585 (235 12™; —2° 4’)

This is a binary 6 79 with components separated by 1’’, and a
period approximating 100 years. The magnitudes are 8.6 and
9.2. Mr. Olivier measured the plates and found a parallax
+ 07025 + 07013 with a proper motion in right ascension
+ 0°235 where the corresponding value from Porter is -+ 0”249.
 

 

 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 623
TABLE 1
Puates or LaLAnpE 45585
No. Date. Hour Angle. Observers. Weight.
3479 | 1916 Dec. 5 +045 e 1.0
3483 Dec. 6 +0.6 ol 1.0
3484 Dec. 6 +1.0 Ol 1.0
3528 Dec. 17 +0.2 M 0.9
4148 1917 June 30 —0.7 Ol 0.8
4181 July 27 +0.7 B 0.7
4218 July 31 +0.3 Ol 0.6
4219 July 31 +0.6 Ol 0.8
4603 Oct. 20 0.0 Ds 0.8
4604 Oct. 20 +0.3 Ds 0.8
4859 Dec. 12 +0.6 M 0.8
5601 1918 Aug. 5 +0.2 A 0.9
5602 Aug. 5 +0.5 A 1.0
5617 Aug. 11 +0.2 A 1.0
5623 Aug. 13 +0.1 A 0.9
5624 Aug. 13 +0.5 A 0.9
5974 Nov. 14 +0.7 Cc 0.7
5975 Nov. 14 +1.0 Cc 0.9
6149 Dec. 29 +0.8 M 0.9
6150 Dec. 29 +1.1 M 1.0
7405 1919 Aug. 2 —0.1 Ol 0.7
7406 Aug. 2 +0.3 ~ Ol 0.8
7425 Aug. 4 —0.8 F 1.0
Comparison STARS
No. Diameter. |~ eo ¥ (Declination). Dependence.
mm. mm. mm.

1 0.12 —39.5 +51.8 +0.1734

2 re —35.4 —30.2 -1411

3 12 +27.2 —36.5 -8027

4 -ll +47.7 | +14.9 +0.3832

Parallax star 0.12 +14.6 | — 0.6

 

 

 

 
624

S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

TABLE 2
REDUCTIONS FOR LALANDE 45585
i i ime i Residual vp-
Piste. | Sefyyion | Weight | Faces, | Bose®. | "in | alk
mm. mm.
3479 —0.0084 1.0 —0.905 —471 —0.0043 —009
3483 — .0163 1.0 — .906 —470 + .0036 + .07
3484 — .0120 1.0 — .906 —470 — .0006 — .Ol
3528 — .0104 0.9 — .896 —459 — .0019 — .04
4148 — .0082 0.8 + .871 — 264 — .0009 — .02
4181 — .0036 0.7 + .634 —237 -0000 .00
4218 — .0040 0.6 + .586 —233 + .0005 + .01
4219 — .0029 0.8 + .586 — 233 — .0006 — 01
4603 — .0042 0.8 — .587 —152 + .0018 + .03
4604 — .0026 0.8 — .587 —152 + .0002 -00
4859 — .0036 0.8 — .905 — 99 + .0024 + .05
5601 + .0051 0.9 + .527 +137 + .0028 + .05
5602 + .0086 1.0 + .527 +137 — .0007 — .OL
5617 + .0070 1.0 + .446 +148 + .0010 + .02
5623 + .00389 0.9 + .418 +145 + .0041 + .08
5624 + .0107 0.9 + .418 +145 — .0027 | — .05
5974 + .0122 0.7 — .822 +238 — .0028 — .05
5975 + .0083 0.9 — .822 +238 + .0011 + .02
6149 + .0078 0.9 — .850 +283 + .0029 + .06
6150 + .0130 1.0 — .850 +283 — .0023 — .05
7405 + .0142 0.7 + .568 +499 + .0050 + .09
7406 ‘ + .0232 0.8 + .568 +499 — .0040 — .07
7425 +0.0226 1.0 +0.543 +501 —0.0034 —0.07
The normal equations are:

19.9¢ — 0.1754 — 2.56117 = + 0.0563 mm.

+ 203 .0398u + 16.19867 = + 0.6477 mm.

+ 10.0325” = + 0.0547 mm.

from which:
c = + 0.00801 mm.

z= + 0.00310 mm. = + 070644, or + 07285 per year.
a = + 0.00122 mm. = + 07025 + 0'013.
Probable error of plate of unit weight
+ 0.00175 mm. = + 07036.
PARALLAXES OF 260 STARS 625

WEISSE xxiii.175 (235 18"; —14° 21’)

This is 8 182, and according to Burnham, “is undoubtedly a
binary, and one of more than ordinary interest from the large
proper motion of the system,” the proper motion amounting
to 1730 per year in position angle 200°. The only value of the
parallax that has been published for the star is the result of
measurements with the meridian circle by Flint who gives
x = — 07048 + 07050. Mr. Mitchell measured the McCormick
plates, and found a relative parallax of + 07028 + 07007, with
a proper motion in right ascension of — 07534, while the value
from Porter is — 07490.

‘

 

 

 

TABLE 1
Puates oF W xxiii.175

No. Date. Hour Angle. Observers. Weight.
138 1914 July 18 —011 M 0.5
144 « July 19 —0.8 M 1.0
150 |. July 21 —0.4 M 0.8
151 July 21 0.0 M 0.7
452 Oct. 31 +0.8 A,M 1.0
472 Nov. 2 +0.5 M 0.7
529 Nov. 9 +1.1 ol 0.6
592 Nov. 19 +0.5 A, Ol 1.0
662 Dec. 14 +0.1 Ol 0.5*
672 Dec. 15 —0.1 M 1.0
684 Dec. 17 +0.2 Ol 0.9
1475 1915 July 16 —0.2 G 0.8
1476 “July 16 40.2 G 0.8
1520 Aug. 2 +0.1 Ol 0.8
1530 Aug. 6 0.0 G 0.8
3446 1916 Nov. 27 0.0 M 0.8
3447 Nov. 27 +0.4 M, O1 0.9
3472 Dec. 2 —0.4 M 0.9

 

 

 

 

 

* One exposure.

41
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

326 S. A. MITCHELL
Comparison STARS
No. Diameter. X (Right Ascen-| y (Declination). Dependence.
sion).
mm. mm. mm.

1 0.25 —77.4 —30.5 +0.2400

2 .19 — 3.7 +31.3 .3169

3 .83 +31.9 + 7.6 - 2439

4 .18 +49.2 — 8.4 +0.1992

Parallax star 0.23 ~ 2:2 + 2.8
TABLE 2
Repuctions For W xxiii.175
Solution Weight Parallax Time in Residual : Vp-o
Plate. (m). (p). Factor (P). | Days (£). (v). in Are.
mm. mm.
138 +0.0227 0.5 +0.731 —268 —0.00385 —0%05
144 + .0182 1.0 + .722 —267 + .0009 + .02
150 + .0183 0.8 + .701 —265 + .0006 + .01
151 + .0200 0.7 + .701 —265 — .0011 — .02
452 + .0102 1.0 — .706 —163 — .0003 — .01
472 + .0118 0.7 — .726 —161 — .0021 — .04
529 + .0066 0.6 — .787 —154 + .0025 + .04
592 + .0072 1.0 — .853 —144 + .0011 + .02
662 + .0077 0.5 — .903 —119 — .0012 — .02
672 + .0070- 1.0 — .902 —118 — .0006 — .01
684 + .0054 0.9 — .897 —116 + .0009 + .02
1475 — .0060 0.8 + .753 + 95 — .0003 | — .01
1476 — .0075 0.8 + .753 + 95 + .0012 + .02
1520 — .0094 0.8 + .567 +112 + .0016 + .03
1530 — .0072 0.8 + .514 +116 — .0009 — .02
3446 — .0417 0.8 — .889 +595 — .0020 — .04
3447 — .0454 0.9 — .889 +595 + .0018 + .04
3472 —0.0483 0.9 —0.905 +600 —0.0007 —0.01
The normal equations are:
14.5¢ + 2.934y — 2.81747 = — 0.0338 mm.
+ 128.64154 — 10.9808r = — 0.9206 mm.

+ 8.89417

ll

+ 0.0908 mm.
PARALLAXES OF 260 STARS 627

from which:
c = — 0.00065 mm.
w= — 0.00703 mm. = — 071462, or — 07534 per year.

Tv

+ 0.00133 mm. = + 07028 + 07007.
Probable error of plate of unit weight
+ 0.00093 mm. = + 0”019.

LALANDE 45638 (238 14"; +4° 52’)

This is 8 80, discovered by Burnham with the 6-inch. Accord-
ing to him, it is “‘one of the most interesting binaries from the
rapid relative motion, and from the large movement of the
system in space.” The total proper motion amounts to 0”51.
According to Aitken (Publications Lick Observatory, 12, 179,
1914), ‘the measures do not define the apastrom end of the
apparent ellipse, hence no reliable orbit can as yet be computed.”
The principal star is of 8.2 magnitude. Mr. Mitchell measured
the McCormick plates, and found the small parallax of + 0”005
+ 07007, with a proper motion in right ascension amounting to
+ 07487. The relative parallax by photography at Yerkes is
— 0700107009, while the absolute value by the spectroscope
is +07044.

Comparison STARS

 

 

 

 

No. | Diameter. i a ee Y (Declination). Dependence.
1 0.19 —68.2 + 7.0 +0.120
2 -1l — 1.9 + 7.4 .168
3 13 + 2.4 +11.4 -173
4 .20 + 3.2 —34.7 .155
5 -18 + 3.7 —37.9 -155
6 .20 +60.8 +46.8 +0.229
Parallax star 0.24 + 7.0 + 3.5

 
628

S. A. MITCHELL

 

 

 

 

 

 

 

 

TABLE 1
Puates oF LaLtannE 45638
No. Date. Hour Angle. Observers. Weight.
157 1914 July 22 —045 Ol 0.7
494 Nov. 4 +0.3 G 1.0
511 Nov. 5 0.0 M 1.0
552 Nov. 11 +0.2 M,G 1.0
583 Nov. 17 +0.1 A 1.0
601 Nov. 21 +0.2 A 1.0
673 Dec. 15 +0.4 M 0.8
685 Dec. 17 +0.8 Ol 0.7
1504 1915 July 23 +0.2 G 1.0
1505 July 23 +0.6 G 0.4
1543 Aug. 12 —0.2 G 0.7
2063 Nov. 25 —0.1 M 0.8
2064 Nov. 25 +0.5 A 0.9
2095 Nov. 30 0.0 M 0.5*
2105 Dec. 4 —0.2 M 0.5*
2176 Dec. 19 +0.3 M 0.9
2836 1916 July 29 +0.1 A 0.7
2837 July 29 +0.6 A 0.7
2918 Aug. 25 +0.1 A 1.0
2919 Aug. 25 +0.5 A 0.8
* One exposure.
The normal equations are:
16.le — 0.880un — 5.44407 = + 0.9917 mm.
+ 103.1167 + 11.91557r = + 0.6102 mm.
+ 8.94437 = — 0.2589 mm.

from which:

c = + 0.06203 mm.

w= + 0.00642 mm. = + 071335, or + 0487 per year.
a = + 0.00026 mm. = + 07005 + 0”007.

Probable error of plate of unit weight

+ 0.00080 mm. = + 07017.
PARALLAXES OF 260 STARS 629

TABLE 2

RepvuctTions For LALAnDE 45638

 

 

 

 

 

 

 

 

 

Soluti : Weigh Parall: ime i i Dp:
rae oe 1 ee" | eee, Lee | ee | sade
mm. _ mm.

157 +0.0369 0.7 +0.696 —364 +0.0019 | +0°03
494 + .0448 1.0 — .739 —259 + .0004 | + .01
511 + .0469 1.0 — .748 —258 — .0016 | — .03
552 + .0466 1.0 — .798 —252 — .0010 | — .02
583 + .0471 1.0 — .838 —246 — .0011 | — .02
601 + .0454 1.0 — .860 —242 + .0009 | +. .02
673 + .0486 0.8 — .902 —218 — .0008 | — .01
685 + .0454 0.7 — .898 —216 + .0025 | + .04
1504 + .0628 1.0 + .688 + 2 — .0005 | — .Ol
1505 + .0620 0.4 + .688 + 2 + .0003 .00
1543 + .0649 0.7 + .442 + 22 — .0013 | — .01
2063 + .0704 0.8 — .858 +127 — .0004 | — .O1
2064 + .0694 0.9 — .858 +127 + .0006 | + .01
2095 + .0718 0.5 — .894 +132 — .0010 | .— .01
2105 + .0675 0.5 — .902 +136 + .0030 | + .04
2176 + .0716 0.9 — .894 +151 — .0001 -00
2836 + .0878 0.7 + .612 +374 — .0016 | — .08
2837 + .0852 0.7 + .612 +374 + .0010 | + .02
2918 + .0885 1.0 + .241 +401 — .0007 | — .O1
2919 +0.0864 0.8 +0.241 +401 +0.0014 | +0.03

 

. PEGASI (235 20"; +22° 51’)

The Allegheny value of the parallax of this star is of Go type,
of magnitude 4.62, and of total proper motion 0°19 is
+ 0”033 + 0009, while the absolute parallax of Adams by the
spectrograph is + 0”021. Mr. Lamb measured the photographs
with the exception of the last six plates which were measured by
Mr. Mitchell. The proper motion in right ascension found by
Boss is + 07189 per year while the result from the photographs
is + 07194.
630

S. A. MITCHELL

TABLE 1

PLATES OF v PEGASI

 

 

 

 

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
2074 | 1915 Nov.27_ —043 M i)
2075 Nov. 27 0.0 G 0.7
2157 Dec. 14 +0.4 M 0.7
2213 | Dec. 23 +0.2 M 0.7
2831 1916 July 20 —0.7 L 0.5*
2832 July 20 —0.3 L 0.7
2893 Aug. 18 —0.5 A 0.9
2894 » Aug. 18 —0.2 A 1.0
2941 Aug. 30 +0.2 A 1.0
3372 Nov. 8 0.0 Ol 1.0
3373 Nov. 8 +0.4 Ol 1.0
3383 Nov. 16 —0.9 L 1.0
8384 Nov. 16 —0.6 L 1.0
4188 1917 July 28 —0.4 B 0.7
4189 July 28 —0.1 B 0.8
4199 July 29 +0.4 ol 0.8
4200 July 29 +0.8 ol 0.6*
4656 Oct. 31 +0.2 B 1.0
4657 Oct. 31 +0.6 B 1.0
* One exposure.
Comparison STARS
No. Diameter. ns a a Y (Declination). Dependence.
mm. mm. mm.

