1976AJ 81. . 2 98M THE ASTRONOMICALJOURNAL THE classofextragalacticsourcesknownasBL member ofthisclass,OJ287,hasbeenthesubjecta observed intheiroptical,infrared,andradiofluxes.A a numberofyearsbecausetherapidvariations number ofinvestigationsintothenatureandtimescale observations ofrapidvariationsatopticalandradio of thefluxvariationsatdifferentwavelengths.Folsom wavelengths. Similarobservationswerealsoreported et al.(1971)andBrandieStullfirstreported by KinmanandConklin(1971). possibility oflarge-amplitudevariationsoccurringon et al.1975;McGimseyVeronand time scalesontheorderofaday.Thissuggests time scalesofhoursorless.Small-amplitudeperiodic have beenreportedbyVisvanathanandElliot(1973). optical variationswithaperiodoflessthananhour 1975) indicatethatsignificantvariationsoccurwith Recent observations(Kinmanetal.1974;Smith © American Astronomical Society • Provided by the NASA Astrophysics Data System Lac objectshasbeenofconsiderableinterestfor H. R.Miller,D.W.Wingert,B.Q.McGimsey,E.S.Anderson,andT.L.Mullikin variability. Noconclusiveevidencewasfoundforstatisticallysignificantintradayvariations. Multiple exposuresweretakenofOJ287on11nightsinanattempttodetectlarge-amplitudeintradayoptical INTRODUCTION 1973 Department ofPhysics,GeorgiaStateUniversity,Atlanta,30303 Department ofPhysics,AgnesScottCollege,Decatur,Georgia30332 On theintradayvariabilityofOJ287 (Received 19December1975;revised3March1976) Fig. 1.ThelightcurveofOJ287 from 1973to1976. 1974 G. H.Folsom VOLUME 81,NUMBER5 298 YEAR periodic variations,suggestingthattheymaybe linger 1975)havefailedtodetecttheselow-amplitude However, otherinvestigations(Kiplinger1974;Kip- optical variabilityofOJ287,observedonatimescale transitory innatureandoccurrelativelyinfrequently. of days,fromearly1973tolate1975and(2)reporton an attempttoobservelarge-amplitudeintradayvaria- tions ofOJ287. with the76-cmtelescopeofBradleyObservatory. plates. Theseplateswereexposedatthe//15Cassegrain focus withnofilterforallobservationsmadepriorto1 All exposuresweremadeusingKodaktype103a-O magnitudes. TheplateswerereducedontheCuffey made usingaGG385filterwhichyieldsstandardB iris photometeratGeorgiaStateUniversityutilizing .Themorerecentobservationswere The purposeofthispaperisto(1)reportonthe The observationsofOJ287reportedhereweremade 1975 I. OBSERVATIONSANDDATAANALYSIS 1976 1976AJ 81. . 2 98M I1 plate. Asecondmethodofevaluatingtheuncertainties for eachplatewereformedusingtheirisreadingand bility ofthemagnitudedeterminedforOJ287onthat of thecomparisonsequenceaboutcalibration comparing filteredandunfilteredexposuresofOJ287 of thephotographictoBmagnitudes,determinedby curve maythenbeusedasanindicationoftherelia- B magnitudesofthecomparisonstars.Thermsscatter estimated inthefollowingmanner.Calibrationcurves taken onthesamenight,wasfoundtobe0.29mag. and Wing(1973).Anempiricallydeterminedcorrection the photoelectriccomparisonsequenceofPenston star. Inaddition,thestandarddeviationofvaria- standard deviationofthevariationthatcomparison of thesemeasurementsistoobservethevariation and itsmagnitudedeterminedbytheremainingstarsin each comparisonstarwhenitistreatedasanunknown comparison-star designationfollowingtheschemeof for allstarsinthecomparisonsequenceoverplates the comparisonsequence.Theresultsofsuchananalysis source andtohaveameaningful assessmentof measurable comparisonstarsand(2)OJ287mustbe rms scatterofthecomparisonstarsonthatplate.We Penston andWing(1973)column2indicatesthe We feelthattheselasttwo conditionsarenecessary of ^0V5occurringonatime scaleoflessthananhour. have imposedthefollowingtwoadditionalconditions only ifthevariationisgreaterthanthreetimes level (Aw>0i294)significant.Inaddition,ifvariations consider onlyvariationsofOJ287whichexceeda3-cr standard deviationof0T098.Therefore,wewill are seentobeassociatedwithstar3whichhasa tion ofOJ287isalsoshown.Thelargestvariations taken ofOJ287areshowninTableI.Column1isthe observation. in ordertoaccuratelydetermine thebrightnessof sequence. Itisinterestingtonotethatiftheselast of OJ287:(1)Theplatemusthaveaminimumfive for