00 CM UD CM 1976AJ. ts] more reddishSobjectswithstonyirons(Chapman population cannotbeclassified asCor5butbelong basis ofUBVcolors.Roughly 10%oftheasteroid identified withcarbonaceouschondritesandthelighter, surface mineralsare,respectively,ferromagnesiansili- distinct SandCtypesinwhichtheopticallydominant plementarity ofabsorbedsolarandemittedthermal ways whicharepoorlydocumented butvitalfor and Gaffey1974).Somedoubtsaboutbothidentifica- and Salisbury1973;JohnsonFanaleMcCord dark, relativelycolorlessCasteroidsaremosteasily cates andcarbon.Intermsofmeteoriticmaterialsthe most oftheobjectscouldbeassignedtobroadbut nary observationsofthepolarizationasafunction tributions overdiameterand orbitalparametersin to rarertypes. radiometric resultsforacombinedsampleof110 radiation isusedtoinferalbedosanddiameters(e.g., spectrophotometric programs(e.g.,McCordetal. most profitablyinterpretedalongwithresultsfrom of solarphaseanglefor43asteroidswerereported makes itoneofthemostpowerfultechniquesfor tions havebeenraisedbyZellneretat.(1975)onthe asteroids, Chapmanetal.(1975)demonstratedthat and Chapman1976). Matson 1971;Morrison1974;Hansen1976; of polarizationmeasurementstohundredsasteroids, tion, andwithradiometricresultsinwhichthecom- by Zellneretal.(1974).Thepolarimetryhasbeen exploration oftheminor-planetpopulation.Prelimi- ture ofroughsurfaces,andthepotentialapplicability THE sensitivityofthelinearpolarizationre- 1970; Chapmanetal.1973;McCordand 1975a, 1975b),whichgiveindicationsofthecomposi- THE ASTRONOMICALJOURNAL The principalclassesofasteroids differintheirdis- In examiningspectrophotometric,polarimetric,and © American Astronomical Society • Provided by the NASA Astrophysics Data System Minor planetsandrelatedobjects.XX.Polarimetrieevidenceforthe flected lighttothecompositionandmicrostruc- or stony-ironmeteorites;34objectsoftheCtype,probablycorrespondingtocarbonaceouschondrites;atleast particulate surfacetextures.Highlyrepeatablepolarizationsarefoundforeachwell-observedobject,withlittle for whichpolarimetricalbedosandhencediameterscanbecomputed.Allasteroidssofarobserved,ranging type. properties suggestthatmaterialofbothkindsisseeninvariousstagesreductiontowardsurfacesthemetallic to pureenstatite;andfiveofothertypes.TheCStypesarewellseparatedinalbedo,withmeanp=0.06 three andpossiblyfiveMasteroidswithsurfacesrichinfreemetal;twohighalbedos(classE)attributable 48 asteroidsbelongingtothebroadSclass,withiron-bearingsilicatesurfacesresemblingordinarychondrites if anyevidenceforvariationwithrotationoraspect.Compositionaltypesidentifiableinoursampleinclude over amorethanfactorof50indiameter,showthepolarimetricsignaturesmicroscopicallyroughor and 0.18,respectively.WefindnosimplemixturesofCSmaterials,butdistributionsvariousoptical New observationsofasteroidsbringthetotalto94forwhichusefulpolarimetryhasbeenobtained,and52 v INTRODUCTION Lunar andPlanetaryLaboratory,UniversityofArizona,Tucson,Arizona85721 albedos andcompositionsof94asteroids (Received 30September1975;revised6January1976) B. ZellnerandJ.Gradie VOLUME 81,NUMBER4 262 understanding theirmodesoforigin(e.g.,Chapman usually becomesunassailablewhenoneotherparame- statistically broadsampleofasteroidsisessential. polarimeter firstdescribedbyGehrelsandTeska indicated byasinglepolarimetricobservationand paper. observations foratotalof94asteroids.Formany As weshallshow,thetypeassignmentisoftenstrongly we incorporateobservationsfromTableHIofZellner wave plate(Serkowski1974)abovethefixedWol- vided byarapidlyspinningsuperachromatichalf- primarily onlaboratoryresultswhicharelargelycon- use ofpolarimetry1566IcarusbyGehrelsetal. ter, suchastheU—Bcolor,isavailable. Tables IandIIofZellner et al.andTableIofthis Thus, thecompletelisting ofourdatacomprises strumental effectswhicharenowbetterunderstood. laston prism.Alongwithpreviouslyunpublisheddata integration, andthepolarizationmodulationispro- January 1973weusephotoncountinginsteadofdc fined tolunarmaterialsandgenerallyofaquality by Dunlap(1974),andof433ErosZellner direction ofthestrongest electric vectorandthe cos 20,where6istheangle betweenthemeasured inferior tothatoftheastronomicaldata. improved phasecoverageorprecision.Wealsomake the objectslistedbyZellneretal.(1974)wehave 1975). Thus,thesecureidentificationoftypesfora et al.(1974),withcorrectionsforvarioussmallin- Gradie (1976).Theinterpretationsarestillbased 1685 TorobyDunlapetal.(1973),of1620Geographos (1960; seealsoCoyneandGehrels1967).Since (1970), ofseveralasteroidsbyVeverka(1971,1973), r Table IgivesobservationsmadewiththeWollaston The polarizationquantity of interestisPrPobs In thispaperwepresentandanalyzepolarimetric I. OBSERVATIONS APRIL 1976 CM UD CM 1976AJ. ts] Table I.Observationsofasteroidswiththephoton-countingpolarimeter.Telescopesareidentifiedbyobservatoryandaperturein © American Astronomical Society • Ast. No. 73 05 73 05 73 05 73 OA 73 OA 7A 07 7A 06 7A 06 73 08 73 06 73 06 73 06 73 05 73 05 73 05 73 05 73 OA 73 OA 73 OA 73 OA 7A 09 7A 09 7A 06 73 06 73 06 73 06 73 06 73 06 73 05 73 05 73 05 73 05 73 05 73 OA 73 OA 73 OA 73 OA 7A 09 7A 08 73 06 73 06 73 06 7A OA 73 08 73 08 73 OA 7A 08 7A 08 7A 06 7A 06 73 08 73 OA 7A 07 7A 07 7A 07 73 07 73 05 7A 06 73 08 7A 07 7A 06 7A 09 7A 07 7A 07 73 10 73 OA 7A 11 73 10 73 10 73 OA 73 OA 73 12 73 12 73 12 73 12 73 12 73 12 7A 02 7A 02 73 12 7A OA 73 12 7A OA 7A OA 7A OA 7A 02 7A OA 7A OA 7A OA 7A OA 7A 05 7A 05 7A 06 7A 06 7A 06 7A 06 7A 06 7A 06 7A 06 7A 06 7A 06 7A 06 7A 06 Dote (UT) 08. AO 08.39 02.39 02.39 22.38 06. A6 07.A6 07. A 26.17 02.38 02.37 1A.36 08.39 02.39 06.AS 08.36 08.3A 09. AO 12.AA 22.IA 26.17 03.36 03.36 13.38 11.29 11.28 13.AA 06. AO 08.36 26.18 11.35 22.37 13.AA 02.28 03.32 13.17 11.A6 11.3A 1A.37 13.38 22.3A 02.30 26.22 22.21 07.23 1A.38 13.18 22.A8 06. A 23.26 23.23 23.32 23.30 08.2A 13.22 01.AA 07. A2 07.A3 31.29 01.A5 15.39 06.15 06.IA 12.IA 08.37 11.AA 11.AA 27.52 25.53 25.51 13.16 28.58 28.56 10.55 10.5A 05.38 01.38 30.51 01.39 30.52 30.51 28.57 05.AA 05.AO 22.38 22.36 22.35 05.A2 10.20 10.22 02.IA 01.16 1A.16 12.15 03.23 28.15 23.15 12.17 23.16 12.16 12.18 23.18 23.17 Ci.5 Cl.5 Ci.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl. 5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 53.3 S2.3 S2.3 Cl.5 S2.3 52.3 SO.5 SO.5 52.3 S2.3 S2.3 S2.3 S2.3 S2.3 S2.3 S2.3 Cl.5 Cl.5 Cl.5 Cl.5 S2.3 S2.3 S2.3 Cl.5 Cl.5 Cl.5 Cl.5 S2.3 S2.3 S2.3 S2.3 Cl.5 S2.3 S2.3 S2.3 Cl.5 S2.3 Cl.5 Cl.5 S2.3 Cl.5 Cl.5 S2.3 S2.3 Cl.5 Cl.5 S2.3 S2.3 S2.3 Cl.5 Cl.5 Cl.5 Cl.5 S2.3 S2.3 Cl.5 Cl.5 Cl.5 S2.3 SO.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 S2.3 S2.3 Cl.5 S2.3 S2.3 S2.3 Cl.5 Cl.5 Cl.5 S2.3 S2.3 S2.3 S2.3 12.05 12.05 15.11 18.67 18.67 12.05 15.11 17.31 20.60 17.31 19.7A 19.88 19.88 16.70 13.97 15.93 18.88 13.A8 13.97 1A.79 17.35 18.55 18.82 17.59 12.78 12.78 10.97 10.97 15.93 19.85 15.12 15.97 22.00 23.OA 17.09 16.13 25.79 21.99 23.OA 17.77 20.12 20.63 20.63 19.2A 2A.8A 20.12 23.83 23.83 18.29 17.77 2A.8A 2A.8A 2A.8A 2A.8A 17.80 17.81 2A.8A 17.80 2A.10 25.OA 2 A.87 20.53 27.39 26. A7 26.A7 26.A7 25.21 27.39 27.39 27.39 26. A7 9.95 7.69 8.88 9.95 9.95 9.96 A.33 1.30 1.11 1.11 7.69 8.08 8.08 8.88 9.97 9.96 A.33 1.30 9.77 5.93 5.93 5.93 8.79 2.08 7.55 5.91 7.55 5.95 5.05 5.58 5.95 5.58 POLARIMETRY OF 1.65 1.22 1.33 1.77 1.67 1.26 1.72 1.67 1.71 1.59 1.A8 1.71 1.69 1.63 1.56 1.5A 1.56 1.56 1.69 1.69 1.56 1.02 1.26 1.02 1.26 .76 .82 .15 .21 • 2A .69 .71 .65 .12 • A5 .66 .58 .31 .53 .SA .73 .16 .A3 .10 .15 .92 .85 . 8A . A8 • A7 .13 .18 .53 .76 .38 .15 .27 .30 .39 .57 .09 .27 .36 .25 .Al .05 .27 .27 .22 .13 .16 .03 .27 .19 .22 .23 .29 .21 .70 .29 .27 .81 .82 .76 .58 • 2A .33 .15 .07 .73 .68 .72 .12 .35 .31 « A6 .32 .21 .21 . 3A meters asinTableIIofZellneretal.(1974). .02 .03 .OA .OA .OA .06 .03 .01 .05 .OA .OA .02 .03 .07 .12 .OA .03 .05 .OA .OA .06 .02 .03 .OA : ®X .05 .13 .07 .05 .05 .07 .01 .01 • 02 .03 .15 • 02 .03 .01 .09 • OA .03 .03 .03 .02 .12 8A.2 .03 .02 .08 —11.A .07 .01 .02 .13 90.7 .01 .10 120.7 .11 92.A .17 81.8 .16 87.9 .03 1.0 .13 .07 • OA .03 .07 .01 .06 .02 .02 .OA .02 .OA .OA .06 .03 .05 .01 .02 .08 .01 .02 .IA .07 .02 .05 .02 .01 .02 .02 .02 .01 .01 .02 .03 .02 .02 .01 .01 -0.0 90.3 92.0 90.8 90.3 89.5 89. A 89.1 89.3 88.7 90.9 91.6 88.3 88.9 89.1 90.0 89.A 91.3 91.0 89.9 89.0 88.6 89.3 89.2 89.2 91.2 90.1 85.2 89.3 93.9 91.2 92.0 9A.1 90.9 90.5 11.5 92.1 90.8 91.6 92.1 91.7 89.1 89.7 11.3 -0.0 95.5 90.9 90.2 89.9 87.2 89.0 92.8 9 A.5 90.6 91.7 93.1 9A.0 — 1.A 85.5 8 A.2 85.9 83.A -6.6 9A.9 90.A 7.5 2.2 2.6 -.2 1.6 -.3 -.2 -.3 -.3 0.0 -.2 -.5 1.2 -.A -.2 2.A .8 .2 .7 .9 -1.26 -1.65 -1.59 -1.21 -1.71 -1.33 -1.77 -1.72 -1.66 -1.69 -1.67 -1.71 -1.63 -1.5A -1.A8 -1.58 -1.56 -1.56 -1.55 -1.69 -1.69 -1.26 -1.02 -1.26 -1.02 —. 