1903ApJ 18. .3415 234 observation ofthespectrafaintobjects,changesin results ofastudythespectrumoCeti>orMira,made,at mum tominimum,orviceversa.Itisproposedgiveherethe fact, thereisnostarwhichundergoesalargevariationinbright- of long-periodvariablestarshavenotbeenwellstudied.In the suggestionofDirectorCampbell,withthirty-six-inch ness whosespectrumhasbeensystematicallyfollowedfrommaxi- refractor oftheLickObservatory,fromJune1902toJanuary obtained aboutthreeweeksafterthepredictedtimeofmaximum, to 9.0magnitude.Thefirstphotographofthespectrumwas and aseriesofplateswassecuredcoveringtheintervaltomini- begun toincreaseinbrightness. mum. Nonegativeswereobtainedafterthestarhadagain are thoseofVogel,Sidgreaves,andCampbell.NeitherVogel nor Sidgreavesfollowedthestarlongenoughtofindmuch the Millsspectrograph. change initsspectrum,andCampbell’sworkwasmainlycon- nection withobservationsofthestarforradialvelocity, 1903. Duringthisperiodthestarfadedinbrightnessfrom3.8 Acad., p.143,1896. of PhilosophyintheUniversityCalifornia,”LickObservatory BulletinNo.41. employed byMessrs.CampbellandWright intheirworkon College Observatory,”MonthlyNotices,58,344,April1898. 9, 31,January1899. r © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 2 1 4 On accountofthegreatinstrumentalpowerrequiredfor The mostimportantarticlesconcerningthespectrumofMira The spectrographusedinmyobservations wastheone 3Walter Sidgreaves,“TheSpectrumof0CetiasPhotographed atStonyhurst H.C.Vogel,“UeberdasSpectrumvonMiraCeti”SitzungsbeHchte derBerliner “DissertationinPartialFulfillmentoftheRequirementsfor theDegreeofDoctor W.Campbell,“Noteon theSpectrumof0Ceti,”AstrophysicalJournal, THE SPECTRUMOFoCETL' INSTRUMENTS ANDMETHODS. By JoelStebbins. 341 1903ApJ 18. .3415 gives gooddefinition,onthesamephotograph,ofregionj graph inthattime.Anexposureofsixhoursatthetimej Nova Persei*designatedas“SpectrographI.”Itistheregularj greater precautionsintighteningthevarious clampsandscrews.j four timesduringeach.exposure,andthe definition wassatis-I earlier plates.Thecomparisonspectrumwas insertedatleast; were imperfect,butthetroublewasfinally removedbytakingj ninth-magnitude starcanbefollowedaccurately.j and Curtiswerereadytomakeanattempt,butbadweatherj to benecessary.Thisestimateagreeswithmyexperience.j being inbrightlines,weshouldexpectastilllongerexposurej logue assignsthephotographicmagnitude5.0.IfoCetiwerej give asatisfactorynegativeofstàrtowhichtheDraperCata-\ of thethree-prisminstrument,itisenoughtoyieldaveryfairj from X3700toX5600.Thelengthofthisrangespectrumisj factory. SeverallongexposuresinSeptember andOctoberj spectrum wasagainbrightenoughtorecorditselfwithafairlyj soon aftersunset,waspossible.EarlyinMarch1903,the¡ could bemadeonthestar,anditwasbrightenoughtophoto-; About Julyi,1902,anhour’sexposure,justbeforedaylight,j of aboutthetenthphotographicmagnitudeatminimum,itwouldj determination ofvelocity.| 28 mm.Althoughthisdispersionisonlyaboutone-fifthofthatj short exposure;andintheabsenceofwriter,Messrs.Reesej date ofmylastnegative,anexposurefivehours,beginningj not sufificienttoproduceameasurableimage,althoughmuchj minimum, usingthefastestphotographicplateobtainable,wasj fifth-magnitude star,oraboutsixteenhours.Someofthelightj require, roughly,anexposureofonehundredtimesaslongaj prevailed. j could beseeninaqualitativeway.OnJanuary5,1903,thej Mills spectrographconvertedintoaone-prisminstrument.Itj 342 JOELSTEBBINS © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem I When theseeingisgood,anexposureoftenminuteswill| No flexureoftheinstrumentwasnoticedonany; A Hugginsreflectingslitisusedwiththisinstrument.j Z. O.BulletinNo.8. I As therewerenomeansofcontrolling electrically thej 1903ApJ 18. .3415 oor Bright Bright, faint Bright, faint Bright, faint Bright made onCramer’s“IsochromaticInstantaneous,”butthe 3 P 4 tine Bright place Bright place Bright temperature oftheinstrument,changesmust 3 poor 5 verywide 4 Bright place 4 5 wide most ofthework.AfewexposuresinJulyandAugustwere have effectedthedefinition.Thespectrographwheninusewas 4 3 H. lineofSun covered withtwothicknessesofwoolenblanket. “Crown” platesweremoresensitive. 4 wide 4 wide 5 wide © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem Description The sameemulsionofCramer’s“Crown”plateswasusedfor o Ceti.13E,IQ02,Julyi6.X=2i23.io-j« 33 -300 32.Ill 36.230 Microm- 32.870 21 .560 45.610 40.345 21.950 43.251 41.665 41.381 40.364 33.950 2Q.012 28.24I 26.3OI 2Ö.124 20.706 47-546 49 •¿30 45.850 45.282 44.170 43.996 43-810 43.5I8 43.116 42.396 40.479 49-84g 48.394 46.436 32.208 50.850 51.274 50.414 eter R. 175-043 180.308 178.988 179.272 180.289 188.542 192.412 194.352 198.703 SPECTRUM OFoCETI343 I75-37I 176.483 176.657 176.843 I77-I35 177.402 177-537 178.257 180.174 184.423 186.703 187.353 188.445 191.641 199.093 199.947 170.804 I7I.523 I73-I07 174-217 194.529 I69.803 I7O.239 I72.259 169.379 174.803 187.783 Ro-R TABLE I. Ro-R -554665 0.00 572073 570220 566627 566069 564541 563692 563263 558697 557812 5^4607 542232 535610 533752 532530 530659 530386 521809 519718 503264 583012 580521 577677 573997 571288 565473 560988 555019 514530 514062 502278 500138 688918 587409 585466 590392 4046.03 3969.24 39O6.OO 4O7I.96 4O24.76 4O2I.2I 4009.25 4OO7.39 4OO5.4I 4OO2.3O 3999.48 3998.05 3982.85 3969.43 3928.04 4O88.36 4063.79 4055.50 4033-78 4O27.38 3990.48 3979.9I 3970.61 3899.82 3895-75 3889.52 3888.61 386O.O6 3853-10 3795-05 3787-91 4083.45 4078.43 3835- 8 3 3834- 2 7 3798.33 Formula \ From Correction Formula —j-o. 04 -\-0.I3 +0.03 +0.03 +0.05 +0.0J -|-0.00 -j-o. 10 +0.06 +0.10 4-0.02 +0.09 +0.14 —0.04 —0.04 — O.O3 — O.O3 — O.O3 — 0.02 — 0.02 — 0.02 — 0.02 — 0.01 — 0.01 — 0.01 — 0.01 —0.04 —o.os — O.O3 — 0.01 — 0.01 — 0.02 0.00 0.00 0.00 0.00 to 220.653—R Reduction —O.38 +O.36 —O.38 —O.38 —O.38 —O.38 +O.37 +0.37 +O.37 +O.39 +O.39 +O.39 —O.38 —O.38 —O.38 —O.38 —O.38 4-O.36 +O.39 —O.38 —O.38 —O.38 — O.38 to Sun 3899 -83 3795-15, 3834-36 3788.03 39à9-4i 3Ç28.08 3803.80 3888.67 3860.06 4063.94 4071.91 4043-98 4034.13 4007.75 4003.41 3998.42 3970.99 3969.62 3906.39 3889.92 3853.52 3798.79 4088.71 4083.80 4078.78 4055.86 4027.73 4025.12 4009.61 4002.67 3990.85 3983.22 3980.28 3836.25 4021.57 3999.85 i ! ! 