Abstract
Photometry of Atens
Polishook, David Brosch, Noah Prialnik, Dina	Tel-Aviv University Tel-Aviv University Tel-Aviv University
Photometric observations were conducted on 4 Atens, with the goal of building overall physical models for the objects: (86450) 2000 CK33, (86667) 2000 FO10, (85989) 1999 JD6 (control object) and 2002 CQ11 (observation test). The results show moderate rotation periods for 3 bodies (1999 JD6: 7.66 ± 0.01 h, 2000 CK33: 6.53 ± 0.03 h, 2002 CQ11: > 8 h) and a long rotation period for the forth (2000 FO10: 25.6 to 26.4 h). The amplitudes are reasonably high with a corresponding minimal a/b ratios of 4.4 (2000 CK33) and 3.31 (2000 JD6). The lightcurves for 2000 FO10 and 2002 CQ11 were not fully covered. H-G values were derived for 2 Atens and show a good fit to the phase curves. The Atens were classified by their B-V and V-R color indices and by their phase curve parameters by using the method of Belskaya and Shevchenko (2000), into mid-albedo groups (1999 JD6 – K type, 2000 FO10 – S complex) and low-albedo groups (2000 CK33 – X complex, 2002 CQ11 – C complex). Our study shows that these Atens have asymmetric and elongated shapes in a way that could be the result of a break-up of a single body into a binary asteroid (2000 CK33 and perhaps also 1999 JD6). Proofs for rotational instability, due to collisions, tidal forces or the YORP effect, are seen in the lightcurve of 2000 FO10, which shows a minor periodicity in addition to the principal one and might be the first known "Tumbler" Aten with slow rotation. The derived Aten spectral taxonomy classification fits the NEOs distribution model of Bottke et al. (2002) and the incidence of the classes in the Solar System. An interesting result shows that the color of 1999 JD6 is changing with the phase angle.
Presenting author:	Polishook, David

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