2A -.76 -.82 -.21 -.69 -.71 -.65 -.58 -.30 -.72 -.91 -.85 — •8A -.15 -• A8 -.17 -• A7 -.76 -.53 -.18 -.30 -.38 -.22 -.27 — •2A -.27 -.06 -.Al -.03 .15 .12 .AS Provided bythe NASA Astrophysics Data System .52 • A9 .66 .15 .10 .12 .A3 .27 .13 .36 .57 .09 .26 .05 .22 .21 .13 .57 .22 • 2A .27 .19 .16 .81 .75 .68 .72 .29 .15 .07 .73 .29 .27 .20 .12 Aot. No. ASTEROIDS 7A 0701.23 7A 0630.18 7A 0628.23 7A 0630.15 7A 0628.25 7A 0711.18 7A 0630.22 7A 0630.20 7A 0711.15 7A 0701.23 73 10 7A 01 73 12 73 12 7A 02 7A 01 7A OA 7A OA 7A 02 7A OA 7A OA 7A OA 75 03 73 07 73 05 7A 08 7A 07 7A 07 7A 07 7A 06 73 07 73 06 73 06 73 05 73 OA 7A 08 7A 07 7A 07 7A 06 7A 06 73 07 73 OA 73 OA 73 OA 73 OA 7A 08 7A 06 08 08.Al 08 08.39 09 19.A8 09 19.A5 08 22.A2 05 05.33 05 05.32 01 12.52 01 29.IA 10 07.31 OA 01.31 OA 01.29 01 29.IA 12 29.23 12 28.26 10 07.30 12 07.25 12 07.2A 12 29.25 09 12.AA 09 12.A6 10 06.51 09 12.A8 10 07.52 10 07.A5 10 07.A5 10 06.52 11 OA.AO 10 31.25 10 07.A7 12 07.29 10 27.A5 01 29.20 01 29.20 01 16.Al 01 16.AO 12 28.3A 11 OA.39 OA 01.IA 02 22.27 02 02.25 01 30.31 01 16.A2 12 28.33 12 07.30 12 07.28 OA 03.AO OA 01.16 02 22.29 01 30.30 12 28.3A 06 1A.18 OA 03.36 02 22.30 02 02.27 25.A9 19.A2 28.50 01.20 28.53 01.22 22.33 22.31 05.51 22.20 19.A3 26.25 22.22 OA.21 OA.21 02.35 01.A2 01.A2 03. A5 02. A6 02.AA 23.20 02.35 06.38 25.39 23.AO 03.A6 23.19 13.36 13.36 06.39 10.AO 10.38 25.AO 22.23 22.31 10.39 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl. 5 Cl.5 S2.3 S2.3 Cl.5 Cl.5 Cl.5 Cl.5 S2.3 S2.3 S2.3 S2.3 S2.3 Cl.5 Cl.5 Cl.5 S2.3 52.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl. 5 Cl. 5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 S2.3 S2.3 SO.5 S2.3 S2.3 S2.3 Tel. Filt.Phese 50.5 S2.3 Cl.5 S2.3 Cl.5 Cl.5 Cl.5 Cl.5 S2.3 S2.3 S2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 S2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 S2.3 S2.3 PI.5 S2.3 S2.3 S2.3 S2.3 S2.3 PI.5 S2.3 PI.5 27.68 27.62 27.72 27.70 27.70 27.68 27.68 27.62 16.88 27.72 21.22 21.81 27.68 21.57 21.39 11.A2 16.87 21.81 2A.07 26.90 2A.AA 2A.AA 21.57 15.89 15.89 11.A2 16. A l 16.A2 21.A2 19.2E 19.28 32.72 21.56 32.23 18.19 21.A2 32.IA 32.15 32.23 32.72 32.72 32.15 28.A6 29.32 32.15 13.Al 27.33 27.33 11.03 13.Al 13.A2 23.2A 23.29 20.29 10.37 17.00 11.OA 10.02 18.12 2A.52 2A.52 27.68 27.68 23.2A 10.37 26.90 2A.11 2A.11 18.58 17.AA 17.00 11.OA 10.01 17.32 27.65 27.65 20.29 26.90 2A.12 18.57 10.02 17.32 17. AA 17.01 9.85 9.86 8.6A 8.65 7.76 8. AA 7.77 8.A3 1.6A 3.93 A.58 1.6A 1.6A 6. A5 A.58 8.76 3.93 8.75 1.26 1.59 1.99 2.OA 1. Al 1.22 1.3A 1.80 1.2A 1.07 .A3 .AA .AA .39 • A5 .62 .Al .22 .58 .AC .37 .37 .21 .28 » 3A .76 .28 • 2A .33 .65 .62 .22 .31 .69 .71 .66 . A7 .38 • A9 • 3A .82 .AO .69 .03 .77 .77 • 8A .23 • 11 .06 .02 .13 .90 • 7A .88 . A9 .60 • 6A .70 .58 .59 .37 .37 .39 .62 .28 .56 .59 .68 . A2 .13 .31 .32 .37 .38 .70 .82 .26 .52 . 5A .78 .90 .58 .56 .56 .36 .76 .66 .32 .88 .26 .16 .19 .85 . 8A .73 .OA : *X .01 .02 .02 .OA .02 .02 .IA .20 -17.1 .15 -21.5 .01 .03 .15 .15 .08 .12 .11 .IA .IA .03 .03 .16 .15 .10 .15 .03 .03 .18 .07 .08 .08 .02 .12 .OA .17 .02 .06 .11 .05 107.0-.19 .17 .02 .OA 86.9 .02 12 -AO.5 -9.3 -3.0 -6.0 —A .1 -2.7 — 1.A -2.3 —1. A -1.3 -1.9 91.3 90.2 93.A 83.6 —A.O 92.0 -1. A 87.3 85.0 9A.2 88.6 88.8 91.9 91.8 88.1 85.0 88.8 -1.3 91.3 90.0 -1.5 -5.3 91.6 17.2 12.9 -1.6 91.1 90.9 9A.2 -1.1 90.1 -A.O -1.2 -7.8 -8.A 91.3 87.0 90.1 86.2 87.9 88.A 95.0 90.1 -1.6 90.A 91.6 89.3 90.8 91.3 90.2 90.8 93.3 89.8 85.A 89.6 89.6 99.6 86.5 88.8 68.5 69.9 83.0 13.2 10.2 -.5 -.9 -.3 3.0 -.2 -.5 -.3 2.7 1.0 -.7 9.7 A.8 -.A 1.0 .8 .2 .A .2 .7 .2 .7 .1 .3 1.80 1. Al 1.59 — •6A 1.3A 1.98 2.OA -.70 -.37 -.39 1.21 1.26 -.82 -.37 -• A9 -.59 1.2A -.65 -.61 -.31 -.32 -.37 -.70 -.66 -.16 -.26 -.56 -.59 -.58 -.59 -.67 -.56 -.35 -.73 -.26 -.13 -.38 -.19 -.56 -.76 1.06 • Al • A2 .AA .59 .AA .37 .AO • A5 .37 .21 .76 .33 .65 .62 .20 .22 • 66 . A9 • 3A .26 • 2A .38 .31 • 69 .71 .69 • A7 .82 .AO .03 .77 .10 .13 .06 .77 • 8A .02 .90- • 7A .86 .58 .Al .32 .51 .78 .90 .AO ,66 . 8A .53 . 8A .25 .03 .01 . A2 .85 263 00 CM UD CM 1976AJ. ts] 264 © American Astronomical Society • 11 11 10 11 11 11 11 11 10 10 12 11 11 11 11 10 10 10 12 12 12 12 12 11 11 11 12 11 11 1A 1A 1A 13 13 12 13 13 12 12 12 1A 1A 1A 13 13 13 1A 1A 1A 1A 13 13 15 1A 1A 15 15 15 1A 15 15 15 16 15 16 16 16 16 16 16 9 9 73 07 73 08 73 08 73 07 73 05 73 05 7A 1113.25 7A 0929.A2 7A 092A.37 7A 092A.36 7A 0930.13 7A 0908,17 7A 0908.17 73 0627.18 7A 09 73 08 73 05 73 05 7A 1113.27 7A 0929.AO 7A 0929.12 7A 0701.31 7A 0701.29 73 0627.16 73 0515.25 73 0508.25 7A 06 7A 05 7A OA 7A OA 7A 10 7A 09 7A 09 7A 08 73 061A.29 73 0513.23 73 0513.21 73 0511.19 73 0511.18 73 0502.33 73 0502.33 73 OA22.27 73 0A13.33 7A 0908.31 7A 10 7A 09 7A 08 75 07 7A 06 7A 06 7A 05 7A OA 7A 10 7A 09 73 0508.25 7A 1002.19 7A 1002.17 75 01 7A 11 7A 10 75 01 75 01 7A 10 7A 09 7A 08 75 07 7A 06 7A OA 7A 0908.31 75 03 75 03 75 01 7A 11 7A 10 7A 09 7A 09 7A 08 7A 08 75 02 75 02 7A 0202.AA 75 03 7A 0327.25 75 03 7A OA05.28 7A 0327.2A 7A 0202.A1Cl.5 7A OA22.16 7A OA22.15 7A OA01.2A 7A OA05.26 7A 0603.39 7A 0612.38 7A 0612.37 7A 0623.AO 7A 0711.AO 7A 0623.39 7A 0711.A1 08.21 08.A2 31.20 13.3A 08.33 02.A2 08.21 1A.33 03.25 08.A3 23.20 13.35 01.A6 01.19 26.29 01.35 01.3A 30.39 30.38 11.A8 22.25 01. A 7 30.A1 07.A2 15.A3 28.17 1A.20 10. A1 02.A5 12.52 02. A 9 23.12 02.35 07.A2 27.AA 11. A2 15.A3 03.16 06.17 06.15 12.36 23.15 27.A5 23.20 12.20 30.AA 11.A3 20.13 05.1A 12.38 13.A6 20.1A Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 S2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 PI.5 S2.3 S2.3 Cl.5 Cl.5 S2.3 Cl.5 Cl.5 $2.3 S2.3 S2.3 S2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 $2.3 S2.3 Cl.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 Cl.5 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 Cl.5 Cl.5 $2.3 $2.3 $2.3 $2.3 Tel. Flit.Phase 23.OA 18.86 18.37 25.25 10.11 10.12 22.98 20.59 23.30 19.32 17.61 16.51 22.99 25.25 2A.19 22.53 20.60 23.3C 23.10 17.61 15.89 15.89 12.AA 20.60 21.63 31.11 23.98 16.50 26.31 18.86 18.37 20,61 25.75 2A.85 21.11 15.56 17.23 17.23 22.99 25.95 17.12 19.50 19.50 21.63 31.11 26.30 2A.58 17.70 22.22 22.95 17.99 17.98 22.2A 22.22 22.95 17.12 25.01 23.50 13.97 23.76 17. A7 16.05 18.76 16.06 15.19 25.01 18.88 13.97 » 18.76 17.39 17.39 1A •89 1 A.90 7.52 7.39 7.51 8.7A 9.66 6.27 6.27 8.73 8.93 9.20 5.56 8.92 5.55 8.91 9.60 9.61 5.72 5.72 8.86 8.10 8.09 8.01 8.01 9.18 9.19 1.53 1.A2 1.52 1.3A 1.53 1.51 2.09 2.18 1.61 1.33 2.07 1.2A 1.16 1.02 .07 .21 .88 .71 .76 .69 .73 .71 .62 .23 .23 .30 .39 .AO • A9 . 5A .73 .58 .81 • A9 .11 .10 • 6A .23 . 3A .22 .18 .37 .69 .25 .1A .27 .99 • 2A • A7 • 7A .09 .71 .72 .60 • A8 .50 »6A .60 .22 . 5A .85 .11 .02 .27 . A1 .53 .15 .77 .26 .1A .21 . 2A .73 .57 .82 .31 .28 .AO .29 .29 • A2 .53 .52 .71 .73 .50 .26 • A6 .37 • A1 .52 .32 .65 .65 .52 .96 ZELLNER ANDGRADIE a .08 .03 .OA .02 .05 .OA .OA .OA .03 .06 .15 .06 .05 .11 .02 88.6 .05 9A,3 .OA .12 .12 .11 .1A .06 .1A .02 6.8 .06 .20 .08 .1A .05 .02 -1.2 .01 88.3 .02 .02 .05 .20 8A.5 .OA 89.6 .OA .06 62.5 .02 .03 .09 .03 .03 80.6 .12 100.1 .OA .02 .02 91.9 .03 .03 .03 .OA .02 .06 107.5 .05 .05 .02 .02 .02 : % .02 .OA .OA .OA .03 .03 .02 .03 .07 -9.2 -6.8 -A.7 — 1•A -2.0 90. A 76.8 91.0 91.8 87.5 89.0 90.1 89.1 90.7 70.9 86.3 88.6 80.0 89.5 88.8 91.8 87.A -1.6 92.6 9A.9 87.5 87.5 91.3 87.3 -1.52 1A.8 9 A.3 89.1 87.8 90.0 97.0 89.8 90.5 89.A 90.5 91.1 88.6 -1.7 91.3 93.A 9A.1 -3.2 9A.3 90.1 89.2 92.6 90.1 88.5 89.8 85.6 92.8 90.3 86.6 88.0 90.6 90.8 87. A 86.5 89.8 -.8 5.5 0.0 3.1 2.2 l.A -.5 2.0 1.2 2.0 3.5 5.A 1.8 2.1 l.A 1.2 .5 .3 .5 .2 Table I{continued) -1.53 -1.A2 -1.3A -1.53 -1.51 -1.2A -2.09 -2.07 -2.18 -1.16 -1.02 -.73 -.69 -.71 -.63 -.26 -.76 -.68 -.22 -.25 -.02 -. A7 -.60 -.1A -.07 -.73 -.52 -.13 1.61 -.26 1.33 -.29 -.82 -.77 -.28 -.51 -.29 -.71 -.73 -.37 -• A2 -.Al -• A6 -.52 -.26 -.51 -.32 -.65 -.65 -.51 -.96 .07 .20 .22 .23 .AO .62 .20 .28 • 2A . A7 .73 .67 .81 .70 .21 . A9 .53 .17 .99 .87 • A9 .09 .66 .37 .53 .58 .85 .60 .71 .72 . A8 Provided bythe NASA Astrophysics Data System .21 • A1 .23 .28 .1A .AO .31 .56 .50 Ast. No. 18 18 17 19 18 18 18 18 18 18 18 18 18 18 18 17 17 17 17 17 17 16 16 16 16 19 18 18 18 18 17 17 16 16 16 19 19 19 18 18 17 19 19 19 19 19 19 19 19 19 19 19 19 19 21 20 19 19 19 20 20 20 20 20 20 20 20 19 19 21 21 21 21 21 20 21 21 21 21 21 21 21 21 21 22 22 21 22 22 7A 07 7A 05 7A 08 7A 07 73 OA 7A 09 7A 07 7A 07 7A 06 7A 11 7A 11 73 07 73 07 73 05 73 OA 7A 1026.19 7A 1026.18 7A 082A.27 7A 082A.25 7A 0725.29 73 05 73 05 7A 11 7A 08 7A 08 7A 08 7A 08 7A 07 7A 06 73 05 73 05 73 05 7A 0908.30 7A 07 7A 06 73 05 7A 09 7A 07 7A 06 7A 06 73 06 73 06 73 06 73 05 7A 11 7A 05 7A 07 7A 07 7A 07 7A 07 7A 06 7A 06 7A 03 7A 07 7A 07 73 05 75 06 7A 07 7A OA 7A OA 7A 10 7A 09 7A 08 7A 08 7A 07 7A 0906.28 73 06 75 06 7A 07 7A OA 7A OA 7A 02 7A 02 7A 10 73 09 73 09 73 05 73 05 73 05 7A 09 73 10 73 09 73 08 73 08 73 08 73 06 73 05 7A 03 7A OA 73 10 73 09 73 OA 73 OA 7A 06 73 OA 7A 06 7A 06 73 05 73 05 Date (UT)Tel.Flit.Phase 01.36 02.38 02.36 08.A2 02.AA 08.27 09.33 09.32 11.A2 01.37 1A.A3 2A.A2 1A.38 13.A5 08.27 08.27 26.3A 26.33 2A.32 2A.31 23.30 23.28 22.AO 03.A2 02. A 2 02.AO 0A.35 08.28 26.33 11. A3 2A.39 13.AO 01.AO 07. A O 03. A O 27.2 5 0A.3A 11.22 13.12 13.09 1A.A6 01.39 07.22 08. AA 09.31 09.30 25.3A 2A.37 23.38 23.37 11.22 08.30 02. A5 12.23 22.38 01. A 2 26.37 07.2A 2A.38 08.31 27.AO 15.AA 15.A2 1A.A2 1A.A1 2A.19 22.36 12. A O 22.A3 20.18 25.33 19.18 26.35 22.A1 20.21 12.27 08.15 08.13 22.2A 27.AO 1A .A1 13.3A 2A.18 2A.15 19.21 23.28 22.Al 08.30 13.35 22.29 12.29 11.25 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 Cl.5 Cl.5 $2.3 $2.3 Cl.5 PI.5 PI.5 $2.3 $2.3 $2.3 $2.3 Cl. 5 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 Cl.5 $2.3 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 Cl.5 $2.3 $2.3 Cl.5 $2.3 $2.3 $2.3 Cl.5 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 27.27 21.03 27.Al 11.6A 22.00 2A.80 1 A.AO 11.60 26.61 27.Al 23.53 26.39 22.23 22.23 16.09 17.A7 17.A8 21.02 26.61 11.6A 22.27 1 A.39 32.97 32.97 16.09 11.61 16.13 22.70 22.82 22.82 16.13 16.82 16.57 22.16 22.70 20.07 19.95 21.36 1A.56 26.18 15.17 16.58 16.A6 22.21 10.61 23.17 23.17 26.19 28.32 28.32 27.79 27.78 22.A6 22.A7 23.81 19.95 16.82 15.17 10.83 29.12 21.76 16.A7 2 A.69 16.82 15.91 10.32 29.12 22.69 10. 