1903ApJ 18. .3415 1 found onallotherplates,except57A. j great flexureduringtheexposure.Something ofinterestwas~j The widthoftheslitisexpressedinterms ofthedivisionsonj kindly turnedthemovertomeformeasurementanddiscussion.; graph I.Mr.Wrightobtainedthreeplatesin1901,andhe the headofscrew,onedivisioncorresponding to0.025mm.j One plate,takenonSeptember16,wasdiscarded onaccountofj were foundtobeinsignificant.j in thesamemannerasbyCampbell.Thecurvaturecorrections| were basedontheCofnu-Hartmannformula,muchofcom-j amount ofthecurvaturecomparisonlineswasdeterminedj reduced withtheironspark-spectrumascomparison.From| the ironspectrumwasphotographedwiththreeprisms.Itj ultra-violet toX4415therearemanystrongandsharpironlines.j of aplateaftertheconstantsformulahadbeenderived.j table. Theexampleonpage343showsthecompletereductionj wave-lengths ofthecomparisonlinesweretakenfromRowland’sj putation beingdonewithaBrunsvigacalculatingmachine.Thej was measuredwithbothvioletleftandrightintheeye-j piece. j them havecompanions.TheregionfromX4800toA5600ofj Italicized figuresareusedforthecomparisonlines.j scopes inusefortheregularlineofsightwork.Eachplatej found thattherewereseverallinesinthisregionwhichhadnoj relative intensitiesoftheircomponents.I companions, andwhichcouldbeusedwithouthesitation.Closej double lineswereassumedtohavepositionsdependinguponthe! From X4415toX5600theironlinesarefainter,andmanyofj 344 JOELSTEBBINS © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 1 A plateoftheskywastakenwithaverylongslitandj The brightnessofthestarattimewhen eachplatewasj The reductionsfrommicrometerreadingstowave-lengthsj In TableIIisgivenalistoftheplatessecuredwithSpectro-j All oftheplatestakeninthisworkweremeasuredandj AstrophysicalJournal,8,144,1898. j The platesweremeasuredwithoneofthemeasuringmicro-j DATA OFTHEOBSERVATIONS.j 1903ApJ 18. .3415 series ofdarkbands,withedgessharptowardstheviolet,andj have absorptionspectraofSecchi’sthirdtype.Someobserversj observation. ; taken isshowninFig.i.Theobservationsofvisualmagnitudej minimum, nogreatchangeinthespectrumcouldhaveescapedj are givenattheendofthispaper.Asplateswellj the solarspectrum. j the intensitiesmaybeverydifferent.Themethodadoptedwasj the tablewhichagreesinpositionwithoneonplate,butj printed. j of Fig.4shouldbeAugust11,instead4,asisj seems tobeverifiedbymyplates,butacloserstudyshowstheI trum isverysimilartothatoftheSun.Atfirstglancethisj they reportthatfrom//ytotheultra-violetdark-linespec-j have foundtheregionfromH?ttowardsredcrossedbyaj there areveryfewwhichcoincidewithlines oflikeintensityinj was notfoundbestsimplytomeasuretheplatesandthenlookj on alantern-slideplate.Theabsorptionspectrumofthestar,j distributed alongthelightcurveuntilabouttimeof! ment ofthesolarspectrum,photographedwithSpectrographIj details tobeverydifferent.Fig.2showsaneightfoldenlarge-j ently, sothatafaintlinemightbemeasured ononeplatewithoutj seven plates.Eachplatewasmeasuredand reducedindepend-j dispersion. Ofthelargenumberoflinesin thestarspectrum,j prominent in0Ceti\fact,theydo not showwithlowj spectrum ofthestar,glinebeingmuchmoreintensethaninj to compareaplateof0Cetiwithonethesky.Thetwoj the solarspectrum.ThestrongironlinesofSunarenotsoj microscope withalowpower.j negatives, filmsidestogether,wereexaminedunderthej for coincidencesinRowland’stable.Itiseasytofindalinej Figs. 3-6,isseentoresemblelittlethatoftheSun.Thedatej © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem As iswellknown,oCetiandtheotherlong-periodvariablesj The strongcalciumlinesg,H,andK,arepresentinthej The absorptionspectrumofMirawasmeasured accuratelyonj In comparingthestarspectrumwithsolarspectrum,it; SPECTRUM OFoCETI345 ABSORPTION SPECTRUM.; 1903ApJ 18. .3415 in differentpartsofthespectrum.Thelines oneachplatewere to thestronglineatX4255.Onthisscale theH,andK assigned aremerelyrelative,andnodoubtthe scalevariesmuch lines mightbe100or500,itmatterslittle. Theintensities intensity 1tothefaintestlinesdistinguishable, andintensity10 strength ofthelines.Itwasintended,on each plate,toassign expressing theintensityindicate,inageneral way,therelative spectrum as.derivedfromallthemeasures.Thenumbers 2235D 2212D 2211C being noticedonanyoftheothers.Thisdoesnotmeanthatit 346 JOELSTEBBINS in pairs,underthemicroscope.Thishasbeendone,andall had developed,orthatitsintensitychanged.Suchlines, changes inintensityorcharacterhavebeennoted. verifying changesistoexaminedifferentplatessimultaneously, irregular arrangementofthesilvergrains.Thebestmethod of whichmanyweremeasured,couldbeeasilyobscuredbyan 3 58A 59A 48A 330 57A 54A 42A 39D 28D 27D 2iF 26D 25 F 18F 14F 13E © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 8D 9E 4E 7C S 2B In TableIIIaregiventhewave-lengthsofabsorption 29 Aug. 3 Jan. 2 Dec. 21 Nov. 25 Oct. 4 Aug. 4 July 6 June 27 Sept. 6 A 1901 1903 1902 17 22 25 26 22 ii 16 16 27 27 3 5 4 6 6 rt 23 30 23 22 23 07 23 35 23 28 22 47 22 46 22 39 22h 09™ s 4> § sw 0 45 0 07 3 18 3 10 ° 53 o 58 4 10 2 20 1 47 1 44 TJ.« c/) 12 Plates SecuredWithSpectrographI. 4 5^ 5 17 o 05 O 02 o. 03 2 30 2 OO o 05 0 10 2 40 oh 45m 1 15 I—] £3 JOEL STEBBINS 15 07 07 09 07 01 00 01 03 02 08 09 03 01 03 05 02 00 15 24 12 12 H *9 10 25F 15 TABLE III. 27D 3à 01 12 04 ii 09 05 08 02 02 07 04 01 13 08 03 II 01 00 17 28D 08 04 08 21 03 02 06 19 23 03 03 09 38 04 09 22 07 05 00 03 14 02 10 2235 D 01 09 08 05 03 04 09 39 // 27 09 04 13 ii 20 26 12 14 il Several Too wideandfainttomeasure. On plates7C,13Eand2235D Too wideandfainttomeasure. Several linesruntogether Perhaps several Perhaps several H lineofSun,verystrong.Ad- K lineofSun,verystrong.Ad- these twolinesruntogether Probably several Probably several jacent brightlinesinterfere with measurementofX jacent brightlinesinterfere with measurementofX Remarks ' i 1 ! 1903ApJ 18. .3415 Intensity 10 6 4 fine 4 fine 3 2 fine 4 fine 3 2 3 5 4 4 wide 3 3 3 3 3 3 4 3 2 7 4 wide 4 wide 2 wide 3 5 wide 3 3 5 6 8 4 2 3 5 2 i 3 3 3 2 1 2 2 1 4 4 5 2 fine wide fine © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem fine 4124.66 4122.62 4121.44 4129.04 4126.99 4130.60 4137-77 4I35-32 4133.00 Observed 4I50-73 4144.— 4140.96 4160.89 4I53-40 4156.78. 4I75-4I 4169.27 4165.82 4I73-56 418.3-73 4180.96 4178.32 4191.79 4188.]7 4214.86 4211.19 4199.79 4242.82 4*35-37 4227.84 4255-46 4251.60 4273.15 4275.84 4261.87 4259.64 4292.45 4290.72 4285.28 4297.56 4295.07 4304.06 4314.29 4307.23 4300.16 4310.57 4326.97 4320.03 4353-60 4348.12 4331-13 4395-89 4390.71 4380.31 4385-49 ?c 01 17 ii 01 10 00 ii 06 00 06 03 06 12 22 24 13E 18F25F27D28D2235D 21 05 04 28 12 08 10 28 13 02 02 33 12 07 17 09 02 18 Absorption ofSpectrumoCeti. Residuals ino.oit.m, SPECTRUM OFoCETI349 00 08 24 TABLE III.—Continued. 15 04 12 00 12 01 07 01 07 17 27 08 04 id ii 03 oó 00 12 10 00 13 04 06 oó 14 13 05 10 03 08 08 16 27 10 2Ô 14 03 03 ii 14 02 3à 17 00 23 23 07 23 06 07 ii 04 18 ii 01 09 ¿J 25 o6 01 04 11 ii 15 05 18 12 04 26 32 06 01 04 02 3à 06 10 00 oó 05 17 18 15 24 02 35 Poor g lineofSun,verystrong Poor Poor Head Head Head Remarks 350 JOEL S TE BBINS