1 0.19 —50.3 —29.4 +0.2810

2 2 .20 —10.2 +15.2 -2105
3 .16 — 6.0 —14.0 2764

4 13 +66.5 +28 .2 +0.2321

Parallax star 0.17 — 2.5 — 2.4

 

 

 

 

 
PARALLAXES OF 260 STARS 63

TABLE 2

REDUCTIONS FOR v PEGasi

 

 

 

 

 

 

 

 

 

Soluti Weigh Parall ime i i Dp:
Plate. oe | Ge memes | Bee | eb ane
mm. mm.
2074 +0.0010 0.9 —0.877 —346 —0.0016 4+ —0%03
2075 — .0021 0.7 — .877 —346 + .0015 ; + .02
2157 + .0011 0.7 — .904 —329 — .0013 | — .02
2213 — .0027 0.7 | — .886 —320 + .0027 | + .05
2831 + .0055 0.5 + .729 —110 + .0005 | + .01
2832 + .0071 0.7 + .729 —110 — .0011 | — .02
2893 + .0044 0.9 + .372 — 81 + .0022 ; + .04
2894 + .0060 1.0 + .372 — 81 + .0006 | + .01
2941 + .0080 1.0 + .193 — 69 — .0012 | — .02
3372 + .0086 1.0 — .762 Sing ial — .0003 | — .O1
3373 + .0072 1.0 — .762 + 1 + .0011 | + .02
3383 + .0118 1.0 — .823 + 9 — .0034 | — .07
3384 + .0076 1.0 — .828 + 9 + .0008 | + .02
4188 + .0171 0.7 + .647 +263 — .0016 | — .08
4189 + .0132 0.8 + .647 +263 + .0023 | + .04
4199 + .0154 0.8 + .636 +264 + .0001 00
4200 + .0180 0.6 + .636 +264 — .0025 | — .04
4656 + .0178 1.0 — .685 +358 — .0004 |; — .O1
4657 +0.0158 1.0 —0.685 +358 +0.0016 | +0.03

 

The normal equations are:

16.0c + 1.373u — 3.56077 = + 0.1384 mm.
+ 82.8561u + 7.08887 = + 0.2259 mm.
+ 7.93877 = — 0.0094 mm.

from which: |

c = + 0.00851 mm.
wu = + 0.00255 mm. = + 070531, or + 07194 per year.
x = + 0.00035 mm. = + 07007 + 07009.

Probable error of plate of unit weight
+ 0.00111 mm. = + 07023.

ll
632 S. A. MITCHELL

t PISCIUM (23 34™; +5° 5’)

This star of 4.28 magnitude and F5 type has a considerable
proper motion 07574 per year. The parallax has been measured
as follows: from the Yale heliometer + 07138 + 07059, from
the meridian circle by Jewdokimov + 07100 + 07100, and by
the spectrograph by Mt. Wilson + 07083. Mr. Alden measured
the plates and found a parallax + 07067 + 07007 with the proper
motion in right ascension + 07361 where the value from Boss is
+ 07370.

TABLE 1

PuatTes or « Piscrum

 

 

 

No. Date. Hour Angle. : Observers. Weight.
3509 1916 Dec. 8 —053 M 0.9
3535 Dec. 19 —0.2 M 0.8
4206 1917 July 30 +0.3 A 0.9
4207 July 30 +0.7 A 0.9
4822 Nov. 28 +0.5 A 0.9
4879 Dec. 15 +0.1 M 0.8
4893 Dee. 21 +0.4 Ol 0.7
5560 1918 July 14 —0.4 A 0.6*
5586 Aug. 2 +0.1 A 0.9
5587 Aug. 2 +0.5 A 0.9
5612 Aug. 6 +0.2 A 1.0
5613 Aug. 6 +0.6 A 1.0
5852 Nov. 2 +0.8 F,M 0.9
5853 Nov. 2 +1.3 F,M 1.0
6099 Dee. 18 +0.3 M 0.9
7426 1919 Aug. 4 —0.7 F 0.8
7427 Aug. 4 —0.2 F 0.7
7430 Aug. 5 —0.4 H 1.0
7431 Aug. 5 0.0 H 0.9
_ 7502 Aug. 18 —1.0 D 0.8
8021 Nov. 6 —0.4 A 1.0
8056 Nov. 14 0.0 A 1.0 |

 

 

 

 

 

* One exposure.
 

 

 

 

PARALLAXES OF 260 STARS 633
TABLE 2
REDUCTIONS FOR - Piscium
Soluti Weight | Parall Time i i D-
Plate. ‘oh esl te! el eee
mm. mm.

3509 +0.0258 0.9 —0.898 —623 —0.0018 —004
3535 + .0234 0.8 — .901 —612 + .0011 + .02
4206 + .0406 0.9 + .669 —389 — .0004 — .01
4207 + .0415 0.9 + .669 —389 — .0013 — .03
4822 + .0404 0.9 — .865 —268 + .0006 + .01
4879 + .0438 0.8 — .904 —251 — .0021 — .04
4893 + .0415 0.7 — .898 —245 + .0005 + .01
5560 + .0562 0.6 + .819 — 40 + .0010 | + .02
5586 + .0568 0.9 + .638 — 21 + .0008 + .01
5587 + .0558 0.9 + .638 — 21 + .0018 + .04
5612 + .0562 1.0 + .591 — 17 + .0014 | + .03
5613 + .0580 1.0 + .591 -— 17 — .0004 — .01
5852 + .0579 0.9 — .660 + 71 — .0001 .00
5853 + .0556 1.0 — .660 + 71 + .0022 + .05
6099 + .0578 0.9 — .902 +117 + .0014 | + .08
7426 + .0757 0.8 + .618 +346 — .0007 — .01
7427 + .0742 0.7 + .618 +346 + .0008 + .01
7430 + .0781 1.0 + .606 +347 — .0081 — .06
7431 + .0728 0.9 + .606 +347 + .0022 + .04
7502 + .0770 0.8 + .439 +360 — .0020 — .04
8021 + .0753 1.0 — .699 +440 — .0001 .00
8056 +0.0764 1.0 —0.772 +448 —0.0011 —0.02

 

 

 

 

 

 
634 S. A. MITCHELL

CoMPARISON STARS

 

 

 

 

 

No. Diameter. |* re naauaaa Y (Declination). Dependence.

1 0.14 —26.4 —36.0 +0.2275

2 12 —16.5 +68.2 -2918

3 ll +42.9 —32.2 +0.4807
Parallax star 0.14 + 9.8 — 3.8

 

The normal equations are:

19.3¢ + 1.38474 — 0.7405r = + 1.0947 mm.
+ 200.8954u + 9.65797 = + 1.0629 mm.
+ 9.97547 = + 0.0362 mm.

from which:
c = + 0.05651 mm.
w= + 0.00476 mm. = + 070989, or + 07361 per year.

a = + 0.00322 mm. = + 07067 + 07007.
Probable error of plate of unit weight
+ 0.00100 mm. = + 07021.

BOSS 6129 (23> 47™; + 74° 59’)

This star of magnitude 6.55 and of magnitude K has the total
proper motion 07332. The only trigonometric parallax is the
photographic result of van Maanen + 0”097 + 0”004. The
spectrographic value of Mt. Wilson is + 07105. Miss Darkow
measured the McCormick plates and found the relative parallax
+ 07088 + 07008 with a proper motion in right ascension
+ 07315 where the corresponding value from Boss is + 0”329.
 

 

 

 

 

 

 

 

 

 

 

PARALLAXES OF 260 STARS 635
TABLE 1
Puates or Boss 6129

No. Date. Hour Angle. Observers. Weight.
4845 1917 Dec. 5 —055 M,A 0.8
4850 Dec. 6 —0.7 M 1.0
4851 Dec. 6 —0.4 M 1.0
4883 Dec. 20 —0.1 M 1.0
5626 1918 Aug. 14 —0.2 A 1.0
5627 Aug. 14 +0.2 A 1.0
5634 Aug. 19 —0.3 A 1.0
5635 Aug. 19 +0.1 A 1.0
5850 Nov. 2 —0.4 F 0.7
5851 Nov. 2 0.0 M 1.0
5877 Nov. 5 —0.8 H 1.0
5878 Nov. 5 0.0 D 0.9
7325 1919 July 23 —0.6 D 0.9
7326 July 23 —0.2 D 0.6
7346 July 25 0.0 F 1.0
7347 July 25 +0.4 F 1.0
8198 Dec. 4 —0.6 A 1.0
8199 Dec. 4 —0.2 A 1.0
8200 Dee. 4 +0.1 A 1.0

Comparison Stars
No. Diameter. x a aaa Y (Declination). Dependence.
mm. mm. mm.

1 0.17 —32.4 —39.6 +0.275
2 .10 —23.1 +20.5 - 246
3 -10 —19.6 +15.1 .247

4 15 +75.1 + 4.0 +0.232

Parallax star 0.13 — 2.0 — 1.2

 

 

 

 

 
636 S. A. MITCHELL

 

 

 

 

 

 

 

 

 

TABLE 2
Repuctions ror Boss 6129

Solution | Weight | Parallax | Time in Residual _Vp-0
Plate. (m). (p). | Factor (P). | Days (¢). (v). in Are.

mm. mm.
4845 —0.0218 0.8 —0.879 —365 +0.0025 +0°05
4850 — .0168 1.0 — .882 —364 — .0025 — .05
4851 — .0228 1.0 — .882 —364 + .0085 + .07
4883 — .0166 1.0 — .902 —350 — .0022 — .05
5626 — .0024 1.0 + .5386 —113 — .0004 — .01
5627 — .0041 1.0 + .536 —1138 + .0013 + .03
5634 — .0020 1.0 + .470 —108 — .0009 — .02
5635 — .0016 1.0 + .470 —108 — .0013 — .03
5850 — .0056 0.7 — .621 — 33 + .0012 + .02
5851 — .0034 1.0 — .621 — 33 — .0010 — .02
5877 — .0044 1.0 — .654 — 30 — .0001 .00
5878 — .0045 0.9 — .654 — 30 -0000 -00
7325 + .0119 0.9 + .777 +230 + .0005 + .01
7326 + .0142 0.6 + .777 +230 — .0018 — .03
7346 + .0116 1.0 + .759 +232 + .0008 + .02
7347 + .0115 1.0 + .759 +232 + .0009 + .02
8198 + .0112 1.0 — .873 +364 — .0002 -00
8199 + .0124 1.0 — .873 +364 — .0014 — .03
8200 +0.0096 1.0 —0.873 +364 : +0.0014 +0.03

 

The normal equations are:
17.9¢ — 0.241 — 3.59107 = — 0.0240 mm.

+ 113.0985u + 7.30857 = + 0.5008 mm.
+ 9.816387 = + 0.0736 mm.
from which.
c = — 0.00043 mm.
B= + 0.00415 mm. = + 070864, or + 07315 per year.

aw = + 0.00425 mm. = + 0088 + 0008.
Probable error of plate of unit weight
+ 0.00110 mm. = + 07023.
PARALLAXES OF 260 STARS 637

p CASSIOPEIZ (238 49™; +56° 57’)

The Allegheny parallax for this star is + 07013 + 07011, while
the absolute value of Adams by the spectrograph is + 07008.
The star is of 4.85 magnitude, of F8p type, and of very small
proper motion 0”007 per year. Mr. Alden measured the plates,
and found a proper motion in right ascension amounting to
— 07028 per year, while the value from Boss is — 07005.

TABLE 1

PuLatTEs OF p CASSIOPEILZ AND Boss 6142

 

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.
2088 1915 Nov. 29 —0h2 G 0.8
2128 Dec. 8 —0.3 M 1.0
2129 Dec. 8 0.0 M 0.9
2225 Dec. 24 —0.2 ol 0.8
2227 Dec. 26 0.0 M 0.8
2854 1916 Aug. 7 |. —0.8 A 0.9
2855 Aug. 7 —0.4 A 1.0
2863 Aug. 12 —0.3 A 0.9
2927 Aug. 26 —0.5 Ol 0.9
2928 Aug. 26 —0.1 re) | 0.5*
8385 Nov. 16 —0.6 L 1.0
3386 Nov. 16 —0.1 L 1.0
3415 Nov. 20 —0.4 A 1.0
3416 Nov. 20 0.0 A 1.0
4204 1917 July 30 —0.9 A 0.7
4205 July 30 —0.6 A 1.0
4246 Aug. 5 —0.6 A 1.0
4247 Aug. 5 -0.4 A 1.0
4787 Nov. 18 —0.7 B 1.0
4788 Nov.18 |. —0.3 B 1.0
4793 Nov. 19 —1.0 A 0.9
4794 Nov. 19 —0.7 A 0.9
4820 Nov. 28 —0.6 M 1.0
2 A 0.9

4821 Nov. 28 —0.

 

* One exposure.
638 S. A. MITCHELL

CoMPARISON STARS FOR p CASSIOPELZ

 

 

 

 

 

 

 

 

 

 

No. Diameter. X (Right Ascen-| y (Declination). Dependence.
sion).
mm. ahi, mm.
1 0.10 —73.9 -— 7.1 +0.2086
2 13 —61.8 +39.9 . 2060
3 .10 +25.7 —51.8 .1982
4 .12 +39.9 +382.4 . 1948
5 .18 +70.1 —13.4 +0.1924
Parallax star 0.15 — 1.8 + 0.2
TABLE 2
REDUCTIONS FOR p CASSIOPELE
Solution Weight Parallax Time in Residual : Vp-0
Plate. (m). (p). | Factor (P). | Days (t). (0). in Arc.
mm. ' mm.
2088 —0.0012 0.8 —0.847 —399 —0.0002 0700
2128 — .0028 1.0 — .885 —390 + .0012 + .02
2129 — .0051 0.9 — .885 —390 + .0036 + .07
2225 — .0028 0.8 — .900 —374 + .0012 + .02
2227 — .0023 0.8 — .896 —372 + .0007 + .01
2854 — .0006 0.9 + .622 —147 + .0011 + .02
2855 + .0017 1.0 + .622 —147 — .0012 — .02
2863 + .0037 0.9 + .562 —142 — .0033 — .06
2927 — .0003 0.9 + .373 —128 + .0003 + .01
2928 + .0011 0.5 + .373 —128 — .0011 — .02
3385 — .0049 1.0 — .760 — 46 + .0023 + .05
3386 - 0000 1.0 — .760 — 46 — .0026 — .05
3415 + .0013 1.0 — .793 — 42 — .0040 — .08
3416 + .0009 1.0 — .793 — 42 — .0036 — .07
4204 — .0020 0.7 + .712 +210 + .0014 + .02
4205 — .0030 1.0 + .712 +210 + .0024 + .05
4246 + .0010 1.0 + .648 +216 — .0018 — .04
4247 — .0027 1.0 + .648 +216 + .0019 + .04
4787 — .0065 1.0 — .775 +321 + .0025 + .05
4788 — .0046 1.0 — .775 +321 + .0006 + .01
4793 — .0022 0.9 — .783 +322 — .0018 — .04
4794. — .0015 0.9 — .783 +322 — .0025 — .05
4820 — .0050 1.0 — .844 +331 + .0008 + .02
4821 —0.0063 0.9 —0.844 +331 +0.0021 +0.04

 

 

 

 

 

 

 
PARALLAXES OF 260 STARS 63¢

The normal equations are:

21.9¢ + 2.202u — 6.74877 = — 0.0416 mm.
+ 149.8022 + 3.388177 = — 0.0522 mm.
+ 12.33927 = + 0.0317 mm.
from which:
c = — 0.00125 mm. \
# = — 0.00037 mm. = — 070078, or — 07028 per year.

a = + 0.00199 mm. = + 07041 + 0’010.
Probable error of plate of unit weight
+ 0.00148 mm. = + 07031.

BOSS 6142 (235 507; +56° 51’)

This star of 6.2 magnitude, and of small proper motion 0701,
is 89 preceding, and 5'2 south of p Cassiopeix. Its parallax
was determined by Mr. Alden from the same series of plates as
were used for p Cassiopeia. The proper motion in right ascen-
sion found by him amounts to — 0”008 per year while the value
from Boss is — 0%005.

 

 

 

TABLE 1
Comparison Srars ror Boss 6142
No. Diameter. = Bie seoen: Y (Declination). Dependence.
mm. mm. mm.
1 0.10 —101.3 0.0 +0.1992
3 .10 - 1.8 —44.7 - 2930
4 .12 + 12.4 +39.5 .1179
5 .13 + 42.6 — 6.4 .2136
6 -10 + 48.1 +11.6 +0.1763
Parallax star 0.07 — 1.7 — 7.8

 

 

 

 

 
640 S. A. MITCHELL

 

 

 

 

 

TABLE 2
Repvuctions ror Boss 6142

Solution Weight | Parallax | Time in Residual _Vp-0
Plate. (m). (p). | Factor (P). | Days (i). (2). in Are.

mm. mm.
2088 —0.0198 0.8 —0.847 —399 +0.0040 +0°07
2128 — .0159 1.0 — .B5 —390 + .0001 -00
2129 — .0201 0.9 — .885 —390 + .0043 + .08
2225 — .0132 0.8 — .900 —374 — .0027 — .05
2227 — .0146 0.8 — .896 —372 — .0013 — .02
2854 — .0139 0.9 + .622 —147 — .0004 — .01
2855 — .0153 1.0 + .622 —147 + .0010 + .02
2863 — .0128 0.9 + .562 —142 — .0016 — .03
2927 — .0110 0.9 + .373 —128 — .0036 — .07
2928 — .0177 0.5 + .373 —128 + .0081 + .05
3385 — .0150 1.0 — .760 — 46 — .0010 — .02
3386 — .0139 1.0 — .760 — 46 — .0021 — .04
3415 — .0140 1.0 — .793 — 42 — .0021 — .04
3416 — .0156 1.0 — .793 — 42 — .0005 — .01
4204 — .0120 0.7 + .712 +210 — .0025 — .04
4205 — .0169 1.0 + .712 +210 + .0024 + .05
4246 — .0146 1.0 + .648 +216 -0000 .00
4247 — .0160 1.0 + .648 +216 + .0014 + .03
4787 — .0193 1.0 — .775 +321 + .0029 + .06
4788 — .0182 1.0. — .775 +321 + .0018 + .04
4793 — .0190 0.9 — .783 +822 + .0026 + .05
4794 — .0134 0.9 — .783 +822 — .0030 — .06
4820 — .0161 1.0 — .844 +331 — .0004 — .01
4821 —0.0145 0.9 —0.844 +331 —0.0020 —0.04

 

 

 

 

 

The normal equations are:
21.9¢ + 2.202u — 6.74877 = — 0.3404 mm.
+ 149.8022u + 3.38177 = — 0.0443 mm.

fee wehtons + 12.33927 = + 0.1168 mm.
c = — 0.01516 mm.
& = — 0.00010 mm. = — 070021, or — 0008 per year.
a = + 0.00120 mm. = + 0°025 + 0”010.

Probable error of plate of unit weight
+ 0.00152 mm. = + 0”032.
PARALLAXES OF 260 STARS 641

w PISCIUM (23" 54™; +6° 19’)

The only trigonometric value of the parallax of this star pub-
lished is the Allegheny result from photography, — 07002 + 07009.

TABLE 1

PLATES OF w PIscIUM

 

 

 

 

 

 

No. Date. Hour Angle. Observers. Weight.

432 1914 Oct. 29 +142 M 0.8

438 Oct. 30 +1.0 G 0.8
' 718 Dec. 27 +0.7 A 0.8

1544 1915 Aug. 12 0.0 G 0.8

1545 Aug. 12 +0.5 G 0.5*
1571 Aug. 23 —0.8 A 1.0

1572 Aug. 23 —0.2 A 0.8

1597 Sept. 1 —0.7 A 1.0

1598 Sept. 1 —0.2 A 1.0

1906 Oct. 29 +1.1 Ol 0.7

2047 Nov. 23 —0.2 G 0.7

2048 Nov. 23 +0.4 G 0.8

2113 Dec. 6 +0.1 M 0.7

2146 Dec. 10 —0.5 ol 0.5*
3462 1916 Dec. 1 —0.2 M, Ol 0.7

3463 Dec. 1 +0.2 Ol 0.8

3473 Dec. 2 —0.6 M 1.0

3474 Dee. 2 —0.2 A 0.7*

 

 

* One exposure.

The spectroscopic parallax is + 07046. The star is of F5 type,
of magnitude 4.03, and of total proper motion 0719. Mr. Graham
measured the McCormick plates with the exception of the last
four plates measured by Mr. Mitchell. The proper motion from
the plates amounts to + 07135 per year in right ascension while
the value from Boss is + 07149.

42
342 S. A, MITCHELL

CoMPARISON STARS

 

 

 

 

 

 

 

 

 

 

 

 

No. Diameter. x ee Y (Declination). Dependence.
mm. mm. mm.

1 0.23 —88.4 — 2.6 +0.1447

2 .14 +18.5 —15.2 .2154

3 18 +18.6 + 2.9 -2111

4 13 +23.4 +50.1 -2025

5 .24 +27.9 —35.2 +0. 2263

Parallax star- 0.21 + 6.2 -— 0.9
TABLE 2
REDUCTIONS FOR w PIscluM
‘Solution | Weight | Parclfae | "Tine ta Residual Vpeo
Plate. (m). (p). | Factor (P). | Days (t). (0). in Are.
mm. mm.

432 +0.0222 0.8 —0.550 —365 —0.0011 —0702
438 + .0190 0.8 — .563 —364 + .0021 + .04
718 + .0214 0.8 — .897 —306 + .0004 | + .01
1544 + .0279 0.8 + .588 — 88 — .0009 — .02
1545 + .0254 0.5 + .588 — 88 + .0016 | + .02
1571 + .0267 1.0 + .446 — 67 + .0005 | + .01
1572 | + .0281 0.8 + .446 — 67 — .0009 — .02
1597 + .0254 1.0 + .317 — 58 + .0019 | + .04
1598 + .0292 1.0 + .317 — 58 — .0019 — .04
1906 + .0279 0.7 — .530 0 — .0003 .00
2047 + .0284 0.7 — .800 + 25 — .0006 — .0l
2048 + .0281 0.8 — .800 + 25 — .0003 -00
2113 + .0281 0.7 — .873 + 38 — .0001 -00
2146 + .03806 0.5 — .887 + 42 | — .0025 — .04
3462 + .0310 0.7 — .854 +399 + .00384 | + .06
3463 + .0338 0.8 — .854 +399 + .0006 | + .01
3473 + .0363 1.0 — .859 +400 — .0018 — .04
3474 +0.0343 0.7 —0.859 +400 +0.0001 0.00

 

 

 

 

 

 

The normal equations are:

14.1e + 1.846u — 4.77377 = + 0.3948 mm.
+ 82.5993 — 7.807897 = + 0.1922 mm.
+ 6.57967 = — 0.1423 mm.
PARALLAXES OF 260 STARS 643

from which:

c = + 0.02805 mm.
B= + 0.00178 mm. = + 070370, or + 07135 per year.
a = + 0.00084 mm. = + 07018 + 07009.

Probable error of plate of unit weight

+ 0.00095 mm. = + 07020.

The average probable error for the 260 McCormick parallaxes
is 070091. This is the same precision attained in the later
Yerkes results, and slightly greater than the probable error of
the Allegheny parallaxes, both of these observatories employing
refractors of greater aperture and also greater focal length than
the McCormick telescope. The Allegheny refractor possesses
a photographic objective, and as a consequence much shorter
exposures are permitted than are necessary for the visual refrac-
tors of Yerkes and McCormick Observatories. With the shorter
exposures at Allegheny it is unnecessary to photograph when
the parallax factor is less than 0.7, and as a result the average
plate at Allegheny has a greater parallax factor than a similar
plate at Yerkes or McCormick, and consequently a greater
weight in the determination of the parallax. The average
probable error of a single McCormick plate with two star images
of good quality is 0.0013 millimeters, or 07027. On the average
4.5 comparison stars were used.

CoMPARISONS WITH THE EARLY PARALLAXES

With the details which are included in the discussion of each
star there is given the parallax measures so far as they have
been published.

‘In the year 1910, there was published in Groningen Publications
No. 24 by Kapteyn and Weersma a list of all the parallaxes whose
determinations were considered reliable. There are 360 stars
on the list. 72 of these stars have had their parallaxes deter-
mined at the McCormick Observatory. Since these 72 form
one fifth of the total list, and should therefore be fairly repre-
sentative of the whole 360, comparisons will be not without inter-
est. This is found in Table 3, where there is added the number
644

S. A. MITCHELL

 

 

 

 

 

 

 

 

 

 

 

 

 

TABLE 3.
* COMPARISON WITH PARALLAXES IN GRONINGEN No. 24.
Groningen. Groningen.
Star. E . MED | Ge. Star. E rm ee | Gat
a a

B Cassiop...... 3 | +7074) +7063) +7011] 61 Virginis..... 1] +7157) +7135; +7022
Pi. 05130...... 1 | +.360) +.091| +.269 é Urs. Maj..... 2; +.033) +.0387) — .004
54 Piscium ....) 1 | +.154) +.106| +.048|| 70 Virginis..... 1) +.149} +.050} +.099
Lal. 1198...... 1 | +.080| +.044) +.036)| Lal. 25224..... 1) +.260) +.029) +.231
n Cassiop...... 3 | +.201) +.184) +.017]| Lal. 25372..... 4) +.176) +.229) —.053
Lal. 1799...... 2] +.061; +.027} +.034|) Lal. 27173..... 2) +.172! +.494; —.022
w Androm..... 1 | +.088} +.028) +.060|| y Serpentis..../ 3/ +.029] +.103} —.074
41 H Androm. .| 1 | +.116) +.097} +.019]| @ Cor. Bor..... 1 +.031 +.061) —.030
7 Ceti......... 2) +.334) +.317) +.017|| 7 Herculis..... 2) +.063) +.052| +.011
Lal. 4141...... 1} +.029; +.039} —.010]} « Herculis..... 2| +.106) +.113) —.007
6 Triang Se ana 2 | +.119) +.132) —.013)| y Draconis ....| 1) +.107} +.005] +.102
o Ceti......... 1 | +.142) +.066} +.076]| 70 Ophiuchi ...) 2) +.168) +.183] —.015
Pi. 25123...... 2 +.143) +.142) +.001]] x Draconis ....} 1) +.119]} +.095] +.024
p Persei....... 1 | +.087| +.034) +.053/| 110 Herculis...! 1} +.068) +.065] +.003
10 Tauri....... 1 | +.069} + .048/ +.021]| 31 Aquile..... 4) +.065) +.079| —.014
Lal. 6888-9... .) 5 | +.055}) +.030] +.025]! @ Cygni....... 1; —.021) +.002) — .023
o? Eridani..... 2 | +.174) +.209) —.035)} Lal. 37120..... 1} +.058) +.047) +.011
a Tauril....... 4 | +.073| +.040) +.033]| « Draconis..... 3} +.197) +.186) +.011
W. B. 4" 1189. .| 1 | +.302) +.129) +..173 6Cygni....... 1) +.066) +.085) —.019
 Aurige...... 2 | +.111) +.069) +.042|| 16 Cygni...... 1} +.158} +.038] +.120
W. B. 5" 592 2 | +.182) +.168} +.014]) a Aquile...... 2) +.238) +.223) +.015
Groomb. 990...| 1 | +.028] +.029} —.001]] Lal. 38287..... 1) +.088]) +.083] +.005
6 Aurige...... 2} +.014) +.031) —.017|| Lal. 38383..... 2} +.029) +.080) —.051
n Gemin....... 1 | +.044) +.004) +.040]| y Cygni....... “T) +.106) +.002} +.104
Lal. 13427..... 2 | +.051) +.012| +.039]| 6 Delphini..... 1) —.010} +.013) —.023
p Gemin....... 1 | +.049} + .0571 —.O08Il « Cygni........ 1] —.182) +.0441 —.226
aGemin...... 3 | +.028) +.081) —.053|| » Cephei 1} +:097| +.069] +.028
a Canis Min. ..} 4 | +.324) +.314] +.010] 61 Cygni...... 11} +.311]) +.312} —.001
Lal. 15290..... 4 | +.045) +.038) —.007]| 6 Equulei...... 2} +.067) +.046) +.021
Lal. 16304..... 1 | +.127) +.065} +.062/| + Cygni....... 1) +.128) +.051] +.077
p Cancri....... 2 | +.085) +.081] +.004|| « Pegasi....... 1] +.028} +.021} +.007
y Leonis.......} 1 | —.035) —.006) —.029) e Cephei....... 1) +.107) +.058] +.049
Lal. 21258..... 5 | +.203) +.182) +.021|| € Pegasi....... 1] +.089) +.051} +.038
6 Virginis...... 1 | +.118) +.101) +.017]) W. B. 235175..| 1) +.052 + .033] +.019
Groomb. 1830..; 6 | +.102| +.111] —.009]| y Piscium.....] 1] —.041 +.049} —.090
B Come....... 3 | +.116) +.145] —.029)] . Piscium...... 1] +.148} + .072) +.076

 
PARALLAXES OF 260 STARS 645

of separate determinations on which the results in Groningen
are based. Kapteyn and Weersma have listed the absolute
value of the parallaxes. Accordingly in the following table,
0°005 has been added to the McCormick observed values in
order to change them from relative to absolute parallaxes.

47 of the differences Groningen-McCormick have positive
values while only 25 are negative. The average difference
Groningen-McCormick is + 0%020, but excluding four stars
where the differences are very large this average reduces to
+ 07015. Apparently, therefore, there appears to be abundant
justification for Kapteyn’s belief that parallax observers may
have a bias in favor of positive parallaxes. With all honesty an
observer may decide to abstain from publishing his results where
a large negative parallax has been obtained until this parallax
has been verified from additional observations. If, on the other
hand, the results of the measures furnish a large positive parallax,
the star would be regarded as specially interesting on account of

‘its nearness, and there would probably be no apparent reason
why the scientific world should not be made acquainted with this
discovery through the publication of the parallax.

Among the 72 stars, only two have more than five early deter-

minations, the star Groombridge 1830, where the average
parallax from the Groningen tabulation is + 07102, while the
McCormick absolute parallax is + 07111, and 61 Cygni with the
mean value for the pair of + 07311 and + 07312, from Groningen
and McCormick respectively. For these two stars, well deter-
mined by the early observers, there is excellent agreement with
the McCormick values. The only series of parallaxes. included
‘in the Groningen list which have an accuracy comparable with
the present measures are the early Yerkes results of Schlesinger.
It is clear, therefore, that the parallax results of the heliometer
and meridian circle, on which the Groningen list mainly depends,
are on the average too large, and, moreover, are subject to errors
which are very large when compared with modern photographic
work. A word of caution might not be out of place that one
should not put too much reliance on the accuracy of the early
parallaxes.
646 S. A. MITCHELL

CoMPARISONS WITH THE YALE HELIOMETER.

The greatest admiration must be felt for the Yale observers
for the indefatigable labor involved in the publication of no less
than 238 parallaxes.. On page 8 there is given the results of 128
observations on the star « Canis Minoris showing values of the
parallax which range from + 07228 to + 0503, with a mean
value of + 07334. As the seven separate series on this star
were made with special care, one can readily see the limitations
of the heliometer.

57 stars of the 238 observed at Yale, or one-fifth of the total,
have had their parallaxes determined at the McCormick Obser-
vatory. A detailed comparison was accordingly made, and
differences were formed in the sense, McCormick-Yale. In view
of what has been said above, it is quite natural to expect large
differences. In fact 14 of the 57, or one-quarter of the number,
have differences between Yale and McCormick which exceed
07050. For the 43 most accordant stars, the average difference
between McCormick and Yale is 0"019, but the Yale values on
the average are larger than the McCormick results by 070055.
For all of the 57 stars, the average difference between McCormick
and Yale is 0"035 with the Yale parallaxes larger than the McCor-
mick by the average value of 07002. In the above comparisons,
values of the relative parallaxes were used. Since Yale employed
brighter comparison stars than McCormick, which stars on the
average would have larger parallaxes that the fainter McCormick
comparison stars, the Yale relative parallaxes in reality should
come out smaller in size than the McCormick relative parallaxes,
and not larger.

