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ࣁࢻ࣭ࣛࢪࢷࣞࢺ [65804] 1996 GT ࡡῼකふῼ 㔓Ᏻᖲ㸝᮶ኬ࣬ISAS/JAXA㸞 Ꮽ㒂ḿ┷㸝ISAS/JAXA㸞 ᡖὊ㸝᮶ኬኮᩝᩅ⫩ࢬࣤࢰ࣭㸞 ふῼཀྵࡦよᯊ࡞ࡗ࠷࡙. ࠈᅂࡡふῼ࡚ࡢࠉ㛏㛣ࡡࣚࢹ࣭࢜ࣇࢅ ཱིᚋࡌࡾࡒࡴ࡞᮶ாኬᏕᮄ᭦ふῼᡜࡡ K.3T 㸝Kiso 30-cm Telescope㸞ࢅ⏕ࡊࡒࠊK.3T ࡢንකኮమࡷ✲Ⓠኮమࡡふῼࢅ┘Ⓩ࡛ࡊ ࡙ࠉ㎾ᖳᮄ᭦ふῼᡜ࡚᩺ࡒ࡞㛜Ⓠࡈࡿࡒࣞ࣍ ࢷࢴࢠࢷࣝࢪࢤ࣭ࣈ࡚࠵ࡾࠊK.3T ࢅ⏕ ࡊࡒふῼ㛣୯࡞ኯ㝟న┞みࡢ 40 ᗐ࠾ࡼ 2 ᗐࡱ࡚ንࡊࡒࠊࡱࡒࠉኣⰅῼකࢅ⾔࠹ࡒࡴ ࡞ 1.05-m Kiso Schmidt Telescope 2KCCD ࡵ ⏕ࡊࡒࠊࡐࡿࡑࡿࡡ᭻㐪㙶࡚ふῼࡊࡒཀྵ ࡦ⏕ࡊࡒࣁࣤࢺࣆࣜࢰ࣭࡞ࡗ࠷࡙ࡢ Table 1. ࡞♟ࡊ࡙࠵ࡾࠊࡱࡒࠉ࢛ࣇࢩ࢘ࢠࢹ ࡡ⤧ᑊකᗐࢅịࡴࡾࡒࡴ࡞ࠉふῼ࡚ Landolt ࡡᵾ‵᫅ࡵ᧔ാࡊࡒ[2]ࠊ ࠈよᯊ࡛ୌฌ⌦࡞ࡢࠉኮᩝᏕ⏤ാよᯊࢮࣆ ࢹ IRAF ࡡࣂࢴࢢ࣭ࢩࢅ⏕ࡊࡒࠊࡱࡍࠉࢱ ࣭ࢠࠉࣁࢪࡡᕣࡊᘤࡀཀྵࡦࣆࣚࢴࢹࡡ ḿࡡୌฌ⌦࡞ࡻࡽῼකࡌࡾࡒࡴࡡ⏤ാ ࢅష ᠺࡊ ࠉphoto ࢰࢪ ࢠࢅ ⏕࠷ ࡙ῼ කࡊ ࠉ instrumental magnitude ࢅịࡴࡒࠊࡐࡊ࡙ࠉẒ ㍉࡛᫅ࡡᕣฦ࠾ࡼ࢛ࣇࢩ࢘ࢠࢹࡡ┞ᑊ➴⣥ࢅࠉ ᵾ‵᫅ࢅ⏕࠷ࡒኬẴ΅ක࡛࢛ࣆࢬࢴࢹࡡḿ ࠾ࡼ⤧ᑊ➴⣥ࢅịࡴࠉ᭩ᚃ࡞㊝㞫ࡡḿࢅࡊ ࡙ reduced magnitude ࢅịࡴࡒࠊ Data Set UT Date Telescope RI Photmetry 11/13,14,16-18, 21-23,25-27/03, & 12/1-4/03 K.3T BVRI Photometry 12/1,2,4/03 Schmidt UBVRI Photometry 12/3/03 Schmidt Table1. Observational summary. ࣚࢹ࣭࢜ࣇ. ࠈࣚࢹ࣭࢜ࣇ࡛ࡢࠉᑚᝠ᫅ࡡ࡞ኬࡀࡈࡷ ᙟ≟࡞㉫ᅄࡌࡾ⮤㌹࡞ఔ࠹කᗐን࡚࠵ࡽࠉ ㏳ᖏぞ์Ⓩ࿔ࢅᣚࡖࡒ࣭࢜ࣇ࡚ᥝ࠾ࡿࡾࠊ ࡊ࠾ࡊࠉࢂࡿࢂࡿࡡよᯊ⤎ᯕ࡞ࡻࡽࠉ1996 GT ࡡࣚࢹ࣭࢜ࣇࡢࡐࡡ࣭ࣜࣜ࡞㐲ࡈ࠷ࡆ࡛ ♟ࡈࡿࡒࠊ2003 ᖳ 11 ᭮ 23 ࡞ K.3T ࡡ R ࣁࣤࢺཱི࡚ᚋࡈࡿࡒࣚࢹ࣭࢜ࣇࢅ Fig. 1 ࡞ ♟ࡊ࡙࠵ࡾࠊ 18.35 Reduced Magnitude ࡢࡋࡴ࡞. ࠈ[65803] 1996 GT ࡢ a = 1.642 AUࠉe = 0.383 AU ࠉ i = 3.396 deg. (MPO 53373) ࡡ PHA (Potentially Hazardous Asteroid) ࡡࢡ࣭ࣜࣈ࡞ ᒌࡌࡾ㎾ᆀ⌣ᆵᑚᝠ࡚᫅ࠉ☔ᏽ␊ྒࡡࡗ࠷࡙ ࠷ࡾᑚᝠ᫅ࡡ୯࡚ࡢࠉHAYABUSA ࡡ᥀ᰕು ኮమ࡞ࡵࡖࡒᑚᝠ᫅ [25143] Itokawaࠉ [10302] 1989MLࠉ[4660] Nereus ࡞ࡗ࠷࡚ࠉ5 ␊┘࡞᥀ᰕᶭ㐡ࡊࡷࡌ࠷ᑚᝠ࡚᫅࠵ࡾ [1]ࠊࡊ࠾ࡊࠉࡆࡡᑚᝠ᫅ࡢ㌮㐠さ⣪௧አࡡ ሒ᪺ࡼ࠾࡞ࡈࡿ࡙࠷࠷ࠊࡱࡒࠉࡆࡡᑚᝠ ᫅ࡢ 11 ᭮ࡡ୯᪢࠾ࡼ 12 ᭮ࡡ୕᪢࡞࠾ࡄ࡙ࠉ ᪺ࡾࡈ 12 ➴⣥ྋ࡞ࡽኯ㝟న┞みኬࡀ ࡂንࡌࡾ࡛࠷࠹㈏㔔ふῼይᶭ࡚࠵ࡖࡒࠊ ࡆࡿࡱ࡚ྜྷୌࡡ᭻㐪㙶࡚ୌ㛣ࡡ㛣࡞ᗀ⠂ᅑ ࡡኯ㝟న┞みࡡࢸ࣭ࢰࢅཱིᚋࡊࡒふῼࡢ࡛ ࢆ࠷ࠊᅂࡡふῼ┘Ⓩࡢࠉḗᑚᝠ᫅᥀ ᰕ࣐ࢴࢨࣘࣤࡡࡒࡴࡡುኮమࢦ࣭࡛࣊ࠉ ᑚᝠ࡛᫅㝱▴ࡡᑊᚺ㛭౿࡞࠽ࡄࡾన┞みࡡᙫ 㡢࡞ࡗ࠷࡙ࡡ㆗ㄵ࡚࠵ࡾࠊ 18.45 18.55 18.65 18.75 10 12 14 16 18 TIME (UT, Nov. 23 2003) 20 Fig. 1: Lightcurve of 1996 GT, taken on Nov. 23 2003 using with K.3T at R-band. € n −(t − µ ) 2 i +∑ si ⋅ exp 2 2σ i i=1 ࠈࡆࡆ࡚ࠉV㸯reduced magnitudeࠉt㸯㛣ࠉA, B㸯ࣆ࣭࢙ࣛ౿ᩐࠉP㸯࿔ࠉs㸯࢝ࢪࡡᙁ € ᗐࠉȣ㸯࢝ࢪࡡࣅ࣭ࢠన⨠ࠉȪ㸯࢝ࢪࡡ ༖ೋᖕ࡚࠵ࡾࠊࡆࡡ⤎ᯕࠉprimary ࡡකᗐን ࡡ࿔ 