TABLE III.— Continued. Absorption of Spectrum of o Ceti.

Residuals in o.i t.m. Intensity Observed Remarks A 7C 13E 18F 25F 27D 28D 2235D

4422.4 Head 4461.1 4463.0 Head 4505-7 Head 4 wide 4514-7 3 wide 4519.8 2 4530-7 4536.8 4548.8 Head 4585.0 3 Head 4626.8 2 Head 4669.6 [21] Head. Measure of Plate 28D 5 4709.2 rejected for discordance 4714.2 Head 10 4739-5 4760.0 Head 4804.2 Head 4842.8 Head 4954-1 Head 5167.0 Head 5308.3 Head 5358.8 Head 5439.4 Head 5447-9 Head 5498.0 Head 5568.7 Head

assigned intensities when the plate was measured ; and when the different results were brought together, a sort of mean of the estimates was taken for each line. Where the estimates did not agree well, the line was compared directly on two or more plates to see if any change had taken place. The residuals in the table were formed by subtracting the mean wave-lengths from the values given by each plate. All plates were assigned equal weight in forming the means. Periods (. . . .) signify that when the plate was measured nothing was noticed in the spectrum at that place. A dash (—) denotes that the line was observed, but could not be measured accurately. When a line was measured on only one plate there is no residual, and the dash indicates the plate referred to. Plate 18 F was measured only from \ 4300 towards the red.

