THE ECLIPSING BINARY SIGMA AQUILAE, 
 THE CEPHEID VARIABLE ETA AQUILAE 
 
 By 
 
 CHARLES CLAYTON WYLIE 
 
 A. B. Park College, 1908 
 
 A. M. University of Missouri, 1912 
 
 THESIS 
 
 SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE 
 DEGREE OF DOCTOR OF PHILOSOPHY IN ASTRONOMY IN THE 
 GRADUATE SCHOOL OF THE UNIVERSITY OF 
 ILLINOIS, 1922 
 
 URBANA, ILLINOIS 
 
Digitized by the Internet Archive 
 in 2015 
 
 https://archive.org/details/eclipsingbinarysOOwyli 
 
1 0 
 
 W9t 
 
 UNIVERSITY OF ILLINOIS 
 
 THE GRADUATE SCHOOL 
 
 1922 
 
 I HEREBY RECOMMEND THAI' THE THESIS PREPARED UNDER MY 
 
 SUPERVISION BY Charles Clay tozY.lyli5 
 
 ENTITLED^ .The__.Eolip8lng Binary SigsiaLAq^ilae.^ 
 
 The _Cephe 1 d_ Variable ta Aqu il ae, 
 
 BE ACCEPTED AS FULFILLING THIS PART OF THE REQUIREMENTS FOR 
 
 THE DEGREE OF. 
 
 Doctor of Philosophy 
 
 In Charge of Thesis 
 
 Head of Department 
 
 Recommendation concurred in* 
 
 
 y. 
 
 •Required for doctor’s degree but not for master’s 
 
 Committee 
 
 on 
 
 Final Examination* 
 
 CS8S99 
 
' .^'Q ^ it* *i r o 3 ns.j/-i .-M If 
 
 ‘SS0^-'M'r ' B .m tj: 
 
 
 *»«♦- i S 
 
 iSl"?! _! 
 
 r 
 
 »\ ' 
 
 ii.V' 
 
 * •ii.iiu,'r-j^i'<> ^u;>n r::‘''ii*TT/ (i’f 
 
 O' 'm. ''■' - V 
 
 ' ^ ^ 'tu^ '■' ''-vV'V--' ^ 
 
 U'^ fii>tii-f£o niki'i/Uttki ^yu i 
 
 a:. '':pffli 
 
 ,<viXi*>5:A < 
 
 i .. 
 
 Lmi 
 
 • «»?■ ai 
 
 <•. • ^'•., • •■* ■ iMHt^.,- . .'' , « W-Ji4‘-ar:. . “i iii iifl'iiih ■; •’;' ^ (f ^ 
 
 iL- i. ' J ' ' ■.' <^ "*''X ' ' 
 
 '• 4 *?^ 
 
 , ir«iL ;i 4 ’ 
 
 tn 
 
 
 
 .TI' 
 
 - •'• i\J' r 
 
 •t ■ ■ : :.*,. 0 * F^v.Jtaw-/; • . V - .:,.‘';i-;iMB' 'vj 
 
 -Til 
 
 •V ■•'.>*> J 'MsV'flj 
 
 
 ' '■'''’^^;f .W 
 
 
 
 
 
 .1 T 
 
 V'vi 
 
 
 0 ».’ u 
 
 Mm 
 
 
 
 ..if^ 
 
 
 t**f .|4 
 
 
 ^ 'i V 
 
 
 I. .'M 
 
 
 t ■'■ ■' r »' i/«*TO?WW“ t ^ 
 
 My\ y ■■(;.■ ' ■.' . 
 
 [jf V .. T^. ■< ■ 
 
 Jil®' W' A' Vv} - ■ 
 
 
 ■* I /' 4 Y 4 W.ll<il/> I ,' ^ 
 
TABLE OF CONTENTS. 
 
 I. The Eclipsing Binary cr Aquilae Page 1 
 
 Tables . 
 
 I Observations of cr Aquilae 4 
 
 II Normal Magnitudes of <r Aquilae 8 
 
 III Constants of the Light-Curve 11 
 
 IV Light-Curve of CT Aquilae 12 
 
 V Spectroscopic Elements of cr Aquilae 14 
 
 VI Elements of cr Aquilae, 15 
 
 Figures . 
 
 1 Light-Curve of cr Acjuilae 13 
 
 3 System of cr Aquilae 16 
 
 Summary 17 
 
 II, The Cepheid Variable op Aquilae 18 
 
 Tables, 
 
 I Observations of op Aquilae 23 
 
 II Normal Magnitudes of f3 Aquilae 28 
 
 III Normal Magnitudes of 7 Aquilae.. 29 
 
 IV Light-Curve of 7 Aquilae 31 
 
 Figures . 
 
 1 Light-Curve of ^ Aquilae 32 
 
 2 Normal Magnitudes of 7 Aquilae 33 
 
 3 Variation in the Period of 7 Aquilae 38 
 
 Summary 40 
 
I 
 
 
 ;x 
 
 r* •* 
 ,1 
 
 v«» 
 
 31 
 
 
 T) X'l&dxQ. s^^XafifioS «»rf'5. 
 
 
 •** 
 
 1 V 
 
 X 
 
 - I.-z.vTo^ 
 
 II 
 
 , i J ■ 0 1 w i c aoO 
 
 nx 
 
 ^ ' 1/ 
 
 VI 
 
 i ., .iX 
 
 V ■ 
 
 X>,p. A \- *;o 7 
 
 
 . r 
 
 
 .c^. IXcpA "io avi- )-4‘agiJ I 
 
 ' ir ii 
 
 ’l^iTJKwS 
 
 ''^ai 
 
 t. I y • 
 
 . . . . ■: irXiij:. \ i’l - bioii-. 0 
 
 ' i,yf c:; 
 
 ‘^/'xXrr* lo I 
 
 f '.>-' 
 
 
 
 X > rj;' A • >; '.. ^ ., '■ i .. J i; a^'J. i iii'/x ;; /: 
 
 . . . . i i^p A ; 'i o f*v 'i v'j'-yjL y.iJ 
 
 :r 
 
 V? *0 
 
 r;jslXL/pA lo a:>jti';)’.ti. V ' ^. .->1 
 
 i :• 'tc iotjo^ *f5:Xv :ii 
 
 YiAya ^. 
 
 
I. THE ECLIPSING BINARY SIGMA AQUILAE. 
 
 The variable radial velocity of (TAquilae (K. R, 7474, 
 magnitude 5,17, spectrum B8 ) was discovered at Mt. Wilson in 1913, 
 and the spectroscopic orbit was published by Jordan in 1916,^* 
 Jordan pointed out that the large value of K suggested an eclipsing 
 system. 
 
 The spectra of both components appear on the plates of 
 this star. Eclipsing binaries showing both spectra are the rare 
 and favorable oases, since by combining the spectroscopic data with 
 that from a good light-curve the dimensions of the system and the 
 masses of the bodies can be found, 
 
 A short series of photometric observations was made on 
 
 this star by Dr, Elmer Dershem at the University of Illinois in the 
 
 summer of 1918, The reduction of these showed variation in light, 
 
 which was announced by Professor Stebbins at the tv^enty- third meet- 
 
 2 
 
 ing of the American AS'tronomical Society. 
 
 A second series of observations was begun in June 1930 by 
 Professor Stebbins and myself. This was carried to the middle of 
 October at which time ninety-seven observations, about equally 
 divided between the two observers, had been secured. 
 
 With two or three exceptions each of these observations 
 is the mean of three complete sets of measures, a set consisting of 
 two readings on the comparison star, four on the variable, and then 
 two more on the comparison star. Throughout the series, 33 
 Aquilae (H. R. 7303, magnitude 5.40, spectrum Ao) was used as the 
 
 ^ Publications of the Allegheny Observatory 3, 189, 1916, 
 
 ^ Publications of the American Astronomical Society , 4, 
 115, 1919. " 
 

 
 
 
 
 i',I'i;L,v. A “v J'VT . ::. .SI. ^ ^ 
 
 ^c*EPPT- 1 ..' -:-.w (.■.■; ■ o.' . ,Vi^. . 
 
 ..’.'::t > V«r b9dliT u-it /.tcTT,' oi':^’OW6'%’ 
 
 
 I r, . 
 
 r.'- i ” 
 
 'I 
 
 ; i'Ki 
 
 ^ , '.'Od 
 
 .’ . .Ti; :' ‘, . ,.• 
 
 • . ' • ; , 'i ' r 
 
 , 1 ' ' I'j 6 •? . 1 - • ^ c;::^ ' . ^ 
 
 i> I 
 
 «■ .'■ ii' — ' ^ 0 fjsl t „,, tlO^: 
 
 : ;7::‘:.,. ,-g<. v<J : ,.ti 
 
 J' , ' I 
 
 C» a,V 3 X« 
 
 
 0 n. -o 
 
 - r r--:^ 
 
 L 0.1 m * 
 
 L 7 <l . - ' 
 
 ,.v I J,, ' 
 
 
 A \ 
 
 
 yd Cu.-' i 
 
 . V, .^i-: 
 
 
 f 
 
 J 
 
 ■ 
 
 I? r:.-. ■ 
 
 » ' ■ ' 
 
 ; 0 ' . ' ;.;i' 
 
 . ^C. : .; ?; j-tv :3 
 
 V .•..:7,,. 
 
 ^ ■. '< 
 
 :•-.*•’ f lOi . 
 
 V .^-.. VC " 
 
 ■ d JK 
 
 ' 1-; 
 
 • 
 
 ■ .: .t ::. 
 
 ■.■Iraat, c.^ 
 
 < , 
 
 . jc ,A'a 
 
 
 
 - 
 
 1 
 
 fief‘s* 
 
 . v.?|H 
 
 !>fr, 
 
 i'i 
 
 •• dQ:X f? 
 
 ;<‘. :> 'lo 
 
 
 
 .U T. :■•'■ iVcu . .. -» ‘CO 
 
 V*«'M 
 
 #f *v 
 
 
 
 
 » -f i.-, -, I ' 
 
 ^ X V ' ^ — 
 
 ■•■' • %<■ 
 
 
 • ' •#— ♦» • — - * - 
 
 ■' Ij *'-r’ r'it k -jJ'.U' ,/•' 
 
3 
 
 comparison star. 
 
 The differential correction for atmospheric extinction be- 
 tween (T Aquilae and 33 Aqullae was taken from tables based on those 
 
 M 
 
 in Mdller's Pho tome trie der Qestlrne . It was less than 0.015 from 
 
 li h 
 
 sidereal time 17.4 to 31.0, and few measures were taken outside this 
 limit. The correction to be applied was determined by multiplying 
 the tabular value by a factor depending on the transparency of the 
 sky, which was obtained in two ways: first, from the light effect of 
 33 Aquilae on the instrument, corrections for instrumental variation 
 having been applied; ajid second, from the observer's estimate at the 
 time of making the observation. The second method may seem some- 
 what crude, but the work at this observatory indicates that the esti- 
 mate of an experienced observer deserves about the same weight as a 
 result obtained by the first method. The factor for each obser- 
 vation was obtained by the two independent methods and the mean used. 
 The two stars are of nearly the same spectral type, and as obser- 
 vations with large extinction have been rejected or given half weight, 
 errors due to uncertainty in this correction should be small. 
 
 The times were reduced to the sun, and the residuals from 
 an approximate light-curve plotted using the total atmospheric ex- 
 tinction on cr Aquilae as abscissae. From this plot of the residu- 
 als it was decided to reject observations with an extinction greater 
 
 M M 
 
 than 0.35, Those with an extinction between 0,18 and 0,35 were 
 
 given half weight, and a few which had been marked weak for some 
 
 other reason, such as smoke, were given weight one-half or three- 
 
 fourths. 
 
 The center of eclipse was determined graphically, and from 
 

 
 
 ‘■ic'^!Kril ji'lt\% cKw^a^Ji ' |R 
 
 ■■' >»;i^,'::'^* ;.,;.'/ "■ ■■,■■ .' v; '.v.'J-..- ' <'''C-^"' r^' 
 
 
 
 Pj , <C. trf •■:->’ t i# 
 
 f v3:-.'^<?’*^#ii‘jc ';-qf feoij e;#^}ifc*»tf^.i2ftXijfq4 /;»gw i« 
 
 ' la •-:bhC‘‘r4:^v-i-i If ^ eUV- :i0 '>(^1 f 
 
 , ■ '■ . -Al. ' ^ 
 
 >. .' ’ ■ • ,. ' _' if. - •,' , *<>»■. ' ' i^'*'- ' :j 
 
 « 4 ';■<?'»'■ UA'^^?nun‘ff iO' i<^*- aAVMcw^’toof 
 
 r<^, '4’ W:* .«'•.*• o-'-.a, f . :fci-tb< ' ' ' 
 
 ■|V' &*s/trf.oaW& 3^4^I-,; • •l5'pri:|*v. 
 
 
 W - * • » -' ^ ^ f vJ\ V" 
 
 'iff., ^ , /■ .-' ‘.■;./v " 'v's^^-'r' V-r^ ’I 
 
 H' '■• '^' ■ ■ . v.v . 'V, .^ ■ . -vi:w ... .__X'«-v.; ^ h 
 
 1 . •tftt;’^r. f.U 5 V'-Pfv: A':'? .’ ‘ •'^* 
 
 ]J.':;iar.»‘wift:ii -s, -1 , , t4* ^avah^«i3^<ii»|'V 
 
 . JS 
 
 % 
 
 i! 
 
 ►T i? Jti 'i .. 
 
 • j. . 'i/‘*^‘ "i- I 
 
 offif'’’ ,ViV? vi\4i^v3t».. 6yl';;e^:; V 
 
 i:.^^-.;,A/; ;• ■;., -„\A.'.',* ,., ' ' '' ? 
 
 ..». >.v, >■ iitU'A-t.W •:'.««-“5/- — .tJ.^i. . . ‘. • ^ 
 
 V\ ■ '‘ I '* ‘*7, '^i * ‘ 
 
 '1 '■ •“' •■ , ,• ✓• ■■.,' 'r ' V •' ■■' . '' , .'i ’ 'I 'i, ■ -^ 
 
 ]j 't . ut-if-')jitir2..fs .ft^'^‘ ;jtv - 'si2z6 '^4 ;>X' 'i&v 
 
 1 ;■ X..LFI. >..■ ■ Mrf. • ,.■ ••". .• >■•' :* • • ^ . ... .• '■ • 
 
 ' .lii® " 
 
 ‘ ^ • ■”» /..r •■' .*7.s V ••. • •'■' -.cT* ■■ ■ •r/>‘^ ' V ■•!***■• . ^v-; •.■,?& 
 
 i‘. ► 
 
 ' ti»-Jv:,» 
 
 A\ ’i 
 
 -i-r.-',',- J^t VX^'T£ 
 
 ifrir 
 
3 
 
 the epoch of the spectroscopic observations and the 1930 photometric 
 series a correction to the Allegheny period off 0^00004 was obtained. 
 The available observations in 1918 were not sufficient for accurate 
 determination of the epoch of eclipse, but a larger correction to 
 the Alle^eny period would bring them into better agreement with the 
 1930 series. 
 
 A plot of the residuals with the time as abscissa showed 
 no evidence of variation in the comparison star throughout the 1930 
 series, but the 1918 observations were systematically high by two 
 or three hundredths of a magnitude. Because of this, and the un- 
 certainty in the period, the few observations of the earlier series 
 were omitted in the formation of the normals. 
 
 By using the spectroscopic period, with the correction of 
 f0f00004 derived above, and the photometric determination of epoch 
 of eclipse the elements 
 
 Minimum . J. D. 3433486.797 H- 1^95036‘E 
 were obtained. These were adopted as final. 
 
 The photo-electric observations of (TAquilae are given in 
 Table I. The times were reduced to the sun, and the phases com- 
 puted from the final elements given above. The difference of magni- 
 tude is the amount that <r was measured brighter than 33. 
 
