Photometry of Aten asteroids—More than a handful of binaries

Photometric observations were conducted on eight Aten near-Earth asteroids, with the goal of building physical models for the objects (85989) 1999 JD 6 , (86450) 2000 CK 33 , (86667) 2000 FO 10 , (137170) 1999 HF 1 , 1999 MN, 2000 PJ 5 , 2002 JC and 2003 NZ 6 . The results show rotation periods from 2.3 to almost 26 h. Some objects exhibit amplitudes higher than one magnitude on their lightcurves (1999 JD 6 , 2000 CK 33 and 2003 NZ 6 ). Phase curve values (β, H ′ , see below) were derived for four Atens and H – G values were found for two. Five Atens were classified by using their B – V and V – R color indices. This taxonomy was compared with the phase coefficient–albedo correlation defined by Belskaya and Shevchenko [Belskaya, I.N., Shevchenko, V.G., 2000. Icarus 147, 94–105]. Color variations during rotation and phase angle change were searched for. Our study demonstrates the high variety among Atens. Five out of the eight Atens are binaries or possible binaries, a significantly higher fraction than the expected 15% [Bottke, W.F., Melosh, H.J., 1996. Nature 281, 51–53]. The lightcurve of 2000 PJ 5 exhibits a binary character with a probable highly eccentric orbital rotation of the secondary component. The different periods of the known binary 1999 HF 1 ʹs are easily detected. Other Atens have lightcurve with features such as high amplitude, V-shaped minima and U-shaped maxima that can be interpreted as a binary asteroid with a synchronous rotation (2003 NZ 6 , 2000 CK 33 and perhaps also 1999 JD 6 ). The very red colors of 2000 CK 33 suggest a unique surface composition for this near-Earth object.