theinclusionofdatainourstudyvariability greater than0V098,theywillbeconsideredsignificant where thermsscatterofcomparisonsequenceis the uncertaintiesassociated withthatparticular bracketed inbrightnessbythestarsofcomparison which exceedthislevelarefoundtooccurforplates two conditionsarenotimposed,onefindsvariations The uncertaintiesofthesemeasurementswere © American Astronomical Society • Provided by the NASA Astrophysics Data System Table I.Variationofcomparisonstars. Comparison stara m OJ 2870286 m m m m m m m m 4 0058 2 0068 8 0091 3 0098 6 0081 5 0051 7 0083 1 0046 VARIABILITY OFOJ287 plotted inFig.1alongwiththenumberofobservations, of twoormoreplatestakenonthesamenightwith observed fromearly1973tolate1974,confirmingthe w, madeoneachnight.Adeclineofnearly2magis and 31October1975.TableIItabulatesthedata the exceptionofnights5May1973,2November flare bymorethanamagnitudeandthentodecline to itspreflarelevelnear15.5mag.Thisflareappears et al.(1975).Inearly1975thesourceisobservedto end ofthelong-termdeclinereportedbyMcGimsey 1973, 23October1974,254April1975, 1. AllmagnitudesofOJ287shownaretheaverage The long-termlightcurveofOJ287isshowninFig. 31 January19741215.08 20 May1973414.24 28 February19742715.40 26 February19743015.39 21 February19741515.51 22 January19744015.07 21 January19741314.92 31 October19751 15.02 21 January1975214.73 25 October1974115.43 23 October1974115.54 27 April1974815.28 27 February1974415.64 21 November1974815.15 19 December1973514.72 11 October19752 15.10 17 April19752 15.34 12 April19753 15.14 15 March1974415.30 13 February19741215.14 13 January19741414.67 13 October19752 14.92 12 October19752 14.99 15 February1975414.81 10 February1975614.78 17 January1975214.82 16 January19751814.74 15 January1975214.72 14 January1975414.76 17 December1974314.96 17 October1974215.26 18 April19741615.37 18 December1974414.97 4 February19731113.36 9 March1975615.14 4 March1975215.30 3 March19742515.33 2 November1973114.60 5 February.1973813.48 6 May19752 15.21 4 April1975115.09 3 March1975215.31 5 May1973114.18 8 February1975314.87 7 February19731813.46 5 April1975415.08 7 March1975315.40 5 January19751214.79 7 January1975214.77 1 February1975214.66 Table II.ObservationalresultsforOJ287. Date II. RESULTS Nightly average 299 1976AJ 81. . 2 98M nights of19December1973and 13 January1974.Photographic magnitudes areplottedfortheremaining nights. 1974, and21February1974.B magnitudes areplottedforthe 19 December1973,13January1974, 22January1974,31 plates. Therefore,thiseventshouldnotbeconsidered statistically significant. uncertainties of0.15mag.Thesewere 0700 UT,indicatingapossible0.4-magflare,have sequence aboutthecalibrationcurveforeachof determined fromthermsscatterofcomparison given eveningdonotexceeda3-crlevelandtherefore were takenofOJ287.Withtheexceptionnight January 1974,threeofthefourobservationsmadenear cannot beconsideredsignificant.Onthenightof22 which yieldatimeresolutionasshort7min.In number ofnightsfromDecember1973toMarch1975 300 22 January1974,thevariationsobservedwithina Fig. 2arefivenightsonwhichormoreexposures mag superimposedontheoverallchangeinbrightness observed duringthiseight-monthperiod. same. Thereareday-to-dayfluctuationsofupto0.5 and declineintheobject’sbrightnessapproximately to beeightmonthsindurationwiththerateofincrease Fig. 2.Theintradaylightcurves ofOJ287forthenights © American Astronomical Society • Provided by the NASA Astrophysics Data System Multiple exposuresofOJ287weretakenona U.T. (HRS) MILLER ETAL. Brandie, G.S.,andStull,M.A.(1971). Nature231,149. Folsom, G.H.,Smith,A.G.,Hackney, R.L.,Hackney,K.R., grant fromtheResearchCorporation. good quality. view “oneplate”indicationsofvariabilitywithextreme from 7minto5h.Thisworkwassupportedinpartbya with anamplitude>0.3magontimescalesranging OJ 287,noconclusiveevidencewasfoundforvariability 0.5 maghavebeenobservedonatimescaleofdaysfor caution, althoughinthiscasetheplateappearstobeof OJ 287of0.35magin10min.However,oneshould with theexceptionofoneplatetakenon26February taken at0600UTsuggestachangeinbrightnessof observed onanyofthesenightsexceedsthe3-