 The observations of the 1930 series were then assembled 
 according to phase and grouped into normal magnitudes. The rule 
 was in general two observations to a normal during eclipse and 
 three to a normal outside of eclipse. At one phase outside of 
 eclipse two half-weight observations taken on the same night were 
 rejected, as the others could be grouped into normals of approxi- 
 

 lT*.i 
 
 
 
 J, 
 
 
 ^ Si 
 
 v' skiai ■ -■ , 
 
 ©A^Jd3oto4^| 069X jbna eno.ttf'J6Vi»acfo oXqoceOi^ oocja^* ^ib Sobac 
 
 .banlMi^io ex-w iOOCQ^aylo lK>i^t©q ©xl;? o^ aoXi’oeatob a adia©© 
 
 * ■■' " ■ ' ’ • 
 
 lol iron 03© w 3X61 at Baot^A^nAgU^ BitSAllavA a/iT 
 
 *J! 
 
 . V t’ , . I 
 
 aol&nBrttoa najixjil a tu^ ^©eqilos' lo'®£tooq© ©(if !to 
 
 9df rfiiw od'xii gnlTb* />Xjaoi™^oi':^sq t 
 
 .a»Xi«a-06€X [Kj. 
 
 bB^odB -asaioecys ©a ©cMi^ 4!fi» iklaxstlz'z^ 9dt \o ^oXq A>- a 
 0i.5X !>£i# »i/oil8boia3 i*Jb ae«ix6g3oo Btf# gx naiJaitar la •ai£«*i»s oo ^ '5 
 
 .-Vv 
 
 "■ 
 
 oy? ye yilioX^^o^aya ciair caoX3-*v^o3cfo 0X$X ^i/d" 
 
 
 fe'' 
 
 '•ajj ,aXri7 Ip ©sx/«©©5 .©irr^^Xi^a* 3 Ic eifi^i>©TbjiSi;tf tflKflft^' ^o |K.^ 
 
 ■« 
 
 *f»X*;De TSilTAd adtf lo 6U:Qt&>i7^&BQi> aiij at xtalM&zBo “« 
 
 I 
 
 *'C 
 
 ^i&l^isnoa Bdf ho £toiJtJW530l ©At^flX 
 lo iioX^siiiico dstt ^bct^3q pXq&wipitoaqa arfw ^ias/ y8 
 
 ' j" ■• gj 
 
 rfcocr© So asfitAi'ilm^ftp oixtm>:otoii(i 90^ bm b^yrtt^b K>CQO^Of 
 
 S £ ■’^ ■ g, ®' 
 
 ^ " a^AamsXa aiqxioa S%J 
 2’3£OdS^X -f V8T .33^tBi^^U'*‘.(2' .^^X^mroci/riK 
 ■It, . .I.iatX 03 ibetqpXjA hrsw oapfJIJ , .b^atAi^ ©3^ j 
 
 /Ji iiavXg ex» «AXixfpA”»^ So oA^i^A^v-rasdo ttiii’CjaXa-oioiiqt- ‘>tff J _ 
 
 ■ I ' fS 6 ^' 
 
 .I*’^»Xcf3T \l 
 
 -330 0 8*;'83d^ 9 d 7 bBA tOUQ &d 7 07 t^OUb^Z ©iff. 
 
 ® ^ t ' ’ 
 
 ^iAgAH So^ ©oa«iaSllJb atfT .*©,ycK/3 asvi^ a^taeatl© X^alS ■::‘03S. 5aJlrq 
 
 . . .- ..... ■ ,_ . .' 
 
 .SS 
 
 asd7 z9^si;s.tz(^ bmtf BAom «©« ^%,&Ad7 ^mfc^stA b 1 -Smt 
 
 ipJ ■. - ** ■■.••■ 
 
 
 t i/f* 
 
 -i 2 
 
 be£dst6B9A ao4f b^Itob 0861 »ri^ So 9SOttA7Z9§xio o41f^, 
 
 ® 1 <f 4‘'-" 
 
 sXi/T edT .«siHrtiix3ja® XjBazoa o^aX Jboqi/oia.taa bba^ki oi’* i»ai^q|ooo3 
 
 JRS 
 
 
 ^. ■ '"*• ' 
 
 Xus« ©aqiXo© lumon a «aoX{fi8vio«db ow^ Lax9fia% at a«v 
 
 *•* •’ 
 
 .e«qXio5 So abtBtao Imzoa a oi 
 
 Xo^obt 24 ao asAdq oao tk 
 
 y ■ - ■ !3i 
 
 <now Jif3ia emiu© od^ ao dadAi aaot^AVZ^ado #d3l««^Sl3d -ow^ ieql|oa 
 b-lxoiqqa So aXasiTOi: 09 if I b^ttoz^ ad i»XjUOp ozadito s;ft' ea »i)3foo^eT 
 
 ■ ' u .: !i xf:.iE,. --“:l' 
 
 ?r^ 
 
 T j. iT ' - i r .. ' ’LKy»j^«ag ? :.)«R 
 
 I .' . • - v» . .' ’ / .. ■ - 
 
 a 
 
 
 f ..I 
 
 ;f i! "JV. 
 
 ir.'jl ^<1 a ‘ 
 
 
 
 «' - '' Wi Bp y^A: fT»* ya ^ 
 
 ->V ■.r'jkl?. 
 
 m 
 
 :) 
 
 •i 
 
 h 
 
 ^ .V: 
 
 (V 
 
 I 
 
 ,'t 
 
TABLE I 
 
 Observations of cr Aqui la e 
 
 Date G.M.T. 
 
 Phase 
 
 Differ- 
 
 Weight 
 
 Date G.M.T. 
 
 Phase 
 
 Dirf er- 
 
 Weight 
 
 
 
 ence of 
 
 
 
 
 ence of 
 
 
 
 
 Magni- 
 
 
 
 
 Magni- 
 
 
 
 
 tude 
 
 
 
 
 tude 
 
 
 
 
 
 
 243 2514.737 
 
 0^641 
 
 0^^472 
 
 
 1918 S« 
 
 CO 
 
 (D 
 
 H 
 
 U 
 
 not usee 
 
 1) 
 
 2517.711 
 
 1.665 
 
 .426 
 
 1/2 
 
 343 1783.765 
 
 1?017 
 
 0^053 
 
 
 2521. 768 
 
 1.832 
 
 .423 
 
 i 
 
 1785. 75S 
 
 1.061 
 
 .445 
 
 
 . 797 
 
 1.851 
 
 .455 
 
 1/2 
 
 1786. 764 
 
 0. 115 
 
 .459 
 
 
 2532. 711 
 
 0.814 
 
 .438 
 
 
 1787. 775 
 
 1.134 
 
 .470 
 
 
 3523.646 
 
 1.749 
 
 (.405) 
 
 
 1793.738 
 
 1.229 
 
 .470 
 
 
 .672 
 
 1.775 
 
 .449 
 
 1/2 
 
 1803.771 
 
 0.520 
 
 .497 
 
 
 2524.679 
 
 0. 833 
 
 .454 
 
 
 1804.743 
 
 0.541 
 
 .500 
 
 
 . 733 
 
 0.886 
 
 .425 
 
 
 1805. 740 
 
 1.539 
 
 .488 
 
 
 .750 
 
 0.,903 
 
 . 387 
 
 
 1806.751 
 
 0.600 
 
 .457 
 
 
 .767 
 
 0.920 
 
 .351 
 
 
 1813.679 
 
 1.677 
 
 .461 
 
 
 .783 
 
 0.935 
 
 . 341 
 
 
 1817.665 
 
 1.763 
 
 .452 
 
 
 2535.697 
 
 1.850 
 
 •409 
 
 
 1827.644 
 
 0.040 
 
 . 433 
 
 
 2526.651 
 
 0.854 
 
 . 430 
 
 
 1828.649 
 
 1.045 
 
 .411 
 
 
 . 668 
 
 0.871 
 
 .436 
 
 
 1837.631 
 
 0.275 
 
 .458 
 
 
 2538.750 
 
 1.003 
 
 . 349 
 
 
 1845.611 
 
 0.454 
 
 .468 
 
 
 3539. 681 
 
 1.934 
 
 . 302 
 
 
 
 
 
 
 3530. 615 
 
 0.917 
 
 . 377 
 
 1/2 
 
 1920 S( 
 
 sries 
 
 
 
 .637 
 
 0.939 
 
 .338 
 
 
 2468. 810 
 
 0.017 
 
 . 313 
 
 
 2531.614 
 
 1.916 
 
 . 300 
 
 1/2 
 
 2498. 774 
 
 0.279 
 
 .474 
 
 
 .672 
 
 0.024 
 
 . 398 
 
 
 .840 
 
 0.345 
 
 .465 
 
 
 2532.643 
 
 0.994 
 
 .315 
 
 
 2506.763 
 
 0.46S 
 
 .480 
 
 1/2 
 
 .701 
 
 1.053 
 
 . 383 
 
 
 . 797 
 
 0.502 
 
 .481 
 
 
 .734 
 
 1.086 
 
 .438 
 
 
 2508.796 
 
 0.551 
 
 .508 
 
 1/2 
 
 . 751 
 
 1. 103 
 
 .442 
 
 
 2509.836 
 
 1.581 
 
 . 496 
 
 
 3535.. 615 
 
 O.OIZ. 
 
 1^21. 
 
 
 

 ,\ 
 
 I 
 
 r 
 
 

 
 TABLE I 
 
 (Contd. ) 
 
 
 
 5 
 
 Date G. M.T. 
 
 Pnase 
 
 Dili er- 
 ence of 
 Magni- 
 tude 
 
 Weignt 
 
 Date 
 
 G.M. T. 
 
 Phase 
 
 Differ- 
 ence of 
 Magni- 
 tude 
 
 Weigni 
 
 243 25 b 5. 629 
 
 0?051 
 
 ( 0 ^'^ 2 ? 4 ) 
 
 
 242 
 
 2561. 706 
 
 0?805 
 
 o5|^417 
 
 3/4 
 
 .647 
 
 0.049 
 
 . 298 
 
 1/2 
 
 
 2566 . 690 
 
 1.887 
 
 . 525 
 
 3/4 1 
 
 . 661 
 
 0.065 
 
 . 528 
 
 5/4 
 
 
 .708 
 
 1 . 905 
 
 .549 
 
 3/4 
 
 .661 
 
 0 . 085 
 
 .415 
 
 
 
 2567 . 680 
 
 0 . 926 
 
 .377 
 
 i 
 
 .692 
 
 0.094 
 
 .402 
 
 
 
 .697 
 
 0.945 
 
 . 328 
 
 1/2 1 
 
 .754 
 
 0 . i 56 
 
 .452 
 
 
 
 2570.619 
 
 1.915 
 
 .315 
 
 
 . 744 
 
 0.146 
 
 .425 
 
 
 
 . 658 
 
 1.954 
 
 .267 
 
 
 2554.605 
 
 1.005 
 
 . 529 
 
 1/2 
 
 
 2574.614 
 
 0.059 
 
 . 555 
 
 
 .619 
 
 1.021 
 
 . 542 
 
 1/2 
 
 
 .634 
 
 0.079 
 
 . 557 
 
 1/3 
 
 1 
 
 .635 
 
 1 . 055 
 
 .554 
 
 
 
 3585. 650 
 
 1.273 
 
 .440 
 
 
 .694 
 
 1.096 
 
 . 424 
 
 
 
 .645 
 
 1.288 
 
 .452 
 
 
 . 710 
 
 1.112 
 
 .451 
 
 
 
 2584.600 
 
 0 . 295 
 
 .453 
 
 
 .724 
 
 1 . 126 
 
 .448 
 
 
 
 .614 
 
 0.307 
 
 . 455 
 
 
 2557.710 
 
 0.211 
 
 .475 
 
 3/4 
 
 
 2585.606 
 
 1.299 
 
 .452 
 
 
 2539.609 
 
 0. 160 
 
 . 450 
 
 
 
 .622 
 
 1.315 
 
 . 448 
 
 
 .624 
 
 0.175 
 
 . 455 
 
 
 
 2587.601 
 
 1 . 544 
 
 .436 
 
 j 
 
 2540. 640 
 
 1. 191 
 
 .455 
 
 
 
 .615 
 
 1.558 
 
 . 451 
 
 
 . 658 
 
 1 . 209 
 
 . 440 
 
 
 
 2588. 592 
 
 0.384 
 
 . 451 
 
 
 .711 
 
 1.262 
 
 .457 
 
 
 
 .605 
 
 0 . 597 
 
 . 461 
 
 1 
 
 .722 
 
 1 . 275 
 
 . 449 
 
 
 
 2589. 574 
 
 1 . 566 
 
 .475 
 
 i 
 
 1 
 
 2555. 690 
 
 0.589 
 
 .485 
 
 1/2 
 
 
 .594 
 
 1 . 586 
 
 .446 
 
 
 2554.647 
 
 1.546 
 
 .457 
 
 
 
 2595.594 
 
 1.485 
 
 (. 432 ) 
 
 
 . 662 
 
 1.561 
 
 . 465 
 
 
 
 . 608 
 
 1 . 499 
 
 (. 424 ) 
 
 
 2559.690 
 
 0.758 
 
 .448 
 
 
 
 2595. 595 
 
 1 . 556 
 
 ,473 
 
 
 . 699 
 
 0 . 747 
 
 .447 
 
 
 
 .608 
 
 1 . 549 
 
 .455 
 
 
 2561.694 
 
 0.791 
 
 .424 
 
 3/4 
 
 
 2596 . 554 
 
 0 . 544 
 
 . 462 
 
 

 V-r * 
 
 * 
 
 ! ‘ 
 * 
 
 » 
 
 
 i 
 
 ' / 
 
 r 
 
 j 
 
 ) 
 
 I 
 
 \ 
 
TABLii: I (Cent a. ) 
 
 6 
 
 Date 
 
 342 
 
 G.M.T. 
 
 Phase 
 
 Dirrerence 
 
 of 
 
 Magnitude 
 
 2596. 566 
 
 0^556 
 
 0^^460 
 
 2600.581 
 
 0.671 
 
 . 441 
 
 2603.577 
 
 1. 716 
 
 .430 
 
 .587 
 
 1.726 
 
 .423 
 
 2605.563 
 
 1. 751 
 
 . 441 
 
 .574 
 
 1.762 
 
 . 435 
 
 2606. 514 
 
 0.752 
 
 . 440 
 
 2609. 542 
 
 1.830 
 
 . 422 
 
 .553 
 
 1.841 
 
 .420 
 
 Weignt 
 
 1/3 
 
7 
 
 mately the same value. The thirty-seven resulting normal magni- 
 tudes and the residuals from the computed light curve are given in 
 Table II. 
 
 A plot of the normals showed a distinct ellipticity effect 
 between minima, A periastron effect might also be suspected, but 
 as the spectroscopic orbit is circular, this was considered error of 
 observation. There is no appreciable reflection effect. The 
 ellipticity factor ^ was obtained by Russell's graphical method, and 
 the result used to determine the limits of the eclipses and check 
 the definitive work which was as follows. 
 
 From normal magnitudes outside of eclipse the ellipticity 
 effect was solved for, using the equation: 
 
 m^ — £ cos^^ = ffi 
 
 where m^denotes the maximum magnitude, m is the observed magnitude, 
 
 0 is the phase from primary minimum, and £ is a constant. Twenty- 
 one equations for the determination of ^ and £ gave 
 
 m « 0?467 0?0025 
 
 “O 
 
 £ . +0^042 ^ 0^0050 
 from which z s 0,075, 
 
 The ellipticity effect was removed from the observations by the 
 formula 
 
 Rectified magnitude * m ^ 0,043 qob^B 
 From a plot of the rectified magnitudes at secondary minimum the 
 center of that eclipse was determined as phase O^’SSO, from which 
 £ cos lA) ■ 40.004, The photometric observations are too few to 
 show with certainty that the orbit is not perfectly circular. But 
 the eccentricity of the spectroscopic orbit is given to only one 
 
U-. 
 
