Radar Shape Modeling of Binary Near-Earth Asteroid 2000 CO101

We observed the near-Earth binary system 2000 CO101 in 2009 Septemberusing the Goldstone and Arecibo radar systems and inverted these imagesto create shape models of the primary. Asteroid 2000 CO101 wasdiscovered to be a binary system from Arecibo images taken on 2009September 26 (Taylor et al. 2009). Analyzing the images, we were able todetermine approximate values for the radius of the primary (310 m) andthe radius of the secondary (22 m). The maximum observed rangeseparation was approximately 610 m. The images show it to appearspherical. Shape modeling of the primary of this system will constrainthe asteroid's size, spin rate, and pole orientation. Because other NEAbinary systems have exhibited shapes similar to that of 1999 KW4 (Ostroet al. 2006, Scheeres et al. 2006), we initially adopted this shape for2000 CO101 and have allowed only the linear scales along the three principal axes to adjust to the radar data. This enables us to constrain the volume. With some constraints on the orbit of the satellite we will place limits on the density of the primary.The near-infrared spectrum of 2000 CO101 was measured on 2009 September 21 and 2010 March 13. The 0.8-2.5 micron spectrum was measured on both dates, and shows a featureless, red-sloped spectrum. On September 21 we also measured the thermal emission between 2-4 microns to determine the albedo and thermal properties. Both standard thermal models and thermophysical models have been applied to these data. The albedo we derive from the thermal modeling must also be consistent with the radar size. Characterization of this unusual NEA binary system will be presented