It might not be out of place to again express admiration for the
splendid Yale results especially when one considers the short
focal length of the heliometer employed. However, some of
their parallaxes show considerable deviations from the average
of the best photographic work with telescopes of great focal
length, and this is specially true where the series of observations
on which the parallaxes depended were short.
PARALLAXES OF 260 STARS 647

CoMPARISONS WITH MopERN PHOTOGRAPHIC PARALLAXES.

120 stars of the McCormick 260, or nearly one half the total,
have had their parallaxes determined by photography with
telescopes of great focal length, the telescopes arranged according
to their apertures being Mt. Wilson, Yerkes, Allegheny, Green-
wich, Swarthmore, and Dearborn. Although the agreement
between these photographic authorities is on the whole very
satisfactory, still there are individual cases where these modern
parallaxes differ among themselves more than one would be led
to expect from the size of the probable errors. An instance of
this may be seen in the results for the well-known star 61 Cygni.
The mean of the values for the two stars of the pair have the
following values arranged in order of the size of the parallaxes:

 

Mts Wils0nt 2 es-s:a sce scurede cee ee $ Sa es tee ee eee 0322
MeCormitek «2 s.65 gs genssatdaccaace sie on ciaet odes oe Dee .307
DS WATtHMOPGs aces ids p dosessd! axed aaa deg Gane sek Gene wee .301
ATG GHEY’ 5.0.2.3 904 eon a RG mama d ame neue aon dave aaa -284.
{VER IKeS ty sid a tho aca cote tobe y a dane ha aha ubeded Aaah 07272
Mie aise reset scale teas, gametes ees PRONE naa OS Bie tesa 0"297

_ Including all determinations of the parallax of this well observed
system, the mean parallax weighted according to the probable
errors is 0”306. The extreme range in values of 0050 is obtained
between that determined by the Mt. Wilson reflector of 60
inches aperture and equivalent focal length of 80 feet and the
Yerkes refractor of 40 inches aperture and 62 feet focal length.
Apparently, therefore, even from observations carefully made
with great telescopes there is still opportunity for occasional
differences in parallaxes amounting to several times the size of
the probable error. With photographs having the scale of the
McCormick plates, 07050 is equivalent to 0.0024 mm.

In order to investigate whether there are any systematic errors
in the McCormick parallaxes, their values were compared in
detail with the results for the 120 stars determined by photogra-
phy elsewhere. Accordingly the differences were found for each
star in the sense McCormick-Others. For only twenty out of the
120 stars was the parallax determined by more than one other
authority. In each and every one of these 20 stars the agreement
648 S. A. MITCHELL

between McCormick and the mean of the other authorities
was uniformly good, for in no case did the difference exceed
0”025. For the other 100 stars there was one other photographic
authority only. When two authorities are compared and
differences are found, it is difficult to know which is in error, or
whether both may not bein error. Twelve times altogether, or
in ten per cent of the total, the McCormick parallax differed from
the other authority by an amount exceeding 0035, which is
approximately four times the probable error.

In testing observations for the purpose of finding systematic
errors, when comparisons are made with the average of other
results, it is difficult to know how to treat discordances which are
large in size. Manifestly a few large differences, if these dif-
ferences happen to be all positive or all negative, will make the
same accumulated difference as a large number of very small
differences, each of the same sign. If the comparisons are
made between two authorities of equal reliability one had prob-
ably best reject the discordant observations. If a third series
of values can be found entirely independent of the first two,
these results will serve as a test for deciding which of the obser-
vations are in error. Such an independent series may be found
in the spectroscopic parallaxes determined at Mt. Wilson by
Adams and Joy. Accordingly, the McCormick and other
photographic parallaxes were compared with the spectroscopic
results after 0"005 had been deducted from the spectroscopic
values to change them from absolute to relative parallaxes.
For the twelve discordant stars, the average difference between
McCormick and spectroscopic parallaxes was less than 07001.

Consequently, for testing the systematic errors of the McCar-
mick parallaxes it will evidently be best that these twelve stars
be discarded from the comparisons. For the remaining 108 stars,
the average deviation between McCormick and the other
photographic authorities is 07015, while the McCormick paral-
laxes on the average are the larger by an amount which is less
than 07001. It should be pointed out that since the comparisons
in most cases are made with only one other authority it is im-
possible to tell whether the McCormick parallaxes are too large by
this minute quantity, or whether the other authorities are too
PARALLAXES OF 260 STARS 649

small by a like amount. Taking all of the 120 stars in common,
the average deviation is 0"018 while the McCormick results are
larger than the other authorities by the average of 0”0027.

93 stars of the 120, of three-quarters of the whole, were ob-
served by Allegheny and McCormick. Of these 93 stars in
common there are eight cases where the difference between
McCormick and Allegheny is greater than 0”035. For the
balance of 85 stars, the average deviation between McCormick
and Allegheny is 07012, while the McCormick values are larger
than the Allegheny results by 070006. For the whole 93 stars
common to Allegheny and McCormick, the average deviation is
07018 while Allegheny is smaller than McCormick by the
average amount of 0”0037.

Tue Ursa Masor Group

Another comparison of interest is that afforded by the stars
of the Ursa Major group. In Astronomische Nachrichten,
4738, Bottlinger investigates the proper motions, etc. and finds
that many stars belong to an extended Ursa Major group.
Under these assumptions, he is thus enabled to calculate values
of the parallaxes. In the table below are given the stars of this
extended group whose parallaxes have been determined in the
present series. 0”005 has been added to the McCormick values
to change them into absolute parallaxes. In the column giving
the difference between the predicted and observed parallax, it
will be seen at once that the star £ Bootis is not a member of the

 

 

Difference Theor.-

 

Star. | Theoretical 7. | Observed 7, Obs.
\
@ Btidaml. 1.5 casecvcvsas +1019 +1015 +7004
B Aurige............005. +.025 +.031 — .006
¢ Urs. Major (m)......... +.046 +.037 +.009
g Urs. Major............. +.042 + .034 +.008
78 Virginis.............. +.014 + .028 —.014
EBootis................. +.044 +.205 —.161
@ Cor. Bore... eee. eee | $.08 | +.061 —.020
8 Serpentis.............. +.023 +.034 —.011
76 Cygni........-....0.. +.013 | -+.010 +.003

 
650 S. A. MITCHELL

Ursa Major group. Of the other eight stars, four have positive
differences and four negative, while the average difference
Theoretical-Observed is — 0°003.

Another method of testing the McCormick parallaxes is to
see whether differences in the magnitude of the parallax star
might not cause a systematic difference in the size of the parallax.
This information can be obtained by comparing the parallaxes of
two stars forming a physical system when these stars appear on
the same series of plates. Among the McCormick parallaxes
there are 27 stars which apparently form physical systems and
for which the parallaxes were separately determined. Some of
these pairs are separated by a small angular distance like Krueger
60, some more widely separated like the components of 61
Cygni. Some pairs have large differences of brightness like
n Cassiopeiae, where the magnitudes are 3.6 and 7.6, while some
are of nearly the same magnitude as in 16 Cygni which differ
only one-tenth of a magnitude. The stars forming a physical
system should have the same parallax. If the difference between
the observed parallaxes of two members of a pair is taken in the
sense Brighter-Fainter, then any difference in the parallax depend-
ing on magnitude should make itself manifest. In 14 of the 27
regions the brighter star has the larger parallax, in 12 the brighter
star has the smaller parallax, while in one region the parallaxes
are identical. The average of the 27 taken in the sense Bright-
Faint is + 070002. 13 of the 27 have differences less than the
average probable error 07009, while in 20 of the 27 the differences
are less than twice the probable error. The largest differences
come from two regions where it was difficult to secure'a satis-
factory series of plates due to the low declination of — 20°.

Still another very satisfactory criterion for testing the syste-
matic errors of the McCormick parallaxes is the comparison of
the values of the proper motions from the photographs with those
determined from catalogues. 216 stars of the present series
have had their proper motions determined by Boss. The average
difference between Boss and the photographic result is slightly
less than 0702. The average deviations in the proper motions
in the sense McCormick-Boss is + 0°%001. Even this small
difference can be accounted for since more parallaxes have been
PARALLAXES OF 260 STARS 651

measured between 18° and 65 of right ascension than between
6> and 185. The solar apex has a right ascension of 184, and in
consequence the comparison stars have a slight parallactic drift,
which is shown by the proper motions.

MerAN PARALLAXES RELATED TO PropER Motions AND
MAGNITUDES.

The present series of parallaxes are sufficiently numerous to
permit a test to be made of the connection between parallaxes
on the one hand and brightness and proper motions on the other.
It is quite natural to expect that the nearest stars should be
those of the greatest brightness or those of the largest proper
motions.

Kapteyn’s empirical formula from Publications of the Groningen
Laboratory, No. 8 is:

T= a pre
where 4; = 1004 =the total angular motion of the star
per century.
m = m — 5.0, if m is the visual magnitude; and a, b,
and e are constants to be derived.
Substituting the values of 4; and m, then the equation re-
duces to:
a= a (100 p)? er5 9

or taking logarithms,
log * = blogu + mloge + log A,
where log A = log a + 2b — 5 loge.

It is not expected that this method will furnish the individual
parallaxes of the stars, but rather that it will give an idea of the
mean or average value of the parallax.

In The Derivation of the Change of Color with Distance and
Apparent Magnitude, Groningen, 1915, van Rhijn makes an
excellent discussion of the subject, and publishes tables of mean
parallaxes. Since the B stars are on the average more distant
than the A-type stars, and these in turn are more distant than
the later types, F, G, K, and M, the stars were grouped by van
Rhijn into three classes for discussion.
652 S. A. MITCHELL

In making up the observing program for the McCormick
Observatory preference was at first given to the later type stars.
It will be interesting, therefore, to see whether the McCormick
results show a relation between the parallaxes and the proper
motions and magnitudes. In investigating. the material, the
two stars forming a physical system were treated as a single star
having the combined magnitude of the pair. At the time that
the computation was carried out the parallaxes of 166 separate
systems of the F, G, K, and M types had been finished. The
results appear in the following table:

Mean ParaLLaxes ComPutTEep rrom McCormick RELATIVE PARALLAXES.

 

 

 

 

 

Limits yp. Limits m. | No. = Obs. a Comp. a O-C.
= 07100 0.00 — 3.50 27 "009 "O11 —"002
=0.100 3.51 — 5.00 22 -017 .010 + .007

"101 — "250 0.00 — 3.50 11 .022 -034 —.012
-101 — .250 3.51 — 5.50 23 -038 -029 + .009
= .250 5.51 — 7.50 ie .009 -016 — .007

.250 — .600 0.00 — 3.50 5 -055 .067 — .012
.250 — .600 8.51 — 5.50 18 ~ 053 -051 + .002
.250 — .600 5.51 — 7.50 4 .042 .050 — .008
-601 — .999 0.00 — 3.50 1 - 108 -100 + .008
-601 — .999 3.51 — 5.50 8 -112 -093 +.019
.601 — .999 5.51 — 7.50 6 .056 -061 — .005
1.000 — 2.000 0.00 — 3.50 2 .170 .161 +.009
1.000 — 2.000 8.51 — 5.50 -7 .172 -135 + .037
1.000 — 2.000 5.51 — 7.50 4 .080 .097 —.017
= .250 > 7.50 3 -017 .022 — .005

.251 — .999 > 7.50 8 .062 -045 +.017
1.000 — 2.000 > 7.50 3 -077 -082 — .005
> 2.000 All magns. 7 - 242 .257 —.015

 

 

 

 

a Obs. denotes the mean of the values of the parallaxes of all
the stars in the group, 7 Comp. the value computed from the
formula. A probable error 07009 results, which is equivalent
to the probable error of the observed parallaxes. Within the
different groups of stars, the ranges in the sizes of the parallaxes
are quite large. In view of this range it is quite surprising that
only one of the eighteen residuals shows a large value. One
PARALLAXES OF 260 STARS 653

should be very cautious, however, in basing any conclusions on
the average where the individuals are few in number, since one
discordant object may very greatly affect the average when the
numbers are small.

The group of stars of total annual proper motion greater than
20 consists of seven stars as in the following table, the stars
being arranged in order of increasing proper motion:

Stars or Large Proper Motion.

 

 

 

Star. | Magn. be Parallax.
Lalaned 27178.................4.. 5.7 2"05 +07189
Pigg 7 Qh 123 seus eo doe new ae aes mn) 2.34 .187
0°40 Evidani..................... 4.5 4.08 204
Lalande 21258.................... 8.9 4.47 177
GLC y ei yi tiie tes, detiecthore RIVE Roe eae 8 5.2 5.22 .3807
Groombridge 1880................. 6.5 7.04 .106
Barnard’s Star...........0.0..0005 9.7 10.3 +0.5389

 

 

 

 

On the assumption that such a great range in values can hardly
represent average conditions a second solution was made by least
squares, omitting this group of seven stars. Very little change,
however, resulted in the constants a, b, and ec.

The measured parallaxes available for Kapteyn’s discussion
were those in Groningen No. 24. As has already been stated,
these older parallaxes are on the whole, too large and they are
also subject to large systematic errors. It is quite natural,
therefore, to expect that Kapteyn’s mean parallaxes as shown
particularly by his constant, a, should be too large. In 1915,
there were available to van Rhijn additional measured parallaxes
as follows: Chase, Smith and Elkin from the Yale heliometer;
Flint, second series, from the meridian circle; Slocum and
Mitchell ‘by photography from the Yerkes refractor; and Abetti
from the meridian circle. Van Rhijn had for his computation
247 parallaxes of the later type stars. Using the proper motions
from the Preliminary General Catalogue of Boss, the radial veloci-
ties from Lick Observatory Bulletin 229, and assumimg the velocity
of the sun to be 19.5 km. per sec., van Rhijn had additional infor-

ta ’
654 S. A. MITCHELL

mation from the parallactic motions of no less than 620 stars.
The values of the constants a, b, and ¢ follow:

Constants For Mran Paraiaxes or F, G, K anp M Srars.

 

 

 

 

 

 

Authority. a b. ce
Kapteyn (Groningen No. 8)..............-. 0.0049 | 0.65 0.905
Van Rhijn, 247 Measured Parallaxes......... .0029 | 0.753 0.889
Van Rhijn, 247 Parallaxes supplemented by
620 Parallactic Motions.................. -0038 | 0.695 0.889
Van Rhijn, Table computed by............. .0038 | 0.695 0.895
166 McCormick Relative Parallaxes......... 0.0031 0.744 0.881

 

For B and A type stars, van Rhijn computes tables from the

constants: ‘
a. b. €
Bestars........... 070031 0.904 0.895
A-stars........... 0.0028 0.80 0.895

The same value of the constant « = 0.895 was used by van
Rhijn to compute all three tables for B, for A, and for the later
type of stars, as given on pages 82, 83, and 84 of his publication.

Using parallaxes published in Groningen No. 24, Hertzsprung
(Astronomische Nachrichten, 4975) derives the constants a =
070018, 6 = 0.75, and e = 0.89.

The constants derived from the 166 McCormick relative
parallaxes differ very little from those obtained by van Rhiin
from 247 measured parallaxes. The addition of the parallactic
motions of 620 stars which are mainly of small proper motion had
the effect of changing the value of the constant b depending on
proper motion, without changing e which depends on magnitude.
A change in the value of a came as a necessary consequence.

Attention should be called to the fact that the McCormick
parallaxes in the above computation are relative and not absolute
parallaxes.