27 9.09 9.10 8.71 3.71 8.70 3. OA 5.A6 5.A5 8.70 8.51 7.36 3. OA 8.51 7.36 6.21 1.5A 6.85 7.29 7.77 6.2C 7.78 7.A8 1.5A 6.85 7.29 7.37 7. A9 5.95 5.95 7.37 1.61 1.72 1 •A3 1.66 1.3A 1.6A 1 .A3 1.5A 1.70 1.57 1.59 1.59 1.22 1.62 1.5A 1.69 1.29 1.07 1.A1 1.61 1.67 1.02 1.12 1.19 .02 .65 .75 .66 .27 .18 .78 .38 .58 .63 .60 .67 .59 .57 .88 .83 .OA .05 ,7A . 9A .99 .AA • A6 .57 .80 .AA .Al .67 .77 .09 .85 .79 .56 .77 .20 .50 .38 .53 . A9 .19 .AO .39 • A9 • A7 .31 .81 .73 .71 .66 . A2 .16 .15 , 7A .65 .65 .28 .30 .66 .72 ,53 .Al .29 .31 .11 .01 .29 • 9A ,77 .07 .78 t .07 .18 -10.3 .03 .02 .05 .19 .1A 108. .03 .01 .02 .03 .05 .03 .05 .15 .19 .1A .22 126.3 .02 .03 .01 .02 .02 .01 .01 .03 ,1A 91.7 .07 .03 .01 .01 .02 .02 .10 .02 .01 .15 .03 .05 .OA .36 .16 .07 .06 .05 .OA .33 .25 • A2 .03 .03 .03 .05 .02 .01 .08 • 2A .12 .03 .02 .02 .03 .1A .13 .20 .08 .07 .08 .11 .05 .10 .07 .07 .07 99.3-.25 .11 87.8-.36 .12 .20 .12 .08 .20 • 2A .05 .07 ,06 .1C .OA .08 86.A-.65 .07 90.8-.78 .03 90.A-.72 .1A .12 -1.5 -1.7 90.5 90.1 92.5 88.7 90.0 91.1 90.2 AA.5 89.8 91.6 91.A 87. A 82.7 89.1 90.9 90.6 90.9 89.1 89.5 -2.6 91.2 90.9 87.8 -1.6 91.5 90.7 90.3 89.6 88.5 90.0 88.5 8 2.8 86.A 95.3 -5.7 -1.1 91.3 89.5 92.5 89.A 89.2 91.8 89.3 90. A 90.9 89. A 87.8 90.0 88. A 89.9 89.3 88.3 77.A 9A.1 85.1 89.8 89.0 88.2 88.2 88.0 88.0 93.3 -.6 2.5 1.7 2.2 5.A 1.0 1. A -.7 -.7 8.6 3.3 5.9 A.9 -.9 A, 1 3.2 2. A 3.3 1.6 5.5 .3 .2 >3 .6 .5 -1.61 -1.72 -1.6A -1.70 -1.21 -1.53 -1.66 -1.5A -1.61 -1.29 -1.59 -1.59 -1.69 -1.67 -1.02 -1.A3 -1.07 -1.12 -1.A1 -1.19 -.66 -.01 -.78 -.75 -. 7A -.67 -. 9A -.99 -.38 -.59 -.OA -.57 -.80 -.AA -.09 0.00 -.67 -.79 -.77 -.77 -. A6 -.85 -.56 -.AA 1.3A -• A8 1.A3 -.97 -• A9 -• A7 - •9A -.Al -.16 -. 7A -.65 -.65 -.39 -.18 — •A2 -.26 -.31 -.28 1.62 1.57 .57 .83 .65 .25 .Al .63 .17 .86 .60 .58 .52 .19 .37 .50 .31 .71 .53 .39 .81 .29 .15 .73 .66 .07 .11 .01 .30 1976AJ. 30 27 27 30 30 30 30 30 29 29 29 29 27 27 30 30 30 30 30 30 29 29 29 29 27 27 27 39 39 30 23 23 23 39 39 23 39 39 23 39 39 39 39 39 39 AO 39 39 39 AO 39 39 AO AO AO Ast. AO AO AO AO AO AO AO No. A2 Al A1 AO AO A2 A2 A2 A2 A2 A2 A2 A2 A2 A2 A2 © American Astronomical Society • Provided by the NASA Astrophysics Data System 75 0112.19 7A 1020.A2 7A 072A.25 7A 0826.31 7A 0826.23 7A 0822.21 7A 0809.27 7A 0711.38 75 0112.15 7A 1020.A3 7A 082A.31 7A 0810.33 73 07 7A 1002.13 7A 0929.21 7A 0929.17 7A 0822.22 7A 0711.37 7A 0827.50 7A 0826.A3 7A 082A.33 7A 0810.3A 7A 072A.A7 75 061A.30Cl.5 7A 0811.22 7A 0701.26 73 OA22.22 75 012A.A6S2.3 73 0513.27 73 06 7A 1020.1A 7A 0809.28 7A 0528.29 73 0508.16 73 OA13.30 73 0627.21 73 060A.19 73 0511.26 73 060A.17 73 08 73 08 73 07 73 06 73 06 7A OA10.A6$2.3 7A OA10.AA$2.3 7A 1020.10 73 09 73 06 73 08 73 06 73 11 73 10 73 10 73 10 73 09 75 01 73 10 73 0627.A3 75 01 7A 12 7A 12 7A 11 7A 11 7A 11 73 11 73 061A.A7 73 061A.A6 73 0731.36 73 0723.A8 73 0723.A7 73 0627.AA 73 1007.23 73 0822.31 73 0808.35 73 0808.37 73 0626.A7 7A 03 75 0126.32Cl.5 75 0116.36Cl.5 75 0112.A8 73 0822.30 73 0731.38 7A 06 7A OA 7A 03 73 1007.21 7A 05 7A OA 7A 06 7A 06 7A 06 7A 06 7A 06 7A 06 7A 07 06.33 08.32 23.A3 26.AA 1A.AA 23.AA 26.AA 1A.A2 2A.15 12.25 26.33 26.29 25.17 12.26 16.13 2A.1A 2A.33 12.A3 16.11 25.15 2A.35 21.A3 21.Al 2A.52 12 •A1 02.20 03.29 02.23 01.22 26.Al 26.AO 26.26 22.32 22.32 12.22 12.25 23.23 11.20 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 S2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl. 5 $2.3 $2.3 $2.3 $2.3 S2.3 Cl.5 $2.3 $2.3 $2.3 Cl.5 PI.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 PI.5 Cl.5 Cl. 5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 Cl.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 $2.3 PI.5 PI.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 $2.3 $2.3 Cl.5 $2.3 Tel. Flit.Phase $2.3 $2.3 $2.3 $2.3 23.8A 16.59 27.53 17.AO 20.31 27.93 27.95 22.OA 22.OA 15.69 1A.0A 16.66 20.31 25.23 15.72 2 A.03 15.96 16.67 19.89 16.82 2A.81 2A.81 1A.05 2A.03 22.99 26.62 26.62 15.62 1A.93 21.29 22.63 22.63 21.29 23.A7 20.96 20.96 1 A.93 21.17 21.17 1A.8A 17.89 23. A7 2A.59 26.36 26.36 11.10 11.09 17.90 17.A3 2 A.59 2A.76 19.80 17.A2 11.92 1A.22 11.92 1.57 10.26 19.79 10.59 10.56 1A.22 21.A6 18.71 17.09 11.90 25.93 23.75 21.A7 19.03 18.70 18. AC 9.10 9.25 6.70 8.10 6.70 9.13 5.72 8.11 9.13 9.A1 9. Al 8.88 8.87 7.A8 6.29 7.A9 6.29 A.13 A. 63 9.A3 1.97 A.13 A.63 .69 .68 POLARIMETRY OFASTEROIDS 1.28 1.32 1.1A .21 . 2A .36 . A9 .81 .78 .39 .27 .09 .66 .76 .35 .53 .77 .78 .75 .36 .15 .10 .72 .56 .78 .87 .60 .37 .68 .20 .91 • A5 .53 .53 • A8 .27 .79 .03 .76 .78 • A8 .31 .06 .25 .06 .OA .70 .25 .08 .10 .AO .A3 .62 .75 .2A .52 .1A .67 .61 . 3A .33 . A2 . A8 .67 .65 .76 .76 .57 .18 .10 .OA .18 .87 . A5 .55 .09 .06 .16 .13 .06 .1A .19 .02 89.3-1.62 .19 .05 .02 .05 93.3-.72 .06 -30.7 .05 .03 .15 .09 .02 .OA .OA .OA .OA .OA .02 .07 .07 .03 .03 .02 .02 .01 .OA .07 .08 .01 .02 .01 .02 .05 .10 .17 .OA .09 83.1 .06 89.5 .09 .19 .11 .23 -1.9 . 3A-17.0 .26 -11.0 .07 .OA .1A .05 111.1 .06 90.0 .07 .OA .06 .OA .03 .03 .05 .05 .03 .23 -A3.5 -A2.7 -l.A 89.5 -7.3 90.7 92.3 -7.0 90.8 87.2 -A.2 -6.2 91.9 90.0 90.9 87.6 95.0 -2.A 89.5 89.5 90.2 89.1 9A.7 -7.5 87.5 89.2 89.8 89.6 86.6 -6.5 90.2 89.A 90.6 87.3 88.8 88.8 -5.7 83.7 90.3 90.5 9A.5 88.5 88.3 90.8 90.2 51.A 90.6 91.8 90.6 89.0 3A.8 92.3 89.0 -5.2 91.0 91.3 89.3 90.5 -5.6 96.5 91.9 89.5 91.1 86.9 90.2 12.9 69.9 0.0 A.7 2.6 7.9 1.5 8.A 2.2 -.3 9.6 3.9 A. A 2.5 1.0 0.0 .A .3 .1 Table I{continued) -1.28 -1.32 -1.57 -1.97 -• 2A -. A9 -.35 -.35 -.66 — .A8 -.78 -. A8 -.76 C.00 -.70 -.59 -.28 -.29 -.01 — .6A -.Al -.23 -.69 -.70 -.25 -.03 -.60 -• 3A -.33 -.70 -.65 -• 6A -• A2 -, A8 -.67 -.1A -.08 -.67 -.65 -.76 -.76 -.57 0.00 1 •1A .20 .81 .78 .39 .27 .OA .76 .53 .60 .10 .36 . A6 .35 .19 .91 .52 .15 .67 .A3 .61 • A6 .87 .AS .70 .56 .26 .15 .03 .03 .10 .06 .31 .16 .51 .51 • 2A .17 .AO .A3 .70 .55 .09 .87 . A5 A3 A3 AA AA 51 51 51 51 5A 51 5A 5A 5A 5A 5 A 5A 5A 5A 5A 56 5A 56 56 56 56 56 63 56 56 6 A 63 63 63 63 58 56 56 56 6A 6A 6A 63 63 63 63 63 63 58 56 7A 0711.22$2.3 7A 06 7A 03 75 0715.36 75 0715.35 75 0505.A7 75 0505.A5 7A 05 7A OA 7A 03 7A 07 7A 06 7A 06 7A 05 7A 08 7A 07 7A 06 7A 08 7A 08 7A 08 7A 08 7A 07 73 12 7A 1113.36Cl.5 75 06 7A 08 73 12 75 06 75 05 7A 01 73 12 73 12 75 OA 7A 0725.37 7A 0723.A3 7A 0723.A2 7A 0827.35 7A 0725.38 7A 0907.32 7A 0827.38 7A 1001.26 7A 1001.19 7A 0907.30 7A 05 7A 1112.11 7A 1020.25 7A 101A.20 7A 101A.16 7A 05 7A 06 7A 06 7A 06 7A 05 7A 08 7A 07 7A 07 7A 06 75 03 75 01 7A 09 7A 09 7A 08 7A 08 7A 08 73 08 73 07 73 06 75 01 75 0615.35Cl.5 7A 08 7A 08 75 0303.28 75 0125.A2 7A 11 7A 09 7A 09 73 10 73 08 73 08 73 07 73 05 73 OA 75 OA01.15 75 0320.23 75 0310.AO 75 0303.31 75 0206.2A 7A 09 73 10 73 10 73 08 73 08 75 OA03.21 75 OA01.18 75 0320.27 75 0206.26 07.22 07.20 1A.25 26.A6 26.AA 12.2A 02.26 1A. 28 10.A9 23.30 2A.21 26.17 26.15 11.20 11.19 2A.23 10.1A 29.36 15.A6 1A.A5 27.15 05. A2 03.A9 31.25 29.Al 29.29 16.A3 02.3A 28.33 1A.36 03.35 03.30 1A .A0 09.2 A 09.23 0A.A5 05.3A 08.25 08.2 5 11.3A 11.33 07. A8 2A.A9 2A.22 2A.19 11.25 30.28 08.A7 08. A5 08.19 07.13 23.27 08.A7 22.A9 2A.52 11.2A 07.15 22.26 31.33 31.31 13.52 26.27 26.25 22.28 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 Cl.5 Cl.5 $2.3 $2.3 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 Cl.5 $2.3 Cl.5 Cl.5 $2.3 Cl.5 Cl.5 $2.3 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 Cl.5 Cl.5 Cl.5 $2.3 $2.3 Cl.5 Tel. File.Phase Cl.5 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 Cl.5 $2.3 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 Cl.5 Cl. 5 Cl.5 Cl.5 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 S2.3 $2.3 $2.3 $2.3 2A.11 15.00 1A.99 25.93 21.06 2A.10 21.06 19.6A 11.85 18.09 21. AO 19.6A 17.36 21.53 21.7A 21.76 21. A6 21.75 21.A6 21.A9 2A. 83 18.5A 2A.86 2A.21 22.09 1A.81 1A.80 2 A.22 22.07 25.98 25.50 21.62 25.98 21.33 21.3A 23.01 20.67 15.25 11.61 10.98 2 A.71 2A.71 20.66 16.OA 16.03 15.26 19.01 13.67 12.18 21.81 21.9A 26.98 20.00 18.66 18.66 20.35 26.71 28.23 18. A3 17.81 21.81 27.02 26.98 19.99 13.69 17.82 6.07 6.08 5.63 5.63 3.69 7.66 1.90 8.13 5.31 1.A2.OA89.8-1.A2 8.A8 8.11 7.56 8.59 9.96 8.58 9.95 7.56 8.A8 8. A 6 6.98 6.97 8.3A 6 •OA 9.39 9.38 9. A8 6. OA 6.69 6.70 8.56 .1C 1.9A 1.9A 2.01 1.78 1.93 1.82 1.91 1.60 1.91 1.53 1.96 1.07 2.32 2.05 1.17 1.A5 1.A7 1.A2 1.02 1.A9 1.66 1.79 1.A5 1.75 .13 .35 .36 .1A .19 .22 .32 .31 .OA .07 .13 .29 .09 .10 .27 .29 .31 .23 .21 .20 .10 .19 .18 .12 .15 .01 .82 .75 . A7 .75 .96 .70 .21 .92 .37 .32 .53 .A3 .78 .92 .63 . 7A .16 .08 . 3A .27 .69 .01 .05 .05 .07 .10 .91 .20 • If .33 .33 .70 .05 .03 . 