 ,... . s>.t -U. 7 C 
 
 O. V .^ 
 
 I 
 
 i!«r) , 
 
 ll . V ^ 
 
 ■. r.i ’7 
 
 
 ■ .i^-tr-.- 
 
 
 r ■’ A r. ^*' 
 
 
 F'W.r- ::,li 
 
 I J 
 
 ■'■'■Cf '.'I :■ 
 
 :■, ex- 
 
 it ’. 7 - '. 
 
 I 14 ■«'• 
 
 
 'u-. 'll 
 
 i 
 
 I 
 
 , j" 
 
 '■ ' nio'i'. r-y-fC^ ii 
 
 ■X 
 
 ' - r 1 .: '7 ... ■_ < :* : piSik*^. : • 
 
 •'7 2 ; " •: - r.ic 
 
 ^ •. Jt : ■•■ 
 
 • - ,.ob 
 
 . -C. 
 
 •tv I; 
 
 ’ ' "'r i 
 
 ' Vi * 
 
 
 
 tdv. 
 
 ■ •< I 
 
 « ■■-■■: I- b^tVtXj :> 9 l. 
 71 :.' tit::'- o'cn ' vi;t' 
 
 , . ' &iXT ^ t rntm.. 
 
 ‘i'./'iO, '-.■'? r^-;J 7' 
 
 •■‘ . 'j 
 
 ■.’> 
 
 7 p.v'V -i 
 *' .■) .tici isr 
 
 
 - V » i 4 
 
 »» • •• < 
 
 : 
 
 
 ? ti 
 
 r •* .f,/ 
 
 t -gtt.gy 
 
 
 
TABLE II 
 
 Normal Magnitudes 
 
 Phase 
 
 Dirrer- 
 
 ence 
 
 of 
 
 Magni- 
 
 tude 
 
 Residual 
 
 0-0 
 
 JMO. 
 
 Obs. 
 
 Phase 
 
 Differ- 
 
 ence 
 
 Of 
 
 Magni- 
 
 tude 
 
 Residual 
 
 0-C 
 
 Nc. 
 
 Obs. 
 
 0?020 
 
 M 
 
 0.305 
 
 M 
 
 +0.012 
 
 2 
 
 1.013 
 
 M 
 
 0. 336 
 
 M 
 
 -0. 002 
 
 2 
 
 0.056 
 
 0.323 
 
 -0. 019 
 
 2 
 
 1.044 
 
 0. 368 
 
 -0. 006 
 
 2 
 
 0.069 
 
 0.348 
 
 -0. 017 
 
 2 
 
 1.091 
 
 0.431 
 
 +0.003 
 
 2 
 
 0.088 
 
 0.408 
 
 +0. 010 
 
 2 
 
 1.114 
 
 0.447 
 
 +0.012 
 
 3 
 
 0. 147 
 
 0.429 
 
 -0. 004 
 
 3 
 
 1.200 
 
 0.448 
 
 +0,005 
 
 2 
 
 0.190 
 
 0.451 
 
 +0.012 
 
 2 
 
 1.268 
 
 0.453 
 
 +0.001 
 
 3 
 
 0. 293 
 
 0.461 
 
 +0. 009 
 
 3 
 
 1.280 
 
 0.446 
 
 -0. 008 
 
 2 
 
 0.375 
 
 0.459 
 
 -0. 003 
 
 3 
 
 1.319 
 
 0.445 
 
 -0.013 
 
 3 
 
 0.512 
 
 0.473 
 
 +0.006 
 
 3 
 
 1.370 
 
 0.451 
 
 -0. 012 
 
 3 
 
 0.563 
 
 0.478 
 
 +0.013 
 
 3 
 
 1. 543 
 
 0.462 
 
 -0. 002 
 
 3 
 
 0. 656 
 
 0. 456 
 
 +0. 000 
 
 2 
 
 1. 668 
 
 0.475 
 
 +0.013 
 
 2 
 
 0.742 
 
 0.448 
 
 +0.004 
 
 2 
 
 1.710 
 
 0.426 
 
 -0. 019 
 
 3 
 
 0.779 
 
 0. 428 
 
 -0.011 
 
 3 
 
 1.760 
 
 0.440 
 
 +0.001 
 
 3 
 
 0.833 
 
 0. 44l 
 
 +0. 008 
 
 3 
 
 1.826 
 
 0.422 
 
 -0. 009 
 
 2 
 
 0.878 
 
 0. 426 
 
 +0. 005 
 
 2 
 
 1.848 
 
 0.424 
 
 +0.006 
 
 i 
 
 3 
 
 0. 908 
 
 0.384 
 
 +0. 000 
 
 2 
 
 1.896 
 
 0.337 
 
 -0. 001 
 
 2 
 
 0.923 
 
 0.364 
 
 -0. 002 
 
 2 
 
 1.915 
 
 0. 310 
 
 +0. 000 
 
 2 
 
 0.938 
 
 0.337 
 
 -0.010 
 
 2 
 
 1.934 
 
 0. 294 
 
 +0. 004 
 
 2 
 
 0.998 
 
 0. 332 
 
 +0. 005 
 
 2 
 
 
 
 
 
I 
 
 / 
 
 J, 
 
 . . 
 
 ft; 
 
 I 
 
 
 t 
 
9 
 
 decimal, and this value of £ cos wj seems possible. The obser- 
 vations about secondary minimum were therefore reflected about phase 
 ©"fsBO for further work. 
 
 From the rectified normals at both primary and secondary, 
 
 elements were derived by Russell's method. It was found, however, 
 
 that as Russell has pointed out^, the value of k can be determined 
 
 from partial eclipses of such small range only with the addition of 
 
 data other than that derived from the light-curve. The assumption 
 
 that the eclipses were grazing total and annular, with k about 0.33, 
 
 gave the best representation of the light-curve. But this means a 
 
 difference of over two magnitudes in the light of the components, 
 
 while from the spectroscopic plates it is known to be much less. 
 
 The estimate published with the spectroscopic orbit is a difference 
 M 
 
 of 0.5. A second independent estimate made by Jordan in April 1921 
 is 0^3. 
 
 The secoixi estimate was used, and from this, with 1 -A]_, 
 
 and 1 - Ag the photometric depth of minima, k, ^ , and o(^were 
 
 obtained. After a few approximations the following elements were 
 
 adopted as satisfactory, 
 
 X =: 1.70 C =r 0,0799 D ^ 0.0470 
 
 k ■ l.OO(adopted) 1 - ^ = 0,121 1 -A^ - ^*0905 
 
 M 
 
 Rectified primary minimum = 0,327 
 
 M 
 
 Rectified secondary minimum s 0,364 
 
 The adopted value for k corresponds to a difference of 
 
 0.31 between the component stars, practically the second estimate. 
 
 M 
 
 Using k m 0,93 the light-curve holds for the first estimate, 0.5 > 
 ^ Astrophysical Journal . 35 . 331, 1912. 
 
10 
 
 80 elements were computed for both values; but the masses of the com- 
 ponent stars, and dimensions and inclination of the relative orbit, 
 were found to be practically the same on the two assumptions, and 
 only the results for k - 1.00 are given. An ephemeris was computed 
 from the adopted elements using Blazko’s tables^, and independently 
 by Russell *8 method as a check. The computed light-curve. Tables 
 III and IV, is shown in Figure 1. The residuals from this curve 
 are given in Table II, and from these we derive 
 
 P. E. Single normal - ^ 0^06 • 
 
 The normal magnitudes are plotted as circles in Figure 1, the radius 
 of each circle being equal to the computed probable error. 
 
 a 
 
 The data of the spectroscopic binary system , is given in 
 in Table V. The value of sin i. was known from the photometric 
 elements. Combining this with the spectroscopic elements the abso- 
 lute dimensions of the system and masses of the bodies were obtained. 
 
 3 
 
 Following Russell , the apparent diameter of the brighter star was 
 computed from the magnitude and spectral type. From this and the 
 actual diameter, the distance and parallax were obtained, the hypo- 
 thetical parallax being 0U006 corresponding to a distance of about 
 550 light years. 
 
 The light elements are assembled in Table VI, and Figure 3 
 is the system represented by them. The ellipticity of the star 
 disks has been neglected in the figure. 
 
 ^ Annales de 1 *observatoire astronomi cue de Moscou. 5, 104, 
 1911, o 
 
 Jordan, Allegheny Publicati ons. 3_, 193, 1916. 
 
 ^ Publications of the Astronomical Society of the Pacific . 
 
 315, 1920. 
 
;;/' :, -.W'' '.^U' 
 
 «i^aa«»S' fiidi\iuf^ '^-ffiieriir* i^Hi^^K'f^jsti' •iite^'4M:'%, ’I 
 
 j( ',y , ■ , ^ , 
 
 ,en:0‘JS>^Elu!l!ij5^?i’ C:'47t J!^(t' HO «JCf ;«’' *■ 
 
 ■ „;'' ■ '; . ^’’ . ■ 'ji^v 
 
 ii4‘‘ .aivM'4 :$f^g rK)^ k t'ti 
 
 - ti . ’“ r ' * f '"■ * > ' ' ’■'. f' 
 
 Xlt tsit^ t dVg^ssiSi^fe ilriv 
 
 ^ , j-air^r.^ ''"'t' "■ - .• r*' 
 
 S?7t aif ,eX*^t^tiaaii''W' n|.^;|iS'CaK' ,^V1 
 
 • ^;i , ■; » A< ' .JJu«.. '^'^lv. i^i 
 
 
 
 
 *i- 
 
 ■ 'it* 
 
 II;-. 4*.^ flat®' *3:43 
 
 1*1^ f 
 
 J 
 
 f.. 
 
 • SOCvOj* - ^^tux »i;^i&: ;s V|® ' 
 
 
 
 ^45^ lJiieiO£' ;44t’: 
 
 
 > '; 3 
 
 tX « ^r.T-f.rsxb* Id- 'few twif- 
 
 . !, ' '■•''■•"■ ' ■■■ . '-j' 
 
 'i -W* Kdoyi •• .a«o«?- 1. n^>tt f"i5 ,. ; Irti i'li5X’j^*X.x.i \ u 
 
 :k 
 
 •/p 
 
 ..'t? 
 
 •*o«iS4 of<;’<so£.oTJ 
 
 • "^ . ' ,♦ ‘ , '•N ,- I \ 
 
 .l>ajU^Cfo mihnd TAt Ic " ^ a.. 
 
 i£ii»v %'t7J^3^*35 ejfl 1o Ta;f i 
 
 rv • ^ ■ ‘ • t ' 
 
 ' ' "W'., e. S ■ ■' 'I'^tiJ '•. ' 
 
 t 
 
 
 
 .v ' , 
 
 
 
 
 II ' .V ■ ', ' ’ '• • 1^>-- i'^- 
 
 ' ^ .unfit Jq a v-i3“- i^itjjbc'aa'tfTOc* &OC^JO-,pn'^dt xnJMji^q, £i»o 1,1^3' - 
 
 8 ^' 
 
 
 
 r-(. 
 
 to ,IV ili 9tffikv^U 
 
 ratv - 
 
 '•ft A * 
 
 j|v^ Tiavtfe i)n t Aoi. 
 
 
 I 
 
 
 Vf'vV '. ('. , y 
 
 « 
 
 u 
 
 ■V »■' 
 
 ,. .1 \ H' .■' 
 
 
 f^_5>ra.v“."l.; 
 
 
 ' r]: fr' ’' . r ': ' ' ’ 
 
 ^^iiobSk-M V^ii..‘i.'^4i' -A X-4tfS? I'VN’.Uliyti.i. V -V ..; '-y«avfr..’ 
 
11 
 
 TABLE III 
 
 Constants of tne Lignt -Curve 
 
 
 Magnitude 
 
 Range 
 
 Lignt 
 
 Maximum 
 
 0^467 
 
 
 1.000 
 
 Primary minimum 
 
 0.285 
 
 M 
 
 0.182 
 
 0.846 
 
 Secondary minimum 
 
 0.522 
 
 0. 145 
 
 0.875 
 
 
 Rectified Curve 
 
 
 Maximum 
 
 M 
 
 0.467 
 
 — 
 
 1.000 
 
 Primary minimum 
 
 0.537 
 
 0. 140 
 
 0.879 
 
 Secondary minimum 
 
 0.564 
 
 0.105 
 
 0.910 
 
 Loss 
 
 0. 154 
 0. 125 
 
 0.121 
 
 0.050 
 
I 
 
 I 
 
 
 ^'V 
 
 ©siubB 5ij et>irJxasjaM j*)] 
 
 ooo\i f — ■ :,>'f ./^ 'v 
 
 K * -/ .1 ' ‘ 
 
 d*e.,0 &6I.0 ■-\\' '25aS' ''O’-,, '■ j^-,_ 
 
 I.' I,.-. itj 
 
 (. ■ ' 
 
 • ' 
 
 
 Coo ,ii. 
 
 fiVfc'.O ^ OfX .C i'vaL^tid! 'a:*! 
 
 7 |, 
 
 Oltt.O c^X.O 4^t,0 
 
 
 rw^V'-c 
 
 
 I ■ .'•» • ^ ' • r s( ■ *p *1. \ t 
 
 * ' 1 ‘ ♦■ftS .v^;pW j. :4B " * C 
 
 !, ..t*jLA*&,£tmhi .. :>■>'■•■. ft:.ir ■> M.'* -• 
 
 ' , ; '*i>- " ^ ‘.1 
 
 , ./ ^ r; /:.-:.;V^l^ .. 
 
 y-M 
 
 *; : 
 
 L 
 
 
 *' j^ » JUyjL3 t iJue - ■ i> ' 
 
 j'A 
 
 13^ , V ' ■\'i\^ ‘ j- • , .'■ ' [i* ' 
 
 I » tsT* 
 
 ■■ 
 
12 
 
 TABLE IV 
 Ligiit-Curve 
 
 Pnase 
 
 Din erence 
 
 Pnase 
 
 Difference 
 
 
 of 
 
 
 of 
 
 
 Magnitude 
 
 
 Magnitude 
 
 ±ofoo 
 
 M 
 
 0. 285 
 
 0^94 
 
 M 
 
 0.345 
 
 ±.0.02 
 
 0. 293 
 
 0.96 
 
 0.328 
 
 ±0.04 
 
 0.316 
 
 0.98 
 
 0.322 
 
 ±0.06 
 
 0.349 
 
 1.00 
 
 0.328 
 
 ±0.08 
 
 0.384 
 
 1.02 
 
 0.345 
 
 ±0.10 
 
 0.415 
 
 1.04 
 
 0.370 
 
 ±0. 116 
 
 0.430 
 
 1.06 
 
 0.396 
 
 0.15 
 
 0.434 
 
 1.08 
 
 0.419 
 
 0. 20 
 
 0.440 
 
 1. 096 
 
 0.430 
 
 0.30 
 
 0.453 
 
 1.20 
 
 0.443 
 
 0.40 
 
 0.464 
 
 1.30 
 
 0.457 
 
 0.488 
 
 0.467 
 
 1.40 
 
 0.466 
 
 0.60 
 
 0.462 
 
 1.463 
 
 0.467 
 
 0.70 
 
 0.450 
 
 1.50 
 
 0.467 
 
 0. 80 
 
 0.437 
 
 1.60 
 
 0.459 
 
 0.864 
 
 0.430 
 
 1.70 
 
 0.447 
 
 0.88 
 
 0.418 
 
 1.80 
 
 0.434 
 
 0.90 
 
 0. 395 
 
 1.834 
 
 0.430 
 
 0. 93 
 
 0. 369 
 
 
 
14 
 
 TABLE V 
 
 Spectroscopic Elerrients of CT Aquilae 
 
 (Jordan) 
 
 P 
 
 1?S5032 
 
 ±0?-0001 (estimated) 
 
 h 
 
 184? 595 
 
 ±0? 0095 
 
 Q 
 
 0.0 
 
 ±0.01 
 
 T(Max. Vel . 
 
 )J.D. 2420054.331 
 
 ±09^0031 
 
 V 
 
 -5.00 km /sec. 
 
 il.04 km/sec. 
 