2.37s0.01 㛣࡚ 17 ㎾࡞ 0.13 ⛤ᗐࡡ΅ක࠵ࡾࡆ࡛ịࡴࡼࡿࡒࠊ ࠈࡊ࠾ࡊዃࡊࡂࡵࠉ᭩㎾ࢂࡿࢂࡿ࡛ྜྷ࡞ ࡆࡡ࢛ࣇࢩ࢘ࢠࢹࢅふῼࡊ࡙࠷ࡒᾇአࡡࢡࣜ ࣭ࣈ࡞ࡻࡽࠉ1996 GT ࡡ binary ㄕࢅ࡞ IAU circular ࡞ሒ࿈ࡈࡿ࡙࠽ࡽ㸝http://www.asu.cas. cas.cz/~ppravec/65803.htm ཤ↯㸞ࠉࢂࡿࢂࡿࡡ ⤎ᯕࡢୠ⏲ิࡡ 1996 GT ࡡ binary system ࡡ ᳠ฝ࡛࠷࠹ࡆ࡛࡞ࡢ⤎ࡦࡗ࠾࠾ࡖࡒࠊࡊ࠾ ࡊࠉᙴࡼࡢ࣭࢜ࣚࡷࢪ࣋ࢠࢹࣜࢰࣈ࡞ࡗ࠷ ࡙ࡱ࡚ࡢሒ࿈ࡊ࡙࠷࠷ࠊୌ᪁࡚ࠉࢂࡿࢂࡿ ࡢࢨ࣐ࣖࢴࢹ᭻㐪㙶ࢅ⏕࠷࡙ኣⰅῼකࢅ⾔ࡖ ࡙࠷ࡾࡡ࡚ࠉࡐࡿࡼࡡ⤎ᯕࢅ௧ୖ࡞♟ࡌࠊ ⣰አ-ྊっ-㎾㉝አἴ㛏ᇡࡡࢪ࣋ࢠࢹࣜ. ࠈࢨ࣐ࣖࢴࢹ᭻㐪㙶࡞ࡻࡽふῼࡊࡒ UBVRI ࣁࣤࢺ࡚ࡡ reduced magnitude ࡻࡽ 1996 GT ࡡ ࣭࢜ࣚࢅịࡴࠉࡐࡿࡼࢅኯ㝟ࡡ࣭࢜ࣚ࡞ንᥦ ࡊࠉࣁࣤࢺ࡞ᑊࡌࡾ┞ᑊཬᑏ⋙ࢅ V ࣁࣤ € ࢺ࡚ぞࡊ࡙⟤ฝࡊࡒࠊࣁࣤࢺ࡚ࡡ୯ᚨ ἴ㛏࡞ࡢ Johnson & Johnson Cousin System ࢅ ⏕ࡊࡒࠊࡐࡡ⤎ᯕᚋࡼࡿࡒ 1996 GT ࡡࢪ ࣋ࢠࢹࣜࢅ Fig. 2 ࡞♟ࡊ࡙࠵ࡾࠊFig. 2 ࡞ࡢ Ẓ㍉ࡡࡒࡴ࡞ S-ࠉX-ࠉC-class ࡡᖲᆍⓏࢪ ࣋ࢠࢹࣜࡵ࢛ࣆࢬࢴࢹࢅ࠾ࡄ࡙ຊ࠻࡙࠵ࡾࠊ S-class ࡛ࡢጙཋⓏ▴㈻㝱▴࡚࠵ࡾᬉ㏳ࢤࣤ ࢺࣚࢹ࡞జࡒ∸㈻࠾ࡼࡾ࡛⩻࠻ࡼࡿ࡙࠷ ࡾᑚᝠ࡚᫅࠵ࡾࠊᑚᝠ᫅ࡡኣࡂࡆࡡࢰࣈ ࡞ᒌࡊࠉHAYABUSA ࡡࢰ࣭ࢣࢴࢹኮమ࡚࠵ ࡾ Itokawa ࡵࡆࡡࢰࣈ࡚࠵ࡾࠊୌ᪁ࠉX-class 3.0 S-class 2.5 Relative Reflectance ࠈ1996 GT ࡡふῼࡡࣚࢹ࣭࢜ࣇࡢᣲᖕ 0.10 ➴ࡡᇱᮇ࿔࡞ຊ࠻࡙ࠉୌⓏ΅ක ࣊ࣤࢹᏋᅹࡌࡾࡆ࡛ࢂ࠾ࡖࡒࠊࡆࡡ⤎ᯕ ࡢࠉ1996 GT ࡡ⾠᫅Ꮛᅹྊ⬗ᛮࢅ♟ြࡊ࡙࠷ ࡾࠊࡐࡆ࡚ࠉ1996 GT binary asteroid ࡚ 㔔࿔ࢅᣚࡗࡆ࡛ࢅᏽࡊ࡙ࠉࡐࡡ࿔ᛮࢅ ịࡴࡒࠊ⮤㌹࡞ᑊࡌࡾකᗐን࡞ࡗ࠷࡙ࠉ primary