Since the time when the constants were derived from the
McCormick parallaxes many extra stars have been computed and
additional parallaxes are available. Instead of making a new
solution, it has seemed preferable to use van Rhijn’s tables in

‘
PARALLAXES OF 260 STARS 655

order to see how closely they represent the McCormick relative
parallaxes. As before, the two stars of a physical system were
treated as a single object. It should be emphasized that the
mean parallaxes from the tables can provide only average
results, and consequently large differences between the observed
and tabular values should be expected. 196 stars of later type
have had their parallaxes determined in the present series.
The differences between observed and tabular parallaxes or
McCormick-Van Rhijn were formed for each of the 196 stars.
In the following table is given the number of stars within the
limits as given by the quantities at the heads of the columns.

ComPaRISONS WITH Mean PaRALLAXES FROM VAN RalsN TABLES.
Differences McCormick-van Rhijn.

 

 

7,000 | .000 | —’’.010
“7,000. to

+/.010 | —7.020 | +”.020 | —’”.030 | +/7.030 |—/”.040 | +/7.040
to to to
—/’,009.) +/7.009 | —’”.019.

to to to to to
+/.019.| —”.029.| +/7.029.| —/”,039,) +/7.039. | —”.049. | +/7.049.

 

|
6 | 32] 26 23 | 20 | 24 of ei] lel) ¢

 

 

 

 

 

 

 

 

 

 

 

 

 

 

—/7,050 | +/7.050 | —”.060 | -+-”.060 | —”.070 | +-”.070 | —”.080 | -+/”.080
to to to to to to to to wr, rR
—',059.| 4-””.059.| —”.069.| +-”.069.| —””.079.| +-”.079.| —”.089.| -+/7.089. 0, 2100.
2 4 1 1 | 2 1 0 2 1 7

 

In the top half of the table where the differences are less than
0"05, it will be seen that 99 stars furnish positive differences
McCormick-van Rhijn, only 70 give negative values, while for
6 stars the observed and tabular values are identical. For
these 175 stars in the top half of the table, the total negative
differences exceed those positive by 07393. If, therefore, all
differences were neglected where the discrepancies were greater
than 0”05 we would be forced to the conclusion that the van
Rhijn mean parallaxes are larger than the McCormick relative
parallaxes by the average amount of 07002.

Of the 21 stars mainly of large proper motion in the lower half
of the table the observed parallaxes are larger than the tabular in
15 cases and smaller in only six. This is a condition of affairs that
might be expected, for stars nearer to us than the average, and thus
656 S. A. MITCHELL

with larger parallaxes, may be observed, while those farther away
than the average may fail of detection. If tothe 175 stars in the
top half of the table there are added 13 stars from the lower half so
that the comparison shall therefore include all stars where the dif-
ferences are less than 0710, then the accumulated differences
McCormick-van Rhijn for 188 stars is —0°143, or the McCor-
mick parallaxes are smaller than the tabular values by 07001.
The addition of any one star from the list of seven in the table
of exceptional stars below which have positive differences McCor-
mick-van Rhijn greater than 0%1 would be sufficient to practi-
cally wipe out the accumulated difference of —0"148. Since
Groombridge 1830 furnishes a large negative difference, then by
taking it with two extra stars with positive differences there will
result an almost perfect agreement on the average between
McCormick parallaxes and van Rhijn tabular values. Only
five stars out of 196 are thus left out of the comparison, each
with a large positive difference. If; however, these five are also
included, then the total difference for all 196 stars is 07932, or
an average of. 07005 that the observed parallaxes are greater
than the tabular values. This should not be interpreted to
mean that the McCormick parallaxes have a systematic error
amounting to + 07005. This positive value results from the
addition of a very few stars which are in every sense exceptional
stars and not average stars. One of these exceptional stars is
Barnard’s Proper Motion star which has the largest proper
motion of any star known, and it has the added distinction of
being one of the faintest stars known, having a luminosity only
0.0004 that of the sun.

Stars are not all formed in the same mold, and on account
of their great differences in mass, in brightness, and in motion
one should not expect that their distances or parallaxes could be
adequately represented by any mathematical formula. Van
Rhijn’s constants probably represent mean parallaxes as well
as any formula can. Attention should again bé called to the
fact that van Rhijn’s constants represent the McCormick ob-
served parallaxes remarkably well. The McCormick parallaxes
are relative to the set of comparison stars chosen and are not
absolute in amount. In order to obtain absolute parallaxes
 

Gaertner Machine for Measuring Photographs.
PARALLAXES OF 260 STARS 657

07005 should be added to the values from the tables of van
Rhijn.

In the following table are listed 15 exceptional stars where the
differences between the McCormick and tabular parallaxes are
greater than 0706. The stars are arranged in order of increasing
difference McCormick-van Rhijn. All of the eight stars where
the differences are greater than 0710 have had their parallaxes
well determined by several authorities.

Firteen Excrprionau Stars.

 

 

 

 

 

 

 

 

Star. a Decl. 1900, ene pre Menor ISIE) SEAN Beam
6 Leporis.......... 5h47™ | —20°53’ | 3,90K +7019 | +7083 | —"064
70 Ophiuchi (m)....| 18 O | + 2 30 | 3.94K +.178 | +.110] +.068
vy Leonis (m) ...... 10 14 | +20 20 | 2.33K —.012 | +.060|) —.072
x Orionis.......... 5 48 | +20 15 | 4.62F; +.105 | +.032} +.073
6 Urs. Majoris......| 926 | +52 7 | 3.26F; +.032 | +.110] —.078
y Leporis (m)...... 5 40 | —22 28 | 3.80Fs +.144 | +.064] +.080
mw Orionis.......... 444 | + 6 47 | 3.31F; +.151 | +.063 | +.088
Lal. 25372......... 13 40 | +15 26 | 8.7 K +.224 | +.104] +.120
a Canis Min........| 7 34 | + 5 29 | 0.48Fs +.309 | +.178) +.181
PCL, aiesic ais eceoe 139 | —16 27 | 3.65K +.312 | +.171] +.141
Groomb. 1830...... 11 47 | +38 26 | 6.46Gp | +.106 | +.274] —.168
£ Bootis........... 14 46 | +19 31 | 4.64Ksp |-+.200 | +.026] +.174
e Eridani.......... 328 | — 9 48 | 3.81K +.302 | +.105| +.197
Krueger 60 (m) ....| 22 24 | +57 11 9.3 Mb | +.266 | +.060] +.206
Barnard’s Star.....| 1754 | + 425 |9.7 Mb} +.539 | +.265| +.274

 

 

CoMPARISONS WiTH SPECTROSCOPIC PARALLAXES.

On account of the much greater number of stars involved, a
better method of deriving the systematic errors of the present
series of parallaxes will probably come from the detailed com-
parison with the spectroscopic values of Mt. Wilson, there being
no less than 194 stars in common. Through the kindness of
Dr. Walter S. Adams, the results in Table 5 were communicated
in advance of publication. Nearly all of the McCormick stars
of later types have had their parallaxes determined spectro-

43
658 8. A. MITCHELL

scopically. As pointed out on p. 38, Adams and Joy have
compared the relative intensities of certain lines in the spectra
of the stars, and by means of curves derived from parallaxes
trigonometrically determined the absolute magnitude of each
star is found. The spectroscopic method is primarily a method
of determining absolute magnitudes. If the visual magnitude is
known, the parallax of the star can be found by a simple formula.
To obtain parallaxes on a uniform system all steps in the process
must be known with great accuracy: the estimations of the
relative intensities of the spectral lines must be carefully made,
the curves of the various spectral types must be thoroughly
investigated, and the visual magnitudes, those of the revised
Harvard Photometry, must be on a uniform system.

Since the publication in 1917 of The Luminosities and Parallazes
of Five Hundred Stars, Adams and Joy have made two revisions
of their results. The first revision was based on all parallaxes
known to 1920, many of the photographic results having been
communicated in advance of publication. A second revision of
the standards of reduction has been based on 657 stars whose
parallaxes have been determined photographically at Allegheny,
Yerkes, Mt. Wilson, and McCormick observatories, about 115
of these stars being common to two or more observers, (Publ.
Astron. Socy. Pacific, 32, 195, 1920). The spectroscopic paral-
laxes for the McCormick stars given in Table 5 are the values
from this second revision. According to the investigations of
Adams, Joy, and Strémberg (loc. cit.), the average difference
between the spectroscopic and the McCormick parallaxes for
194 stars is 070006, the spectroscopic being the larger in value,
while the mean deviation is 070193.

Since the spectroscopic parallaxes in Table 5 are founded on
the best of the modern photographic parallaxes, the close agree-
ment between the McCormick and the spectroscopic parallaxes
shows that the McCormick parallaxes must be nearly on the same
system as the average of the photographic values. In other
words, there is little indication of any systematic errors in the
McCormick parallaxes. What is here said regarding the
McCormick parallaxes is equally true of the results determined
by photography at Allegheny, Mt. Wilson, and Yerkes Observa-
PARALLAXES OF 260 STARS 659

tories. There are indeed errors in the parallax values for the
individual stars furnished by each of the four observatories, at
times unfortunately, much larger than one would expect nom
the small size of the probable errors.

If the difference from the spectroscopic results should be treated
as a systematic error, then the McCormick parallaxes should
have a systematic correction amounting to + 0”0006. In the
Astronomical Journal, 33, 17, 1920, from less complete data, Boss
finds the systematic correction to the McCormick parallaxes of
+ 070014. An unpublished investigation by van Maanen,
referred to in Mount Wilson Contributions, 182, 9, 1920, shows
the correction to the McCormick parallaxes to be between
— 07001 and — 07002. If one should take the mean of these
three independent determinations, the conclusion is reached that
the systematic errors of the McCormick parallaxes is less than
0”001.

The writer believes that the photographic parallaxes of Alle-
gheny, Mt. Wilson, Yerkes and McCormick are without system-
atc errors, the differences between the parallaxes from these four
observatories being entirely due to differences in the individual
results of a very small number of stars.

When one recalls the various steps in the process of deter-
mining parallaxes spectroscopically one cannot but wonder at the
marvelously good agreement of the spectroscopic parallaxes. One
of the steps involved is a knowledge of the visual magnitudes
which were derived from the Revised Harvard Photometry. The
excellent agreement of the spectroscopic parallaxes speaks well
for the uniformity of the visual magnitudes derived at Harvard.

Massgs.

When the orbit of a binary system is known, the sum of the
masses of the two components compared with the mass of the
sun is readily determined by a well-known and simple formula.
In selecting the stars for the observing program at the McCor-
mick Observatory, there was no special plan on hand to put
double stars under special observation. Where the elements of
the stellar orbit are known with a degree of precision sufficient
to give a good idea of the size of the semi-major axis and the
660 S. A. MITCHELL

period, the masses were found, and the results are collected in
Table 4 below.
Mass-RATIOS.

In a binary system measured for parallax, the proper motion
determined by photography may differ from the value obtained
from star catalogues. As already pointed out (p. 36), by photog-
raphy the proper motions are determined with respect to a particu-
lar group of comparison starsinstead of being referred tothe system
of stars as a whole, as in meridian circle work. To obtain photo-
graphic proper motions on the same system as those from meri-
dian circles it would be necessary to know the proper motions
of the comparison stars which on the average are of the 10th
magnitude. It is manifestly impossible at the present state of
astronomical investigation to know these individual proper
motions. However, it might be possible to make allowance
for the parallactic drift of these tenth-magnitude comparison
stars with respect to the system of the stars, for, manifestly,
these drifts per year will amount to about four times* the size of
the annual parallax of stars of tenth magnitude. Of course it is
still uncertain what is the size of the average parallax of stars of
tenth magnitude.

In a binary system like 7 Cassiopeia, the proper motions of
both stars of the system have been determined by photography.
Each of the stars in the orbit moves about the common center of
gravity. The motion for each star with respect to this center of
gravity is inversely proportional to the mass. Consequently,
if the meridian circle observations could furnish the proper
motion of the center of gravity with a precision comparable with
that attained by photography it would be a simple matter to
obtain the ratio of the masses of the two stars. In the average
meridian circle a double like y Cassiopeia would appear as a
single star, and the position furnished would be that of the center
of brightness, which does not necessarily coincide with the center
of gravity. Fuller information on this subject can be found by
reference to the Preliminary General Catalogue of Boss. The
proper motion of a double star given by Boss is therefore not

* Publications of the Astronomical Laboratory at Groningen, 29, 34.
PARALLAXES OF 260 STARS 661

necessarily the proper motion of the center of gravity. To
eliminate the effect due to orbital motion, the meridian circle
observations should stretch throughout a whole period of the
double. For very few stars is the proper motion of the center
of gravity known with sufficient precision to permit the deter-
mination of mass-ratios even with a fair degree of accuracy.
When the photographs furnish the proper motions of both
components of a binary, the determination of the ratios for the
masses is a very simple process. Where only the brighter star
has been measured the method shown by van Biesbroeck,
Astronomical Journal, 29, 173, 1916, must be followed.

 

 

 

 

 

 

 

 

TABLE 4.
Massres anp Mass-Ratio.
Mass of | Ratio of

Star. Ri ae fee Magns. System, Masses,
Piazzi 0130 ......... 032™ | —25°19’| 6.6, 6.7 0.68
n Cassiopeia......... 0 438 +57 17 3.6, 7.6 0.34
o? Eridani, BC....... 410 |— 748) 9.4, 10.8 372. | BHC
a Geminorum........ 728 | +82 6 2.0, 2.8 A>B
a Canis Min......... 734 | + 529 | 0.5, 13.5 1.41
9 Puppis ............ 747 | —1338| 5.8, 64 11.0 0.32
e Hydre............. 841 |+ 647| 3.9, 4.4 71.3 A=B
Lalande 25224...... -| 13 34° | +11 15 6.5, 6.5 0.88
éScorpii, AB........ 1559 | -11 5] 4.8, 5.1 436 | A<B
d\ Ophiuchi........... 16 25 + 212 4.0, 6.1 19.7
» Herculis, BC ....... 1742 | +27 47 | 10.0, 10.5 4.1
70 Ophiuchi.......... 18 0 ;,+2381! 4.1, 6.0 “1.67 0.79
99 Herculis.......... 18 3 | +3033] 5.2, 10.5 4.1
¢ Sagitarii........... 1856 | —30 1] 3.4, 3.6 33.1
Secchi 2............. 19 8 | +88 387 | 8.7, 8.7 0.38
@ Delphini........... 2032 | +1414] 4.0, 5.0 | 3.92
< Equulei, AB........ 2054 | 4+ 355] 5.8, 63 5.8
6 Equulei........... 21 9 | +936] 5.8, 54 6.2
7 Cygni............. 2110 | +3737} 3.8, 8.0 6.15
x Pegasi ...........-- 2140 | +2511) 5.0, 5.1 20.4
Krueger 60, AB...... 22 24 +57+11 9.3, 10.8 0.40 6:5*

 

*See Astronomical Journal, 767.
662 S. A. MITCHELL

In the preceding table are collected the masses and mass-ratios
determined from the McCormick photographs. In calculating
the mass-ratios allowance was made for the parallactic drift of
the comparison stars.

SUMMARY.

1. The parallaxes of 260 stars have been fotind with an average
probable error of 0009. The average probable error of a single
plate of good quality on which are impressed two images is 0.0013
millimeters, or 07027.’ On the average 4.5 comparison stars
were used.

2. Although there may be departures from the truth for indi-
vidual stars by amounts greater than is indicated by the probable
error, comparisons with other recent photographic parallaxes
for one-half of the stars measured show an excellent agreement,
the average deviation between McCormick and other parallaxes
photographically determined being 07015. On the average the
McCormick parallaxes are larger than those of the other photo-
graphic authorities by an amount which is less than 07001.

8. 194 of the McCormick stars have had their parallaxes deter-
mined by the spectroscope at Mt. Wilson. The average devia-
tion between McCormick and the spectroscopic is 07019 so that
the McCormick parallaxes agree with the spectroscopic values
almost as well as with the best photographic values. On the
whole the McCormick results are smaller than the Mt. Wilson
spectroscopic parallaxes by 070006.