 S.1 
 
 163.53 km/sec. 
 
 ±0.35 km/sec. 
 
 a]^ sin ^ 
 
 4,380,000 km 
 
 ±3600 km 
 
 m]_ sin'll. 
 
 5. 3 G 
 
 
 KS 
 
 199 km/sec. 
 
 ±4,1 km/sec. 
 
 ap^ sin i 
 
 5,340,000 km 
 
 ±110,000 km 
 
 mp sin^_i 
 
 4.40 
 
 
TABLE VI 
 
 
 15 
 
 Elements of CT Aquilae 
 
 1 
 
 1 
 
 1 
 
 Primary minimum, J.D. 243 
 
 
 3486.797 G.M.T. 
 
 1 
 
 Period of revolution (Photometric). . . . 
 
 P. 
 
 1?95026 1 
 
 Phase of secondary minimum 
 
 
 0?980 
 
 Semi-duration of eclipse 
 
 
 0?116 j 
 
 Component of eccentricity 
 
 ^ cos mj 
 
 + 0.004 
 
 1 
 
 Cosine of inclination 
 
 cos 
 
 0.314 
 
 Ratio of radii 
 
 k 
 
 1.00 
 
 1 
 
 Ratio of axes 
 
 b/a 
 
 0.955 
 
 Major semi-axis 
 
 ^1=^2 
 
 0.242 
 
 Minor semi-axis 
 
 
 0.231 
 
 Light of brighter star 
 
 hi 
 
 0.572 
 
 Light of fainter star 
 
 
 0.428 ' 
 
 Ratio of surface brightness 
 
 Jl/i2 
 
 1.34 
 
 Magnitude of system 
 
 
 5^*17 
 
 Magnitude of brignter star 
 
 
 5?78 
 
 Magnitude of faini;er star 
 
 
 6?09 
 
 From Allegheny spectroscopic elements 
 
 Sun s= 
 
 1 
 
 Major semi-axis 
 
 ^1=2:3 
 
 3.56 
 
 Minor semi-axis 
 
 bl=fc3 
 
 3.40 
 
 Density of brighter star 
 
 
 0.150 
 
 Density of fainter star 
 
 />2 
 
 0, 125 
 
 Mean density of system 
 
 Po 
 
 0. 138 
 
 Masss of brignter star 
 
 iLi 
 
 6. 19 
 
 Mass of fainter star 
 
 mg 
 
 5.14 
 
 Parallax (from surface brightness^ .... 
 
 TT 
 
 o'.' 006 
 
fii 
 
 s 
 
 
 J ■ , 
 
 f: 
 
 
 1 
 
 I 
 
 r ' }. iU t' ^ 
 
 qmaU Si 
 
TME SYSTEM OF CT AQUILAE. 
 
 FIGURE 
 

 Ft- 
 
 
 < - 
 
 
 
 
 1 
 
 V 
 
17 
 
 SUMMARY 
 
 1. A series of observations made with a photo-electric 
 photometer during 1930 gives the light-curve of cr Aquilae. 
 
 3, Using residuals from the computed curve the thlrty- 
 
 4 - M 
 
 seven normal magnitudes show a probable error of 0.006. 
 
 3, The comparison star 32 Aquilae was constant within 
 the limit of the measures from July to October, 1920, but a change 
 of 0^?02 between 1918 and 1920 is indicated for either 23 Aquilae 
 or (T Aquilae, 
 
 4, Because of the small range in partial eclipse, ele- 
 ments of cr Aquilae from the light-curve alone would be indetermin- 
 ate, but since two spectra appear on the Allegheny plates, the in- 
 formation on this eclipsing system is unusually complete. The 
 elements and absolute dimensions derived are given in Table VI, and 
 the system is shown in Figure 3. 
 

 
 
 0 V J ' ■ I - •? 7 
 
 V 
 
 
 
 
 
 j 
 
 ♦ 
 
 TT ^ <»i •• 
 
 . ■ w 
 
 
 ^: t;^ • 
 
 
 
 . I 
 
 
 t I 
 
 (•■ «» 
 
 i-i.' i-.v!'j wiit?.! 
 
 ■ 'W'-^. J '‘ :- 
 
 11 
 
 
 
 
 U 
 
 t‘ 
 
18 
 
 II. THE CEPHEID VARIABLE ETA AQUILAE. 
 
 A photo-electric study of tj Aqullae, one of the best 
 known Cepheid variables, was undertaken at the University of Illinois 
 in the hope that something of value might be contributed to the dis- 
 cussion of this type of variation. In particular, irregularities 
 and secondary oscillations might be too small for certain detection 
 by visual observers and yet be conspicuous in a photo-electric light- 
 curve . 
 
 Observations were begun in July 1930 and carried through 
 to November of that year. In all one hundred and eleven observa- 
 tions were secured, one third by Professor Stebbins and the remain- 
 der by myself. The variable and comparison stars are in the Harvard 
 system 
 
 H. R. 7570, 
 
 
 Aquilae , 
 
 magnitude 3,66-4.45, 
 
 spectrum G. 
 
 H. R. 7377, 
 
 S 
 
 Aquilae, 
 
 « 3.44 
 
 « F. 
 
 H. R. 7603, 
 
 
 Aquilae , 
 
 " 3,90 
 
 " K. 
 
 The Mt, Wilson spectral types are <>7 Aquilae F9, 5 Aquilae A9, and 
 ^Aqullae 07. An observation normally consisted of thirty-six 
 measures taken in the following order 
 
 53 , f36, 73 , ^6, 73 , /36, 73 , ^3, 
 
 one measure being a timing of the rate of motion of the electrometer 
 thread between two scale divisions. Since S Aquilae is brighter 
 than Aquilae, a neutral tinted shade glass was used to reduce the 
 light to approximate equality. Throughout this paper comparisons 
 of other stars with 6 Aquilae should be interpreted as comparisons 
 with S Aquilae observed through the shade glass, which reduced its 
 light about 0^82. 
 
 The differential correction for atmospheric extinction 
 
;JbAIHHTT .Ul .11 
 
 S-Btir(f *ro 2::‘j ,'nsllifpk ^ 1o vJtiL’^a -o^oc'^i A. 
 
 u€i: .iir*. “iO vj iE'T^vi c j 6 Si0h.^tz9l.z:r bi^rfqaC xf*ro(T-> 
 
 j -eit -.r:? v-J- lo :/ Tzd3‘ 9qod »&r 
 
 >0 j. - XTiXi' -*r * ^ t *! . *X; ; i~ "i XKJ n. . 'j'.-i.: l jlV Xo Bjtdf-’XO £iOl9B^'’: 
 
 nojc ctii’ob .iLcir’z:>T icl I Xaaarf c i)^ ^.o 34* in: it«.Xiioao VT.:^fcnoo^ i:rr 4 
 
 c.^--.^r^-ffi-07 •'.'■c, £ HL0tr',:.vr.7€'i- ocf tf»\ 4i.^v-6./cfo lex/eiv 
 
 uSi/orrf? tblzziio l£j: 0S91 '^bt/l r.i xiL-^ertf *^ci^ i^visedO 
 
 » -XSVltQXfO li-lb.zu.. 2,40 I.h i.T . ti»t* ^ ic TSOffi^VSli; , 
 
 * . “ 1 
 
 -^.i.^:.■■.s•: i«n;t iofi onirXcf8?B T :> i * v*^ s' i)iid7 ■. o .i/&i4'-8e -‘^caw EX2oif 
 
 i-^.V’TiC'i arf;f r.i x?*;.*: sa'T .^teavs YO 
 
 I 
 
 
 
 . .C vfu 
 
 ,ej»SUr-A 
 
 ,^>aT ,H .H 
 
 nr 
 • » 
 
 11 
 
 •S,. ** f»' 
 
 .1 • *> 
 
 XXx/pA , k 
 
 t‘^VCV .fl .F 
 
 
 ft 
 
 o 
 
 c 
 
 1 X* oX i:.].' a -O, 
 
 tSOo^ .H 
 
 ' 'f-'ni 
 
 ,t-A t'aXii/pA 
 
 ^^X • rSbiq^.K ^ or A 
 
 '“C-nvo 
 
 sq^: ,'OsIitT .; 
 
 xiB-Yr-ii't xc \'IL*:r.T4.: no tex^VT^osjcfo .VC ©jeliirpA 
 
 isb':7 '^^-4 ; *.oJ Xc'i’ ‘'•xfJ c eti.Ti/axiiK 
 
 .S'- .V .'“■■.,?*■ ..r-.- ,CA. ,,J • 
 
 •■ '* i V 
 
 -5»t c'.xtC'T^vC:'-:! '- ^,.‘.x i':; .'ioiJt;::! “te 'io gni"'!?' .a r, -ivo ^msssfe enc 
 
 ■2^- *. I ,4'*::: ai oaiI;jpA i, eL'.:tr . .:,iOJf^ivil>' sXAoa oitj /teav^'scf bjaaijrfj 
 snJ eaitl5 ate;'& XjSvt-iif x. , T-nXircA , 
 
 1 
 
 is.ioti x'lxqmco fLlr,t .‘rirDii: . .vi’ifxx^p© ftt£4rJtXCi.jq- o7 
 
 sroci'* .-q.ro;> €0 tvrc'xq're-^.'i Utl I ^-voda 3J5li;;pA :1,U r< GXC^fi lo 
 
 p.7i r-oot/i-oi Mof.'iY ■o.Si^rTe Lovitacfo saXiijpA ?> 
 
 ,E;{3^^ i'l/odxi ifdjjii 
 
 fic-iif on J:rJ5 oi:jS:;^*.'Oirjs:3 ri'oixri&'joo; ijaiJaeTellib sdb 
 
19 
 
 between 7 Aqullae and the comparison stars was taken from tables 
 based on those in M<iller*s Pho tome trie der Gestirne . Nearly all 
 observations were within the limits 19^^0 and 23^5 sidereal time, 
 during which interval the maximum tabular differential correction 
 was for S Aquilae, 0^018, and for Aquilae, 0^043 . The quantity 
 
 from the table was multiplied by a factor depending on the trans- 
 parency of the sky, which was obtained as in the work on cr Aquilae. 
 The residuals from the preliminary curve were examined for a system- 
 atic hour angle correction; first, by plotting them for nights on 
 which observations were carried on throughout nearly the entire three 
 and a half hours during which the star could be observed; and second, 
 by comparing residuals at different hour angles on different nights, 
 using only the best nights. There was no indication of any appre- 
 ciable systematic error remaining after the computed correction for 
 differential extinction has been applied, although these corrections 
 were larger than is usual in the work here. 
 
 The times were reduced to the sun, and the preliminary 
 phases computed from the elements 
 
 Minimum » J. D, 2422606.562 -h 7^176382 • E 
 The period is that of Luizet^, without his harmonic term. A plot 
 of the observations indicated that both comparison stars are prob- 
 ably variable. At certain times S Aquilae was distinctly faint, 
 in one case as much as a tenth of a magnitude, and toward the end of 
 the series ^ Aquilae was fainter than at the beginning. 
 
 In 1918 Messrs. Stebbins and Dershem used S Aquilae as 
 a comparison star for Nova Aquilae No. 3, and at that time it was 
 
 ^ Astronomische Nachrichten . 163, 361, 1903. 
 

 liL'Xr.'A? ,.i 
 
 
 .r 
 
 aoai-r^'KOO ed& btj£: . xjeeirrf-sd 
 
 IIjp •{It..-, .-^ :'--^.t..^O afrt^.ir:p yorfq s'^oII/JU al stCil^ ixc 
 
 ,oaiij- 0^€I a^iniiX &.i*3* Ciid^lXi 
 
 X 
 
 .77i^ ; r *-i.j.".:r£M ©rf? X£vt:.?-r:i dbirlw tiri-r . 
 
 ^1 . . €s 7 0'1 fc/ . 
 
 ?Lf ;, v^./j.-naqi-i: icir-M A vcf t-ilfq!: Xrni b3u ©XcfA? .*1+ ’^oi; 
 
 . :<^o;r «;’? rri ta X'-' sA«r -:oiJ>v ,xit> "io 
 
 -.-::5.‘c,^ /. ir''i ov r. ©'viXi-o v" -A tialXe-xq idJ .’ac^-1 «Xj-. .,;. ©iil 
 
 ^ no -'■ VO , c.v i;r ;.-^i-3:i>u fiX^rw ut'orf ct^^J 
 
 r— ■^' *n.. L^tzr/^o i>i9r .,anoX?j?vt©f.tfv xlot-fw 
 
 ,>i:- : Lr. ; ‘-.ev- otcj'o ©itf Mi/o^i i.o.?ci aciaw \:il^ul 6*ux>d ^.f«£i J3 
 
 ,?L.:/ :i.7 nx.i.iAllXit rto bstliiCL^ ? n 'lo'l-. .. . eXiit/t Uo^i \^a1i-^oiod ’:c 
 
 V.7, noiiitoifcxTi *.ii otoT, .?ivJ8i:a yaatf ,.Xno s^iax; 
 
 j 7:': r..;;. nos Clio;. tad'LXimoc -on>- ‘rpi'ro c ‘:t^o,r.o + c<70 ©XrfAlo 
 
 ■•■ 5 ' •; 
 
 I 
 
 t / 
 
 V ^•L v.-t np;.or:?i- ,L;^i£qq« rii-ed UAid ’: ln‘oxiitv& Xj^ita©TO":'ti.x; 
 
 XlO' »; 1 J^ ■'tt a^di 'X9^z^t »t©w 
 
 \ni...iT’i*0i£sT^, x.rta ^.;ca nq Xcoi.'i:.©i- aioir drfY 
 
 ni'xrJWi^Xa mci’y ' oft^qiaoc* essAxiq 
 :i « 4- u , .-iriji • -. 
 
 t 
 
 .rf 
 
 ...i'lO^ oirroAnAC , ^tsixiuj lo botitq hdT 
 
 CIA rso.pii^-.-.A j;;od t-:i^sotbtil Mt.oltsv%t^^::o :>di io • 
 
 <.'.. l 3 l 0 ',r. ©Aily; A J bbicif r.iAiJ^ 7 ©D . iw'At^.OV yXuA 
 
 ;,.'0 ..-^n Zy 2 ^V’,)t ^•'.: JJ ^ , j. rfjjiyjj , 3 ,- ^^0 flX 
 
 i 
 
 u; 
 
 don Tdiro-.!^"i ^ eoXiaa 9dt 
 
 or-. soXio^A : ..,o:’. ..n'l Xfiu: Oi.iddt-? ' BX?! xil jfj 
 
 3 E>i!to i£ , :'V: sAX Jij'pA jsvo'tl *io'i Txs^n nccXT::.iajoo ^ 
 
 —I 
 
 # 
 
20 
 
 suspected of variation. It has been announced as a spectroscopic 
 3 - 
 
 binary oi unknown period, and may be an eclipsing variable of small 
 range. The other comparison star, p Aquilae, being of spectral 
 type K, may be expected, if it varies at all, to be irregular. 
 
 As a first step toward unravelling the variations of the 
 three stars, the observations where 8 Aquilae was noticeably faint 
 were marked. Then using only nights on which the transparency of 
 the sky was good, and including no nights on which S Aquilae had 
 been marked faint at any time, the observed values of p y S were 
 plotted and a free hand curve dra'^wi. The plotted values were com- 
 pared with the curve, and one or two more rejections mads on the 
 ground that 5 Aquilae was perhaps faint that night. The remainder 
 were grouped into normal magnitudes which are given in Table II and 
 plotted in Figure 1, From a free hand curve drawn through these 
 normal magnitudes, the photo-electric reduction of p Aquilae to 
 S Aquilae could be obtained for the time of any observation. 
 
 The observed values of p y 8 'wexe compared with this curve 
 and from the residuals an unsuccessful attempt was made to get the 
 period of variation of 8 Aquilae. Phases were computed and the 
 residuals plotted, at least around the supposed minima, for several 
 different periods, but none was considered satisfactory. The range 
 of variation is so small that it is probably better to await the de- 
 termination of the period from spectroscopic observations. 
 