© American Astronomical Society • Provided by the NASA Astrophysics Data System 1903ApJ 18. .3415 the platewasnotmeasuredinthatregion. The comparisonon7CbeingunderexposedtotheredofX4415, velocity itwouldappearinthemeanresiduals.Thearithmetical velocity wasaboutthesameduringcorrespondingphaseof variable velocityinthelineofsight.ThosefromMr.Wright’s that thewave-lengthsofbutfewdarklinesmeasuredon to measure,theresidualsfromdifferentplatesarenotlargerthan plate havebeenaveraged;andiftherewereanychangeinthe the star’slightcurve,ayearprevious.Theresidualsforeach several platescanbeinerrorbyasmuch0.2t.m. the violetofX4400wereused. error ofthewave-lengthadarklinederivedfromoneplateis means oftheresidualstovioletX4400,andcorre- plate No.2235D,whichwastakenin1891,indicatethatthe the probableerrorofitsmeanpositionistherefore±10.04t.m. When itisrememberedthatalllines,good andpoor,were sponding velocitiesinkilometerspersecond,areasfollows: each otherisnotatestastosystematicerrors,yetIfeelsure the plates,butnosensibleerrorisintroduced bythisassumption. plates, theaverageresidualofoneplateisnot strictlytheaver- would beexpected.Whiletheagreementofresultswith age deviationofthemeasuresonthatplate from themeanofall In computingtheprobableerror,residualsfromalllinesto zho.io tenth-meter.Whenalinewasmeasuredonsixplates, © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem A glanceattheresidualsshowsthatthereisnoevidenceof Since manyofthelineswerenotmeasured onallofthese From theresidualsinTableIIIitisfoundthatprobable Many ofthelinesbeingbroadorunsymmetricalanddifficult 1901, Aug.17 1902,July 6 Date Aug. 4 25 SPECTRUM OFoCETI ii 16 Plate No. TABLE IV. 27 D 28 D 25 F 13 E 7 C + O.06 +0.02 +0.02 — O.O3 — 0.02 — O.O3 t.m. +4 +1 +1 — 2 — 2 — I km 351 i 1 ! 1903ApJ 18. .3415 and noneofthesearefinesharpenoughtogivethebestj of +66kmwasthereforederivedfrommeasuresonlysixlines,j other dataofthesolarlinesarefromRowland’stable.| son ofthestarplateswithasolarplate,andonlycoincidencesj requires anassumptionastowhatthewave-lengthsofstarj known lines.Adeterminationoftheactualradialvelocityj the starlineswithofsolarspectrum,orotherI included inthemeans,andthattheseplatesweretakenwithaj the velocity;anditwasthoughtbesttomeasureonlyfirst-classj a titaniumlinemakeupstellaratX4079.51.Thevelocityj double manganeselineat\4030.92givesadiscordantresult,j lines wouldbeiftheywerenotaffectedbyvelocity.Agree-j determination. \ which wasrejected,anditlooksasthoughbothastrontiumj which seemcertainaregiveninTableV.Thewave-lengthsandj one-prism instrumentgivingadispersionofbutone-fifththat| ments ofstarandsolarlineswerelookedfor,bydirectcompari-j period wasderivedwithoutassumingthecoincidenceofany! plates inthisconnection.; plates isverysatisfactory.Noneofthetakenlaterinj of theregularMillsspectrograph,rangeonly6kmonsixj 3 52JOELSTEBBINS 1902 aregoodenoughtoaffordcomparableconclusionsasj Intensity and © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem Strong Strong Strong 10 Character The HandKlinescouldnotbemeasuredaccurately;thej The resultthatthestar’svelocitywasconstantoveracertainj 8 6 5 wide 7 wide 7 5 wide Coincidences ofDarkLinesintheSpectra0CetiandSun.| 0 Ceti 4275.84 4O32.22 4255.46 4227.84 4O79.5I 4O34.O4 3962.55 3945-09 3936.— 3969.6- x 44.I6 74.96 77.88 78.63 33*22 3O.92 68.62 33.82 54-50 26.90 6I.67 Sun A TABLE V.I Displacement [+1.30] -j-o. 88 -|-o. 88 +O.93 +0.96 +0.94 -¡-0.82 t.m. Mean +66km Velocity. [+96] +67 +71 -Hi km Al 20 Sr 8 Al 15 Fe-Mn 7 Mn 4and5 Ca 1000(K) Ca 700(H) Cr 7 Cr 8 Ca 20(g-) Ti 3 Substance and Intensity Sun 1 1903ApJ 18. .3415 therefore beenobservedtobeconstantoverabouttwo-fifthsof ment. TheintervalbetweenAugust29,1898,thedateofhis prism plates,theintensitiesareexpressedonanarbitraryscale The resultsaregiveninTableVI.Aswasdonefortheone- more thanfourperiodsof331days.Theradialvelocityhas first platethatyear,andAugust25,1902,isequalto130days Several Several coincidences werefoundbydirectcomparisonwithasolarplate. measured betweenX4300andX4420,morethantwenty high-dispersion platesof0Ceti,takenbyDr.Campbellin1897. the periodoflightchange. Bright place Several Absorption Spectrumof0Ceti.HighDispersion.Plate576B;December15,1897. Poorj* of 10.. Although theplateisunderexposed,aboutseventylineswere © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem Intensity and^ To determine.morecoincidences,Ihavemeasuredoneofthe Campbell in1898found+62kmwiththethree-prisminstru- Character 4 3 2 6 4 3 5 5, double? 3 5 I i I I I o Ceti 4326.85 4325.93 43I6.I- 43O8.94 433O.3O 4329.53 4328.69 4327.96 4319*77 4315*2- 43I2.9O 43IO.83 4308.16 4307.10 4303-56 4302.17 4301.58 4300.8- 4299.7- 4333- 9 2 433I.I3 4338.16 4337-07 4335- 9 1 4335.29 4334- 6 8 4336.38 SPECTRUM OFoCETI 25-94 02.69 37-22 32.99 30.I9 18.82 Sun A TABLE VI. +0.91 +0.95 +0.87 +0-93 +0.94 +0.94 place- ment Dis- t.m. +63.O +65.9 Velocity +64.4 +65.0 +60.6 +65.O km Not © Fe 8 Not © Not O Not 0 Not O Not O Not O 07.91 Ca3,08.08Fe6 Narrower inO Fes Same in© Not O Not O Not © Not © Closer doubleinO Possibly weaklinesin© Ca, Mn?4 Ca 4 V 0) Stronger thanin© Remarks 353 ! 354 JOEL STEBBINS

TABLE VI.—Continued.

o Ceti Dis- Sun place - Velocity Remarks Intensity and A ment km Character A t.m.

2 4338.61 37-72 + O.89 +61.5 Cr 3 I 4339.11 Not O 3 4345.56 44.67 +O.89 +61.4 Cr 4 4 4348.27 Not O i 4352.16 51.22 +O.94 +64.8 Cr 3 Poor 2 4352.90 51.93 +O.97 +66.8 Cr 3 Head of band Not O. Mean of 4 plates with 4353.7- one prism 4353.6 Fe 4. This line always gives + 5 4353-91 52.9: [+1.00] [+68.9] residual in other stars 3 4356.97 Perhaps O, not certain i 4349-70 i 4360.12 i 4360.65 1 4361.73 All weak lines in star ' Poor i wide 4363.05 No coincidences certain 2 4365.56 2 4367.10 I 4367.87 4 4369.07 Not O i 4370.48 Not 0 I 4371.23 Not O (71.14 Zr I, 71.22 —I, 71.44 4 4372.22 i Cr 4) same appearance i 4373.17 Not O Several to violet of 4376.4- Different in © Bright place 4376.68 Not O. This develops into a ! bright line 5 4377.06 76.II +0.95 +65 Fe 6 ! i wide 4378.06 Different in O i wide 4379.17 ¡ 10 4380.27 79.4O +O.87 +59 r4 1 4383.67 Not O 6 4384.62 83.72 +O.9O +61 Fe 15 7 double? 4385.90 84.87 V 3, 85.14 Cr 2 5 4390.26 89.4I + 0 +58 Fe 2 \ 4 4391.06 9O.I5 +0 +62 V 2 V Stronger in star than in © Poor 2 wide 4392.76 91.92 +0 +57 Cr I ) 7 4396.20 95.20 7*3,95.41 V2 2 4401.61 OO.74 +0. +59 Vi io wide 4405.89 04.93 +0. +65 Fe 10 2 4407.02 Not © 1 4 4407.72 06.81 +0.91 +61.9 V 2 4 4408.70 07.81 V 2, 07.87 Fe 4 io 4409.41 08.36 V 2, 08.58 Fe 3, 08.68 V 2 i Several to violet of 4416.7- Different in © 4 4417.59 1.6.64 +0.95 +64.4 V 0. Stronger in star than in © Head of band 4422.5- Not ©. Mean of 6 plates with i prism, 4422.4 Mean of 20 lines -(-62.7 km

© American Astronomical Society • Provided by the NASA Astrophysics Data System SPECTRUM OF o CETI 355

A comparison of Table VI with the corresponding part of Table III is ä test of the reliability of the results obtained with one prism. TABLE VII.