4. Comparisons of the McCormick parallaxes with the theoreti-
cal parallaxes determined for an extended Ursa Major group show
the observed and theoretical parallaxes to be in good agreement.
The large observed parallax of £ Bootis (07200) shows that it is
not a member of the Ursa Major group.

5. Constants derived from the McCormick parallaxes for
Kapteyn’s empirical formula are in good agreement with those
derived by van Rhijn.

6. Comparisons with van Rhijn’s tables of mean parallaxes
show that these tables represent the McCormick parallaxes as
well as could be expected from any empirical formula giving
mean parallaxes.
PARALLAXES OF 260 STARS 663

7. Large departures from mean parallaxes are shown by fifteen
exceptional stars. ;

8. Comparisons with the best visual work by heliometer and
meridian circle show that on the average the visual parallaxes
are larger than the McCormick values by 07015.

9. The parallaxes determined visually are subject to large
systematic errors, and they have a much smaller degree of
precision than the photographic parallaxes.

10. Barnard’s star of larger proper motion and the companion
B of Krueger 60 are intrinsically among the faintest stars yet
known to astronomy, each possessing a luminosity about 0.0004
times that of the Sun.

11. In the present work, the masses of 21 stellar systems have
been found. The companion of Krueger 60 has the smallest
mass of any star yet known with certainty, having a mass about
one-seventh that of the sun.

12. The ratios of the masses of the components of 8 stellar
systems have been found.

13. Comparisons of the proper motions from the McCormick
photographs with those from the Preliminary General Catalogue
of Boss show a very close agreement.

14. The McCormick parallaxes have been treated by various
methods with the conclusion that any systematic errors must be
less than 07001.

15. The first parallax was measured in 1838. In 1880 there
were 20 parallaxes, in 1900 there were 60. In 1910 Kapteyn
listed the parallaxes of 360 stars, though according to Campbell
most of these distances were known with little accuracy. In
1910, we had “approximate knowledge of the distances of 100
stars.” In May 1917, the measured parallaxes of 625 stars were
compiled by Walkey, and in September of the same year a
similar compilation was made by Heath of 734 stars.

16. Parallaxes are now being determined by photography
with telescopes of great focal length at the rate of at least 200
per year. With the information already available from the
determination of proper motion and the measures of velocities
in the line of sight, modern astronomers will soon be in a position
to solve anew such interesting questions as the construction of
the universe, the motions of the stars, star-streaming, etc.
664 S. A. MITCHELL

17. In Table 5 are gathered the summary of measures of
parallax and proper motion. 07005 has been subtracted from
the values of the spectroscopic parallax of Mt. Wilson. The
proper motion measured on the plates was the component in
right ascension, or nwa Cos 6. The corresponding value is taken
from Boss or Porter, those from Porter being marked by an
asterisk (*). In the column ‘‘Measurer” is given the initials
of the person responsible for the measurement of the plates.
It has always been the policy of the McCormick Observatory to
have each series of plates measured when possible by one person
only. On account of changes in the personnel of the observatory
staff the measurement of a series of plates started by one person
at times has been completed by another. In such cases the
initial of the person is given who measured the majority of the
plates, as follows:

ae =§. A. Mitchell.
= C. P. Oliver.
= H. L. Alden.
= P. H. Graham.
= R. C. Lamb.
= G. B. Briggs.
= Marguerite D. Darkow.
= M. Alberta Hawes.
= Jennie V. France.

ears
665

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PARALLAXES OF 260 STARS

 

 

 

 

 

 

 

 

 

 

 

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S. A. MITCHELL

676

 

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*panurwoj—G ATAV.L
677

PARALLAXES OF 260 STARS

 

 

 

 

 

 

 

 

 

 

 

 

 

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‘penmjwog—s FTAVL
PART II.

MEASURES OF DOUBLE STARS
ON PARALLAX PLATES

BY
CHARLES P. OLIVIER.

From the beginning of the work of the determination of
parallaxes by photography at the McCormick Observatory it
has been the intention of Director S. A. Mitchell to utilize the
plates for other purposes than the determination of parallax,
although this was the principal program.

Although no attempt was specially made to select double stars
for the parallax program as has been the ‘case at Sproul Ob-
servatory, nevertheless quite a number of the stars whose
parallax was sought were doubles. Where the rotating sector
was utilized to cut down the brightness of the parallax stars it
frequently happened that the fainter star was so decreased in
brightness that its image was invisible. In many regions photo-
graphed, however, both components of the double star appeared
on the plates.

In photographing, each McCormick plate covered an area in
the sky 1° in length parallel to the celestial equator, and three-
quarters of a degree at right angles thereto, and since these
plates cover such a considerable area, it is only natural that many
doubles should be photographed on them. Many of these
doubles thus accidentally photographed were already known,
but quite a number of them are new discoveries. ~

The actual measurement of the photographs to determine the
position angle and distance of these double stars, old and new,
were undertaken independently by Dr. H. L. Alden and the
writer. Later it was decided that Dr. Alden should devote his

679
680 S. A. MITCHELL

energies to other fields of astronomical work. The measure-
ments herewith given are exclusively those of the writer.

The idea of measuring doubles upon photographic plates is an
old one, and has been tried often before with more or less success.
For wider pairs excellent results were obtained, but as the 5’
limit was reached most of the observers found large errors.
For example in The Observatory, June, 1917, p. 233-236, Mr. R.
Jonckheere discusses three astrographic catalogues containing
double star measures. He was able to compare one of these,
namely the one made at Potsdam, Zone + 31° to + 40°, with
visual measures. His conclusions were that the measures showed
large discordances from plate to plate and also large disagree-
ments from visual measures; further, that many of the doubles
could not be found in a visual search with the Greenwich 28-inch.
In other words such measurements of photographs are useless
for inclusion in a double star catalogue.

In the Monthly Notices R. A. S. for April, 1917, there is an
extensive paper by Mr. F. A. Bellamy on this subject. From a
close study of the Oxford astrographic plates he finds that while
there is a good agreement in the angles, for all distances, with
the best visual measures, yet in the distances very large system-
atic errors enter for stars of 5”0 and under. He concludes,—
“however useful photography may be for wider pairs, it cannot
at present replace visual work for close pairs.” Since these
are both very recent papers, it seems unnecessary to quote from
older ones on the same subject.

Before giving the results of the McCormick measures, some
preliminary statements should be made. First, the plates were
in all cases taken to determine parallaxes, not to furnish the
best images of doubles. Hence, unless the parallax star happened
itself to be double, the exposures were never timed to give the
best sized images. For other doubles that happened to be on
the plates it should be understood that no special effort was
made to photograph these stars under good conditions of seeing
when they would be better separated, nor were the stars placed
near the center of the plate. In brief, the measures of doubles
come as an additional by-product, no special photographs having
been made for the purpose.
PARALLAXES OF 260 STARS 681

This paper contains the measures of 95 pairs, and estimates of
four others which were merely elongated on the best plates.
Since these four are new these estimates will aid in future identi-
fication. Altogether 32 pairs were discovered on the plates
where the separation is less than 5”, and ten others with a greater
angular distance.

The measures were always made in X and Y coordinates from
which the position angle-and distance were calculated. These
measures were made in both the direct and reversed positions
of the plate, personal experience having proved at the very
beginning that measures in one position only might be subject
to considerable errors. The scale of the plates is 1 mm. = 2078.
The standard plate of each region contains a trail obtained by
stopping the clock and allowing a bright star to pass across the
field. The parallels for the other plates were obtained by merely
tracing this trail, through the glass, in ink. This introduced a
purely accidental error, which usually amounted to a few tenths
of a degree. The results prove that this practice which saved
the immense amount of time that more careful orientation would
have required, had no harmful results.

Two images of every star appear on most of the plates. But
frequently one was unsuitable for measurement due to a sudden
change for the worse in seeing, elongated images, etc. In such
cases only one image was used. The plate was then denoted by
an asterisk (*), and weighted one half. When both images
were measured it was weighted unity. The 32 new doubles
found on our plates are in each case designated by the name or
initials of the person who first detected them. A number has
been given only to those whose distances are less than 5”. The
ten new double stars separated over 5” are followed by (r)
which means that none of our staff cares to announce stars
wider than 5” as “doubles,” but since it was more or less neces-
sary to assign them to the person who first noted them, his name
accompanies each such star, the (r) meaning it was rejected as a
discovery. Yet the measures of a few such pairs are not without
interest in this preliminary work on the subject, hence the results
are retained.

During the early stages of the work many plates of each double

45
682 S. A. MITCHELL

were measured because it was desired to find how small the
residuals would be. Later only enough were measured to give a
result of the desired accuracy. In some cases only one plate of
the whole series had long enough exposure in good enough
seeing to show the double plainly. For certain binary stars
several plates in each epoch were measured, since nothing could
prove better the accuracy of these results than a comparison of
such measures with accurate orbits, based upon the former visual
observations. Special attention is called to the measures of 70
Ophiuchi and Krueger 60 in this connection. The plates of
Krueger 60 were independently measured by Director S. A.
Mitchell. The measures from the photographs were compared
with measures made visually by Professor E. E. Barnard with
the 40-inch Yerkes refractor, which measures were kindly sent
by Professor Barnard for comparison. In 1919, the com-
ponents AB were separated by an angle of 18, or less than 0.1
mm. on the McCormick photographs. Although this a rather
easy object in a telescope the size of the 40-inch, and a more
difficult one on the photographs owing to the scale of the photo-
graphs, comparisons with the visual measures of Professor
Barnard show that the photographic measures agree among them-
selves quite as well as do the visual measures, and moreover
the position angles and distances from the photographs agree
perfectly with the visual measures, no systematic error of any
sort being discoverable. In other words, measures of doubles
from photographs taken with the 26-inch McCormick refractor
are quite as accurate as are visual measures made with the filar
micrometer attached to the same refractor. A more complete
discussion of the measures of Krueger 60 appears in the Astro-
nomical Journal, 766.

The measurements of doubles on the photographs where the
separation is greater than 3” should be classed as “‘easy.”” With
a closer separation, the measures become more difficult. If
there is not too much difference in magnitude, stars separated
2” are not difficult. A and B of Krueger 60 differ one and a half
magnitudes. One of the doubles discovered on the plates,
Alden 1, was measured by him to be separated 1”66. The
mean of three nights at the telescope visually by the writer gave
PARALLAXES OF 260 STARS 683

1763. One or more of the elongated stars are probably about 172.
Two of the later discoveries, Ol 76 and Ol 78, were measured on
the plates as 1735 and 1"36, respectively, but these distances
have not been checked visually.

When possible all measures have been compared with Burn-
ham’s General Catalogue. Most of them agree quite as well
with the visual measures as the latter agree among themselves.
But there are obvious difficulties in making out a table of differ-
ences, for the question arises which measures in Burnham, when
they are discordant, are we to compare with? Short notes
following the measures, give the more striking results of indi-
vidual comparisons. Only for 8 GC 9114 is there a really curious
difference. Though the double on the plates is widely separated
and easy to measure, and the visual measures in Burnham are
accordant, yet my distances are 0”5 wider. For this case I have
no present explanation. A similar holds for 8 GC 9574, but here
there is a magnitude difference of 2.2, which might explain the
matter.

As a result of these measures the conclusions are:

1. Without special care it is possible to discover and measure
on the average McCormick plates any double of 3” or wider, as
faint as the 11th magnitude, if the components do not differ
more than two magnitudes.

2. With good seeing and with exposures specially timed for the
purpose a double of 2” is an “easy”’ object.

8. If the components are nearly equal in magnitude it would
be possible to measure stars separated 175, or under special
circumstances, stars as close as 170.

4. No evidence of any systematic errors is found in the mea-
sures of doubles on the McCormick plates.

5. The present paper probably offers the first published proof
that measures of close doubles can be made from photographs
which are comparable in accuracy with the best visual measures,
and hence a rather extensive field is thus opened up for the
double star astronomy of the future.

Double star observers are familiar with the arrangement in
the tables below. Immediately following the name of the star
is its number in Burnham’s General Catalogue, and enclosed in
684

square brackets [ ] if the star is found there.
heere’s catalogue is given as { }.

S. A. MITCHELL

A star from Jonck-
The magnitudes of the com-

ponents are next given, and then follow the right ascension and
declination for 1920. The measures of the plate give the plate
number, the initial of the observer at the telescope, the time in
years added to 1900, and the position angle and distance.

~ 3057 [12735] 7.2-9.2

 

 

 

 

 

R.A. 02 0™ 468 Decl. +58° 5’
7546 D 197644 297°95 4716
7547 D 19.644 298.3 4.16

19.644 297.9 4.16

E 315 {84} 10-11
R.A. 04 83™ 338 Decl. +28° 46’
6018 M = 18.906 77.4 2.26
6017 M = 18.906 80.8 2.32
18.906 79.1 2.29
A 2208 {89} 9-11
R.A. 05 35™ 228 Decl. +2° 52’
6193 M 19.022. ..... 2.22
6194 =F 19.022 122.6 2.33
6251 D 19.041 121.8 2.28
19.028 122.2 2.28
n CASSIOPELE [426] 3.6-7.6

R.A. 05 44™ 158 Decl. +57° 24’
554 G 14.863 250.2 6.66
584 M 14.877 248.8 6.64
660 A 14.948 251.6 6.80
14.896 250.2 6.70

4364 B 17.658 255.5 7.08
4373 B -17.661 253.8 6.90
4374 B 17.661 253.3 7.02
17.660 254.2 7.00

 

 

4840 M 17.921 253.7 7.01
4841 M 17.921 255.2 7.14
4847 A 17.929 254.5 6.84

17.924 254.5 7.00

Angle and distance both increasing.

 

 

S 390 [513] 9-10
R.A. 08 54" 11* Decl. +16° 7’
8167 Ol 19.917 214.9 6.38
8168 Ol 19.917 215.2 6.32
19.917 215.0 6.35
A 1909 {221} 9-9.2
R.A. 15 25™ 148 ~~ Decl. +21° 31’
6301 D 19.058 126.6 1.69
6302* D 19.058 121.2 1.65
7505 D 19.630 127.9 1.69
19.297 126.0 1.67

ALDEN (r) 9.3-10.6
R.A. 15 30™ 398 Decl. +40° 58’

 

 

38561 M_ = 17.017 7.1 5.64
38662 M_ = 17.017 7.2 5.64

17.017 7.2 5.64

84 Curt [1386] 6.0-9.2

R.A. 25 37™ 68 Decl. —1° 2’
4448 A 17.717 318.2 4.41
4449 A 17.717 314.6 4.48

17.717 316.4 4.44

Angle and distance decreasing.
E 305 [1427]
R.A. 28 42™ 56¢

 

4424 A 17.699
4425 A 17.699
4475 B 17.737
4491 B- 17.751

17.722

Distance increasing.

= 422 [1787]
R.A. 35 32™ 418

7.3-8.2

Decl. +19° 2’
315.2 3.52
815.7 3.54
315.1 3.78
815.4 3.40
315.4 3.56

6.2-8.2

Decl. +0° 20’

PARALLAXES OF 260 STARS

685

= 443 [1854] 8.2-8.8

R.A. 34 41™ 35s

 

4504 A 17.754
4505 <A 17.754
4550 A 17.773

17.760

in distance.