 Not knowing the variation of 8 Aquilae, the following ar- 
 bitrary rule was adopted. If any observed differed by more 
 
 ^ Astrouhvsica l Journal . 49 , 354, 1919. 
 
 ^ Lick Observatory Bulletin . 2, 126, 1903. 
 
 As trophy si cal Journal . 39 . 265, 1914, 
 
Pit, _ - n . r .■ 
 
 llte^agaor ,1 •- 'ift.-i t;vT»r- - r 
 
 r* 
 
 
 ,V.;> 
 
 
 
 ■c f i. Mi- o::a^ i.; i:»c e.^;. 
 
 i 
 
 ! 
 
 . aoi;tci’;/sv iw j 5 >etreqot;B 
 
 lii'.UB 1o 5.r-i:jL'i.i:v n^- tn, ^Loiioq xiTPO/fiuTx/ 
 
 lo t'' T»£i^o ®iiT . 
 
 j . ..j,: . iTi :?^ , riij Sj 3 sa2t£V Cl li otjqx© ■ V" t ccit* 
 
 / ”^ • i;; 
 
 f :r;.-' -’c* ♦riioXtrisI'X^V Oa*- ill® vis^fl* Ll^WCf^ a®i^S » A:aA 
 
 I :' • '.' * ' 
 
 'cIuJrtDi^ :'.i psr A vT9iiW ..anci3^.\rT^&<fo ,s*r<to^e 
 
 lo vi>,.oTi:'C:c’ .'lo.M’-' ua er.:^in ^irjfa nerTT .LuitAiA 
 
 fci,:: s£lj.,:rpA ' ioL"'w :to fivtrijgic Oi: tiACp*’5jt aj$v 6f:j- 
 
 ‘‘■^ •, ^ .I.“;V l)ovitv3c'(j v: w 4 ?.-.’',"? ^is' fc®iT£.-: rrtecf 
 
 -Y.-^c ft. T'-r.toX-; t.X? . 'f«r, to ^VTifO o.t./?.*.. o."! \te Jt>r..^ 6cj?yoIa 
 
 s 
 
 .t no i't**'. ‘ OTO.: 'O cno ha? ^^r'TU'J d^Lv 
 
 •c»baiAi'-. ..T ■•:':? - -t'£u/oi:' 
 
 htJA II oXc'iiT r.i n»vi^ ei4 dcid'- 'latato.T b^nl. Jbtqaois 
 
 .r,:; ^*'. •Tr-'nb 3-srr:i.'0 X.-ia.-l -zzl h .1 rtX ,ba^J“oIq 
 
 .. ' '-.ili'. c).. lo noi&xiubri^ Dii^'ooXs-c^Oflq ©dJ- «';ejL3 , ;t tn^fc ?} 
 
 * . i:' avti.-oo ((ir> lo ©ftiX? . 1i ’Xo %>iiXi.Kcfo '. . joo aAlttspA Z 
 dv?:..rr. •■rXrt3' A.‘ *'' :. x^i ;; ’ .’imij ^ 6z>jJU\v b^^rl^^n(^o s4T 
 
 J»:w oC" ffijji,:. ai’.% jop;...- ux; iia a r.*i;,/jbia©x tnoil tn-*? 
 
 s:rt bas. . ••t.Ax.Tioo' im:sv fe©«s4iX*5 . , 'UJopA "A \o ' do lo boll 
 
 ro'i t-.:i»o.'.Tv'.r« ?dc Xnuo’Xta tOOvO’oXq, bXax/Msox 
 
 o-'.y.n e.:'." ., ^^i©i»xa;ioo a>;v/ i’jaon j'.ra ^iJioXisq ,trjOT3'i‘iit 
 
 ■•'ji. ;-ifv CtBr<J5 oC X3AJ vXc.>rioTq o.i ji :t^dC fXr.iTfO cX nci’JiriTav 1*0 
 . .4*j ta‘«vxo<ic^o ^iqoc^ o'ly o®q& r;ox^; .h0i'isc. arfi lo aoi^imXiKX©^ 
 T^nixoIXot' ode ^oy,.it:r;z\ >\ lo rtoX#Jili^>v 6rf:t. snin^joat ?o';l 
 e^TTr. 11 II . hi'.-ri?Eao -p::3 ?wqoh3 b4.w 0X;j'r 
 
 •v’lj 
 
 J 
 
21 
 
 M r 
 
 than 0.040 from the curve value, all comparisons with c Aqullae 
 
 M 
 
 were rejected on that night. If no residual exceeded 0.040, hut 
 
 M 
 
 some exceeded 0.030, the observations on that night were given half 
 weight. A few other observations had already been marked half 
 weight because of poor observing conditions. 
 
 Observations of^7'’7were reduced to <5^7^ by applying the 
 correction scaled from Figure 1. Normal magnitudes for 07 were 
 then formed, keeping the work on the two comparison stars separate , 
 and a free hand curve drawn. As a check, the variation of/oAquilae 
 was then determined by combining observed values of with the 
 
 light-curve of 0 ^ as based on 6 , using only good nights. These 
 computed values of y3 7 5 as derived through 07 were assembled into 
 normal magnitudes, which are plotted in Figure 1 for comparison with 
 the values of direct observation. The satisfactory agreement shows 
 that the progressive change between p and S during the time of ob- 
 servation must be due to a variation of /3 , and that the light vari- 
 ation of 07 repeats itself from period to period within the limits 
 of the present measures. 
 
 The times of maximum and minimum, and the amplitude of 
 variation for Aquilae were derived graphically from the normal 
 magnitudes as follows: 
 
 d M 
 
 Maximum, phase 0.09, magnitude -0.501 
 
 Minimum, phase 5^17, magnitude -0^616 
 
 d M 
 
 Maximum - minimum 2710 > magnitude 1.12 
 The correction to the time of maximum from the preliminary ephemer- 
 is is thenh0.09. This was applied, giviig the following elements 
 which were adopted as final: 
 
 d 
 
 Maximum • J.D. 2422606.652 + 7.176382* E 
 

 
 \, 
 
 >/'■> 
 
 I' 
 
 Wii^ 
 
 ^ 1.^ ■ J.'.^ 
 
 .’■ -7 
 
 :sr:t -5 
 
 s .» 
 
 
 • :,o 
 
 
 ■ r V ' t 
 
 . A" 
 
 
 K,*. nV/-'' 
 
 V 4 -, •‘•’I, 
 
 . , |i 
 
 . ^ i. 
 
 •U>:' i. 
 
 I -• 
 
 - n/ ^ J . . 
 
 i ^ 
 
 •■ ^ i ..fl- 
 
 O'.. •■•.■ (r.rrtyr:: 
 
 I '■ . * J" 
 
 '., ■ ■ 
 
 
 
 
 V*' 
 
 n 
 
 V I 
 
 
 ■ r*£ 
 
 ^0 ;>'-*v„cv. > 
 
 • - !< 
 
 :r 
 
 , :■ ' 
 
 
 
 4 i 
 
 e * V I 
 
 -r.», ■ ’1 
 
 T. 
 
 i -t fl 
 
 ■!-< ■ 
 
 ' r*v , ofclb 
 t ■■•*>■ - 
 
 • ‘ 
 
 V 
 
 
 
 ’ . ^' 2 . 1. 1 } 
 
 
 
 OX . <• „j<w4(£a - 
 
 •x ■ <'-:s7 ,.«'C .U-, i/. .•• A“, i o 0| 
 
 
 
 
 . ^ ■' 
 
 •7.asJV^^J 
 
22 
 
 Table I gives the photo-electric observations of Aquilae. 
 The first column gives the Greenwich mean time of observation, and 
 the second the phase computed from the final elements; the third 
 column gives the difference between 07 Aquilae direct and S Aquilae 
 measured through the shade glass, and the fourth is the measured dif- 
 ference between 07 Aquilae and ^ Aquilae, A positive sign means 
 in each case that the comparison star was brighter than op . Re- 
 jected observations are in parentheses, aind half weight observations 
 are noted under remarks. Since the average time of observation is 
 the same for each star, the differences p brighter than S are ob- 
 tained by subtracting the third column from the fourth. 
 
 The normal magnitudes, with phases from the final elements, 
 are given in Table III, and plotted in Figure 2, where points from 
 the two comparison stars are kept separate, and the rejected S 
 Aquilae observations are plotted as crosses. No p Aquilae observa- 
 tions considered satisfactory at the time of making have been re- 
 jected, so all comparisons with that star are incorporated in the 
 normal points. 
 
 The adopted light-curve of 07 Aquilae is given in Table IV. 
 It has not been drawn on Figure 2 as the observations themselves 
 mark the course of the curve satisfactorily. Further, anyone ex- 
 amining suspected fluctuations will probably prefer a plot of the ob- 
 servations free from any evidence as to the judgment of others. 
 
 A glance at the figure shows that the reality of a con- 
 siderable "humj?” cannot be questioned. Since absolutely all of the 
 observations are represented in Figure 2, it is evident that the 
 variations of p and ^ do not affect the establishment of this 
 
St 
 
 J. 
 
 
 t, 
 
 
 
 L^Xlc/pA to «rtDj;i"3vi»©cfo o^s^o«X^'-o^ocf<^A9^Ct esvig^ r' eXcfoeT l^ 
 
 l . -..♦ 
 
 I 
 
 '.ijcw ,ROX^j 8 TPi« 4 id'o to itoXtrniiSiO aovis iTSttfloo ^aiXt eiSt 
 
 B ■ -} 
 
 9£f^ X^jjXt *201! jb©i;uqfBjoo sa 
 
 -i • '^ •' 
 
 ban n^ljpk K- x»aiftf:acr aofidT«ltXl> oii* aavi^ xlt:{;Xoo 
 
 II ■ • "' 
 
 i>05X?cii«w al arfi taa . 
 
 T r '■ ^ 
 
 ♦.'M« aax» ol'X^iaoq A .0i*Xt{jp4 tern ^ naaw^Ad aoc«Toi ^ 
 
 -oj^ , HT T»/^5i*rcf c^w xa^a «toe 1x451000 4oa» 
 
 iffoX^ 4 Ts^»ado J-Haiaw !tXjsci Jbfw tSoaerJifsox^ aX er# aaoXtjsvrtado ied-oot 
 
 
 ' ai rtoi^javreacfo to auX;f «oaJ3- 
 
 ,«stT^«i x%tar bo,roxt ®f« 
 iS* n ' I 
 
 -cfo i>TJ 3 ir iM£f^ •:^44^l’i€ e®onoxattx'& -sfi^ «T 4 ;fs lot bom •J'jf 
 
 ■12; 
 
 K 
 
 ! I 
 
 t*!<- 
 
 .n?T4«ot ffloxt xwjXoo Ijiisir e4^ | v 
 
 .B^aoateXo XaoAi Boil _ £t4a:lq a'lfiT*' X^ritOB acTJ ^ ku^ 
 
 «ioit e;tfi7oq siujIv ,S han ,UV%1^$T la flovXs^l'JB 
 
 ..^ AoJotj^ax od2 i?a^ ,etaxaq^aa tcrasf *»xj 8 aiita notxVaqjBoo 
 
 yfi « /-' 
 
 a 
 
 T 
 
 /•Avxaaoo OAXiiijpA oH -soscotc’ 8oig6s»3’tfoiq 0x4 aaoit^'ntlao’o ^IXi;pA 
 ^ D 
 
 -OT noacf ®v5:f to, aaX;f Xioxo^teX^Aa AaxoAisateo aftoX^ 
 
 i: 
 
 ^■j 4 
 
 oif;? zjl Ao^AToq-xoccX 0X4 xiai* fiftflW aac^ix^qajoo XXji o« ,x>«rci®{ j 
 
 ,. .;.>-%•■•■, j ■ I, ' 
 
 .VI' eX3fi-.T Hi Havi 3 ai flupXlxipA to avxtro-stifcgiX fco^v.ioii4 arit' ^ 
 
 
 » V 
 
 aevlotistai^# ajjolt^vioado arft a4 £ mr^xi) /i03d"^toa 5 
 
 ^ -5,8 octo^ffiA ,x©il^ra/V .xXixo^cw&tsii^e otxjo orl^ te aaiupa oili* Aiao 
 
 ^ ■< ; .n ' *':Vi|; 
 
 rcfc o 4 t to ?oXq * f»tat.T iXir BWictJiijtQ^Xt ^oaqaai 24HiflAfl^ 
 
 
 ,Bi 9 dtc to oiii ot 60 rorit-l^iT© aott aozt Bnoitf4tT%« 
 
 -noo 4 to v^iTwot oxi? swpjiii otraXV ^^4 s^omiXg A 
 
 i‘: _, “ J t 
 
 04 f^ to XX» vXAx»- 4 fXo&iA oo;iiB ,.A©X2oit«ojjp e<f ;^ 0 fl*T 40 ♦’cJjsjjrf’^^elo'^TOl^ie 
 aiU" tAiV tm-£>iaa aX pt^llL at !!^«^oi^s^«6l'qol 01:4 •aoi^ATi^acfo 
 
 ' r/, 
 
 Blitj to oxip J"oott 4 tCH oi> ^ to anojt^'#it4Tf| 
 
 tt; 
 
 *u’ " 
 
 
 
 Li ..*‘4'^ 7 f A. ^sid 
 
 
 
 n 
 
 ,<<j 1 
 

 
 
 
 23 
 
 
 TABLE 
 
 I. 
 
 
 Obaervations 
 
 of 97 Aquilae 
 
 
 
 Difference 
 
 
 
 of Ma^ 
 
 5'nitude 
 
 Date, G. M. T. 
 
 Phase 
 
 8 
 
 (3 
 
 Remarks 
 
 2423523.713 
 
 3?183 
 
 (+0^283) 
 
 
 
 ,717 
 
 3.187 
 
 
 +0?345 
 
 
 .746 
 
 3,216 
 
 (+ .355) 
 
 
 
 .751 
 
 3,321 
 
 
 f .384 
 
 
 2524.706 
 
 4.176 
 
 + .448 
 
 + ,552 
 
 
 .804 
 
 4.374 
 
 + .455 
 
 f .566 
 
 
 2525.765 
 
 5.235 
 
 .588 
 
 + .680 
 
 
 2526.711 
 
 6.181 
 
 + .138 
 
 + .262 
 
 
 2528.713 
 
 1.006 
 
 - .280 
 
 - .133 
 
 S half weight 
 
 .813 
 
 1.106 
 
 - .216 
 
 - .120 
 
 It n 
 
 2530.761 
 
 3.054 
 
 + .311 
 
 + .294 
 
 
 3532.682 
 
 4.975 
 
 + .606 
 
 + .718 
 
 
 2533.713 
 
 6.006 
 
 + ,270 
 
 + .384 
 
 
 ,784 
 
 6.077 
 
 f .189 
 
 + .283 
 
 
 2534.661 
 
 6.954 
 
 (- .566) 
 
 - ,332 
 
 
 .749 
 
 7.042 
 
 (- .536) 
 
 - .365 
 
 
 .801 
 
 7.094 
 
 (- .500) 
 
 - .420 
 
 
 2537.739 
 
 2.856 
 
 + .116 
 
 + .306 
 
 
 2538.663 
 
 3.779 
 
 + .366 
 
 + .467 
 
 
 ,760 
 
 3.877 
 
 + ,377 
 
 + .483 
 
 
 3539.675 
 
 4.792 
 
 + .566 
 
 + .686 
 
 
 .756 
 
 4.873 
 
 + . 59 ; 
 
 + .699 
 
 
 2540.685 
 
 5.802 
 
 + .404 
 
 + .517 
 
 

24 
 
 TABLE I -(continued) 
 
 
 
 Difference 
 
 
 
 of Magnitude 
 
 Date, G, M. T. 
 