One Prism THREE Prisms

Description Description

99-7- 4300.16 00.8- 2 4304.06 3 4307.23 07.10 3 4310.57 10.83 Head 4314.29 2 4320.03 19.77 3 4326.97 26.85 2 4331.13 31.13 2 4348.12 48.27 Head 4353.6- 53.7- 4 4380.31 80.27 84.62 5 4385.49 85.90 90.26 4 4390.71 91.06 Head 4395.89 Head 4422.4- 22.5-

As might have been expected, many lines observed as single with one prism are really made up of two or more components. This comparison also shows that the wave-lengths of Table III ! are probably not quite so accurate as the residuals indicate. A brief summary of the number of dark lines of different ele- ments observed in the spectrum may be of interest.

TABLE VIII. Element No. of Lines Ca - - - - 6 Fe ------ii Cr ------q 1 V ------ii Al ------2 Sr ------i i

Mn ------3) ? Ti ------2 f ’ There can be no doubt of the presence of the first four ele- ments in the list, and the aluminum and strontium lines are

© American Astronomical Society • Provided by the NASA Astrophysics Data System 1903ApJ 18. .3415 to fallintoerrorinjudgingaschangestheintensityand prominent ;butmanganeseandtitaniummustbeconsideredas \4227.84. Figs.3-5showhowitbroadenedasthestargrew doubtful. which therealityiscertain.Thisgcalciumlineat character ofdarklines.Ifallthenegativesweresame 356 JOELSTEBBINS faint. Measuresofitswidtharenecessarilyrough,andmust changes. Thereisonedarklinewhichshowedchangesof density andofuniformexcellence,itwouldbeeasytonotesuch of twoplatesareasfollows: depend muchuponthejudgmentofobserver.Themeasures values. Theintensityofcontinuousspectrum,intheneighbor- plates isthatmanyotherlinesalsogrewbroaderasthebright- hood of\4227,isalmostthesameonPlates2Band33D. width oftheslit,reducedintensityresultingnegative,and The HandKlinesarenotshownonmostoftheplates, would alltendtomakethelineswiderandlesssharplydefined* flexure andtemperaturechangesresultingfromlongerexposure, ness declined,butthisisnotcertain.Theeffectsofgreater nothing canbesaidastochangesintheircharacter. later. Foursuchlineshavethefollowingpositions: these linesfirstappeared. have notbeenfound.TheresidualsinTable IIIindicatewhen Lines ofthesolarspectrumwhichcertainly coincidewiththese © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem On accountofthevaryinginstrumentalconditionsitiseasy Other platestakenbetweenthesedatesgaveintermediate The generalimpressionformedfromexaminingtheseriesof A fewlinesnotvisibleontheearlyplatesbecameprominent X3990.64 M093-55 4045.16 4097.08 1902, June27 September 6 Date TABLE IX. Width 9 t.m. 2 t.m. 1903ApJ 18. .3415 the regionabovewheretherearenobands,thancor-j tions ofthebandedspectrumarecertainlybrighterrelativetoj think themtobebrightflutingslikethoseofthearcspectrumj responding portionsofthespectrumasolar-typestar.How-j of carbon.Forconvenience,theywillbeconsidered,inthisI sidered bysomeobserversasaseriesofdarkbands,withsharpj edges towardstheviolet,andshadingofftowardred.Othersj solar typeofspectrum.j considered asbrightordark.Whilethelineofseparationis; that themeasurementsremainsamewhetherbandsbej ever, thedarkportionsarefainterthansameplacesinj other third-typestarstakenwithSpectrographIthebrightpor-j paper, asdarkabsorptionbands.OntheplatesofoCetiand| tant partindirectvisualobservations.Sincethebandscon-j probably sharpinmosteases,itsexactpositionisnoteasytoj division betweenadarkandbrightportionofthespectrum,soj of theheadstoolarge.Correspondingtothisvisualerrorisj determine. Nodoubttheeffectofirradiationplaysanimpor-j effect ofirradiationwouldbetomaketheobservedwave-lengthsj sidered asbrighthavetheirsharpedgestowardsthered,j effect ofspreadingtheimageonaphotographicplate,caus-j being thatmuchfarthertothered.Althoughthiswasonlyj ing anerrorinthesamedirection,andaslightallowancewasj made foritinexecutingthemeasures.Atmyrequest,Dr.; ence betweenhismeasuresandminewas0.3t.m.,myestimateI meter inthemeasurementofasharplydefined head.j able thattwopersonsshoulddisagreebyas muchasonetenth-j comparison madewithanotherobserver,itseemshighlyimprob-; Reese madeseveralsettingsontheheadofaband.Thediffer-j the sharpedge,spectrumgrowinguniformly brightertothej gradually fromheadtohead,therebeing heavy absorptionatj diffuse endsofthebands.Inmanycases intensitychangesj next lineofdemarcation. I © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem The prominentbandsinthespectrumofMirahavebeencon-j In measuringtheplatesmicrometerwirewassetonj No attemptwasmadetodeterminetheposition ofthemorej SPEC TRUMOFoCETI357 BANDS. j 1903ApJ 18. .3415 a Herculisandotherthird-typestars,founddifferenceinthe wave-length ofthesamebandindifferentstars.Forhead and intermediatevaluesforaOrionisßPegasi.Hesuspected at X5447in0Ceti,hefoundthepositionofX5458aHerculis, these discrepanciestobedueinstrumentalcauses,butofthis he wasnotcertain.Hisworkbeingdonewithanobjective prism, hehadnocomparisonspectrumwithwhichtotestthe 3 5BJOELSTEBBINS are allbright,theexposuresonthemwerecomparativelyshort, a Herculis,ßPegasi,pPersei,Ceti,andOrionis.Asthesestars reality oftheobserveddifferences. the fivestarshasbeentakenafterapplying these corrections. velocity referredtotheSunwerezero.Themeanresultfrom in ordertoreduceitwhatwouldbeifthestar’sradial ing correctionisthatwhichmustbeappliedtoeachwave-length from fiveminutestoonehour.Isochromaticplateswereused, The resultsforanystararefromallthe plates ofthatstar, corrected fortheorbitalmotionofEarth.Theaccompany- heads ofthebands.InspectrumMiratherearefew so thatarangeofspectrumasfartotheredX5600was covered. Theyweremeasuredonlyforthepositionsof position ofabandisnotgivenforstar, itwasnotapparent. first theobservedwave-lengthsofheadeachband,already except inthecaseofaHerculis,whereone oftheplateswasa bands arelessprominent,andinthecaseofaCetiOrionis, by theradialvelocities,itisnecessarytoapplyeachobserved “Crown” plateandshowednothingtothered ofX4954. ties havebeendeterminedfromtheirdarklinespectrainthe only threebandscouldbemeasured.Allofthesestarsareon many lineswererecorded.Wheretherearemorethe wave-length acorrespondingcorrection.InTableXisgiven, region ofHj the fine,darklinesinH