asteroid ࡡ ⮤ ㌹ ࢅ ࣆ ࣭ ࣛ ࢙ ἴ ࡚ ࠉ occultation ࡞ࡻࡾ΅කࢅ࢝ࢪ㛭ᩐ࡚よ㔐ࡊ ࡙⩻࠻ࡾࡆ࡛࡞ࡻࡽ௧ୖࡡᘟ࡚ࠉ Fig. 1 ࡡ 1996 GT ࡡࣚࢹ࣭࢜ࣇࢅ්⌟ࡊࡒࠊ m 2πl 2πl V (t) = V0 + ∑ Al sin ( t − t 0 ) + Bl sin (t − t 0 ) P P l=1 X-class (EMP) 2.0 C-class 1.5 1996 GT 1.0 0.5 300 500 700 900 Wavelength (nm) Fig. 2: Relative reflectance of 1996 GT normalized at V-band. Those of S-, X-, C-class are added to compare. ࡢࢪ࣋ࢠࢹࣜࡡሒࡓࡄ࡚ࡢ༇ืࡗ࠾࠷ E-ࠉM-ࠉP-type ࡡᑚᝠ᫅ࢅྱࡴࡒࢡ࣭ࣜࣈ࡚ ࠵ࡾࠊࡆࡡ୯࡚ M-type ᑚᝠ᫅ࡢ㝱㕪ࡡࡻ࠹ 㕪ࢼࢴࢢࣜྙ㔘ࡡᅖࡱࡽࡡࡻ࠹ᑚᝠ࡚᫅ ࠵ࡾ࡛⩻࠻ࡼࡿ࡙࠽ࡽࠉᑚᝠ᫅ࡡ୯࡚ࡢ⛝ ࢰࣈ࡚࠵ࡾࠊࡱࡒࠉC-class ࡢ᭯ᶭ∸㈻ࢅኣ ࡂྱࡳ⅛⣪㈻ࢤࣤࢺࣚࢹⓏ∸㈻࠾ࡼࡾ ᑚᝠ࡛᫅ࡊ࡙⩻࠻ࡼࡿ࡙࠷ࡾࠊࡆࡆ࡚ࠉ1996 GT ࡡ spectral slope ࢅịࡴࡾ࡛ moderate ೋ ࡞ࡽࠉX-class ࡞┞ᙔࡌࡾࡆ࡛⩻࠻ࡼࡿ ࡾࠊ ኯ㝟న┞み࡞ᑊࡌࡾකᗐን. ࠈᑚᝠ᫅ࡡකᗐࡢኯ㝟న┞みᑚࡈࡂࡾ ᪺ࡾࡂࡾࡆ࡛ࢂ࠾ࡖ࡙࠽ࡽࠉࡐࡡ㛭౿ ࢅㄕ᪺ࡌࡾࢵ࣭࡛ࣜࡊ࡙ࠉIAU H-G Magnitude System ࠵ࡽࠉ௧ୖࡡᘟ࡚⾪ࡈࡿࡾ [3]ࠊ H R (α ) = H R (0) − 2.5log[(1− G)Φ1 (α ) + GΦ2 (α )] ࠈࡆࡆ࡚ࠉ HR(Ș)ࡢᚨ㊝㞫ࠉ ᆀᚨ㊝㞫ࢅ 1 AUࠉ న┞みࢅ Șdeg. ࡛ࡊࡒ࡛ࡀࡡᑚᝠ᫅ࡡ R ࣁ ࣤࢺ࡚ࡡ⤧ᑊ➴⣥࡚࠵ࡾࠊࡱࡒࠉG ࡢࢪ࣭ࣞ ࣈࣂ࣒࣭ࣚࢰ࡛ࡻࡣࡿࡾᑚᝠ᫅⾪㟻ࡡ࢛࣎ࢩ ࢨ࢙ࣘࣤࣆ࢘ࢠࢹࡡຝࡀරྙࢅ⾪ࡌࡻ࠹ࣂ ࣒࣭ࣚࢰ࡚ࠉ㐛ཡࡡ◂✪ࡡ⤣ゝࢸ࣭ࢰࡻࡽࠉ ࡆࡡೋ࠾ࡼᑚᝠ᫅ࡡ taxonomical type