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Physical Characterization of the Potentially Hazardous Asteroid and Planetary Radar Target 68216 (2001 CV26): An Excellent Shape/Pole Modeling Candidate.

ATel #2502; M. Hicks (JPL/Caltech), K. Lawrence (JPL/Caltech), J. Somers (Moorpark), J. Foster (CSULA)
on 23 Mar 2010; 21:12 UT
Credential Certification: Michael D. Hicks (Michael.Hicks@jpl.nasa.gov)

Subjects: Asteroid, Planet (minor), Solar System Object

The Near-Earth Asteroid (NEA) 68216 (2001 CV26) was discovered February 1 2001 by the LINEAR NEA Discovery Survey (MPEC 2001-F15). With an Absolute Magnitude H=16.2 and a Minimum Orbit Intersection Distance MOID=0.023 AU, it has been flagged as a Potentially Hazardous Asteroid (PHA) by the Minor Planet Center. The asteroid's 2009-2010 apparition allowed for radar observation at both the Arecibo and Goldstone facilities in October 2009. We obtained low-resolution long-slit spectroscopy at the Hale 5-m telescope and Bessel R lightcurve photometry at the JPL Table Mountain Observatory (TMO) 0.6-m telescope on March 14 and March 21 2010, respectively, with observational circumstances summarized in Table 1.

Figure 1 plots the normalized reflectance of 2001 CV26 as measured March 14. A comparison of our optical spectra with the 1341 asteroid spectra as archived in the SMASS II database (Bus & Binzel 2002) allowed us to determine an S classification in both the Tholen and Bus taxonomies, as listed in Table 2. The TMO R-band photometry was obtained through heavy cirrus but we were able to extract a relative lightcurve on a frame-by-frame basis using background field stars. After converting from magnitude to flux units, we performed a period search using standard Fourier techniques. Figure 2 plots chi-squared 5th and 6th-order Fourier model misfit as a function of assumed rotation period. We found a best-fit synodic period P_syn = 2.409+/-0.021 hr, as shown in Figure 3 . Two additional minima in our periodogram, P_syn = 1.20 hr and P_syn = 3.62 hr, require single-peaked and triple-peaked lightcurves, respectively, which can be considered unlikely for a tri-axial ellipsoid observed at modest solar phase angles.

We consider 2001 CV26 an excellent candidate for shape/pole modeling using optical lightcurve inversion (Kaasalainen et al. 2002). The object remains accessible to observers in the northern hemisphere (V < 18 mag; dec > -5 deg) until May 11 2010. The object will be well placed for southern observers June-November 2012, returning at high declinations in late 2012. We invite collaborations with other small body observers in order to characterize 2001 CV26's shape and spin state.

Copyright 2010. All rights reserved. The research described in this telegram was carried out at the Jet Propulsion Laboratory, under a contract with the National Aeronautics and Space Administration. J. Foster was supported by the NSF REU grant 0852088 to the California State University Los Angeles.

Table 1: Observational circumstances.  
UT Date    r(AU)  d(AU)  p(deg)  V(mag)  Exp Time      Observers  
Mar 14.46  1.35   0.40    23.0    16.0   7 x 300 sec   Hicks, Lawrence, Somers  
Mar 21.35  1.38   0.41    14.8    15.8  296 x 60 sec   Foster  

Table 2:  Best-fit SMASS II spectral analogs.  
                        (Tholen) (Bus)  
0.522   2827 Vellamo               S  
0.523    470 Kilia         S       S  
0.528    170 Maria         S       S  
0.529    115 Thyra         S       S  
0.539     37 Fide          S       S