 Phase 
 
 s 
 
 
 Remarks 
 
 3422540.742 
 
 5^859 
 
 f0*?364 
 
 f0¥468 
 
 
 2553.671 
 
 4,435 
 
 (+ .492) 
 
 + .598 
 
 
 .729 
 
 4.493 
 
 (+ .456) 
 
 + .643 
 
 
 2554 . 604 
 
 5.368 
 
 •J* .563 
 
 + .682 
 
 
 .679 
 
 5.443 
 
 + .559 
 
 + .654 
 
 
 2555.607 
 
 6.371 
 
 + .005 
 
 + .136 
 
 
 2558.786 
 
 2.374 
 
 - .070 
 
 + ,036 
 
 
 2559.717 
 
 3.305 
 
 + .273 
 
 + .370 
 
 
 2561.731 
 
 5.319 
 
 + .597 
 
 + .681 
 
 
 3566.622 
 
 3.032 
 
 + .235 
 
 f .396 
 
 
 2567.599 
 
 4.009 
 
 + .383 
 
 + .506 
 
 S half weight 
 
 .738 
 
 4.148 
 
 + .393 
 
 1* .496 
 
 n R 
 
 2570,594 
 
 7.004 
 
 - .443 
 
 - .381 
 
 
 .659 
 
 7.069 
 
 - .470 
 
 - .427 
 
 
 2573.709 
 
 3.943 
 
 + .106 
 
 + .220 
 
 S half weight 
 
 2580.585 
 
 2.642 
 
 - .008 
 
 + .058 
 
 
 .689 
 
 2.746 
 
 ^ .053 
 
 + .106 
 
 
 2583.604 
 
 5.661 
 
 f .499 
 
 + .549 
 
 
 .669 
 
 5.726 
 
 + ,471 
 
 ^ .559 
 
 
 .703 
 
 5.760 
 
 + .424 
 
 + .522 
 
 
 2584.562 
 
 6.619 
 
 - .140 
 
 - .068 
 
 
 .634 
 
 6.691 
 
 - ,216 
 
 - .147 
 
 
 . 665 
 
 6.722 
 
 - .278 
 
 - .194 
 
 
 .694 
 
 6.751 
 
 - .373 
 
 - ,322 
 
 
35 
 
 TABLE I “(continued) 
 
 Difference 
 of Magnitude 
 
 Date, G. M. T. 
 
 Phase 
 
 S 
 
 
 243585.560 
 
 0^440 
 
 -0^?427 
 
 -0^?363 
 
 .586 
 
 0.466 
 
 - .410 
 
 - .359 
 
 .634 
 
 0.514 
 
 - .414 
 
 - .340 
 
 .649 
 
 0.529 
 
 - .389 
 
 - ,328 
 
 .664 
 
 0.544 
 
 - .377 
 
 - .315 
 
 .679 
 
 0.559 
 
 - .390 
 
 “ .322 
 
 3586.552 
 
 1.432 
 
 (- .137) 
 
 - .045 
 
 .599 
 
 1.479 
 
 (“ .123) 
 
 1 
 
 « 
 
 o 
 
 ♦-* 
 
 .643 
 
 1.523 
 
 (- .122) 
 
 “ .008 
 
 .685 
 
 1.565 
 
 (- .119) 
 
 - .044 
 
 2587.560 
 
 2.440 
 
 “ .029 
 
 + .042 
 
 2588.549 
 
 3.429 
 
 + .302 
 
 + .392 
 
 .620 
 
 3.500 
 
 f .291 
 
 f .391 
 
 2593.557 
 
 0.260 
 
 - .472 
 
 “ .378 
 
 .617 
 
 0.320 
 
 - .491 
 
 - .371 
 
 .656 
 
 0.359 
 
 - .511 
 
 “ .362 
 
 .676 
 
 0,379 
 
 - .430 
 
 - .382 
 
 2593.543 
 
 1,346 
 
 
 - ,082 
 
 .576 
 
 1.279 
 
 (- .158) 
 
 - .077 
 
 .636 
 
 1.339 
 
 (- .194) 
 
 - .076 
 
 .660 
 
 1.363 
 
 (- .151) 
 
 “ ,088 
 
 2594.559 
 
 2.262 
 
 - .033 
 
 .048 
 
 2596.613 
 
 4.316 
 
 + .465 
 
 .553 
 
 .628 
 
 6.331 
 
 (+ .059) 
 
 4 .081 
 
 Remarks 
 
 (3 half weight 
 
 Half weight 
 
 ^ half weight 
 

 
 I 
 
26 
 
 TABLE I -(continued) 
 
 Difference 
 of Magnitude 
 
 Date f G« M« T* 
 
 Phase 
 
 S 
 
 
 2422598.648 
 
 6^351 
 
 (+0^f040) 
 
 +0^f094 
 
 2599.615 
 
 0.141 
 
 - .469 
 
 - .417 
 
 .662 
 
 0.188 
 
 - .500 
 
 - ,398 
 
 2600. 545 
 
 1.071 
 
 - .308 
 
 - .144 
 
 .599 
 
 1.125 
 
 - .188 
 
 - .131 
 
 .644 
 
 1.170 
 
 - .203 
 
 - .135 
 
 2601.569 
 
 2.095 
 
 - .074 
 
 .012 
 
 .590 
 
 2.116 
 
 - .032 
 
 + .029 
 
 .636 
 
 2.162 
 
 - .068 
 
 + .002 
 
 .655 
 
 2.181 
 
 - .051 
 
 - ,011 
 
 2603.604 
 
 4.130 
 
 t .433 
 
 + .498 
 
 2604.633 
 
 5.159 
 
 ^ .616 
 
 .690 
 
 2605.526 
 
 6,051 
 
 + .250 
 
 .342 
 
 .598 
 
 6.123 
 
 + .191 
 
 * .254 
 
 2606. 537 
 
 7.062 
 
 - .487 
 
 - ,396 
 
 .577 
 
 7.102 
 
 - .495 
 
 - .415 
 
 2607.547 
 
 0.896 
 
 (- ,304) 
 
 - .220 
 
 .572 
 
 0.921 
 
 (- ,337) 
 
 - .306 
 
 .589 
 
 0.938 
 
 (- .315) 
 
 - .178 
 
 2608.544 
 
 1.893 
 
 - .042 
 
 ^ ,018 
 
 .-587 
 
 1.936 
 
 - ,054 
 
 + .015 
 
 .632 
 
 1.981 
 
 - ,084 
 
 - .006 
 
 2609.581 
 
 2.930 
 
 .120 
 
 + .215 
 
 2614.545 
 
 0.718 
 
 - .346 
 
 - .286 
 
 Remarks 
 
 S half weight 
 
 II n 
 
 Half weight 
 

 u 
 
 r 
 
 t 
 
 \ . 
 
 
 j’- 
 
 i 
 
 r 
 
 I 
 
 
37 
 
 
 TABLE I 
 
 “(continued) 
 
 
 
 Difference 
 
 
 
 of Magnitude 
 
 Date, G, M. T, 
 
 Phase 
 
 s 
 
 
 Remarks 
 
 3433615.535 
 
 1^707 
 
 (- o ¥ 055 ) 
 
 40?011 
 
 
 .558 
 
 1.730 
 
 (“ .107) 
 
 4 .009 
 
 |3 half weight 
 
 3618.547 
 
 4.719 
 
 V- .566 
 
 4 .637 
 
 
 .587 
 
 4.759 
 
 + .558 
 
 4 .634 
 
 
 3619.515 
 
 5.687 
 
 f .481 
 
 4 ,558 
 
 5 half weight 
 
 .558 
 
 5.730 
 
 4 ,437 
 
 4 ,537 
 
 N n 
 
 3636.553 
 
 5.547 
 
 4 ,543 
 
 4 .609 
 
 
 3637.540 
 
 6, 534 
 
 - .073 
 
 - ,036 
 
 
 ,558 
 
 6.553 
 
 - .074 
 
 - .033 
 
 
 3638.543 
 
 0.360 
 
 - .450 
 
 - .367 
 
 
 .565 
 
 0.383 
 
 - .475 
 
 - .393 
 
 
 3633.561 
 
 4.379 
 
 4 .505 
 
 4 ,558 
 
 
 3633.515 
 
 5.333 
 
 4 .588 
 
 4 .648 
 
 
 3641.535 
 
 6.175 
 
 4 .170 
 
 4 .310 
 
 
 3643.531 
 
 7.171 
 
 - .485 
 
 - .449 
 
 
 3649.494 
 
 6.958 
 
 - .433 
 
 - .387 
 
 
V 
 
 J. 
 
 •tt 
 
 
 1 
 
 
 ' *1 
 
 t 
 
 
 
 
 
 .V . u 
 
 } 
 
 
 
38 
 
 TABLIl’ 1 1 
 
 Normal Magnitudes of ^ Aquilae 
 
 Date G.M.T. Dirierence Number of 
 
 of Observations 
 
 Magnitude 
 
 342 25b7.7 
 
 dh06 
 
 7 
 
 3561.7 
 
 . 090 
 
 4 
 
 2582.2 
 
 .076 
 
 4 
 
 2585.2 
 
 . 066 
 
 10 
 
 2600.7 
 
 . 066 
 
 8 
 
 2615.5 
 
 . 065 
 
 1 
 
 2656.0 
 
 .057 
 
 2 
 

 S€ 
 
 f 5 ':■' . 
 
 '.''?flsS V-5f 
 
 ^ jcl'i , 
 
 ‘"‘‘A-,, 
 
 II aOSAf' ■' 
 
 ^ ^ 0 . XjmsioH 
 
 
 g«0i jiivisfc.jo 
 
 \'y 
 
 VdO. 
 
 .< '■’ 
 
 
 -i ;, ■'iv ,, 
 
 ■ • ■ ■A ■ 
 
 ■■ iC ..'■ 
 
 - ‘ i I'’* i ' ‘ 
 
 
 I 
 
 ^ . \'Vv;- 
 
 .■.-•^ • 'i .♦, , ■ ‘‘1 
 
 '' ir ■ 
 
 i:? 4 fiu 
 
 a^^ vw-ffiST- i-J 1 .■ 
 
 V-M — 
 
29 
 
 TABLE III. 
 
 Normal Magnitudes of Aqullae 
 
 Difference 
 
 Difference 
 
 
 
 of Magnitude 
 
 No. 
 
 
 
 of Magnitude 
 
 No. 
 
 Phase 
 
 
 S 
 
 
 Obs. 
 
 Phase 
 
 
 
 |3(re<^ucec/^ 
 
 Obs. 
 
 0^164 
 
 -o¥484 
 
 -c 
 
 C474 
 
 2 
 
 3^043 
 
 t0^318 
 
 40^^197 
 
 2 
 
 0.313 
 
 
 
 - 
 
 .440 
 
 3 
 
 3.204 
 
 
 
 4 .250 
 
 2 
 
 0.373 
 
 - 
 
 .463 
 
 
 
 2 
 
 3.305 
 
 
 .273 
 
 ,279 
 
 1 
 
 0.374 
 
 
 
 - 
 
 .442 
 
 3 
 
 3,464 
 
 
 ,396 
 
 4 .320 
 
 2 
 
 0.473 
 
 - 
 
 .417 
 
 - 
 
 .428 
 
 3 
 
 3.779 
 
 + 
 
 ,366 
 
 4 .362 
 
 1 
 
 0.544 
 
 - 
 
 .385 
 
 ~ 
 
 .396 
 
 3 
 
 3.877 
 
 +■ 
 
 ,377 
 
 4 ,378 
 
 1 
 
 0.718 
 
 - 
 
 .346 
 
 - 
 
 .347 
 
 1 
 
 4.009 
 
 
 .383 
 
 4 ,421 
 
 1 
 
 0,918 
 
 
 
 - 
 
 .264 
 
 3 
 
 4.136 
 
 + 
 
 ,420 
 
 
 2 
 
 1.061 
 
 
 
 - 
 
 .239 
 
 3 
 
 4.139 
 
 
 
 4 .422 
 
 2 
 
 1.064 
 
 
 ,228 
 
 
 
 3 
 
 4,176 
 
 -#■ 
 
 .448 
 
 4 .437 
 
 1 
 
 1.148 
 
 - 
 
 .196 
 
 - 
 
 .199 
 
 2 
 
 4.274 
 
 4 
 
 .455 
 
 4 .451 
 
 1 
 
 1.315 
 
 
 
 - 
 
 .151 
 
 4 
 
 4.348 
 
 4 
 
 .485 
 
 4 .494 
 
 2 
 
 1.456 
 
 
 
 - 
 
 ,104 
 
 2 
 
 4.464 
 
 
 
 + .526 
 
 2 
 
 1.544 
 
 
 
 - 
 
 .100 
 
 2 
 
 4,739 
 
 4 
 
 ,562 
 
 4 .570 
 
 2 
 
 1.715 
 
 
 
 - 
 
 .050 
 
 2 
 
 4.832 
 
 4 
 
 .578 
 
 4 ,588 
 
 2 
 
 1.928 
 
 
 .055 
 
 - 
 
 .051 
 
 3 
 
 4.975 
 
 4 
 
 . 606 
 
 4 .609 
 
 1 
 
 2.124 
 
 - 
 
 .058 
 
 - 
 
 .052 
 
 3 
 
 5.197 
 
 4 
 
 .602 
 
 4 .596 
 
 2 
 
 2.208 
 
 - 
 
 .045 
 
 - 
 
 .058 
 
 2 
 
 5.326 
 
 4 
 
 .592 
 
 4 ,592 
 
 2 
 
 2.407 
 
 - 
 
 .050 
 
 - 
 
 .044 
 
 2 
 
 5.406 
 
 4 
 
 ,561 
 
 4 .574 
 
 2 
 
 2.642 
 
 - 
 
 .008 
 
 - 
 
 .019 
 
 1 
 
 5.547 
 
 4 
 
 .542 
 
 4 ,551 
 
 1 
 
 2.746 
 
 
 .053 
 
 + 
 
 .029 
 
 1 
 
 5.674 
 
 4 
 
 .490 
 
 4 .486 
 
 2 
 
 2.856 
 
 + 
 
 .116 
 
 
 .100 
 
 1 
 
 5. 727 
 
 
 .460 
 
 
 2 
 
 2.934 
 
 + 
 
 .115 
 
 
 
 2 
 
 5.728 
 
 
 
 4 .481 
 
 2 
 
 2.936 
 
 
 
 + 
 
 .146 
 
 2 
 
 5,760 
 
 4 
 
 .424 
 
 4 .447 
 
 1 
 
30 
 
 TABLE III. -(continued) 
 
 Difference 
 
 Difference 
 
 
 of Magnitude 
 
 No. 
 
 
 of Magnitude 
 
 No. 
 
 Phase 
 
 S 
 
 (3(rediyced^ 
 
 Obs, 
 
 Phase 
 
 
 
 Obs. 
 
 5<?802 
 
 ^■0¥404 
 
 f0^413 
 
 1 
 
 6?736 
 
 -0“276 
 
 -0¥283 
 
 2 
 
 5.359 
 
 f .364 
 
 + .364 
 
 1 
 
 6.956 
 
 
 - .440 
 
 3 
 
 6.006 
 
 4 .270 
 
 + ,276 
 
 1 
 
 6.958 
 
 - .422 
 
 
 1 
 
 6.064 
 
 ,320 
 
 ^ .236 
 
 3 
 
 7.004 
 
 - .443 
 
 
 1 
 
 6.133 
 
 4 .191 
 
 f .190 
 
 1 
 
 7.023 
 
 
 - ,468 
 
 2 
 
 6.178 
 
 ^ .154 
 
 .152 
 
 2 
 
 7.064 
 
 - .481 
 
 - .477 
 
 2 
 
 6.355 
 
 
 .026 
 
 3 
 
 7.123 
 
 
 - .503 
 
 3 
 
 6.371 
 
 t ,005 
 
 
 1 
 
 7.136 
 
 - .490 
 
 
 2 
 
 6.543 
 
 - ,074 
 
 - .086 
 
 3 
 
 
 
 
 
 6.619 
 
 - .140 
 
 - .143 
 
 1 
 
 
 
 
 
 6.691 
 
 - .216 
 
 - ,322 
 
 1 
 
 
 
 
 
j 
 
 i 
 
 i' 
 
 ! 
 
 i 
 
 \ 
 
 
 .' ' *V : . 
 
 i 
 
 f 
 
 . » - 
 j . .': 
 
 I 
 
 I 
 
 f 
 
 J 
 
 iV 
 
 V~ r 
 
 fA 
 
 ;t 
 
 h 
 
 ,( 
 
 'i 
 
 V, 
 
 .. w?' 
 