2A .OA .8 .03 103.A .03 0.0 .02 .6 .29 .03 108.1 .03 .01 .20 • 2A .09 .03 .05 .09 .05 3.2 .02 -16.1 .06 .03 .06 .06 -33. .03 .06 .02 .03 .16 .02 .02 .05 .05 .15 .03 .15 .07 .OA .03 .02 .06 .05 .OA .02 .OA .03 .06 .02 .15 .09 .10 .10 66.0 .05 92.2 .05 89.3 .05 87.5-.70 .05 .12 .16 .09 .10 .OA -16.1 .03 .02 .OA .11 .13 .11 .11 .10 .11 .09 .02 -10.A .03 118.1 .02 .03 .OA .02 .02 .02 -3.3 95.9 A3.3 91.1 91.1 92.0 90.5 -1.9 88.1 26.3 88.7 -1.3 90.0 88.9 88.6 90.1 89.8 90.0 90.1 88.2 -1.9 90.1 90.5 90.A 91.2 90.7 -1.8 55.1 89.2 90.5 89.7 91.6 96.8 89.7 -1.3 -1.8 -8.2 -l.A 89.3 -2.1 -1.3 91.A 90.1 97.8 90.1 89.0 91.6 89.3 89.3 88.3 86.6 87.5 91.0 89.8 86.6 8.2 5.2 -.2 -.9 2.3 3.5 -.1 2.5 1.9 -.5 1.3 1.3 2.3 1.7 8.2 5.6 .A .8 .A .8 .7 .1 -2.00 -1.89 -1.93 -1.78 -1.93 -1.53 -1.59 -1.96 -1.90 -1.93 -1.82 -1.91 -2.01 -1.A7 -1.A2 -1.A9 -1.A5 -1.77 -1.A5 -.10 -.20 -.31 -.32 -.29 0.00 -.07 -.27 -.29 -.30 -.52 1.32 -.05 1.07 -.96 2.05 -.92 -.99 2.32 1.17 -.75 -.05 -.10 -. 3A -.27 -.33 -.32 -.07 -.63 -• 7A -.02 -.19 -.15 -. 2A -.1A -.69 1.12 1.66 1.75 .36 .35 .95 .19 .1A .18 .07 .09 .19 .06 .OA .22 .21 .17 .12 .75 .01 .82 .62 . A7 . 9A . A6 .21 .37 .A3 .78 .92 .01 .15 .91 .07 .52 .32 .05 .05 .70 265 00 CM UD CM 1976AJ. ts] 266 © American Astronomical Society • 192 172 172 141 139 182 182 145 141 141 141 141 139 115 115 145 141 141 141 141 141 141 141 141 141 139 192 192 192 192 141 141 141 141 139 139 139 115 115 114 115 114 192 192 192 139 192 192 95 95 89 89 95 93 93 89 84 84 84 84 84 80 80 83 750505.36Cl.5 71 71 70 70 68 68 Ast. No. 73 0413.38 74 0930.47 75 0505.39 73 12 73 12 73 12 73 11 73 10 73 09 74 0907.36 74 0826.47 74 0826.45 74 1002.31 74 0930.34 74 0930.26 75 0403.41 73 12 73 10 73 10 73 10 73 10 73 09 73 08 74 0422.28 74 0405.35 74 1113.32Cl.5 75 0116.39Cl.5 74 0924.32 74 0907.37 74 1001.32 74 0811.45 73 11 73 10 73 10 73 10 74 0528.23 74 0514.22 74 0422.26 74 0410.25 74 0405.32 74 0827.32 75 0305.39 75 0125.48 73 1231.45 73 1231.29 75 0124.38S2.3 73 0826.42 74 0811.46 73 08 74 0827.30 75 0403.45 74.10 20.35 74 1002.25 74 1002.25 74 0116.44 74 11 74 1112.37 74 1020.49 74 1020.48 74 1001.35 75 0403.47 73 0919.38 74 11 74 09 74 09 74 09 74 08 74 09 74 08 74 08 74 08 75 0505.26 75 0403.31 75 0715.39 75 0715.40 74 1221.36 74 1218.27 75 0505.29 75 0403.39 75 0403.33S2.3 75 0505.17 75 0505.21 75 0403.22 07.21 07.18 08.23 29.16 29.12 16.18 04.31 26.21 24.19 08.31 08.27 25.09 24.19 08.2 5 19.28 12.30 26.39 23.34 12.25 08.34 13.15 24.28 08.32 26.36 11.40 24.30 26.37 11.39 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 32.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 32.3 Cl.5 32.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl. 5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 32.3 32.3 32.3 32.3 32.3 32.3 32.3 32.3 Cl.5 32.3 Cl.5 Cl.5 Cl.5 Cl.5 32.3 32.3 32.3 32.3 32.3 Cl.5 Cl.5 Cl.5 Cl.5 32.3 Cl.5 S2.3 Cl.5 Cl.5 Cl.5 S2.3 S2.3 S2.3 S2.3 S2.3 Cl.5 Cl.5 Cl.5 S2.3 Cl.5 S2.3 Cl.5 S2.3 Tel. Filt.Phase 1\. 56 27.64 27.12 27.11 24.28 18.30 17.82 11.57 14.58 22.50 12.14 16.02 32.81 10.35 27.64 21.41 11.59 11.57 16.02 24.50 33.87 33.87 11.17 18.22 17.82 15.75 11.84 11.83 10.17 13.02 24.51 32.81 19.49 12.15 10.17 16.94 28.65 28.50 10.37 10.36 17.95 17.95 10.36 24.01 24.01 18.43 9.51 8.17 6.85 6.84 3.78 9.59 7.25 7.12 1.48 8.51 7.65 6.23 5.90 8.07 8.22 7.88 3.77 8.34 8.07 2.89 7.32 6.00 9.82 8.33 3.93 9.83 3.93 7.03 7.85 1.45.0590.4-1,45 8.11 6.58 9.78 6.11 7.04 9.17 8.09 1.28.0589.9-1.28 1.83 2.21 1.81 1.48 1.56 2.49 1.63 1.08 1.87 2.30 2.21 1.47 1.71 1.42 1.22 1.18 2.20 1.77 1.30 1.62 1.19 1.00 1.40 1.74 1.14 1.16 1.18 1.25 2.54 1.40 1.57 1.74 1.41 1.53 1.54 1.79 1.52 1.83 1.68 .75 .97 .92 .52 .63 .71 .98 .84 .28 .84 .90 .63 .65 .07 .96 .72 .74 .63 .56 .42 .65 .54 .40 .55 .83 .87 .33 .99 .75 .66 .60 .30 .67 .76 .59 .69 .62 .29 .21 .08 ZELLNER AND .16 .16 .10 .17 .20 .38 .32 .10 .06 85.4 .06 .04 .27 .32 .21 .09 .12 .09 .12 .16 .01 .02 .03 .02 .05 .06 .20 .20 87.9 .16 .06 .10 .09 .14 .14 .07 .06 .03 89.7-1.48 .10 .07 .01 .01 .03 .10 .05 .04 91.3-.96 .20 84.1-.70 .02 .03 .04 .07 .07 .11 .09 .14 .16 .06 .06 .06 .02 .02 .03 .07 .01 .02 .06 .02 .06 .03 .03 .04 .03 .05 .04 -3.6 .05 .02 118.9 .05 -7.8 -29.9 -1.9 90.0 89.8 90.9 85.4 86.3 89.5 -1.9 -1.1 90.6 87.9 87.4 88.4 89.9 92.5 90.3 90.2 90.6 89.6 90.3 89.0 90.2 95.7 86.4 88.9 88.5 90.0 90.6 90.1 90.2 89.6 90.6 91.5 94.9 87.0 86.6 87.1 88.1 89.0 89.6 89.2 87.9 87.5 83.7 , 97.0 91.6 89.6 89.3 89.5 90.6 89.3 89.8 90.7 90.4 93.7 88.5 88.4 92.7 90.9 89.9 88.5 92.0 1.9 1.9 1.8 1.8 1.0 .8 .5 .5 .4 Table I{continued) -1.87 -1.48 -1.77 -1.83 -1.47 -1.71 -1.80 -1.56 -1.22 -1.74 -1.42 -1.30 -1.14 -1.25 -1.41 -1.50 -1.00 -1.52 -1.54 -1.16 -1.18 -1.62 -1.74 -1.79 -1.19 -1.18 -1.83 -1.68 -.75 -.97 -.91 -.84 -.42 -.55 -.63 -.64 -.87 -.29 -.28 -.84 -.82 -.62 -.74 -.63 -.89 -.73 -.65 -.33 2.29 2.21 2.21 -.56 -.99 -.66 -.67 2.20 -.72 -.54 2.49 -.76 -.59 1.63 1.40 1.57 2.54 -.69 -.62 1.40 -.59 .98 .04 .51 .54 .40 Provided bythe NASA Astrophysics Data System 324 324 324 324 324 324 324 324 230 410 324 324 324 324 230 230 230 230 416 410 349 345 345 324 324 324 324 230 230 230 230 230 230 230 192 192 192 471 451 451 416 410 410 349 349 349 338 750615.29Cl.5 324 230 230 230 192 192 192 471 410 410 410 349 349 349 192 192 471 354 354 511 Ast. 511 511 511 511 511 511 511 511 511 511 511 511 511 511 No. 511 511 511 GRADIE 73 08 74 10 73 08 73 08 73 04 74 12 74 10 73 08 73 08 73 08 73 04 73 04 75 0615.40Cl.5 74 0929.32 74 0929.27 74 0924.35 74 0907.38 75 0615.25 74 0603.26 74 0326.31 75 03 75 03 75 03 74 12 74 1113.17 74 1112.29 74 0811.28 74 0809.36 74 0725.42 75 0124.31 74 1218.25 74 1124.11 74 0826.21 74 0711.30 74 1113.30 74 0401.27 74 0326.30 75 0206.19 75 0124.39 75 04 74 0924.34 74 0907.39 74 0725.44 74 0612.42 75 0124.28 74 1218.26 74 1124.10 74 1124.43 74 1113.49 75 0310.51 74 0724.28 74 0612.30 75 0206.22 74 0628.35 75 0614.25 74 0811.29 74 0809.34 74 1221.23 74 1112.39 75 0320.33 75 0206.28$2.3 74 0711.31 74 0628.32 74 0401.29 73 0731.45 74 0603.26 74 0602.17 74 0908.14 74 0612.31 75 0614.38Cl.5 73 0827.40 73 0823.41 73 0822.36 73 0731.44 75 0615.42 73 0827.44 73 0823.39 73 0822.38 73 0806.45 73 0806.42 73 0927.38 73 1229.22 73 0919.41 74 1112.48 74 1112.46 73 1228.23 73 1024.28 73 1007.27 Date UT) 08.20 06.51 22.18 08.18 26.19 22.45 06.50 05.30 21.49 26.51 20.51 27.19 22.16 03.18 20.21 20.18 21.46 Cl.5 Cl .5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 Cl.5 Cl.5 $2.3 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 Cl.5 Cl.5 $2.3 $2.3 Cl.5 Cl.5 Cl.5 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 Cl.5 $2.3 $2.3 $2.3 $2.3 Cl. 5 Cl.5 $2.3 $2.3 $2.3 $2.3 $2.3 $2.3 Cl.5 B $2.3 G Cl.5 Cl.5 Cl.5 $2.3 8 Cl.5 $2.3 $2.3 $2.3 $2.3 Cl.5 Cl.5 Cl.5 Cl.5 $2.3 $2.3 Cl.5 $2.3 Tel. Flit.Phase Cl.5 Cl.5 23.75 19.57 20.53 20.24 20.24 22.55 19.22 25.61 24.46 19.08 23.27 23.10 18.15 18.75 22.55 26.30 27.37 27.37 20.59 19.57 19.22 13.17 23.75 20.53 18.15 18.75 11.12 18.67 11.33 11.62 20.14 16.98 13.16 25.87 24.62 16.54 10.62 11.33 10.67 25.65 10.61 17.07 19.33 11.12 27.10 10.87 10.83 11.83 18.95 19.33 16.44 17.07 17.22 18.96 16.45 17.22 21.59 20.52 20.57 13.39 21.59 9.27 9.47 9.47 7.81 7.81 8.56 6.85 8.02 9.25 9.56 T.93 8.50 9.56 4.63 6.71 6.71 9.68 1.26.0289.0-1.26 5.69 7.61 8.94 3.89 8.91 9.45 7.76 8.21 5.68 8.47 8.91 1.15 2.03 1.51 1.58 1.23 1.54 1.33 1.75 1.43 1.35 1.05 1.67 2.29 1.86 1.87 1.49 1.78 1.66 1.52 1.71 1.27 1.16 1.63 1.72 .96 .96 .92 .22 .84 .08 .03 .60 .69 .05 .10 .15 .35 .91 .95 .27 .29 .26 .45 .22 .91 .14 .59 .42 .47 .73 .84 .33 .16 .15 .81 .02 .33 .04 .38 .92 .06 .53 .40 .41 .66 .39 .58 .47 .10 .77 .65 .71 .57 .13 .59 .66 .72 .80 .72 .63 .20 .65 .59 .11 .64 .25 .21 .03 .04 .15 .03 -8.0 .05 .03 .05 .05 .04 .04 .05 .04 .02 .03 .10 .35 103.1 .17 1.0 .03 92.7-.65 .06 .05 .02 .04 .04 .04 .03 .11 .02 .27 .23 .04 .05 .06 .14 .03 .05 .06 .06 .03 .06 .13 .18 .04 .04 .02 20.9 .04 103.6 .03 89.1 .04 89.5-.71 .05 69.8 .05 89.7 .05 89.5 .06 .03 .09 .04 .04 .04 .03 .17 .08 .05 .09 .12 .20 .17 .14 .08 .03 .03 .13 .17 .13 .15 .19 .09 .16 -6.6 -9.4 -6.5 -1.3 -1.4 89.1 90.5 89,6 82.9 89.6 91. 