Decl. +41° 15’

49.5 8.38
49.5 8.34
49.5 8.30
49.5 8.34

Very slow increase in angle, decrease

32 Ermani [1939] 5.0-6.3

R.A. 35 50™ 168
3147 M
4520 A

16.768
17.762

1700 M_= 15.706
1770 M = 15.752
1771* M_ = 15.752
2988 M 16.689
3642 M_ 17.102
3643 M_ 17.102

16.405

S.A.M. 1
R.A. 3} 32™ 528

1700 M_ 15.706
1770* M = 15.752.
1771* M_ 15.752
3642 M = 17.102

16.187

 

 

ALDEN 1 9.2-9.6

R.A. 35 37™ 08
4429 A 17.698
4429 A 17.698

251.38 6.25
251.3 6.35
250.6 6.45
251.7 6.34
252.2 6.26
252.8 6.38
251.7 6.33

10-12

Decl. +0° 27’
176.4 3.98
176.0 4.18
175.7 3.81
173.8 4.30
175.4 4.09

Decl. —3° 39’
144.7 1.65
1384.9 1.39

First of these measures by Alden.

A 1541 9.2-10.2
R.A. 34 38™ 49°

777 M

778 M
1618 Ol
3619 L

15.027
15.027
15.684
17.072

 

15.702

Decl. +42° 14’

251.2
250.8
252.2
252.2

251.6

4.14
4.28
4.30
4.08

4.20

 

4543

Fixed.

6 309 [2044] 8.0-11.3

Ol

17.767

 

17.432

 

R.A. 45 3™ 418
361 A 149748
5381 G_ 14.858
762 G 15.021
886 G 15.125
2360* A 16.092
15.063
Fixed.

Decl. —3° 12’
347.0 6.78
345.9 6.81
845.5 6.82
346.1 6.80

Decl. +19° 32’

278°8
278.4
278.9
278.6
278.2

278.6

5°87
6.12
6.21
5.94
6.17

6.05

o? EriDant [2109] 9.1-10.8
R.A. 44 11™ 488

875
876
934
935
936

Binary.

AZAD

15.112
15.112
15.142
15.145
15.145

 

15.131

Decl. —7° 41’
23.6 2.92
26.3 2.96
26.8 3.22
28.2 3.00
26.1 3.00
26.2 3.02
S. A. MITCHELL

 

686
Our 66 10-10.1
R.A. 45 29™ 528 Decl. +16° 20’
3151 M 16.768 148.2 4.46
4550 A 17.773 149.9 4.46
4551 A 17.773 148.6 4.36
17.488 148.9 4.48
WEIssE 4 [2288] 9.0-9.1

R.A. 45 34™ 308

 

 

 

Decl. +42° 11’

4637 M 17.819 112.1 2.28
S.A.M.2 9.5-11.5
R.A. 5» 9™ 528 Decl. —9° 2’

6473 D 19.101 258.3 5.17

6641 D 19.181 259.7 5.10

6642 D 19.181 258.4 5.15
19.154 258.8 5.14

E 281 {836} 9.0-9.6
R.A. 55 14™ 55s Decl. +40° 15’

4528 M 17.765 211.3 2.51

4720 D 17.850 212.6 2.16

4769 B 17.877 214.1 2.20
17.831 212.7 2.29

No sensible motion.

Fox 7 (?) {902} 9.5-11
R.A. 55 27™ 478 Decl. —3° 18’

5716 M_ 18.726 42.7 2.62

6600 D_ 19.170 46.0 2.76

6601 D _ 19.170 45.5 2.71
19.022 44.7 2.70

 

 

Ou 67 9.5-9.8
R.A. 64 15™ 178 Decl. —2° 48’

3163 A 16.776 109.0 3.33
3360 L 16.853 109.7 3.08
3361 L 16.853 108.3 3.03
3423 L 16.891 109.4 3.18
16.843 109.1 3.16
5885 M 18.846 110.1 3.28
5886 M 18.846 110.3 3.18
6477 D 19.101 111.0 3.13
18.931 110.5 3.18

Or 68 9.5-10

R.A. 64 18™ 10°

4574 B

17.784

Decl. +22° 12’

37.7

Ou (r) 9.2-10.4
R.A. 64 18™ 328

4574 B

A.G. 115 [3399] 8.8-9.1

17.784

R.A. 65 25™ 98

8088* Ol
8116 F
8117 F

19.878
19.887
19.887

 

19.885

4.95

Decl. +22° 12’

55.2

6.52

Decl. +380° 30’

353.9
352.6
354.2

353.6

4.24
4.22
4,24

4.23

The position as given by Fox prob-
ably in error.

8.A.M.3 10-.10
R.A. 55 50™ 49s Decl. +45° 4’
3749 M 17.188 304 1.24

 

8.A.M.4 10-10.5

 

R.A. 65 51™ 88 Decl. +1° 36’
5981 D 18.871 153.4 1.79
5982 H 18.871 154.1 1.90

18.871 153.8 1.84
PARALLAXES OF 260 STARS

S.A.M.5 10-10.5

 

 

R.A. 62 52™ 288 Decl. +1° 7’
5981 D 18.871 272.6 3.65
5982 H 18.871 274.2 3.84
6750 D 19.230 272.1 3.72

18.991 273.0 38.74
Ho 33 [3968] 9-12
R.A. 72 15™ 158 Decl. +22° 19’

586 G 14.858 320.2 2.51
1088 G 15.213 325.2 2.64
38825 A 16.837 323.9 2.65
3768 Ol 17.3881 325.6 2.68
4830 B 17.918 328.2 2.69

16.441 324.6 2.63
Fixed?

a GEMINORUM [4122] 2.0-2.8
R.A. 75 29™ 308

 

 

Decl. +32° 4’

687
Ou 69 11-12
R.A. 74 48™ 1s Decl. —13° 54’
3269 M 16.815 121.7 3.04
Ox 70 11.5-12
R.A. 74 49™ 15s Decl. —13° 52’
3269 M 16.815 183.8 4.80

Ou 71 B.D. —11°.2299 9-11
B.A. 8 12™ 388

3304
3306*
3770
3771
3889*
6751

M
M
Ol
Ol
Ol
D

16.826
16.826
17.214
17.214
17.294
19.230

 

17.509

317.3
321.3
320.2
320.2
322.8
321.1

320.3

Decl. —11° 35’

2.59
2.65
2.76
2.75
2.29
2.57

2.63

2 Cancri [4763] 4.2-6.6
R.A. 84 41™ 528

620*
633
680

3797
3798
3828

A
G
G

M
M
L

14.892
14.895
14.958

 

14.920

17.227
17.227
17.240

 

17.231

Decl. +29° 3’

307.4
307.9
307.0

307.4

307.3
307.0
307.2

307.2

30.75
30.74
30.82

30.77

30.80
30.92
30.86

30.86

 

1931* M 15.829 219.2 5.45
1966 M 15.848 218.6 5.38
1967 M 15.848 218.5 5.38
2106* M 15.925 219.7 5.36

15.854 218.8 5.39
4553 A 17.773 217.0 5.25
4554 A 17.773 218.2 5.26
4660 A 17.789 217.9 5.35
4684* M 17.8383 218.2 5.384

17.786 217.8 5.29
Binary.

S.A.M.6 10-11
R.A. 74 33™ 45" = Decl. +5° 24’

1932 M_ 15.191 74.2 2.54
1933* M 15.191 70.2 2.32
2460 A 16.191 69.8 2.51
2461 A 16.191 71.5 2.65
2554* M 16.262 71.3 2.59

15.825 71.6 2.54

Angle constant, distance increasing.

7.5-7.6
Decl. +71° 8’

E 1280 [4815]
R.A. 82 47™ 598

 

 

6785 M 19.244 40.2 4.58
6808 M_ 19.252 47.2 4.54
6809 M 19.252 48.9 4.42

19.249 45.4 4.51

Rapid motion.
688

 

 

 

Ou 72 10-11
R.A. 9® 12™ 278 Decl. +37° 3’
5292* A 18.284 63.0 2.47
8144* M _ 19.908 57.7 2.14
19.094 60.4 2.30
= 1334 [5014] 4.0-6.7
R.A. 9® 13™ 538 Decl. +37° 9’
5292 A 18.284 233.0 2.82
6753: D 19.229 234.3 2.72
8125 F 19.887 240.0 2.79
19.133 235.8 2.78
Ou (r) 9-9.5
R.A. 9» 45™ 268 Deel. —12° 42’
6160 M_ 18.994 79.7 5.41
6161 M_ = 18.994 79.3 5.30
6747 F 19.227 78.2 65.41
19.072 79.1 5.37

y LEontIs [5388] 2.6-3.8
R.A. 105 15™ 325 Decl. +26° 59’

 

3504 M 16.9385 117.0 3.90
3507 M_ 16.935 116.9 4.09
3912 A 17.810 116.0 4.07
3918 A 17.310 116.3 3.92
3920 M_ = 17.332 113.9 3.86
3921 M = 17.332 120.0 3.83

17.216 116.7 3.93

Confirms Burnham that system is
not a binary.

 

y Vireinis [6243] 3.6-3.6
R.A. 125 37™ 40° Decl. —1° 0’

5* M 14.854 325.0 6.16
18 M_ 14.870 323.6 6.00
387 M 14.3892 824.7 5.88
51 M = 14.412 326.0 5.96
55 M 14.414 323.8 5.96
56 M = 14.414 323.8 5.94
14.395 324.2 5.97

Rapid binary.

 

S. A. MITCHELL

ALDEN 2 11-11.5
R.A. 135 9™ 548 Decl. +28° 8’

 

 

 

 

3702. Ol 17.150 1604 1.44

= 1733 [6438] 8.2-9.8
R.A. 135 12™ 258 Decl. +17° 40’
6168 M 18.994 142.7 4.76
6214 D 19.028 145.4 4.82
7199 M 19.466 143.6 4.78
19.163 143.9 4.79

6 117 [6896] 8.3-9.2
R.A. 145 26™ 548 Decl. —15° 15’
723 G 14.988 83.1 2.02
815 G 15.055 87.7 2.38
3722 L 17.178 87.0 2.41
6468 M_ 19.099 90.3 2.22
6279 D_ 19.052 89.5 1.98
7162 =F 19.422 90.3 2.04
17.466 88.0 2.17

Ou 73 9.8-11.5

R.A. 145 30™ 49 Decl. —11° 42’
6786 =F 19.244 105.7 2.82
6787 F 19.244 107.8 3.05
7185 F 19.4838 112.7 3.30
7186 F 19.488 109.0 38.11
19.388 109.2 3.11

= 1955 [7313] 8.7-9.3
R.A. 155 30™ 288 Decl. +26° 59’
1101. G 15.221 239.1 7.78
2741 M = 16.472 288.6 7.89
2742 L 16.472 238.2 7.76
16.055 238.6 7.81

Fixed.
PARALLAXES

 

 

S.A.M. (r) 8-9.5

R.A. 15" 40™ 558 Decl. +15° 33’
1403 G 15.487 321.4 6.36
1404 G 15.487 319.6 6.31
1431 Ol 15.511 320.7 6.42
2385 G 16.103 319.9 6.44
2814 M 16.530 321.7 6.44
4112 M_ 17.477 320.1 6.32
4113 B 17.477 321.4 6.36
16.356 320.7 6.387
ALDEN 3 B.D. +15°.2936 9.5-9.8
R.A. 155 54™ 338 Decl. +15° 47’
25384 A 16.248 454+ 1.54

£ Scorpr [7487] (4.9+5.2)-7.2
R.A. 155 59™ 58° Decl. —11° 10’
114 Ol 14.518 60.5 7.47
129 M = 14.528 60.1 7.34
1423 A 15.500 61.9 7.54
1424 A 15.500 61.3 7.33
1453 G 15.525 61.3 7.60
15.179 61.1 7.47

Angle decreasing, distance increasing.

> 1999 [7488] 7.48.1

 

R.A. 164 0™ 28 Decl. —11° 14’
114 Ol 14.518 100.4 11.42
129 M 14.528 100.0 11.43
1423 A 15.500 100.2 11.37
1424 A 15.500 100.3 11.32
1453 G 15.525 100.2 11.42
15.114 100.2 11.39

Angle decreasing, distance increasing.

 

OF. 260 STARS 689

49 Serpentis [7551] 7.1-7.3
R.A. 165 9™ 388 Decl. +13° 45’

 

3818 L 17.231 336.4 4.18
3819 L 17.231 335.6 4.12
4077 B_ 17.461 336.8 4.16
4078 M 17.461 335.1 4.15

17.346 336.0 4.15

Angle and distance slowly increasing.

o Coron [7563] 5.8-6.6
R.A.16511™ 41° Decl. +34° 4’

 

 

5315 Ol 18.310 218.7 5.16
5316 Ol 18.810 220.4 5.28
6528* M 19.129 219.8 5.11
6529 M 19.129 218.2 5.26
6961 F 19.8384 219.5 5.07

18.811 219.3 5.18
Binary.

Ou (r) 9.2-11

R.A. 165 39™ 338 Decl. +39° 16’
3886 A 17.290 279.4 5.10
3887* A 17.290 279.4 4.93
3895 A 17.296 279.9 5.10
5563 A 18.550 278.4 5.23
5574 A 18.553 278.7 5.09

17.852 279.1 5.09

a Hercuis [7914] 3.5-5.4
R.A. 175 10™ 59s Decl. +14° 29’

 

1442 M 14.548 111.8 4.84
1508* Ol 15.561 113.1 4.83
1509* Ol 15.561 113.9 4.80
2648 A 16.3849 112.6 4.84
2649 A 16.3849 112.5 4.72
2817 M = 16.580 114.8 4.65
2818 M_ 16.580 114.0 4.42

15.978 113:2 4.71
Fixed.
690

ALDEN (r) 7.8-11.2
R.A. 175 30™ 228 Decl. +52° 40’

 

5250 A 18.241 348.6 6.08
5251 A 18.241 347.3 6.20
18.241 348.0 6.12

70 Opxaiucat [8340] 4.1-6.1
R.A. 185 1 268 Deel. +2° 33’

 

 

 

 

 

1 M = 14.335 386.8 4.32
6 M = 14.354 37.8 4.56
7 M = 14.354 385.5 4.66
10 M = 14.357 87.0 4.50
14.350 86.8 4.51
249 M = 14.706 36.6 4.64
386 M_ 14.742 388.0 4.76
353 M = 14.745 38.1 4.59
365 M = 14.750 88.4 4.58
14.733 37.7 4.63
1183 M_ 15.280 38.7 4.70
1203 A 15.286 39.2 4.72
2113 M_= 15.288 38.4 4.70
15.285 88.8 4.71
3908 L 17.307 43.0 4.98
3909 L 17.307 43.1 5.00
3996 M _ 17.392 42.5 5.04
3997 M_ 17.392 41.9 5.02
17.350 42.6 5.01
4278 B 17.630 43.3 5.14
4279 B 17.630 43.6 5.06
4322 Ol 17.647 42.2 5.22
4323 Ol 17.647 43.2 5.27
17.638 43.1 5.17 |
Rapid binary.

 

S. A. MITCHELL .

Scus. 16 [8483] 7.9-9.2

 

R.A. 18> 15™ 31s Decl. —5° 0’
4386 B 17.672 202.5 2.98
5420 L 18.427 203.3 2.80
5421 L 18.427 203.0 2.78

18.175 202.9 2.85

Motion shown?