 .uic^;v 
 
 if;4 
 
 . *:l 
 
31 
 
 TABLE IV 
 
 Light-Curve of ^ Aquilae 
 
 Phase 
 
 Difference 
 
 of 
 
 Magni tude 
 
 Phase 
 
 Difference 
 
 of 
 
 Magnitude 
 
 -2^50 
 
 f0?56 
 
 1^50 
 
 -o¥li 
 
 -2 ,25 
 
 f .60 
 
 1.75 
 
 - .06 
 
 -2.00 
 
 f .61 
 
 2.00 
 
 - ,05 
 
 -1.75 
 
 f .57 
 
 2.25 
 
 - .05 
 
 -1.50 
 
 + .49 
 
 2.50 
 
 - .03 
 
 -1.25 
 
 t .33 
 
 2.75 
 
 f .03 
 
 -1.00 
 
 t .16 
 
 3.00 
 
 f .21 
 
 -0.75 
 
 .00 
 
 3.25 
 
 f .27 
 
 -0,50 
 
 - .20 
 
 3.50 
 
 4 .31 
 
 -0.25 
 
 - .41 
 
 3.75 
 
 f .36 
 
 0.00 
 
 - .50 
 
 4,00 
 
 4 .40 
 
 +0.25 
 
 - .47 
 
 4.25 
 
 4 .45 
 
 0.50 
 
 - .40 
 
 4.50 
 
 4 ,52 
 
 0.75 
 
 - .33 
 
 4.75 
 
 4 .57 
 
 1.00 
 
 - .24 
 
 5,00 
 
 4 .61 
 
 1.25 
 
 - .17 
 
 5.25 
 
 4 .60 
 
TSr 
 
 f 
 
 f 
 
THE UGHT-CUKVE OF^ AQUILAE 
 
 6 T] 
 
 o © 
 
 .11 
 
 FI<5U1^E \. 
 
 DAY5. 
 
 2330 Z550 Z5TO Z5SO E6\0 2630 
 
NORMAL MAGNITIUDEIS Of y) AQUILAEL^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 "A t 
 
 /T\ 
 
 
 
 
 
 
 
 
 
 lu V 
 
 J Q; 
 
 ^ O 0 >c 
 
 if) 
 
 1 
 
 O 
 
 (/I 
 
 z 
 
 o 
 
 s 
 
 S f. 
 
 Ui 
 
 O-uJ 
 
 QI^O 
 f UJQ 
 ^tOid 
 I^CDh- 
 
 oohi 
 
 9uJ“) 
 
 ^Zui 
 
 HOIL 
 
 C$) 
 
 
 0) 
 
 O). 
 
 <D 
 
 0» 
 
 © <p 
 
 
 GO 
 
 qt> 
 
 O' X 
 
 <© 
 
 ®0 
 
 00 
 
 © 
 
 © 
 
 KO 
 
 #0 
 
 \9 
 
 >0 
 
 ro 
 
 cs» 
 
 -xG^ 
 
 GD 
 
 o> 
 
 
 v9 
 
 i:_ 
 
 in 
 
 1 ’ 
 
 '+• 
 
 j' 
 
 © 
 
 © 
 
 xXx O 
 
 O 
 
 (0 
 
 cO 
 
 ©G>, 
 
 O 
 
 © 
 
 
 •© 
 
 CNj yf) 
 UJ >- 
 
 §< 
 
 ij Q 
 
 (D> 
 
 Od. 
 
 
 
 
 (Of® 
 0 ® 
 
 3anj-lN5VU JQ 30N3y3iJIQ O© 
 
 (vJ _ _ CvJ 
 
 r r r U + ■*■ o ■•■* 
 
 'I'- 
 
 + 
 
 ifi 
 
 4 
 
 vSl 
 
 + 
 
 nl 
 
 I 
 
 10 
 
 I 
 
4 
 
34 
 
 secondary fluctuation. Luizet’s^ description of the irregularity, 
 ”comme un arret dans la diminution d'e^clat de la variable", or the 
 German "Stillstand" , fits the photo-electric curve. The observa- 
 tions indicate a practically constant magnitude for about 0?6 be- 
 
 d 
 
 ginning at phase 1,8, Some of the older curves from visual obser- 
 vations show a pronounced increase in brightness at this point. It 
 was considered a real "secondary maximum", but the more recent light- 
 curves have been drawn with no irregularity in the downward slope" 
 
 The modern tendency is to regard with suspicion permanent Irregu- 
 
 3 
 
 larities in curves by any but the most accurate photometric methods. 
 Photo-electric work has in general justified this skepticism, but in 
 this particular instance we find confirmation of a secondary oscil- 
 lation in Cepheid variation, while in addition to the pronounced 
 secondary, there is indication of another fluctuation with maximum 
 about phase four days. Lockyer believed the irregularities due to 
 a secondary oscillation with period 1?8, one-fourth that of the prin- 
 cipal light variation. But it is evident they cannot be represented 
 by a superposing a simple sine curve of any period on the principal 
 variation. Using Lockyer ‘s sub-period we might assume that the 
 secondary oscillation rises to its strongest maximum about phase 2?’5, 
 A weaker maximum is reached at phase 4,3, the following minimum being 
 coincident with the principal minimum. The two succeeding second- 
 ary fluctuations are negligible, 
 
 i 
 
 s tr onomi sc he Hachrichten . 165 . 364, 1903. 
 
 ^ Astronomische Nachrichten. 183 . 265-78, 1909. 
 
 Mt. Wilson Contributions . 7_> 1916. 
 
 Aatronomi sche Hachrichten , 214 . 195, 1921, 
 
 3 
 
 Publications American Astronomical Society , 4, 265, 1921. 
 

 
 
 
 r' C 
 
 t 
 
 yt 
 
 
 :c i' 
 
 i': 
 
 /d. . D.' ■ X':- \*: •i.^nc oaa 
 
 r.h^ifc L . ■•'I'l/J 'LL' OBlROG.^ 
 
 -rtv:-; 
 
 ;■ ^ “Jtru^c 5 iIX;? 6 '' rr£jp.x.-'L( 
 
 IP : . ‘ 
 
 , f 
 
 II 7 
 
 \ 
 
 .2 Zll Hi wil-3i‘P.\0 0 . 1{IX •••. ..i .1 0*17'^ : e?AOil:ni anoXv 
 
 \ '^■'•-tO- _ .. 
 
 .un": iif'ViL"? -'«■*: Ic» ud;r 'io -Bas^S .4^* 
 
 >t.v\:: :-.- ? :xt • c.;::X'ac;i.i: IJOcriJ ';'Cr'; J unoii^v 
 
 ■. " A.,:,oTi a i)4n,. oieqoc 
 
 . Xv .X-'- ■ -. .irtoi •) :t , : 'Z x.'iJisj.y: \'it o.z di.X7ir m?.fcTjb ..-■•-vi’ t fisvuro 
 
 .*.;L,;., x . . otr.iyyB m\5r?3i- ^4 ai -\for/. - ,not!5::x lirT 
 
 / 
 
 -;*&« oiiv' ;rBOi ;• t .yyJ \,w. ^:' aoviiio .;i a6i?iigel 
 
 ..tfcX 
 
 ,i 
 
 ■ -vf ; ‘ liw'OL'.', X^'rf/19% flX aud XiOf ciiJ'ooIa-or f.d'I 
 - ••c i.'.-) Ji ;i^X,: .-s .1 t^/yob IsaXi ow r^r.^ *j^^uoi^24jq sixiJ- 
 
 ..V.01 . z.'j o? *iuirJ ; .;X ^i.Xdw rXi'fvoO fli aoljjal 
 
 ^x/od-c 
 
 . r : 
 
 i .'.oX2 AiXtf 3* \ fc.iOo&t 
 
 ‘ T'J-i , ..ots vdf'XX Xaqli: 
 inig 2X^„,i<j / r'.rtX' wqi&q^'g a vcf 
 
 ' , i! 
 
 ■ . / 
 
 . :r:::,v,.;.. /- • 
 
 ■* is - ^:S ': 1 -^. ; 
 
 n.: '>'-C G; i. 
 
 ? :X , je'ixX yC y *■ ■ . v ?: tX 
 
 ' ix -m.:’ t/o j 
 
 («. 
 
 .: S .i:f -T.^y* -2a<: , o'7 C xjc 
 
 5'.i;i';- . . t f*' 
 
 So :P^yj X^:1S tt 
 
 
 r :\' Xc.;:r^, yw*^ 'to t : 
 
 
 vay. v:^-: ■•; • ■ i s t>v. t. X '•■•; 
 
 # ' ^ '' 
 
 'V, -:ix^ r Cr ;;. 
 
 nX*?'X .y:u' X . . 
 
 .-.tHOXIo't . 
 
 
 '’ ''S . , X ■ 1 
 
 cx. 8*. r^,''Xx«r. rodiStv? A 
 
 ••91-. r-i^r> it lijs o::t t \,r& 
 
 ■*T' — 
 
 . . 
 
 ,iV- 4. . . v^>d 0j.7 u ay>rs X.-ao:: c? TuA 
 
 'X 'lid:2iX2J^-5-l ' 
 
 
 5 ■' •'■ 
 
 t i r'O' *’ - f <7 ^ ( 
 
 i..., ,, 
 
 ,)v 
 
 
 ,c>ya ,J^. , yy e t Z03 I- J. . ;A 
 
 
35 
 
 As a matter of some interest, the light-curve was com- 
 
 1 
 
 pared with the velocity curve as determined toy Wright. This shows 
 
 that the pronounced halt in decreasing light is at apastron on the 
 
 "binary hypothesis, and just before the star reaches maximum volume 
 
 on the pulsation hypothesis, following Eddington. 
 
 Possible variation from epoch to epoch of the light- 
 
 curves of this and other Cepheids has been discussed by previous 
 2 
 
 workers. The photo-electric observations give evidence that there 
 was no appreciable change in the form of the curve while the 
 observations were in progress, and the curve is not greatly differ- 
 ent from curves previously published for this star. The maximum, 
 however, is somewhat sharper, and the interval from minimum to 
 maximum light is less than in other recent curves. From the cuirves 
 previously referred to the values of this interval were found to be: 
 in 1900, 2^38; 1906-07, 2^38; 1917, 2?20; and 1920, 2^10. A de- 
 cTease for the more recent series is noticeable, but in all strict- 
 ness comparison should be made between curves determined with the 
 same type of photometer. 
 
 The variation of the period of y Aquilae has also been 
 
 3 
 
 discussed. Lockyer, from "his discussion of observations of the 
 
 4 
 
 past century, concluded it was variable, Luizet also found a vari- 
 i~ 
 
 Astrophysical Journal . £, 62, 1899. 
 
 ^Lockyer, Dissertation , p. 78-86, (Gottingen, 1897), 
 
 Luizet, Astronomische Nachrichten . 193 . 83, 1913. 
 
 Shapley, Wilson Contributions . £, 179, 1915, 
 
 Jordan, Publications American Astronomical Society . 4, 
 
 365, 1921. 
 
 3 n 
 
 ^Lockyer, Dissertation , p. 91, (Gottingen, 1897). 
 
 Luizet, Astronomische Nachrichten . 165 . 361, 1903. 
 

 c' 
 
 i<f r rji- 
 
 t 
 
 '^r: ■ .. ..'.'4 Nv'‘'i ■: 
 
 t '■■■ 
 
 ‘ .uT '. liT 
 
 ■i 4 . ' 
 
 ' H 
 
 
 i '4 
 
 ■i • I. - 
 
 
 
 ktxtr t {. - . 
 
 4 ?' 0 / 
 
 ,'Ai ; 
 
 ' >•' :•••■ • ■ •' -yiy-; ,. ' 7 t.-ycttV.- 
 
 ■ ■■ ' ' i«l ' 
 
 tail C :: • 4. : i ’ 'm-9 -t . ' - 1 . . 
 
 ;ld ©q , 
 
 !{' u:M:, ‘ 'Xcr A‘ '.■•■ ‘w:v i ;rT 
 
 . . '■ 
 
 r.e .(■#«*»■ ■: 
 
 ■ . ^c. 
 
 ■ t /- 
 
 «* 
 
 M , 
 
 I. 
 
 3 if dn-a 
 
 I w , a»M .(fc. 
 
 , .-.4 .V 
 
 ». ' "•'' < 
 
 . . " . ' ' .'..j,' ., ■ ■*■ 1 ) ' <' ^ 
 
 V .. 
 
 * •* ' 
 
 ; 0«4 
 
 '(M 
 
 
 : " ■■' ' '"• ■' J/.' '(j ■’•■-i*-"‘ 
 
 ■■ >. 
 
 t 
 
 i's 
 
 
 I -N.. ^ ** 
 
 ' , ■* i »• 
 
 
36 
 
 atlon, and included a harmonic term in his value for the period, the 
 
 value which has been used by most observers of Aqullae in recent 
 
 1 
 
 years. On the other hand some have rejected the harmonic term. 
 
 The elements are 
 
 Maximum - J.D. 2396168.732 f 7?176382 • E 
 
 ^ + 0.14sin(0?044‘E Jr 304®) 
 
 Maximum - minimum • 2,373 
 
 Including the harmonic term the epoch of maximum derived from the 
 
 photo-electric curve gives as correction to the ephemeris, -0,006, 
 
 This is good agreement, provided we go no further, but for the 
 
 d, 
 
 minimum the correction is +0.271, which is not so satisfactory, 
 
 A more accurate determination of the length of the period 
 in recent years was therefore made using the photographic observa- 
 tions of Kohl sc hut ter" made in 1906-07, The photographic and photo- 
 electric amplitudes being practically the same, comparison of the 
 curves is direct. Using Luizet’s mean period between the two series 
 normal magnitudes were formed from the photographic observations. 
 Three observations were combined in a normal point except on the 
 steep portion of the curve where two were used. This steep portion, 
 between minimum and maximum, was used in the determination of the 
 period, as the phase can be determined with more accuracy here than 
 at the time of maximum 'or. minimum, 
 
 A plot showed these points nearly a quarter of a day out 
 of phase with the photo-electric curve, a graphical determination 
 giving as a correction 0,22, This gives as the correction to the 
 period +0^00032, from which the value for the period between 1906 
 and 1920 is 7^17670 
 
 ^Hellerich, Dissertation , p 6, (Bonn, 1913). 
 
 Astronomische Nachrichten , 183 . 265, 1909. 
 

 
 7 w 
 
 
 i. - waja--':jtk ' . , ': 
 
 ^ *J 
 
 -:'T vi^’xy .,.- 
 
 
 <50 ■. 
 
 1.r.fx- fil g! 
 
 kJ ■•' 
 
 : ; t ■ ■■ 'r. oill . Is 
 
 f « ,~ f . t . ►•' > 1 1 , . 
 
 , .v' 
 
 r'-'C" 
 
 V ;:> f-r’y ' ,r '.ji<' : k-j 
 
 
 V .'h') 'A 
 
 
 ' r ,ii sa . 
 
 I Z-iy 
 
 :,• ■ 
 
 ?i lo u. 
 
 j 
 
 ■>: W'.'*X^ .;•»'* X i ' 
 
 
 k.V‘ 
 
 
 ^ ^ t if 
 
 .1 
 
 
 ‘Uv., r ■„ 
 
 v.i 
 
 » 3 WH. ui?i 
 
 
 - '..1 /;! . 
 