ࢅ༇ื ࡌࡾࡆ࡛࡚ࡀࡾࠊȍࡢన┞㛭ᩐ࡚࠵ࡾࠊࡐ ࡆ࡚ࠉK.3T ࡻࡽᚋࡼࡿࡒࢸ࣭ࢰⅤ࠾ࡼࠉ㟸 ⥲ᙟࡡ᭩ᑚἪࣆࢴࢷࣤࢡ࡞ࡻࡽ᭩㐲 ࣂ࣒࣭ࣚࢰࢅᑙ࠷ࡒࠊࡐࡡ⤎ᯕࠉHR = 17.7s 0.03ࠉG = 0.20s0.02 ࡛ࡖࡒ (Fig. 3 ཤ↯)ࠊ 17.5 系列1 Photometric Value Reduced Magnitude 系列2 G = 0.20 1996 GT G = 0.09 C,P,D 系列3 18.0 G = 0.21 M 系列4 G = 0.23 S,Q 系列5 G = 0.42 E,V,R 系列6 18.5 Taxonomical type B, C, D, F, G, P, T, Slope parameter (G) Geometric albedos 0.09s0.09 0.02-0.11 M 0.21s0.06 0.10-0.18 S, Q 0.23s0.11 0.10-0.22 E, R, V 0.42s0.08 0.25-0.60 This study 0.20s0.02 0.15 19.0 Table 2: Comparison of slope parameter and geometric albed. Data from [5], [6]. 19.5 0 5 10 15 20 25 30 35 Solar Phase Angle (degrees) 40 45 Fig. 3: Solar phase angle behavior of 1996 GT at R-band. Phase curves derived from various slope parameter G are also presented to compare. ࢩ࢛࣒ࢹࣛࢴࢠࣜ࣊ࢺ. ࠈᑚᝠ᫅ࡡฦ㢦ࡢࢩ࢛࣒ࢹࣛࢴࢠࣜ࣊ࢺ࡛ ࡻࡣࡿࡾࠉኮమ⾪㟻ࢅᏰධࣚࣤ࣊ࣜࢹ㟻࡛௫ ᏽࠉన┞みࢅ 0 deg. ࡛ࡊࡒ࡛ࡀࡡኮమࡡཬᑏ ⋙ࠉ࠾ࡼࡵᑙࡀࡓࡌࡆ࡛࡚ࡀࡾࠊᑚᝠ᫅ࡡ ├ᙼཀྵࡦ V ࣁࣤࢺ࡚ࡡ⤧ᑊ➴⣥ࠉࢩ࢛࣒ࢹ ࣛࢴࢠࣜ࣊ࢺࡡ㛭౿ࡢ௧ୖࡡᘟ࡚⾪ࡈࡿࡾ [4]ࠊ D(km) = 10− HV / 51329 / pv ࠈ1996 GT ࡡ├ᙼࡢ୕㏑ࡊࡒᾇአࡡふῼࢲ࣭ ࣑࡞ࡻࡾ࣭ࣝࢱ࣭ふῼ࠾ࡼᚋࡼࡿࡒೋࢅ⏕ € ࡊࠉࡱࡒ V ࣁࣤࢺ࡚ࡡ⤧ᑊ➴⣥ࡢ୕オ࡚ị ࡴࡒ R ࣁࣤࢺ࡚ࡡ⤧ᑊ➴⣥࠾ࡼ࣭࢜ࣚንᥦ ࡊ࡙ịࡴࡒࠊࡐࡿࡼࡡೋࢅ୕ᘟ࡞ථࡊࠉ1996 GT ࡡࢩ࢛࣒ࢹࣛࢴࢠࣜ࣊ࢺ pv Ҹ 0.15 ࡚࠵ࡾࡆ࡛ᑙ࠾ࡿࡒࠊ ࠈࡐࡆ࡚ࠉ௧୕࡚ịࡴࡒ 1996 GT ࡡࢪ࣭ࣞ ࣈࣂ࣒࣭ࣚࢰ࡛ࢩ࢛࣒ࢹࣛࢴࢠࣜ࣊ࢺࡡೋ ࢅ㐛ཡࡡ◂✪࠾ࡼịࡴࡼࡿࡒᩐೋ࡛Ẓ㍉ࡌࡾ ࡛ࠉ1996 GT ࡢ E-ࠉM-ࠉP-ࡡ X-class ࡡ࠾ ࡚ࡢ M-type ࡞┞ᙔࡌࡾࡆ࡛♟ࡈࡿࡒ 㸝Table. 2㸞 ࠊ ࡱ࡛ࡴ. ࠈᅂࡡふῼࡡ⤎ᯕࠉK.3T ࡞ࡻࡽᚋࡼࡿࡒ ࣚࢹ࣭࢜ࣇ࠾ࡼ 1996 GT binary asteroid ࡚࠵ࡾࡆ࡛ッ᪺ࡈࡿࡒࠊࡱࡒࠉࢨ࣐ࣖࢴࢹ ࠾ࡼᚋࡼࡿࡒ࣭࡛࢜ࣚ K.3T ࠾ࡼᚋࡼࡿࡒࢪ ࣭ࣞࣈࣂ࣒࣭ࣚࢰཀྵࡦࢩ࢛࣒ࢹࣛࢴࢠࣜ࣊ ࢺࡡೋ࠾ࡼࠉ1996 GT ࡡ taxonomical type M-type ࡚࠵ࡾࡆ࡛ࡈࡿࡒࠊ1996 GT ࡢ ᥀ᰕᶭࡡ㐡ࡊࡷࡌ࠷ኮమ࡚࠵ࡾࡡ࡚ࠉbinary ࡚࠾ࡗ M-type ᑚᝠ࡚᫅࠵ࡾ࡛ࡾ࡛ࠉ࣐ࢴ ࢨ࡛ࣘࣤࡊ࡙ࡢኣࡂࡡ⛁ᏕⓏណ⩇㎲ࡴࡼࡿ ࡾ࡛ᛦࢂࡿࡾࠊ ཤ⩻ᩝ⊡㸯 [1]: Abe (2003) Proceedings of 24th the Solar System Symposium in ISAS 89-92. [2]: Landolt A. U. (1992) Astron. J. 104, 340-371. [3]: Bowell E. B. et al. (1989) In Asteroids ϩ pp.524-556. [4]: Harris A. W. (1998) Icarus 131, 291-301. [5]: Harris A. W. and Young J. (1988) Bull. Am. Astron. Soc. 20, 865. [6]: Verbischer A. J. and Veverka J. (1995) Icarus 115, 369-373.