AtpEN 4 10.5-11
R.A. 18" 40™ 568 Decl. +20° 11’

 

1566 A 15.687 337.6 3.81
1592 A 15.662 341.3 3.91
4235 B 17.592 338.9 3.85

16.297 339.3 3.86

Ou (r) B.D. +5°.3994 9.5-10

 

R.A. 184 54™ 398 Decl. +5° 54’
7696 Ol 19.701 106.2 5.65
7697 Ol 19.701 106.4 5.71

19.701 106.3 5.68

S.A.M.7 9-11.5

 

 

R.A. 19" 7™ 68 Decl. +38° 14’
1310* M 15.681 175.7 3.54
1689 M_ 15.692 177.9 3.57
1640 Ol 15.692 178.8 3.80
2693 M 15.918 176.7 3.56

15.894 177.6 3.64

= 2481 [9114] 8.0-8.0

R.A. 19" 8™ 47s Decl. +38° 39’
1310 M = 15.681 217.1 4.87
1689 M 15.692 217.6 4.68
1640 Ol 15.692 214.9 4.66
2693 M 16.418 215.9 4.82

15.871 216.4 4.76

Angle decreasing, distance increasing.
PARALLAXES OF 260 STARS 691

J 1304 {2885} 9.4-9.7 = 2570 [9574] 7.3-9.5

R.A, 19 21™ 20° Decl. +11° 28’ | R.A.19841™ 8 — Decl. +10° 35’
2993 Ol 16.697 55.0 1.74] 403 14.798 278.1 4.59
3189 Ol 16.765 55.7 -1.96 | 1405 15.487 277.7 4.78
4370 A 17.661 58.5 1.79 | 16293 15.687 277.8 4.70
4371 A 17.661 59.0 2.23 | 4397 15.694 276.0 4.68
4463 B 17.732 59.7 2.14 —
—_— ——. ; 15.416 277.4 4.69
17.803 57.6 1.97 | Distance increasing.

Pbpb =

 

 

OL 74 9.5-9.6
R.A. 19 42™ 15s Decl. +18° 20’
Ox (r) 10-11 3133 L 16.763 167.9 4.28

R.A. 195 26™ 168 Decl. +27° 39’ | 4555 A 17.778 168.5 4.34
8 M 14.854 256.5 7.84 | 4576 M 17.787 169.9 4.32

16 M 14.360 255.6 7.44
17° M_= 14.360 256.7 7.62 17.443 168.8 4.31
1651 M 15.695 255.6 7.60

 

 

14.692 256.1 7.62 J 150 {3023} 9.4-9.6

R.A. 194 42™ 488 Decl. +10° 12’
1405 A 15.487 190.0 1.91
1406 A 15.487 190.2 2.15
1623 A 15.687 191.4 2.12

 

Z 2539 [9394] 7.9-9.7

 

 

R.A. 198 28" 52 Decl. +28° 6’ 15.554 190.5 2.06
8 M 14.354 3.9 5.87
11 M 14.357 1.6 5.46
16M 14.360 2.9 5.47 OL75 9.5-9.5
17 M 14.360 1.1 5.69 | R.A.19®43™11° Decl. +18° 27’
25* M 14.376 4.0 5.73 | 7068 F 19.389 10.2 4.35
1651 M 15.695 2.1. 5.75 | 7069 F 19.389 10.4 4.31
— —/| 71 F 19.408 9.2 4.27
14.603 2.5 5.66 s —— +=
Fixed. 19.395 9.9 4.31
J 497 {3049} 9.5-11.5
B.D. +0°.4339
2 2563 [9538] 8.3-9.5, R.A. 198 48™ 48° Decl. +0° 40’

R.A. 198 39™ 238 Decl. +17° 15’ | 1484* A 15.511 130.4 3.36
7899 M 19.768 285.1 6.22 | 1435* A 15.511 180.7 3.58
7900 M 19.763 282.3 6.23 | 1743* M 15.728 1381.3 3.50

 

19.763 283.7 6.22 15.583 130.8 3.48

 

 
692

S.A.M.8 10-12
R.A. 194 49™ 438 Decl. +8° 19’

 

1721 M 15.717 341.6 2.92
1722 M 15.717 344.2 2.71
4017 Ol 17.398 349.5 2.84

16.277 345.1 2.82

S.A.M.9 10-11.5
R.A. 195 51™ 43° Decl. +8° 13’

 

 

 

 

1721 M = 15.717 22.6 4.58
1722, M_= 15.717 27.1 4.52
4017 Ol 17.398 24.1 4.44

16.277 24.6 4.51

= 2618 [9852] 8.6-8.9

R.A. 195 59™ 46° Decl. +15° 14’
3107, Ol 16.741 115.6 5.65
4422 Ol 17.699 114.8 5.58
4423 Ol 17.699 115.0 5.66

17.880 115.1 5.63

H 907 [9986] 9.5-10.5
R.A. 205 8™ 298 Decl. +20° 45’

46389 M 17.824 131.9 6.08
4640 M 17.824 1382.8 6.09
5845 F 18.8388 131.7 6.02

18.162 132.1 6.06

Our 76 9.8-10.8
R.A. 205 9™ 328 Decl. +20° 58’

4639 M 17.824 132.9 1.32
4640 M 17.824 127.4 1.51
5845. F 18.8388 187.2 1.22

18.162 1382.5 1.35

 

S. A. MITCHELL

 

 

 

 

> 2671 [10135] 6.0-7.4
R.A. 205 16™ 268 Decl. +55° 8’
3256 M 16.815 337.5 3.27
3298 Ol 16.826 3837.2 3.25
4577 M_= 17.789 338.5 3.39
17.143 337.8 3.30
Ou 77 11-11.2
R.A. 205 21™ 78 Decl. +54° 49’
3298 Ol 16.826 40.7 3.79
p Capricorn [10228] 5.0-10
R.A. 204 24™ 188 Decl. —18° 5’
5217, A 18.230 171.4 2.38
5508 <A 18.501 168.0 2.20
5509 A 18.501 164.8 2.09
5818 M 18.791 172.3 2.33
7096° D 19.400 169.9 2.10
7097 D 19.400 165.4 1.87
18.604 168.6 2.16
Ou 78 10-11.0
R.A. 205 26™ 18 Decl. +29° 52’
7528 D 19.641 1386.0 1.81
7529 D 19.641 183.5* 1.45
19.641 135.2 1.36
E 505 {3300} 9.6-10.2
R.A. 205 27™ 20s Decl. +30° 13’
7528 D_= 19.641 14.6 2.13
7529 D = 19.641 16.0 2.04
16.641 15.3 2.08
PARALLAXES

=z 2625 [10504]
R.A. 205.41™ 8.

7.3-8.0

 

 

73 M = 14.452 4.0 5.25 |
74 M = 14.452 3.0 5.34
461 M 14.836 3.0 5.51
467 M 14.839 3.3 5.42
4106* A 17.474 4.6 5.42
4107 A 17.474 4.2 5.47
15.416 3.6 5.40

Angle and distance increasing.
y Devpuini [10509] 4.5-5.5

R.A. 205 42™ 57s Decl. +15° 50’
73 M 14.455 270.3 10.87
74 M = 14.455 270.3 10.89
461 M 14.8386 270.0 10.75
4094 M 17.464 270.2 10.69
4095 M_ 17.464 269.8 10.73
4106 A 17.474 269.6 10.78
4107 A 17.474 270.3 10.82
16.232 270.1. 10.79

Angle and distance decreasing.

 

 

Decl. +15° 37’

E 368 {3391} 9.5-9.6

R.A. 205 44™ 425 Decl. +30° 38’
31384 L 16.763 356.7 3.10
3191 L 16.787 360.5 3.02
3192 L 16.787 361.1 2.98
8251 M 16.812 359.3 2.98
16.787 359.4 3.02
e Equu er [10643] (5.7+6.2)-7.1

R.A. 205 55™ 58 Decl. +4° 0’
4385 G_ 14.830 73.2 10.74
548 M = 14.862 72.9 10.94
580 M_ = 14.876 72.0 10.82
1370 G_ 15.459 72.2 10.87
1371 G_ 15.459 72.3 10.74
15.097 72.5 10.82

Change very uncertain.

OF 260 STARS 693

ALDEN 5 9.2-10.6

 

 

 

R.A. 215 8™ 8s Decl. +30° 13’
1486 A 15.511 60.2 3.82
1498 A 15.547 62.9 3.55
1511 A 15.561 63.8 3.62

15.540 62.3 3.66
J 577 {3484} 9-11

R.A. 215 9™ 13° Decl. +17° 42’
5921 M_ = 18.860 19.1 2.51
7133 Ol 19.411 20.0 2.51
71384 Ol 19.411 20.0 2.60
7190 Ol 19.485 23.2 2.59

19.279 20.6 2.55

B 271 [10881] 7.2-9.7

R.A. 215 15™ 10° Decl. —26° 41’
7251 Ol 19.496 246.6 3.49
7252 Ol 19.496 241.6 3.52
7253 Ol 19.496 244.6 3.51

19.496 243.3 3.51
Binary.

OL 79 9.5-10

R.A. 215 26™ 208 Decl. —22° 24’
3402 M 16.884 3404 2.54

ALDEN 6 9-5-11.5
R.A. 225 10™ 208 Decl. +56° 31’

 

 

5582 A 18.586 249.5 2.13
5583* A 18.586 254.0 2.04
5597 A 18.594 252.5 1.95
5598 <A 18.594 249.8 2.26

18.591 251.1 2.11
694

53 Aquaru [11715] 6-6.5
R.A. 225 22m 238 Decl. —17° 12’

 

1919 A 15.829 310.7 6.32
1991 A 15.856 310.6 6.28
1992 M 15.856 311.0 6.23
3193 L 16.787 311.0 6.28
3194 L 16.787 311.8 6.15

16.223 311.0 6.25

Angle and distance decreasing.

¢ Aquaru [11743] 4.4-4.6

 

 

 

 

R.A. 224 24m 428 = Decl. —0° 24’
3255 L 16.810 308.6 2.74
38354 L 16.851 307.1 2.88
3355 L 16.851 306.6 2.98
4703 A 17.845 305.4 2.80
4704 A 17.845 306.3 2.88

17.240 306.8 2.86

Kr 60 [11761] 9.3-10.8

R.A. 225 25™ 138 Decl. +57° 15’
3244 M 16.809 61.4 2.44
3418 M 16.891 59.2 2.35
3419 M 16.891 60.2 2.41
3488 M 16.905 61.1 2.32

16.874 60.5 2.38
4166 M_ 17.507 57.6 2.31
4167* M_ 17.507 57.4 2.41
4168 M_ 17.507 57.0 2.42

17.507 57.3 2.37
4696 M_ 17.844 55.2 2.20
4697* M 17.844 54.2 2.17
4701 M_= 17.847 53.2 2.20
4702 M_ = 17.847 53.4 2.16
4727 M = 17.852 54.2 2.22
4728 M = 17.852 54.4 2.32

17.848 54.1 2.22

 

S. A. MITCHELL

 

 

 

 

5511 A 18.501 49.4 1.87
5512 A 18.501 49.2 2.02
5513* A 18.501 49.4 2.08
5569 A 18.550 49.0 2:14
18.513 49.3 2.02
5870 M 18.841 46.2 .2.19
5871 M_ 18.841 46.4 2.18
5908 M_ 18.852 45.1 2.30
5904 H 18.852 46.6 2.20
5970 M = 18.871 46.2 2.08
5971 M = 18.871 46.4 2.23
18.855 45.2 2.20
7850 M = 19.744 86.2 1.84
7851 M = 19.744 37.9 1.86
7852 M = 19.744 39.6 1.91
7946 M_= 19.799 34.4 1.99
7947 M_= 19.799 34.6 1.90
19.766 36.7 1.90
= 2095 [12265] 7.7-8.0
R.A, 235 12™ 26 Decl. —2° 1’
3479 L 16.930 30.4 5.00
3528 M = 16.962 28.8 5.04
16.946 29.6 5.02
Fixed.

ALDEN 7 10-10.9
R.A. 235 47™ 14s Decl. +50° 56’

 

2225 Ol 15.980 201.5 4.17
4205 A 17.578 203.0 4.19
16.779 202.2 4.18
PARALLAXES

ALDEN (r) 9.2-10.2 ;
R.A. 235 48™ 288 Decl. +51° 07’

 

2225 Ol 15.980 255.7 8.58
2227 M 15.986 255.8 8.58
16.983 255.8 8.56

ALDEN (r) 9.6-10.4
R.A. 235 52™ 098 Decl. +51° 11’

 

2225 Ol 15.980 238.6 11.36
2227 M 15.986 239.2 11.14
4205 A 17.578 238.5 11.29

16.515 238.8 11.26

 

OF 260 STARS 695

ALDEN 8 B.D. +5°.5244 9-11
R.A. 23" 55™ 418 Decl. +6° 14’

 

1571 A 15.648 28.2 2.96
1572* A 15.643 26.5 3.11
1597* A 15.667 27.9 3.02
1598* A 15.667 25.9 2.99

15.653 3.01

27.3

Ou 80 B.D. +33°.4824 9-11

 

R.A. 235 59™ 238 Decl. +34° 8’
8165 Ol 19.917 252.1 2.66
8166 Ol 19.917 257.2 2.52
8167 Ol 19.917 257.4 2.61

19.917 255.6 2.60
COLUMBIA UNIVERSITY PRESS

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Publications of the Ernest Kempton Adams Fund
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No. 1. Fields of Porce. By VILHELM Friman Koren Bserxnes, Professor of Physics
in the University of Stockholm. A course of lectures delivered at Columbia Uni-
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Hydrodynamic fields. Electromagnetic fields. Analogies between the two. 5S
a . Sup-
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No. 2. The Theory of Electrons and its Application to the Phenomena of Light and
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No. 3. Eight Lectures on Theoretical Physics, By Max Puancx, Professor of Theo-
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Columbia University in 1909, translated by A. P. Wiis, Professor of Mathemat-
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Introduction: Reversibility and irreversibility. Thermodynamic equilibrium in
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gas. Radiation, electrodynamic theory. Statistical theory. Principle of least
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No. 4. Graphical Methods. By ©. Runeu, Professor of Applied Mathematics in the
University of Géttingen. A course of lectures delivered at Columbia University,
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Graphical caleulation. The graphical representation of functions of one or more
independent variables. ‘Ihe graphical methods of the differential and integral
ealeulus. 148 pp. $1.50.

No. 5. Four Lectures on Mathematics. By J. Hapamazp, Member of the Institute,
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lectures delivered at Columbia University in 1911.

Linear partial differential equations and boundary conditions. Contemporary re-

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No. 6. Researches in Physical Optics, Part I, with especial reference to the radia-
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Edition exhausted.

No. 7. Neuere Probleme der theoretischen Physik. By W. Wien, Professor of

Physics in the University of Wirzburg. A course of six lectures delivered at
Columbia University in 1913.
Introduction: Derivation of the radiation equation, Specific heat theory of De-
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electron theory for metals, The Einstein fluctuations. Theory of Roentgen rays.
Method of determining wave length, Photo-electric effect and emission of light
by eanal ray particles. 76 pp. $0.75.

No. 8. Researches in Physical Optics, Part IT, Resonance Radiation and Resonance
Spectra. By R. W. Woop, Adams Research Fellow of Columbia University, 1911-
1914, Professor of Experimental Physics in the Johns Hopkins University.

line spectra, magneto-optics of iodine vapor,
eotaietele: Te eno rence. Seino rincaute of pases excited by ultra-
Schumann rays. Seattering and reflection of light by an absorbing gas. Mono-
chromatic illuminator, Resonance radiation of sodium vapor. 181 pp. With 10
plates. $1.50.

No. 9. Parallaxes of 260 Stars, derived from Photographs made at the Leander Me-
Cormick Observatory. By 8. A. MircHELL, Adams Research Fellow of Columbia
University, 1918-, Director of the Leander McCormick Observatory of the Uni-
versity of Virginia, assisted by C. P. Olivier, H. L. —- and sae ;

i i arallaxes, ectorscopic Fre-
Detail ot cna Mer tn, Comparinens aiinzes. Masses and ianeeattid. Double
stars measured. 695 pp. With 4 plates. $3.00. :