 
 *:ji btla :i:tui j :..t: .r*s^i»'r/ •.■ . ' 
 
 $A'J V'l-ni.- 
 
 '■< 
 
 -w 
 
 
 ;'r 
 
 ^ ‘ O.Xl £.<t (i ,; 
 
 T ^'i-v 
 
 ftcijo/tn 'ev-,:. iil .".'’/feV 
 
 r j ;:i ^ : , ) X »'j i rfcf 
 i; .■',* XK'i C?v. 0.i ‘ 
 
 'j "j:: 
 
 
 ®a*t^ to li 
 
 1 i" 
 
 -■• 5 -- », 
 
 • h . 
 
 .: j.'tr 
 
 V ' • 
 
 oJttmg:i 
 
 
 ^r- ■ ; ■ zf - 
 
 
37 
 
 This value for the length of the period is so much larger 
 than the mean values of Lockyer and Luizet obtained from a discuss- 
 ion of observations of the past century that Luizet 's tabulation of 
 
 i 
 
 coTrections to an ephemeris from a constant period was brought up 
 to date. Corrections computed from the light-curves of 
 
 It 2 
 
 Kohlschutter and Lacchini, and from the photo-electric light-curve, 
 were added to the list. These residuals are plotted in Figure 3, 
 points from maxima and minima being plotted separately. Normal 
 points are formed, giving the determinations equal weight except 
 that in the last point the photo-electric determination has been 
 given double weight. The normal points are connected by a heavy 
 line. 
 
 This line is distinctly concave upward, hence observa- 
 tional evidence indicates an increasing period at least in recent 
 years. Certainly there is no evidence of an appreciable decrease 
 at any time in the last 140 years. If the variation is harmonic 
 the available portion of the curve is too little to determine 
 either the amplitude or the period with any accuracy. However, 
 both must be much greater than the values found by Luizet. 
 
 The question of variation of period is of importance in 
 
 Cepheid theory. The pulsation hypothesis demands a shortening of 
 3 
 
 the period, about 40 seconds annually for S Cephei on the con- 
 traction theory of a star's energy. Similar conclusions follow on 
 the rotation hypothesis, while according to the binary theory the 
 
 1 
 
 2 
 
 3 
 
 Luizet, Astronomische Nachrichten . 163 . 360, 1903, 
 Lacchini, Astronomische Nachrichten . 214, 195, 1921. 
 Eddington, Observatory . 41, 379, 1918, 339, 1919 
 
i' 
 
 I' 
 
 
 .’♦i . . . »'.i I ,'.’ t ''n 
 
 ■» / ■,^' xt , >" a j 9*- tuxi^ 
 
 V ' ' ' ' ■ -‘ ' 
 
 • ’ •. • . r..^r:^.*oc ,a 
 . ^:. :r .t 
 
 iT^ ixyri 
 
 
 
 
 (j ‘a 
 
 ■ ’ ‘ . \ -/OL f KVi'.-- 
 
 E? C5 . . 
 
 . r » 
 
 .- ‘ * .^TJI 'iS 
 
 . .V ^ ^ 
 
 M'-Xt.Wji' 41 V It: /. . . -** 
 
 ' >. 
 
 ’ ,, •»' f'rril .s f ■' * ,J,-I ■' 
 
 *4 »..•.. . ' 1.' 1 . 
 
 V < ’ 
 
 ^4 ^ «4b« u* »JL ._.. ^‘4 A' ' 
 
 o.'ii 
 
 ly 
 
 ■ -;. '-t t'.' 
 
 1} 
 
 ; 1 '•> 
 
 \i 
 
 e-.n. 
 
 !, 
 
 . A . * .«i— «t 
 
 7 
 
 
 » 
 
 ^ ... 
 
 
 .' -3 V*rr 
 
 t 
 
 
 •«• .A* .fw 
 
 
 I, " 
 
variation \NTH^ PE.RIOD Of r] AQUlLAf 
 
 O 
 
 0 
 
 'i 
 
 k. 
 
 o 
 
 c\l 
 
 9^ 
 
 O 
 
 5 \ 
 
 O 
 
 o 
 
 OS 
 
 o 
 
 (f\ 
 
 oQ 
 
 «o 
 
 <0 
 
 <o 
 
 s 
 
 00 
 
 ^ If) 
 UJ 
 
 <( S 9 
 iti 
 
 55 
 
 I 
 
 o 
 
 Si 
 
 «0 
 
 o 
 
 oD 
 
 § 
 
 sxva 
 
 r* 7 - I- O I- 7 - 
 
39 
 
 period may either increase or decrease! Tidal action should in 
 general lengthen the period if it is equal to or greater then the 
 rotation period of the principal star. But if the satellite 
 revolves in less than the rotation period, the orbital period 
 should decrease. 
 
 There is evidence that the period of S Cephel is 
 2 
 
 decreasing. If these suspected variations of period are accepted 
 
 as real and attributed to tidal action, the deduction that 
 
 07 Aquilae probably rotates faster than 6 Cephei follows. 
 
 Since either a rotation or a pulsation should affect the 
 
 appearance of the spectral lines, the fact that the lines of 
 
 'Tj Aquilae are broader than those of S Cephei is wortiy of mention, 
 ^ 3 
 
 6 Cephei has the narrow well defined spectral lines typical of 
 
 4 
 
 giant stars, while the lines of 07 Aquilae, also classed with the 
 giant stars ”have the general characteristics of breadth and 
 haziness, which tend to make them objectionable for purposes of 
 accurate measurement". In a footnote to this reference the 
 statement is made that "There is undoubtedly a resemblance between 
 the spectra of ^7 Aquilae and 6 Cephei, the lines of the latter 
 being, however, better defined, - 
 _ 
 
 Plummer, Monthly Notices . 80 . 507-09, 1920, 
 
 Eddington, Observatory . 42 . 338, 1919. 
 
 Ludendorff, Astronomische Nachrlchten . 312 . 185, 1920, 
 ^Adams, Observatory . 43 . 167-68, 1919, ~ 
 
 ^Wright, Astrophy 8 icar~Journal . 9, 60, 1899. 
 

 lull 
 
 -V’f: ■ •■.■•*.’^\:;;j-, ;,ij 
 
 ,^. SI sS i5 it^iiijas 
 
 •■> ^ . * •?■■;'' ■■• j' . ’ .■•' ^ .■ ‘ i-.!^TSsi! 'V~' f 
 
 v" Wr '-.7 mt ‘ V '^ 5- ?7f 3 
 
 . ‘--''t^av i4i^.M’;..>> ,A'k;^.u- :'>-;• ■ ‘ r AiiSt'-, ^ 
 
 c i‘‘. ■' i .■ - ® 
 
 
 
 f ^i A '•■■ /. 
 
 ' '’ ' ^ ' >< E 
 
 li • E' tife.v 
 
 
 i^is 
 
 a;. 
 
 i*?d 'H‘i i V,J% 
 
 |tTs->sn 1 ,*^ il '^' r.iV*':; , »''‘-'.r;' ‘ ' ' "*’tV'1 
 
 ‘ -lo »r.‘/::i •■ i -Vijxlcl*. "^C-fii 
 
 ■' '- ' i. . ..f» ■ » , :' ' ' iA']J V 
 
 ^9 ''.t. 3 >r 4 SJiS: 
 
 . ''lit 
 
 
 f'* T!*'‘ »v t ^>^.^^bS.‘^'i•^;;^■^?ct.‘' 
 
 -!|i^’' ' .I ‘.. Wh'-'i'i'- . Jii 
 
 
 
 sifcv>:r/- . . •.-. 
 
 - • 'A»i . I :■ ■» / , ■ , 
 
 ■'*'. :■ '^ t 
 
 ri,r.i ■ 
 
 “%v*. .V'Si ,i.^i_ '■ 
 
 
 • ■■"c.km 
 
 
 
 
 
 tf' .'';.i'.i*i. it„S 
 
 TTTji 1 
 
40 
 
 SlPwIi^ARY 
 
 1 
 
 1. A series of photo-electric observations made in 1930 ! 
 
 gives an accurate light-curve for Aquilae. 
 
 i 
 
 3. The observations indicate a long period or irregular | 
 
 M 
 
 variation for /3 Aquilae. A progressive decrease of 0.05 is found 
 for an interval of three months. 
 
 3. $ Aquilae, which has been announced as a spectro- 
 
 scopic binary of unknown period, is suspected of being an eclipsing 
 variable with range about 0?1, but no period has been found. 
 
 4* The "secondary maximum" in the light-curve of 7 Aquilae 
 
 I 
 
 is confirmed as a pronounced halt, or pause, in the decrease of light 
 Another fluctuation, with maximum about phase four days, is indicated 
 
 5. Within the accuracy of the measures the light-curve did 
 not change between July and November 1930. There has perhaps been 
 
 a shortening of the interval from minimum to maximum since 1900, but 
 accurate curves determined with the same photometric equipment and 
 at different epochs are needed for a thorough investigation of this 
 point. 
 
 6. The period, between 1906 and 1930, is determined by 
 comparison with KohlschiSltter 's photographic observations, Luizet’s 
 tabulation of residuals from the constant period 7^176383 is brought 
 up-to-date by including observations of 1906-07, 1917, and 1930, 
 
 Both methods of investigation favor an increasing period at present. 
 The evidence is decidedly against a perceptible decrease in the peri- 
 od at any time since 1784, 
 
 7. The pulsation hypothesis demands a shortening of the 
 period, while according to the older binary theory, tidal action may 
 

 ::.-va 5 eJ 3 .j or.'i lo >i 
 
 ic 5 t eviuo-irfsil €iv‘>Jij;/ocMi sll tdvis 
 
 *i i : 1- bc*i^aq ^ a; JiV’.TSacfo srf' 
 
 ! I,'. 
 
 \f 
 
 ic\ .. - ft 
 
 1 : 
 
 • . IdVUSiJCi £m Tol 
 
 '. • '• * ‘ ,, V , ' 
 
 • o'i ’■Q^r '9 4 * ^ rioirf'«v "K 
 
 "io 4 : eZ tJ^oiTC ; .'T 5 '": j oi<jo ’- 
 
 . ': r>'^?c< iitn on cTj.'Co.e *? -rTr-i a;;-' .eXrf,.-liiiv i 
 
 'to ;.i " lO'.Tii.xrfi' ^liitycrooai*'' *r 
 
 Ih 
 
 il io !>r'.. rti 4 j a- Dv^aiiinoo 2t 
 
 . 1 
 
 
 - *■ t 
 
 :r jil' *i . o'i OGJu,’. ' Tij-::: ...rxZxja,*? iTijIw -leiMi 
 
 ijlr :';v;.\ - :i;'r •■'Ot 3 1 iO ' \ ^^TX-’OCiS ‘ 
 
 ^'uoiiT .. *-tX ‘iionu?vo*' f n^/ *■ - 'fitfid 
 \ it 4 '/ .v^CrX 60 .- oJ" . .. ^.* 4 i;’. ..rtil XteVTeTni ■? ::^nta'itzo 6 Q ~ 
 
 fcrria fft i; : .0 oi':? • inoJ or. ’ ?.-a 6 »s. Js’/.-ft to^u'-.o. n" '. f . /^uo oifjyTJL'ooi! 
 
 
 a;: ; ':o c.o i . .s" ir. -■v*:i; /r ..c'lz a: 
 
 f .. A 
 
 ‘ ij.i.-' C 7 : ^ja 
 
 . .oioq 
 
 t i 
 
 ■■ yj-X:.r_Xfr,-ii- .-V 4 j: , 0 Lh’,L dvQX notified ^bOjL-jSii er^' 
 
 . .io ^r«v: ‘ ?’5:. o ' d^iV3 r^c^XiJsqaoo 
 
 i ^r’':3'L*:d : 
 
 •' r ^ 
 
 -n r* tr -r 
 
 r ocf rr.Av ' . : ^^r.t r^ci'i: aX^vJtXBOT: 3ro fto Z^aXt-'dAi 
 Vo : :\3v-'eado yd st.-xj-Ow -qju 
 
 xq r; doxooo -'7 . .i .u Xv/Vjit oo •JbOA'l^sa /f?cS 
 
 I 
 
 r -.4'j«4 odt r.t "■siikOto&^ f. I':’ j ■t rc'ciDo -' •+=■*- ‘ C'v 4 ; vlbtfli: 'x t si V? ?xfi 
 
 > 5 VI oor-.ia oslv+ <rT^ tii to 
 
 (ad 7 1 0 \ ?:? 3 x:'v 9 JL'i . . : • : .• 7 : , y** «- i I jsa X itq ndT , > 
 
 nclJCMs L^ciz- tVxo!jr'j y-:....J-d tfi-Ic t.'-.' os n^'il/Jioooja ei idvv' ^thOXTOq j ] 
 
41 
 
 increase or decrease the period. Other investigators have found 
 evidence of a decrease in the period of S Cephei, 
 
 Either pulsation or rotation should affect the spectral 
 lines of a star. Attention is called to the evidence that the 
 lines of Tj Aquilae are broader than those of S Cephei, which have 
 been examined for a pulsation effect. 
 
 ACKNOWLEDGMENT. 
 
 I am indebted to Professor Joel Stebbins for supervision 
 and direction throiighout these investigations, and for some of 
 the observational data, and to Mr. J. K. Willy for checking some 
 of the reductions. 
 
•“ " ') ' ■ ‘ ' HI-' ''aI» *5T# 'V 
 
 '■'imfcol sTC4t4^iiet7ai: laift’itO ; ^ 
 
 V' ^ . C "* ' 53^-'" ''’" ^ ■■■■■ ''-l^ 
 
 ■ 6rft; i i. !»5:’i:« Li»j{>fi*« .. t<y xmitil- ■ ■' '* > . ^-'' ’ ■ '' '■* 
 
 -■A. , ' •-. ■ , ■ fif "<., - ■ ."V" . “ 
 
 fAY 
 
 " T*> ►, /' ■■ *. . ‘ ■ ' ‘Tf*^ ' * . . ■ I ,•• 
 
 4 lo RiHiX'S 
 
 r ’ ' '■ * ' ‘,‘" •^‘ '■% ,«-.r. , 
 
 r:ojti®_ tiadviao A 
 
 & 
 
 ^ ^ m'' -:.,M '3»-^ '" ■ ■' f* ■ ' , •■•' » - 
 
 CI9C8 i2.'L6 
 
 yf \ _ ’ ■■ • '_ ^ '■ '' ■' 
 
 M 
 
VITA 
 
 Charles Clayton Wylie. 
 
 Born at Idana, Kansas, on June 18, 1886. High school 
 education received at Marissa, Illinois. Graduated from Park 
 College, Parkville, Missouri, with A. B. degree in 1908. Graduate 
 student, as University scholar in Astronomy, at the University of 
 Missouri, 1908-09, and summers of 1909-10; assistant and graduate 
 student 1911-13, receiving the A. M. deg'ree in 1913. Professor of 
 Mathematics, Buena Vista College, Storm Lake, Iowa, 1909-11. 
 Assistant, U. S. Naval Observatory, Washington, D, C., 1913-19. 
 Assigned to testing of nautical instruments 1918-19. Member of 
 U. S. Eclipse Expedition to Baker, Oregon, June 1918. Assistant 
 and graduate student. University of Illinois, February 1930-1923. 
 Married December 25, 1918, to Miss Lirl Bunn, Three Rivers, Michigan. 
 
 Magazine articles published include: Determination of 
 the Longitude and Latitude of the U. S. Naval Observatory Eclipse 
 Station at Baker, Oregon, Popular Astronomy . 37 . 359, 1919; The 
 Auroral Radiant from American Observations of 1915-1920, Terrestrial 
 Magnetism and Atmospheric Electricity . 35 , 163, 1920; The Effect 
 of the Barometric Gradient on Meridian Observations, Popular 
 Astronomy . 29 . 479, 1921 (Read at the twenty-fifth meeting of the 
 American Astronomical Society); Elements of 1917 W15, Astronomical 
 Journal . 31 . 65, 1918 ( with E. C. Bower); Second Elements and 
 Ephemeris of 1917 W15, Astronomical Journal , 65, 1918 (with 
 
 E.C. Bower).