Fig. x>> 1903ApJ 18. .3415 © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem

Fig. 4.— 0 Ceti, 1902 August 4. 27 D. 1903ApJ 18. .3415 differences werenoticed,theysmallcomparedwiththe longer andshorterwave-lengths. the portionnearA,4275wasmadeequalto10,andestimated were determinedfromplatestakenofotherstars,andwhilesome A, 5500.Myplatesshowadecreaseinintensityoftheregion which maybeheadsofbrightbands. figure, thelinesjoinestimateswithoutreferencetointen- by meansofthescale.Theseestimateswereplotted,and,in same portionsofthestarspectrumwereestimatedoneachplate which wereallofthesameemulsion.Theintensities changes observedinthecaseof0Ceti. disk ofHearth's motion;Under“DarkLines"isgivenanassumeddis-j iron spectrumreachedtheplate.Atwo-second exposuregavej other darklines.j absorption components,thedisplacementsareequaltothoseofI amount asthebrighthydrogenlines;andifironproducesj is ofabrightlinewithanadjacentdarkoneontheredside.Ifj same asthatofand//8,thiseffectisprobablynotlarge.I the red,greaterexposureprobablyslightlyincreasesappar-j displaced about0.25tenth-meterfarthertotheredthanare! changes ofintensityamongthebrightlines,bothrelativetoeachj the brightlinesbeduetoiron,theyaredisplacedbysame; hydrogen lines,whichwherenotoverexposed,isaboutthej many oftheplates.Sincelinesseemtoshadeofftowardsj made bythefollowingmethod:Anoccultingstripwasarrangedj doubt, topersonalerrrors.j 368 JOELSTEBBINS duced anoverexposedimageofgreaterbreadth andblacknessj © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem The darklinesinthisregionofthespectrumareapparentlyj The brightlinesatXX4308and4376,markedaspossiblyduej A glanceattheseriesofplatesshowedthatthereweremanyj In ordertoestimatetheamountsofchanges,ascalewasj 1903ApJ 18. .3415 trary factor,theresultingintensityofbright lineis1.On intensity ofthecontinuousspectrumbetween Hhandgwas the portionofcontinuousspectrumbetweenA,4102and The intensitiesofbrightlineswere,therefore,allreferredto The quotientsformedinthismannerwillbereferredtoasthe image ofthesamelineduetoanexposurefivesecondswas second totenminutes,wasmade.Atintervalsthecurrent and aseriesofcarefullytimedexposures,varyingfromone assigned iscalled1.Onplate27Dtheline atX3908.18was X 4227. already beenshown,thereisevidencethattheintensityof to eachlinewasassignedasintensity,thenumberofseconds estimated withthebrightlinescaletobeof intensity3.5.The approximately thesameintensitiesofbrightlines.Ashas intensities ofthebrightlines.Itisevidentthatlongandshort intensity ofthebrightlinereferredtocontinuousspectrum. ous spectrumonthesameplate,wegetwhatmightcall are accordantwitheachother. required toproducetheequallineinscale.Independent and thedifferentimagesreceivedsamephotographictreat- test oftheconstancylight,andasreferencepoints,for recorded ontheplate.Theseextraimagesservedasarough switched totheothersideofcomparisonapparatusandan exposures ofthestartakenonsamenightshouldgive mated withthescale,bedividedbyintensityofcontinu- common standard.Iftheintensityofabrightline,asesti- ferent platesarenotcomparable,unlesstheyreferredtoa on thedifferentplates,intensitiesofsamelinedif- estimates ofthesamelinemadeinthismanneratdifferenttimes called 24.Dividing3.5by24andmultiplying by10,anarbi- continuous spectrumvariedindifferentpartsasthestarfaded. ment. the scale.Theexposureswereallmadeonsameplate, It happensthatthefaintestbrightlinetowhich anintensitywas © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem The developmentofthebrightlinesisshown inTableXVI. As thedensityofstarspectrum,asawhole,variedgreatly The brightlinesofoCetiwerecomparedwiththisscale,and 6 SPECTRUM OFoCETI39 1903ApJ 18. .3415 tinuous spectrum,butitcertainlycouldnotproducesuchgreat with thelongexposure2B,takenonsamenight.Theplates but thatitwasnotvisible.Adash(—)meansthelinedid Hh istherefore420.Thesenumericaloperationsarecrude,but tinuous spectrumwasofintensity6.Theresulting the lineatA,4571wasremarkable.Thisline, whichisperhaps by theotherplatestakenonsamenight.Figs.8-12truth- been arbitrarilyreducedtoaccordwiththeevidencefurnished The intensitiesarerepresentedbyordinates.Itwillbeseen variation amongthelinesthemselves. This discordanceshowsthattheestimatesareveryrough. the dataareinsufficientonaccountofunderexposure. Theline the red.InFig.13andtovioletofHh ontheotherplates fully indicatethedevelopmentofbright linesfromHhto the stargrewfaint.InFig.8,Plate2B,intensityofH

TABLE XVI. © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem Intensities of Bright Lines. U H "'O WVO ?§ « o OPQ 1 N H ^ ro• ^QO < 'Pom < P (N ¿S I hQ «o ° p cTió .Q ^ &s^. O NIO Ät ^ Tt-O- P KJ .. 04 i-Oï-OOnCOhh-^-hhrj-OOI^-nOt^COvO0-00 ^ 04nO■r^iOCOi-i•OTfO-ONO040t^OO COCOCOCOCOCOCOCOCOCOCOCOTj-Hi-T}-'<^-Tt-Ti-Tj-Tj-Ti-Ti-j- hh OOOCOOnnO0004t}-00cOvO I ^1 I I T I - I ^S I I I 04OOHHHHvO00mOONr>»Theohhhh04OCOhh0004tí- I ^ I I MM ‘£I CO hhsO 00 04•tí- 1 vO •O Tj-O-I-I »OCO04lOLOO-•O•—1vO00010ON HH co CO !>■'-OIOOí-Oo•Ot-1Tj-vOQO1004 HH 04hh00 i-. hho04i_ CO CO Tf- M I>.OOt^ •O04O*'-IIOONVOOO>-i ^ Ö3 I-H O-COi-tcocot-ivOt-1 I-I ONCOi-ihHCOi^1-104!-< rt- •O HH vO04i>. HH .OhhoCO3004 CO rfO• CO •OOnt>»04*00«IO hh IOnvO 04 IOco•00 HH ONhhIr} H- ONhhHH 0000 Ti-O o <0 m oco CO 00t-1•-I^04MON O CON000-004 M Tj"vOHH On 1-1O CO 04 CO 1-1 04 hh 04 1-1 04 04 04 hh 2 I tT tJ" ••§,•• M • Tt- • O CO O •HH • I 371 372 JOEL STEfíBINS Fig.