84.8 -.94 85.8 66.6 94.4 95.7 53.9 77.5 89.2 89.5 -1.0 38.9 31.9 95.1 95.1 -6.0 90.4 -1.43 89.9 95.3 93.3 91.6 93.8 90.6 -1.54 89.4 90.0 90.6 94.5 92.8 87.2 91.7 89.5 89.7 95.9 90.0 95.4 89.6 83.5 91.0 89.5 87.0 91.0 31.8 88.7 89.8 85.5 89.4 -.8 -.4 2.1 1.9 6.5 -.4 -.2 -.3 4.9 1.4 .2 .4 -1.35 -1.33 -1.16 -1.62 -1.67 -1.52 -1.70 -1.27 -1.04 -1.86 -1.87 -1.66 -1.67 -.38 -.02 -.15 -.15 -.80 1.15 -.33 1.51 1,57 1.23 -.33 -.41 -.38 -.91 2.03 1.71 -.38 -.47 -.53 -.40 -.59 -.57 -.59 -.77 -.64 -.72 -.63 -.19 -.13 -.11 -.57 -.66 2.29 -.80 -.71 1.78 .28 .03 .60 .33 .96 .21 .84 .06 .03 .59 .69 .10 .15 .47 .95 .92 .18 .21 .25 .44 .91 .01 .91 .05 .04 .25 .21 .64 .64 .05 00 CM UD CM 1976AJ. ts] íí, polarization isunambiguouslypositiveor“nega- normal totheSun-asteroid-Earthplane.Allobserva- Observations sincethattimehavesystematicallysmallerbutprobablymorerealisticestimatesoftheerror. nights inMarch1975provideasinglenotableex- phase anglewithintheobservationalaccuracyof hardly anytwowell-observedasteroidsarepolari- or somethingdifferent. metrically indistinguishable,thesystematicdifferences both nights.Wecannotaccountforthecuriousresults, ception. Misidentificationisunlikelysincemotionof tions withPobs^>€pshow6near0°or90°,i.e.,the night, andapparitiontoatthesamesolar found toberepeatablefromhourhour,night within afewminutesoflocatingnewasteroidat between thevarioustypesareapparent.Generally and 554willnotbeconsideredfurtherinthispaper. rotation andaspecttoone partin40.McCordand asteroids areplottedinFigs.1,2,3,and4.While shows markedcolorvariation. Simultaneousphotome- the asteroidwithrespecttofieldstarswasnotedon tive.” Observationsofasteroid554Peragaontwo plitude wasthelargestyet observed(Taylor1971), rotation period,atatime when thelightcurveam- try andpolarimetryofFortuna overroughlyhalfa roughly ±0.05%.For433Eros,ZellnerandGradie the telescope,weknowwhetherhavean5,aC, Chapman (1975a)havesuggested that19Fortuna r (1976) foundthepolarizationtobeconstantover a ThemethodofcomputingtheformalerrorepinobservedpolarizationunderwentchangesFebruaryandMarch1974. With fewexceptionstheasteroidpolarizationsare The observedpolarization-phasecurvesforselected © American Astronomical Society • Provided by the NASA Astrophysics Data System 602 602 584 584 584 584 584 584 584 584 584 584 563 532 584 584 584 563 563 563 554 532 532 554 532 532 532 532 532 532 532 511 511 511 511 511 511 74 0930.22 74 11 74 11 74 11 74 09 74 09 74 09 74 08 74 08 74 08 74 08 74 1020.45 74 0930.18 74 11 74 09 74 08 74 1124.19 74 0827.41 74 0810.23 74 0908.39 75 0310.44 74 0810.22 74 0701.34 74 0701.33 73 0603.15 75 0305.46 73 0513.17 73 0511.15 73 0508.22 73 0422.33 73 0413.32 75 0125.37 75 0125.39 75 0112.46 74 1221.54 75 0112.44 74 1221.52 07.46 07.44 29.38 29.36 24.36 11.32 24.17 24.15 12.34 12.31 24.38 11.34 10.29 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 S2.3 S2.3 S2.3 Cl.5 Cl.5 Cl.5 Cl.5 S2.3 S2.3 Cl.5 Cl.5 Cl.5 S2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 S2.3 S2.3 S2.3 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Tel. Flit.Phase 13.79 30.56 19.98 27.41 27.42 30.55 32.39 32.49 17.97 17.96 13.78 32.39 16.27 23.91 24.97 19.98 21.52 25.19 10.65 26.33 24.63 21.98 19.89 16.15 16.15 9.69 7.75 8.49 7.47 9.71 8.63 4.84 8.63 7.47 9.22 9.23 4.84 POLARIMETRY OFASTEROIDS 1.32 1.74 1.83 1.06 1.40 1.51 1.73 1.62 1.61 1.33 1.68 1.30 1.70 1.38 .04 .69 .10 .52 .31 .88 .28 .07 .28 .27 .56 .61 .77 .82 .02 .84 .76 .72 .66 .49 .90 .72 .19 : "X .03 .10 .02 .04 .07 .03 .04 .04 .02 .08 .06 .07 .06 .03 .14 .04 .03 .03 .03 .15 -23.2 .03 .07 -21.6 .03 .10 .08 .03 .02 .04 .02 .02 .05 -1.5 89.9 92.3 20.6 92.9 -2.2 84.9 88.9 91.7 90.6 89.0 97.8 90.7 91.2 92.5 90.6 88.4 88.6 88.7 89.8 6.8 2.2 2.3 -.3 3.1 1.1 1.7 1.5 -.5 4.3 .6 .9 .7 Table I{continued) -1.30 -1.33 -1.62 -1.83 -.31 -.27 -.69 -.82 -.51 -.77 -.72 -.02 -.07 1.40 -.76 1.06 1.73 1.74 1.11 1.01 1.51 1.32 .03 .10 .87 .28 .72 .66 .49 .16 .61 phase curveobservedovertwoapparitions.TheUBV variability inFig.5,or1forthepolarization- is illustratedinFig.5.Whileourrotationalandaspect phase. Least-squaresfits to datapointsatphase phase curvesaregivenin Tables IIandIII.The phase arediscordantwithrespectto1973data,and coverage isnotcomplete,weseenoevidencefor phase coverageisstillincomplete.Forexample, phase. Evenforafewofthebrighterasteroids modest colorvariations(WarnstekerandSather1974), maximum depthofthenegative branch,denotedby radiometric albedosbyMorrison(1974)andHansen colors ofFortunafoundbyZellneretal.(1975),the jPin> isestimatedfromdata between5°and11° variegation. The1974resultsfor63Ausonianear22° in 1972wastheresultofmisidentification. angles near15°andlarger givetheslopehof inclination. during recentapparitions,duetoitshighorbital only theresultsfrom1973areusedbelow.Misiden- scatter inourdatabetween6°and12°phasesuggests teroid, andwesuggestthattheiranomalousspectrum McCord andChapmanareappropriateforaCas- tion ofveryweakpolarizationfor43Ariadneat15° 2 Pallashasnotbeenobservableatphasesbelow12° tification seemslikelyforthesinglenight’sobserva- (1976), andthe1973spectrophotometriedataof m 704 654 737 704 704 704 704 704 704 654 654 654 654 747 747 737 737 704 704 654 654 887 887 887 887 737 704 887 887 877 887 887 887 Ast. Numerical parametersdescribing thepolarization- No. For asteroid39Laetitia,whichisknowntoshow 73 1231.16 74 0907.28 74 0130.27 74 0115.35 74 1020.29 74 0811.38 74 0811.37 75 0320.31S2.3 74 0130.27 74 0115.34 73 1231.15 74 0116.30 73 1228.45 74 0907.34 74 0827.47 74 1112.19 74 1112.16 74 1020.31 74 0924.22 74 0924.20 75 0614.33 74 0116.30 73 1231.37 73 1230.30 73 1228.47 73 1116.33 75 0320.29 75 0305.42 74 0827.48 74 0822.26S2.3 74 0907.27 74 0119.46 74 0116.49 74 0825.30$2.3 74 0116.49 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 Cl.5 S2.3 S2.3 Cl.5 Cl.5 S2.3 $2.3 S2.3 Cl.5 Cl.5 Tel. Flit.Phase 16.52 15.83 28.53 28.53 23.56 16.51 13.68 27.52 12.23 20.25 10.51 10.31 15.83 23.57 12.41 15.74 20.25 16.03 10.50 10.31 15.76 16.04 9.53 6.63 7.75 8.24 7.83 5.52 5.75 6.63 8.47 5.92 5.75 4.46 5.92 1.36 2.89 2.81 1.50 1.27 1.18 1.14 1.19 1.15 1.08 1.27 1.40 .09 .03 .94 .97 .29 .08 .80 .85 .67 .70 .32 .90 .12 .56 .44 .87 .77 .72 .67 .60 a î 7. .12 .06 .14 .08 .03 88.8-.80 .22 .11 .10 .12 .03 .02 .02 .05 .05 .02 .20 .12 .02 .01 .02 .13 .18 .03 .02 .03 .08 .10 04 85.5 02 91.0 03 -15.4 90.0 -1.1 88.4 -0.0 83.9 90.6 90.7 91.8 85.0 91.8 91.0 86.8 92.2 90.2 90.0 92.5 87.8 88.7 87.2 88.7 89.5 0.0 1.5 8.4 .2 -1.36 -1.14 -1.27 -1.27 -1.29 -1.06 -1.15 -.97 -.03 2.81 -.44 -.31 -.29 -.83 -.90 2.89 -.72 -.67 -.70 -.56 -.79 -.87 -.60 -.77 -.67 1.40 1.19 1.50 .85 .94 .08 .08 .12 267 00 CM UD CM 1976AJ. ts] sion angleinthelattercase. Thecurvatureofthe or aparabolicfitismade, as seemsappropriatefor the data,andslopeistaken atthederivedinver- ascending branchbetween15° and30°phaseisfound to besmall(<1%)butpositive forallwell-observed marks (?),andnoisyordiscordantdatabycolons(:). ao wherethepolarizationchangessign.Fragmentary ascending polarizationbranchandtheinversionangle Fig. 1.Polarization-phasecurvesofthetypicalCasteroids1Ceres, 19Fortuna,56Melete,and324Bamberga.Opencirclesindicate data orpoorphasecoverageareindicatedbyquestion 268 For thedeterminationsofh andaoeitheralinear © American Astronomical Society • Provided by the NASA Astrophysics Data System data takeningreenlight,andfilledcirclestheblue. ZELLNER ANDGRADIE see alsoVeverkaandNoland 1973;Bowelletal. paucity ofdata,itispossiblethatweunderestimate slope-albedo lawasformulated byZellneretal.(1974; albedos atthelistedwavelengths derivedfromthe we areconstrainedtouselinearfitsbecauseofthe slightly boththeinversionangleandslope. objects. Inafewcasessuchasfor410Chloris,where The seventhcolumnofTable IIIgivesgeometric II. ALBEDOSANDDIAMETERS 00 CM UD CM 1976AJ. ts] poorly knownoronlyguessed,andthetransforma- wavelength fromthevaluesinblueandgreenlight. The lastcolumngivesalbedosreducedtothevisual uncertainty. Bowell andZellner1974),namely In somecases(e.g.,12Victoria)theasteroidcoloris itself. InTableIIIthevisualgeometricalbedos more directmeasuresofasteroidalbedosanddiame- lunar materials,whichisusefulintheabsenceof essentially anempiricalresult,well-calibratedonlyfor et al.(1974)andbyChapman(1975).Itis tion totheasteroidshavebeendescribedbyZellner tion tothevisualwavelengthintroducesadditional ters. Onelimitationcanbeseeninourasteroiddata Fig. 2.Polarization-phasecurves of thetypicalSasteroids3Juno,7Iris,8Flora,11Parthenope,18 Melpomene,and192Nausikaa. The limitationsoftheslope-albedolawforapplica- © American Astronomical Society • Provided by the NASA Astrophysics Data System P% “I + 1 0 0 0 Symbols areasinFig.1,exceptthat opensquaresfor7Irisrepresentresultsintheultravioletfilter. log p=—logh—1.78. 10 POLARIMETRY OFASTEROIDS 20 30 very wellforsomeasteroids(3,5,7,21,29,63,192, derived fromtheslopesinblueandgreenlightagree examined inFig.6,whereweplottheratioofblue defined atbothwavelengths.Thiscuriouseffectis and 230)butdisagreebyasmuch15%forothers holds constantinsomecases.Ifthealbedosderived in proportiontothedecreasealbedo;factit slope doesnotincreasetowardshorterwavelengths line. Fortheanomalousasteroidspolarimetric applies atbothwavelengthsshouldliealongthedashed color. Surfacesforwhichthesameslope-albedolaw from observationsingreenlightwereassumedtobe to greenslopes,inmagnitudeunits,versustheB—F correct, thenuseofthesameslope-albedolawfor the blue(andformanyobjectswehaveblue-light (8, 9,11,18,and20)evenwhentheslopesarewell- SOLAR PHASEANGLE 10 2030 269 00 CM UD CM 1976AJ. ts] filings, withsize<50jum,fromunpublishedworkbyDollfus 270 and Zellner.Thefilingsareslightlyoxidizedbutstillstrongly average ofblue-andgreen-lightlaboratoryresultsforfineiron magnetic, andhavealbedo0.12atthevisualwavelengthrela- tive toMgOat5°phase. data only)wouldleadtoanoverestimateofthevisual albedo. 