© American Astronomical Society • Provided by the NASA Astrophysics Data System 1903ApJ 18. .3415 trum fromX4000toX4800.j spectrum fromX4000toX4150,alsoX4200X4585.j of anycontinuousspectrum.j to giveresultswhichcanbeenteredinTableXVI.Abriefj prominent objectinthespectrum.j magnitude 5.4,andasthestargrewfainteritbecamemostj summary ofwhatwasfoundontheplatesmaybeinterest:! growing fainterasthestardeclined,andlinesX4202,4308,j recorded iftheyhadremainedasintensewereamonth; am notpreparedtosaywhethertheintensitiesoftheselastthreej preceding minimum.Figs.8-13showthat7/yand//Swerej fore strengthenstheconclusionthatbrighthydrogenlinesj either case.Theevidencefurnishedbytheselaterplatesthere-j the plateswerecarefullyexamined.InfactlinesonPlatej which wereasprominentthosealreadyunderobservation,forj lines increasedordecreasedafterthattime,buttheydidnotj disappeared atminimum.andHhwouldcertainlyhavebeenj with thebright-lineandcontinuous-spectrumscalesweremadein| phases, itisobviouslytoosoontoadvanceany theorytoaccountj change much.Itiscertainthatnonewbrightlinesappearedi and X4571wereincreasinginintensityasfarPlate48A.Ij Afy andHhregions,butnotraceofabrightlinewasseeninj spectrum andinthebrightlinesarereal. j come out,andtherelativechangesobserved inthecontinuousj subject tomanyerrors,itaffordsabetterideaofthechangesj for theobservedchangesinitsspectrum or initsbrightness.; know, whenusingthescales,howfinal intensities-wouldI such awayastoavoidpersonalbias.The observerdidnot; than becouldgivenbyameredescription.Alltheestimatesj 54A wereentirelyoverlookedonthefirstexamination.j © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem The imagesontheplatesfollowing48Aarenotstrongenoughj While themethodofestimatingintensitiesherepresentedisj On 58Aand59Athecontinuousspectrumwasvisibleinj 58A. Brightlines4202,4308,4571allcertain.Faintcontinuousspec-j 54A, Brightlines4202,4308,apparentlypresent,4571certain.Notracej Until thisstarhasbeensuccessfullyfollowed throughallitsj 59A. Brightline4202notfound.4308,4571present.Faintcontinuousj SPECTRUM OFoCETI373 374 JOEL S TEBB IN S •oi

© American Astronomical Society • Provided by the NASA Astrophysics Data System 1903ApJ 18. .3415 The lightgatheringpowerofthegreatrefractorisnotsufficientj small relativemass,weremovinginaveryeccentricorbitandj sive scaleusedbyme.Anidealequipmentforworkonvariablesj to followthespectrumsatisfactorily,atleastnotondisper-j that thevariationsinbrightnessarenotduetoinfluenceofaj arranged foruseinallpartsohthespectrum.j approached veryclosetotheprimary.Thedisplacedsystemofj purpose alone,withspectrographsofvariousdispersivepowers! would consistofalargereflectorwhichcouldbeusedforthisj binary system,thoughperhapsnotabsolutelyso.j bright linescouldnotbelongtosuchacompanion,astheirwave-j companion star,unless,indeed,thewereofveryj the apparentabsenceofHebyassuminghydrogentobeataj period ofthelightcurvepracticallyprecludequestionaj lengths areapparentlyconstant.Thelargeirregularitie'sinthe| lying absorptionstrata.Itisusuallyexpectedthatthebrightj calcium absorptiondestroyingtheHeradiations.Thistheory; lower levelinthestar’senvelopethancalciumlayer,Hj seems asyetimpossibletoexplain.MissClerkehasexplainedj hydrogen serieswilldiminishinintensityfromredtowardsthej apparently bycausesotherthanradialvelocity andpressure,itj as thediminutionfromZ/ytoHßisentirely toogreat.Inas- violet. Thisappearstoholdevenfornewstars,inwhichthej intensity thanisHe;andwiththemtherenoevidenceofoverj been proven.However,H$andHaaremuchmorereducedinj may stillbetrue,thoughtheexistenceofafaintbrightHehasj lar form.ThesuppositionthatinAfïrathehydrogenseriesmayj seems probablethatthepeculiaritiesof hydrogen-line inten-j reference tothedark-linesystem)fromtheir normalpositionsj much asthebrightlinesarestronglyshifted (tothevioletwithj regularly decreaseinbrightnessfromviolettoredisnottenable,j haps bemadeforHawhennewstarspectraapproachthenebu-j disturbance hasbeenverysudden,thoughexceptionshouldper- of thebrightironlinesX4308andX4376, absenceofothersj sities areduealsotocausesnowunknown us.Thepresencej © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem The apparentconstancyofradialvelocityisstrongevidence; The remarkabledistributionoflightinthehydrogenseriesj SPECTRUM OFoCETI375 376 © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem

33D JOEL STEBBINS

Fig. 13. 1903ApJ 18. .3415 similar unknowncauses.j of thesameelement,anddiversitystructureobservedbyj show thatthestar’sdecreaseinlightisproducedbyothercausesj Campbell inthetripleandi/Sbandsareperhapsduetoj tions duringthecourseofwork;toMessrs.Wrightandj who providedthenecessaryapparatusandmadevaluablesugges-j the star’svariationinbrightnessisduetoactionofinternal! than generalabsorption.j hydrogen andotherbrightlines,inthecontinuousspectrum,j glass. Afterithadbecometoofainttobeseenwithanoperaj Curtis, forenlargingthenegativesreproduction.j glass, thethree-inchfinderoftwelve-inchtelescopewasused.j forces. I the HarvardPhotometry,Annals,45.Forfainterj about onceaweek,beginningwithJune23,1902.Atfirstthej in 29,144ofthesamepublications.Nostars thatarenotinI any ofthecomparisonstars,andinbutfewcasesdidIremem-j two later.Whenobserving,Ididnotknowthemagnitudeofj the sakeofuniformity,allestimatesweremade ingrades,andit; star’s magnitudewasdeterminedwiththenakedeyeoroperaj Reese, forcontinualadviceandassistance,toDr.H.D.j observations tobe0.11magnitude.However, mostofthecom-j made, recorded,andthenlaidaside,tobereducedamonthorj ber whattheestimateonanypreviousnighthadbeen.| stars theadoptedmagnitudesarethoseofH.M.Parkhurst,given; resulting magnitudeisindependentofthevalue ofagrade.Forj parisons weremadeandreducedinsuch amannerthatthej one ofthesetwosourceswereusedforthecomparisons. I © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem The greatvariationsofrelativeintensityobservedinthej Considering alltheevidence,itseemsreasonablycertainthatj The brightnessof0CetiwasobservedbyArgelander’smethodj I begtoacknowledgemyindebtednessDirectorCampbell,j The magnitudesofallstarsbrighterthan7.00weretakenfromj The valueofone“grade”hasbeendetermined fromthej In ordertoavoidprejudice,theobservationsin“grades”were¡ OBSERVATIONS OFTHEBRIGHTNESS0CETIINI9O2-I9O3.| SPECTRUM OFoCETI377 1903ApJ 18. .3415 two assumed6.8magnitude. two starshasbeengiventwicetheweightofanestimatebased taking themeanofseveralestimates,anestimatederivedfrom the variablehasbeentakenproportionallybetweenthem.In with twostars,onebrighterandfainter,themagnitudeof possible. Inreducingobservationswhere0Cetiwascompared was triedtokeepthevalueofonegradeasnearlyconstant 3/8 JOELSTEBBINS © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem Letter 1 J J f P y Harvardmagnitude7.06,has8.5companion. Combinationofthe M k N L K I Q n l g H F A u t s r m h E D B X w e d a c b C i G Reference LettersandMagnitudesAdoptedfortheComparisonStars. 1 9.44 9.99 9.48 9*35 8- 9 5 8.12 8.80 8.65 8.44 4.88 4- 73 4.46 4*33 7.86 7.27 6.8- 6.71 6.47 6.30 5.22 4.62 3-64 7- 3 6.00 5-63 5- 54 5.05 3-64 5-76 5-73 5-66 5.64 Mag. 30 90 96 91 86 71 10 2I + + + °4 -j- 2°2Ç0 + + 8°455 + + 9°359 + 7°388 + °37 -|- 2°422 - 2°375 - i353 —i6°295 — o°4o6 — 8°244 — 10240 ( ( B. D. 3 371 o° 4 4 8 4°390 4°379 4 3°374 3°375 2°389 3‘ 3 5°438 ’377 ’393 ’322 ’336 ’293 ’362 ’373 ’347 418 273 394 260 363 355 340 372 370 TABLE XVII. 2 X Ceti fi Ceti £ Ceti t Ceti y Ceti £ Piscium 0 Piscium a Piscium 0 Ceti f Ceti r¡ Ceti 71 Ceti 63 Ceti 84 Ceti 67 Ceti 66 Ceti ô Ceti 70 Ceti 75 Ceti v Ceti v Piscium Name R. A.1900 2 54.4 2 22.8 2 39-5 i 48.4 i 40.1 1 46.5 1 36.2 m 20.0 20.0 07.7 38.1 06.5 36.1 37-7 27. i 30.6 56.9 34-4 39-4 10. i 14.6 12.8 036 12.0 17.1 19.0 2 + o15 — 801 + 49 -- 509 — 831 " 459 -- 839 + 217 +1 -- 242 -- 942 - 3 — 1628 — io°43' — 420 - 4 — 2 — i — 6 — i — 2 — 4U — 1050 — 006 — 842 — i28 Decl. 1900 48 08 53 20 52 14 17 18 i ! ! 1903ApJ 18. .3415 is oflittlesignificanceinobservationsthiskind,thefinal upon asinglecomparisonstar.Ashundredthofmagnitude taken tohundredths.EvidenceofthePurkinjephenomenon but thelight-curve,showninFig.i,wasdrawnwithmeans shows inthechangefromoperaglasstothree-inchfinder. means havebeenroundedofftothenearesttenthofamagnitude, Astronomical June 23 July 2 Aug. 4 © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 1902 Date 27 22 29 29 14 25 18 ii 18 2 M.T. 22.8 3 .5 22.9 22.8 22.2 23.1 23.1 23.2 23.1 22.6 22.7 23.8 22.2 G. v 2f V 2g j 2v3n v —f v 2g f Iv b 2v a 2v V =b d 2v v 4e v =d v —k g 2v3i d 2vh v =e d 2v3m g 2V b 2v v 2c y =m v —k i Iv1 e 3v2m f Iv3m m 5vs v =n v =j n 2vt V P Comparisons V =s n 2vs p 3v2q v =t v n v =w r 2vx V —Z v —y s 3vy q 2vr Observations oftheBrightnessoCeti* 2 e 2 1 SPECTRUM OFoCETI Mag. IMean 3-74 4.02 3.86 3-86 3-69 3-74 3- 9 0 4.08 3.86 4.11 4- 1 5 4.27 3-77 3-46 3-49 3-64 4.08 4.14 3-91 4.46 4.62 4- 5 3 4.49 4.70 4.88 4.62 5.22 5- 0 5 5.-6 5-36 5-41 5-34 5.66 5-73 5-64 5.58 6.30 5-76 5.81 5-97 6.47 TABLE XVIII. 4.1 4.0 3.8 3.8 4-5 4- 7 5- 0 5.3 5-4 5,6 5*9 Astronomical Aug. 25 Sept. 3 Oct. Nov. ii Jan. Dec March 17 Feb. 28 I902 Date 190 27 27 17 24 24 15 17 29 12 9 8 5 3 M.T. 22.5 21.6 20.8 22.2 19-5 19.0 19.3 19.0 18.5 19.8 19.8 19.8 17.8 19.5 16.8 17.8 16.2 16.0 15-5 G.. mv y 8v3C v 3D v 2C y 6v4C V =J v =C v =D v =B v =A J 5vN J 3v6L V —I v 2I B 2VD X 2VB v iH C 2v3G V=rC J 2v5L v 4L F 3v2J v 2G E 5v2F B 2VD J 2vK v 2K E 5v2F E 4v2F Comparisons I 2v3M H 2v4M J 3vK vL v =I I 2vM v =J v =I 5q V2*C G 2vH 5 Mag. 8.22 6.98 6.80 7.05 6.88 6.71 b.42 8.93 8.95 8.58 8.54 8.61 8.05 8.05 8.04 7.27 7.27 7.06 7.06 9.00 9.11 9.07 8.80 7-74 7-33 7.00 9-47 9.09 9.14 9.13 8.80 8.89 9-15 9-15 8.80 8 95 8.54 7.05 5-21 Mean 379 6.9 8.9 6.4 8.1 7.0 7.0 9.1 8.6 7-9 6.9 7.8 9.0 9.2 7-3 9.1 9.0 8.7 7.0 5-2 1903ApJ 18. .3415 After January10,1903,theobserverwasinresidenceatBerke- ley, andafewobservationsofbrightnessweremadetherewith various instruments. 4 grades. 380 JOELSTEBBINS © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem March 17:Berkeley.Operaglass. January 29:Berkeley.One-inchtelescope. October 5:Identificationscertain. June 27:Fifthcomparisonassignedweightonaccountofinterval October 8and15:RememberedcomparisonwithEFon5. August 18:Firstofoperaglassseries. February 28:Berkeley.Two-inchtelescope. September 3:Couldseevwithnakedeye. September 17:Firstwiththree-inchfinder. May i,1903. REMARKS.