16 Psyche,withsymbolsasinFig.1.Thedashedcurveisthe Fig. 3.Pointsrepresentpolarimetricobservationsofasteroid Thus, wehave,forsomeobjects,awavelength- © American Astronomical Society • Provided by the NASA Astrophysics Data System Fig. 4.Polarization-phasecurves of thehigh-albedoasteroids44Nysaand64Angelina(left), the unusualdarkobject 10 20 30 1020 ZELLNER ANDGRADIE 704 Interamnia(right). polarimetric albedosbelow0.05mayreflectonlya ratory data,anddonotexistforlunarmaterials masked bytheirweakcolors,butitdoesrepresent orbital parameters.IfpresentfortheCasteroidsitis dependent failureoftheslope-albedolaw.Analogous propriate forthehighalbedolisted64Angelina. effects havenotbeenclearlydemonstratedinlabo- bodies coveredwithbright,low-opacitymaterialmay While fewifanylunarpowdersandmeteoritesstudied saturation ofthelaw.Also,anotecautionisap- very darkmaterials,andtheabsenceofderived to correlatewithanyotherspectral,polarimetric,or show substantiallimbdarkening.Thus,theglobal small incidenceangles,whereasactualastronomical law refersessentiallytonormalalbedosmeasuredat is noreasontodoubttheslope-albedolawitselfin in thelaboratoryhavealbedosashigh0.5,there an opticalproperty,ofunknownnature,inwhich geometric albedomaybelowerthanthederivedvalue. the Sasteroidsdifferfromoneanother. this domain(BowellandZellner1974).Howeverthe (Bowell etal.1973).This“0-effect”doesnotseem The slope-albedolawispoorlydocumentedfor SOLAR PHASE ANGLE 00 CM UD CM 1976AJ. ts] which asteroidsaredarkandoneslighter. plication thatalbedosareknowntothenearest in subsequentpapers. and radiometricasteroidalbedoscaleswillbemade More detailedcomparisonsbetweenthepolarimetric listed byHansen(1976).However,weallagreeasto results byMorrison(1974)andsubstantiallymore puted fromtheadoptedabsolutemagnitudesin discrepant withreferencetotheradiometricdiameters systematically about15%smallerthanradiometric given forcomputationalpurposes,withoutanyim- the nearestkilometer.Thepolarimetricdiametersare wavelength derivedfromweightedaveragesofresults thousandth orthatdiametersmaybecomputedto second column.Threesignificantdigitsareusually objects itis0.060±0.005.Diametersarethencom- ric albedois0.18withrmsscatter±0.02;fortheC in TableIIIwithoutregardforthedifficultiesdis- belonging totheStype(Sec.IV),averagegeomet- cussed above.Forasteroidsclearlyidentifiableas In TableIVwegivegeometricalbedosatthevisual © American Astronomical Society • Provided by the NASA Astrophysics Data System 42 Isis 40 Harmonia 44 Nysa 41 Daphne 46 Hestia 39 Laetitia 31 Euphrosyne 28 Bellona 30 Urania 29 Amphitrite 27 Euterpe 24 Themis 23 Thalia 20 Massalia 22 Kalliope 21 Lutetia 19 Fortuna 18 Melpomene 11 Parthenope 17 Thetis 16 Psyche 15 Eunomia 14 Irene 13 Egeria 12 Victoria 10 Hygeia 4 Vesta 3 Juno 5 Astraea 2 Pallas 6 Hebe 9 Metis 8 Flora 7 Iris 1 Ceres Asteroid Table II.DepthP m Pmin% POLARIMETRY 0.31 0.78 0.64 0.77: 0.88? 0.73? 0.78 0.66 0.74 0.71 0.80 0.70 1.54? 0.98 0.72? 0.68 0.55? 0.76 1.88? 0.74 0.80? 0.75 0.80 1.32? 2.10 0.73 1.63? 0.68 0.74 1.72 1.30? 1.00 1.38 1.72 1.50 ofthenegativepolarizationbranch,variousspectrophotometric n parameters, andopticaltypeforasteroids. B-V* 0.67 0.68 0.84 0.83 0.88 0.88 0.70 0.87 0.81 0.76 0.83 0.65 0.72 0.82 0.71 0.83 0.75 0.81 0.83 0.81 0.71 0.81 0.82 0.84 0.70 0.87 0.77 0.74 0.85 OF ASTEROIDS in greenlight,andfilledcirclestheblue.Thepolarization points areaveragesfrom5minofintegrationtime. and polarization(bottom)forasteroid19Fortunaon24July a UT 1974,atphase7?3(TableI).Opencirclesindicatedata U—B 0.24 0.22 0.41 0.45 0.49 0.45 0.43 0.35 0.36 0.39 0.26 0.19 0.35 0.43 0.45 0.39 0.28 0.42 0.42 0.36 0.40 0.45 0.41 0.44 0.38 0.46 0.25 0.50 Fig. 5.Lightcurve(top)withrespecttoacomparisonstar b Bend 0.06 0.16 0.16 0.16 0.15 0.18 0.10 0.13 0.18 0.09 0.21 0.09 0.16 0.17 0.24 0.17 0.13 0.14 0.13 0.22 0.14 0.11 0.07 0.16 0.12 0.15 0.04 0.24 0.14 b Depth 0.88 0.93 0.84 0.93 0.93 0.88 0.93 0.92 0.93 0.83 0.89 0.90 0.91 0.81 1.00 0.74 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 s C pec E S pec S S S S S s s C S S S s s S S S C? C M M S S C pec M C S C c S C U Type 271 1976AJ. 272 a b FromZellneretat.(1975). Millisetal.(1976)for433Eros. FromChapmanetal.(1975). Pietersetal.(1976)for433Eros. © American Astronomical Society • Provided by the NASA Astrophysics Data System 1685 Toro 1620 Geographos 1566 Icarus 1058 Grubba 389 Industria 324 Bamberga 354 Eleonora 345 Tercidina 230 Athamantis 338 Budrosa 306 Unitas 356 Liguria 114 Kassandra 471 Papagena 416 Vaticana 410 Chloris 349 Dembowska 135 Hertha 129 Antigone 115 Thyra 451 Patienta 433 Eros 415 Palatia 367 Amicita 182 Elsa 141 Lumen 139 Juewa 563 Sulieka 674 Rachelle 654 Zelinda 602 Marianna 584 Semiramis 532 Herculina 145 Adeona 887 Alinda 511 Davida 192 Nausikaa 737 Arequipa 747 Winchester 704 Interamnia 54 Alexandra 95 Arethusa 88 Thisbe 64 Angelina 63 Ausonia 58 Concordia 57 Mnemosyne 56 Melete 89 Julia 80 Sappho 65 Cybelle 51 Nemausa 93 Minerva 85 lo 84 Klio 83 Beatrix 68 Leto 71 Niobe 70 Panopaea Asteroid Pin% m 0.32 0.71 0.68 0.70 0.52? 0.80? 0.90 0.71? 0.94 0.64 0.75: 0.61? 0.98? 0.70 0.77 0.71? 0.75 1.70? 1.95 0.70 0.63 0.80? 0.39 0.66? 1.47 1.96 1.46 1.78 1.06? 1.24? 0.69? 0.78 1.78 1.50? 1.49 1.83 0.76 0.81? 1.86 1.22 1.36? 1.47? 1.29? 0.84 1.50? 1.31 1.62 1.94 1.55 1.28? 1.69 1.30 1.76? 1.45? 1.46? ZELLNER ANDGRADIE & B—V 0.76 0.86 0.77 0.91 0.67 0.80 0.93 0.69 0.83 0.83 0.74 0.71 0.87 0.71 0.72 0.72 0.92 0.86 0.96 0.89 0.88 0.90 0.88 0.67 0.80 0.66 0.91 0.71 0.72 0.89 0.71 0.84 0.87 Table II{continued) U-B* 0.42 0.36 0.27 0.46 0.47 0.54 0.29 0.27 0.45 0.43 0.44 0.37 0.49 0.45 0.36 0.55 0.49 0.46 0.50 0.50 0.47 0.53 0.44 0.35 0.31 0.54 0.27 0.26 0.32 0.50 b Bend 0.19 0.16 0.30 0.16 0.10 0.18 0.20 0.17 0.13 0.27 0.20 0.15 0.15 0.21 0.26 0.07 0.15 0.14 0.14 0.16 0.17 0.17 0.15 0.24 0.19 0.26 0.17 0.29 0.06 0.27 b Depth 0.89 0.90 0.83 0.90 0.75 0.97 1.00 1.00 0.93 1.00 1.00 0.90 1.00 1.00 0.84 1.00 0.93 1.00 1.00 0.95 1.00 1.00 1.00 1.00 S S E s C C C S pec M? S pec C c S C C? S pec C pec S pec S M? S C C C S C 5 S C C C pec? C C 5 C ? U S 5? S S S 5 s S C pec? C s S S C U S c C pec C C U Type 1976AJ. Asteroid 230 410 324 192 141 139 © American Astronomical Society • Provided by the NASA Astrophysics Data System 20 21 12 23 13 11 14 16 29 27 42 40 39 30 19 18 17 15 44 84 64 56 89 63 51 54 8 4 9 7 6 3 2 5 1 Table III.Polarimetrieslopes,inversionangles,andgeometricalbedosforasteroids. b Filt. B B B B B B B B B B B G G G G G G B G B B X G G G G G G B B B B B G G G B B G B B B B B B B B G G G G B B B B B G B B B B B G G G X G G G G G G POLARIMETRY OFASTEROIDS C 14 14 12 d N 4 4 8 8 4 4 8 8 8 8 6 8 4 6 5 6 5 6 8 5 5 7 4 5 7 7 6 6 6 5 4 5 7 7 5 7 4 4 4 4 5 9 2 2 4 2 4 5 5 3 5 2 4 4 8 6 6 5 8 7 7 6 8 5 7 7 7 7 7 0 Ascending branch 0.04 0.05 0.01 0.08 0.04 0.04 0.04 0.02 0.03 0.03 0.02 0.02 0.05 0.03 0.04 0.05 0.04 0.03 0.04 0.02 0.01 0.04 0.03 0.03 0.10 0.03 0.02 0.04 0.01 0.01 0.04 0.05 0.05 0.05 0.08 0.13 0.05 0.02 0.03 0.06 0.04 0.09 0.05 0.05 0.01 0.03 0.08 0.04 0.01 0.03 0.04 0.01 0.02 0.08 0.02 0.06 0.05 0.07 0.03 0.04 0.06 0.03 0.03 0.02 0.13 <% 21.3 21.7 21.1 21.1 21.2 20.4 20.8 20.2 22.0 21.8 20.0 20.5 21.9 20.2 20.5 23.1 20.8 22.5 20.5 19.3 21.7 21.6 21.3 19.1 18.9 19.6 18.7 24.5 21.4 18.1 18.1 18.2 20.6? 24.2 18.9 18.4 20.0 20.6 20.1 20.6 20.2? 20.8 22.0 21.3 20.6? 20.3? 20.7 21.0 20.5 18.8 20.0 22.2 22.0 20.3? 19.8 22.1: 19.6 18.4 19.8 18.2 19.8 19.9 19.9? 19.3 19.6 19.7 17.3 19.8 17.1 19.8 19.4 18.5 OiQ 0.099 0.103 slope h 0.257 0.137 0.104 0.097 0.108 0.091? 0.110 0.067 0.098 0.258 0.102 0.086? 0.096 0.066 0.107 0.230 0.190 0.257 0.253 0.080? 0.105 0.116 0.120 0.124 0.123 0.305 0.131 0.090? 0.169 0.176 0.092 0.090 0.302 0.101 0.098 0.097 0.278 0.330? 0.129 0.112 0.140 0.0365 0.100 0.090 0.104 0.109 0.098 0.099 0.313? 0.122 0.299? 0.133 0.106 0.098 0.308 0.084 0.102 0.306? 0.318 0.316 0.357? 0.292? 0.052 0.306 0.262? 0.119: 0.0379 0.102 0.124 0.300? 0.065 0.168 0.161 0.143 0.064 0.122 0.163 0.160 0.171 0.158 0.134 0.153 0.182? 0.194? 0.173 0.151 0.250 0.248 0.170 0.155 0.138 0.134 0.087 0.066 0.207? 0.072 0.064 0.054 0.164 0.170 0.126 0.184? 0.094 0.180 0.185 0.055 0.098 0.171 0.148 0.060 0.050? 0.168 0.118 0.129 0.166 0.160 0.153 0.170 0.053? 0.136 0.054? 0.056? 0.454 0.046? 9.125 0.184 0.169 0.054 0.163 0.054 0.140: 0.052 0.053 0.057? 0.317 0.156 0.198 0.063? 0.438 0.134 0.055? 0.163 0.067 0.205 0.200 0.171 0.072 0.173 0.171 0.179 0.282 0.167 0.163 0.181 0.193 0.233 0.183 0.182 0.260 0.179 0.145 0.149 0.142 0.066 0.202 0.152 0.229 0.183 0.073 0.089 0.071 0.189 0.100 0.102 0.190 0.218 0.056 0.062 0.173 0.213 0.176 0.177 0.205 0.061 0.147 0.172 0.192 0.179 0.058 0.145 0.056 0.472 0.137 0.153 0.213 0.210 0.052 0.062 0.062 0.066 0.347 0.190 0.197 0.057 0.213 0.059 0.067 0.148 0.498 0.174 0.053 0.055 0.048 0.176 pv 273 00 CM UD CM 1976AJ. ts] -B —F=0.63isthecolorofSun. polarimetric albedointhegreen tothatintheblue.Objects tion fromB—VtoB—Gcolors (Zellner andCapen1974) for whichtheslope-albedolaw indicates thesamediameterat wavelengths; Qistheratio,inmagnitude units,oftheindicated asteroids withwell-determined polarimetric slopeshatboth both wavelengthsshouldfallalong thelinegivenbyQ=0.70 (Æ— F—0.63),wherethefactor0.70 arisesfromthetransforma- may becomputedfromthedepthofpyroxene comings ofthisapproachareobviousinFig.7.While absorption bandnear0.95-/miwavelength.Theshort- 274 c b d Fig. 6.ThequantityQ=2.5\og(¡íb/Iig)vsB—Vcolorfor OnemeasurementattheVwavelengthisincorporated. ® Parametersarederivedbyleast-squaresfitstoNpointsatphasesnear15°andlarger;eisthermsdeviationfromfittedcurve. SymbolXindicatesmeasurementsbyVeverka(1973)withnofilter. Datafrom1973only;seetext. © American Astronomical Society • Provided by the NASA Astrophysics Data System Widorn (1974)hasproposedthatasteroidalbedos Asteroid 1685 1620 1566 887 654 704 563 584 532 433 511 b Filt. B B G B B B G G B B G B V B B B G V 10 17 -N 8 4 4 4 4 3 3 5 3 3 5 6 3 6 8 8 ZELLNER ANDGRADIE Ascending branch® 0.16 0.13 0.25 0.10 0.16 0.08 0.04 0.06 0.04 0.03 0.05 0.05 0.05 Table III(continued) 20.5? 21.1? 20.2 20.6 19.4 15.7 15.8 17.4 19.1 18.8 19.6 19.4 19.4 or polarimetricmethods. both thelightestand darkest objects.Arela- in oursample,butneutral colorsarefoundamong valents), canbeusedfordiametercalculations.The or Pinjthenthecorrespondingmeanalbedosof0.18 is securelyidentifiedasan5oraCfromitsspectrum no well-delineatedalbedo-colororalbedo-Pirela- and color;noverydark, redasteroidsappear a singlenoisyalbedodeterminationbytheradiometric certainly betterthanassumingthatallasteroidshave results shouldbesatisfactoryforstatisticalpurposes, S andCtypesmakedistinctclumps,butthereare tionship betweenPinandalbedo, namely the samealbedo,andperhapsbetterthanrelyingon and 0.06,respectively(ortheirradiometricequi- tionships withineachgroup.Thus,onceanasteroid situation isseeninFigs.8and9.Inbothcasesthe to thepolarimetricalbedosofTableIV,actual but doubtedbyHansen(1976).Onemightalsoat- tempt tocomputealbedosfromPi.Withreference and diametersforcasesinwhichonlycolordataare mittedly crudebutadequateforestimationofalbedos available, wasproposedbyChapmanetal.(1975) albedos ofasteroids. of anunfortunatechoicepreliminarydataforthe Also, nobandisexpectedfortheverybrightEas- roxene) donot,withnosystematicdifferenceinalbedo. of theSasteroidsdoandsome(containingnopy- teroids (Sec.IV).Widorn'sconclusionsweretheresult none ofthedarkCasteroidsshowsuchaband,some m mn m mn The rarertypesofasteroidsscatterwidelyinalbedo The existenceofacolor-albedorelationship,ad- log pV^—1.31 logPmin—0.9±0.1, 0.130? 0.074? 0.108? 0.082? 0.107? 0.101? 0.338 0.305 0.280? 0.328? 0.108 0.114 0.108 0.122 0.100 0.277 0.287 0.082 slope h 0.128? 0.224? 0.154? 0.202? 0.155? 0.164? 0.054 0.049 0.051? 0.153 0.146 0.059? 0.058 0.166 0.154 0.136 0.060 0.203 0.161 0.192 0.224 0.212 0.181 0.210 0.055 0.050 0.061 0.055 0.188 0.165 0.196 0.166 0.062 0.209 0.061 0.203 pv CM UD CM 1976AJ. ts] and estimatedorpoorlyknownB—V; (6)Zellner(1976),magni- Zellner etal.(1974);(3)UBVphotometry byGehrelsetal.(1976); tude andmeandiameteratphotometric maximum. ally largeranddarker thanisindicatedbytheformal results. (4) UBVphotometrybySather(1976) ;(5)cataloguevaluesofB (1) UBVphotometrybyZellneret al.(1975);(2)compilationof b a Asteroid Thereisreasontobelieve(Sec. IV) thatPsycheissubstanti- Adoptedabsolutemagnitudesare fromthefollowingsources: © American Astronomical Society • Provided by the NASA Astrophysics Data System 1685 1620 1566 b 433 410 324 230 563 532 511 887 654 141 139 704 192 584 23 27 20 39 30 29 21 14 12 16 42 40 15 13 11 44 19 18 17 54 51 84 89 64 56 63 4 3 2 6 8 5 1 9 7 Table IV.Derivedgeometricalbedosand a F (1,0)Source 10.78 13.8 16.75 14.5 3.72 4.53 15.80 3.55 5.63 5.87 6.60 6.67 6.03 8.0 7.17 6.4 5.48 6.45 6.97 6.53 7.90 6.67 7.15 7.47 6.97 6.38 7.90 7.50 7.86 8.0 7.66 8.10 7.35 7.56 9.60 8.91 7.86 8.01 7.53 diameters for52asteroids. 7.0: 9.0 9.0 8.47 7.75 8.76 6.46 7.41 7.14 7.71 6.81 9.11 9.2 3 2 2 2 2 2 2 2 2 5 2 1 4 3 2 2 2 2 1 5 1 1 1 1 1 POLARIMETRY OFASTEROIDS 0.068 0.181 0.082 0.206 0.178 0.271 0.180 0.169 0.149 0.186 0.145 0.189 0.182 0.069 0.152 0.213? 0.205 0.178 0.205 0.213 0.101 0.204 0.060 0.187 0.152 0.184 0.066? 0.148 0.055 0.347? 0.055 0.059? 0.148? 0.490 0.174 0.056 0.146 0.067? 0.201? 0.059 0.212 0.15 ? 0.20 ? 0.165 0.062 0.201 0.058? 0.053? 0.22 ? 0.196 0.058? 0.177 pv Diameter 914 496 233 573 279 116 158 194 195 154 137 156 187 136 123 150? 110 171 (km) 166 145 135 138 137 272 251 103 180 122 86 91 82 86 92 95 87 94 47 99 76 66 98 88 88 83 21 47 53 80 3.6 5.9 1.3 1.9 2+ from TableIV,versusthespectrophotometricparameterDEPTH wavelength (McCordandChapman1973a,1973b);DEPTH indicating thestrengthofFeabsorptionbandnear0.95-Mm matter ontheirsurfaces(Sec.III). small asteroidsiftheyareunabletoholdparticulate seems toholdmoregenerallybutmayfailforvery = 1.0meansthatnobandispresent. Fig. 8.Polarimetriealbedosofasteroids atthevisualwavelength Fig. 7.Asteroidgeometricalbedosatthevisualwavelenth, versus theB—V color. 275 00 CM UD CM 1976AJ. ts] Fig. 9.Polarimetriealbedosofasteroidsatthevisualwavelength 276 microscopic appearanceoflunarsoilsquiteaccurately highly diagnosticphaserange beyond100°isnot more thanadecadebefore thefirstlunarlandings particularly oftheinversionanglecannotbetrusted. rough, porous,orparticulatesurfaceinwhichthe polarimetric slopebetween15°and35°phase.The laboratory polarimetrybyDollfusandZellner.Inthis accessible, andwemustdraw ourconclusionsfrom for thePultuskordinarychondrite,fromunpublished teroids, canbeproducedonlyinamicroscopically inversion angle,andmuchstrongerpolarizationsat have thesamealbedo(fortuitously),and by asmuch±0.2%,sothatnumericalvalues work thezeropointofpolarizationwasuncertain scattering elementsareopaqueenoughformutual the depthPmmofnegative branchandthein- the Moon,Dollfus(1955)wasabletosynthesize interior surfaceshouldbecorrect.Bothpreparations curves forthepowderedsampleandbroken The dependenceoftheshapepolarization-phase shadowing (BowellandZellner1974;Wolff1975). version angle. large phases. However, theshapesandrelativepositionsof curve onsurfacemicrostructureisillustratedbyFig.10 dust-free chiphasaweakernegativebranch,smaller (e.g., Fig.14ofDollfus1971). Fortheasteroids The negativepolarizationbranch,seenforallas- Working withthefullpolarization-phasecurveof © American Astronomical Society • Provided by the NASA Astrophysics Data System versus thedepthPofnegativepolarizationbranch. mm III. SURFACESTRUCTURE ZELLNER ANDGRADIE larimetric inversionanglesbetween17°and22°. for lunarmaterials,DollfusandGeake(1975)con- fall near20°.Bycomparisonwithlaboratoryresults characteristically havedustysurfacesonthebasisof Bowell andZellner(1974)concludedthattheasteroids and 704,alloftheasteroidsinTableIIIhavepo- lunar materialscanbeextendedtotheasteroids;for more characteristicofconsolidatedsurfacescovered Fig. 9,i.e.,essentiallythattheinversionanglesall made onmechanicalgrounds(Chapman1971,1976) inversion angles. However, compositionaleffectsarecertainlyimportant, with adhesivedebristhanofaregolithiclayersoil. clude thattheasteroidalvaluesofPiandaare the proportionalitybetweenPinandalbedoseenin regolith. Argumentsforadustcoatingcanalsobe example, rathersmoothmetallicsurfacesshowlarge and itisnotatallclearthatinferencesbasedon neither microscopicallycleannorsoilcoveredbutin formity ofmostasteroids(e.g.,Zellner1976).Thus, and Goldstein1976)argueagainstawell-developed meteoritic materials.Wenotethatwithintheoptically and onthebasisofremarkablephotometricuni- homogeneous CandSclassestherearenocorrelations improved laboratorymeasurements,especiallyfor some intermediatestate.Betterunderstandingawaits between asteroiddiameterandthemeasuredPmin the bestevidencefavorsasteroidsurfaceswhichare larimetry hasarelativeprecision of±0.1%withacomparable light byDollfusandZellner.The solidlinerepresentsapowdered systematic errorinthezeropoint. and showsmaximumpolarization 32%near140°phase.Thepo- surface withaveryroughmicrostructure, blowndustfreewitha sample withparticlessmallerthan 100/¿m,ofalbedo0.173rela- ordinary chondrite,fromunpublishedlaboratorydatainblue mn0 m mild airjetbutnotwashed.The broken surfacehasalbedo0.176 tive toMgOat5°phase.Thedashed lineisforabrokeninterior With theexceptionofpeculiarobjects16,21, Fig. 10.PolarizationversusphaseangleforthePultuskH5 Radar observationsofasteroid433Eros(Jurgens 00 CM UD CM 1976AJ. ts] identified inSec.IV. Pmin ofthenegativepolarization branch for90asteroids.Typesareas or oto.Thus,ifdustlayersdonotformonthesurfaces of verysmallasteroids,thecriticaldimensionswould appear tobelessthan5km. polarimetric albedoatthevisual gross bimodalitiesofFigs.11and12forthedistribu- wavelength for52asteroids. the CandScompositionaltypesarereflectedin Fig. 11.Distributionofthedepth Fig. 12.Distributionofthe The prevalenceandrelativeopticalhomogeneityof © American Astronomical Society • Provided by the NASA Astrophysics Data System IV. COMPOSITIONALTYPES POLARIMETRY OFASTEROIDS spectral range(McCordandChapman1975b)in bimodalities inthebroad-bandcolorovervisible radiometric albedos(Hansen1976).[Strictlyspeaking, tions ofPminandpolarimetricalbedo,similar However, wefeeljustifiedindescribingtheC,5,and other asteroidpopulationsas“compositionaltypes” tion buttothecomplexrefractiveindex(Wolff1975). the polarimetryissensitivenotdirectlytocomposi- 277 00 CM UD CM 1976AJ. ts] optical propertiesandthefactthatdifferences and U—Bfromtheaverageoffournickel-ironmeteoritespectra the U—Bcolorforasteroids.Thecrossrepresentspresumed in viewoftheirobservationaldistinctnessvarious measured byGaffey(1974). domain ofpuremetallicsurfaces,withPifromFig.3above ferrous iron,probablyidentifiablewiththeaubrites position suchasthatofthenickel-ironmeteoritesor near 1.0%,andinversionangleslargerthan23°are low-iron ordinarychondrites(McCordandChapman are readilyattributabletothecontentofsilicates, with gentlyslopinglinearspectra,valuesofPmin Veeder etal.1975;LarsonandFink1975).Theas- to certainbasalticachondrites(McCordetal.1970; and itssurfaceisfirmlyidentifiedascorresponding carbon, iron,etc.] 278 Laboratory polarimetricdata formetallicsurfacesare suspected ofafree-metalormetal-richenstatitecom- belonging toaclassE. object and64Angelinaweprovisionallydesignateas or pure-enstatiteachondrites(Zellner1975).This composition oflowopacityandtotallylackingin teroid 349Dembowskaissimilarlyidentifiedwith enstatite chondrites(ChapmanandSalisbury1973; scanty, butasshowninFig. 3theidentificationof and wedenotethisclassofasteroids bythesymbolM. Johnson andFanale1973;McCord andGaffey1974), 1975b). Thehigh-albedoobject44Nysahasasurface mn albedo theMasteroidsgenerally seemtobeinter- 16 Psychewithfreeironseems plausibleenough.In Fig. 13.DepthPiofthenegativepolarizationbranchversus mn Among theoutliers,4Vestaisspectrallyunique Asteroids 16Psyche,21Lutetia,andafewothers © American Astronomical Society • Provided by the NASA Astrophysics Data System ZELLNER ANDGRADIE 2+ is nowreservedforasteroidsnotbelongingtoanyof and Morrison1976). it resemblestheCasteroid511Davida(Chapman observations ofpolarizationandB—Vcolorarenot were obtainedfor16Psycheinlate1975. for 21Lutetia.Much-improvedthermophysicaldata with Pv=0.12,whichismuchclosertotheradiometric may beseeninFigs.13and14,whichshoware- consistent withanyrecognizedtype;inJHKcolors classifications arenoted.ThesymbolU(unclassified) tions describedabove.Peculiaritiesanduncertain and alsospectrophotometricradiometricobserva- albedo byMorrison(1974)andsimilartoourvalue Pv~ 0.21,butthephasecoverageispoor.InFigs.3 mediate betweenthetypicalCandSvalues.For markable distributionofPi(essentiallyanindicator the abovefourtypes.For129Antigonesingle types C,S,M,andEonthebasisofpolarimetry and 9thedataareseentobereasonablyconsistent of albedo)versustheU—Bcolorindexandspec- parameters maybetakenascrudeindicatorsofthe metallicity orFe/Feratio;thecurvingvisiblespec- and Chapman(1975a).Foriron-bearingsilicatesboth trophotometric parameterBENDdefinedbyMcCord 16 PsychetheformalsolutionsinTableIIIyield mn flectance spectrumbetween0.40- and0.73-Mmwavelength for asteroids.BENDisameasure ofthecurvaturere- sumed domainofpureironsurfaces. (McCord andChapman1975a). The crossrepresentsthepre- In thelastcolumnofTableIIweassignsurface Relationships betweentheprincipalasteroidtypes Fig. 14.Pminversusthespectrophotometric parameterBEND V. INDICATIONSOFMETALLICITY 00 CM UD CM 1976AJ. ts] 2+ 5 proto-C andproto-Smaterialarebothseeninvarious parameters forvariousmineralassemblagesiscom- may representextremelyreduced examplesofeitherC find noexamplesoftransition casesbetweentheC objects belongingtoother compositional types.We meteoritical evidenceorcosmologicalconsiderations. of moderate-albedoasteroidsrangingfromdomains plex. However,noasteroidinoursamplehaslarge surfaces (classE)suchas pureenstatite,andfive We haveatleastthreeandpossiblyfiveMasteroids larger heliocentricdistances(Chapmanetal.1975). properties, weidentify48asteroidsbelongingtothe whether suchinterrelationshipsareconsistentwith widely varyingmetal/silicateratioisseenfortheC faces whicharepresumablymoremetalrich,tothe C andSmaterial.Inbothfiguresweseeacontinuum values ofPin.Thatis,weseenosimplemixtures values ofBENDorU—Btogetherwithintermediate and Sclasses,butwesuggest thattheMasteroids because oftheirlowalbedosandconcentrationtoward fron 0.05toalmost0.5.Intermsoftheirpolarimetric face textures.Albedosderivedfor52objectsrange have microscopicallyveryroughorparticulatesur- iron. Forthepresentweleaveittoothersevaluate stages ofreductiontowardthecommonstatepure representing alowFe/Feratio,throughtheSsur- interplay ofopacitysensitiveandmetallicity strated fortheCobjects. inner partsofthebelt.Thesamemaybedemon- have notedthatamongtheSasteroidslargevalues with surfacesrichinfreemetal,twolow-opacity are underrepresentedrelativetotheirtrueabundance of theCclass,withalbedosnear0.06,probablyiden- sibly iron-richordinarychondrites.Wefind34objects broad Sclass,withalbedosnear0.18andcomposi- Over arangeofmorethanfactor50indiameter, asteroids. Itisasifdistinctoriginalpopulationsof Fe-dominated objects16and22.Asimilartrendof of BEND(lowmetallicity)occurpreferentiallyinthe senting pureiron.McCordandChapman(1975b) tifiable withcarbonaceouschondrites.TheCasteroids or afactorof10inmass,theasteroidsallseemto asteroids andfragmentarydataforseveralothers. tions inFigs.13and14,givingevidencethatthe indicated the(poorlyestablished)parametersrepre- licity increasestotheleftinbothplots,andwehave and linearizedbyadditionofafree-metalcomponent tions correspondingtostony-ironmeteoritesorpos- transition-metal ionsinasilicatelatticeisflattened or Scompositions. trum andsharpUVdropoffthatischaracteristicof m (Gaffey 1974;Zellneretal.1975).Thus,themetal- To summarize,wehaveusefulpolarimetryfor94 Many objectsdonotfallatexactlyanalogousposi- © American Astronomical Society • Provided by the NASA Astrophysics Data System VI. CONCLUSIONSANDFUTUREWORK POLARIMETRY OFASTEROIDS metal content,etc.,butbetterunderstandingofthe has substantiallyadvancedbeyondthelaboratoryand incognita forthemainbelt. papers wewillexaminethedistributionsofvarious fruitful discussions.Thisworkissupportedbythe mental results. be invaluable.Thepolarimetrydoubtlessholdsindica- 40-km diameterrange,whichispresentlyalmostterra Bowell, E.,Dollfus,A.,Zellner,B.,andGeake,J.E.(1973). observations nowavailableawaitsimprovedexperi- servational thrustwillbetowardobjectsinthe10-to some ofthebrighterasteroids,butourprincipalob- will continuetofillgapsinthephasecoveragefor metric surveyisessentiallycomplete.Insubsequent National AeronauticsandSpaceAdministration. in advanceofpublication,andtoC.Chapmanfor ephemerides, toD.MorrisonandO.Hansenfordata tions ofparticlesizeaswellabsolutecarbonand tive sampleofmeteoriticmaterials,forexample,would Plots similartoFigs.6,9,13,and14forarepresenta- theoretical investigationsneededforitsinterpretation. orbital parameters.Duringthenextapparitionswe Bowell, E.,andZellner,B.(1974).InPlanets,Stars,Nebulae the MinorPlanetCenter,forfurnishingaccurate types ofasteroidsovershape,size,rotationrate,and Gehrels, T.,andTeska,T.M.(1960). Publ.Astron.Soc.Pac. Dunlap, J.L.,Gehrels,T.,andHowes,M.L.(1973).Astron. Dunlap, J.L.(1974).Astron.79,324. Gehrels, T.,Taylor,R.C.,and Capen,R.C.(1976).Tobe Gehrels, T.,Roemer,E.,Taylor, R., andZellner,B.H.(1970). Gaffey, M.J.(1974).Ph.D.thesis, MassachusettsInstituteof Dollfus, A.,andGeake,J.E.(1975).InProceedingsoftheSixth Dollfus, A.(1971).InPhysicalStudiesofMinorPlanets,edited Dollfus, A.(1955).Doctoralthesis,UniversityofParis;NASA Chapman, C.R.(1971).Doctoraldissertation,Massachusetts Coyne, G.V.,andGehrels,T.(1967).Astron.J.72,887. Chapman, C.R.,andSalisbury,J.W.(1973).Icarus19,507. Chapman, C.R.,andMorrison,D.(1976).Icarus.Tobe Chapman, C.R.,McCord,T.B.,andJohnson,V.(1973). Chapman, C.R.(1976).Geochim.Cosmochim.Acta40.Tobe Chapman, C.R.,Morrison,D.,andZellner,B.(1975).Icarus published. Technology. J. 78,491. published. Studied withPhotopolarimetry,editedbyT.Gehrels(Univ. by J.ChamberlainandC.Watkins(LunarScienceInstitute, 72, 115. Astron. J.75,186. Lunar ScienceConference(LunarInstitute,Houston), 25, 104. published. Houston), Vol.3,p.3167. In ProceedingsoftheFourthLunarScienceConference,edited Vol. 3,p.2749. by T.Gehrels(NASA,Washington,DC),SP-267,p.95. Astron. J.78,126. Institute ofTechnology. TT F-188(1964). Arizona P.,Tucson),p.381. We areindebtedtoDr.PaulHerget,Directorof It shouldbeevidentthattheasteroidpolarimetry For thelargerandnearerminorplanetspolari- ACKNOWLEDGMENTS REFERENCES 279 CM UD CM 1976AJ. to Johnson, T.V.,andFanale,F.P.(1973).J.Geophys.Res. Larson, H.P.,andFink,U.(1975).Bull.Am.Astron.Soc.7, Hansen, O.L.(1976).Astron.J.81,74. Jurgens, R.F.,andGoldstein,M.(1976).Icarus28.Tobe McCord, T.B.,andChapman,C.R.(1975b).Astrophys.J. McCord, T.B.,Adams,J.andJohnson,V.(1970).Science Matson, D.L.(1971).InPhysicalStudiesofMinorPlanets, McCord, T.B.,andGaffey,M.J.(1974).Science,186,352. McCord, T.B.,andChapman,C.R.(1975a).Astrophys.J. 280 Pieters, C.,Gaffey,M.J.,Chapman,C.R.,andMcCord,T.B. Morrison, D.(1974).Astrophys.J.194,203. Millis, R.L.,Bowell,E.,andThompson,D.T.(1976).Icarus28. Morrison, D.,andChapman,C.R.(1976).Astrophys.J.204.To published. edited byT.Gehrels(NASA,Washington,DC),SP-267, p. 45. 377; submittedtoIcarus. 78, 8507. To bepublished. be published. 197, 781. 168, 1445. 195, 553. (1976). Icarus28.Tobepublished. © American Astronomical Society • Provided by the NASA Astrophysics Data System ZELLNER ANDGRADIE Taylor, R.C.(1971).InPhysicalStudiesofMinorPlanets, Veverka, J.,andNoland,M.(1973).Icarus19,130. Veeder, G.L.,Johnson,T.V.,andMatson,D.L.(1975).Bull. Zellner, B.(1976).Icarus28.Tobepublished. Zellner, B.(1975).Astrophys.J.Lett.198,L45. Veverka, J.(1973).Icarus19,114. Veverka, J.(1971).Icarus15,11. Serkowski, K.(1974).InPlanets,Stars,andNebulaeStudied Zellner, B.H.,andCapen,R.C.(1974).Icarus23,437. Wolff, M.(1975).Appl.Opt.14,1395. Widorn, Th.(1974).Ann.Univ.-SternwarteWien31,Nr.1. Wamsteker, W.,andSather,R.E.(1974).Astron.J.79,1465. Sather, R.E.(1976).Astron.J.81,67. Zellner, B.,andGradie,J.(1976).Icarus28.Tobepublished. Zellner, B.,Gehrels,T.,andGradie,J.(1974).Astron.79, Zellner, B.,Wisniewski,W.Z.,Andersson,L.,andBowell,E. Tucson), p.135. edited byT.Gehrels(NASA,Washington,DC),SP-267, with Photopolarimetry,editedbyT.Gehrels(Univ.ArizonaP., Am. Astron.Soc.7,377. p. 117. 1100. (1975). Astron.J.80,986.