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Broad-band Photometry of the Potentially Hazardous Asteroid 2009 KC3.

ATEL # 2247; M. Hicks (JPL/Caltech), T. Barajas (LACC), A. McAuley (CSULA)
on 19 Oct 2009; 3:11 UT
Password Certification: Michael D. Hicks (

Subjects: Optical, Asteroids, Planets, Planets (minor), Solar System Objects

The near-Earth asteroid 2009 KC3 was discovered by the Siding Spring Survey on May 23 2009 (MPEC 2009-K39). With an Absolute Magnitude H=17.9 and a Minimum Orbit Intersection Distance MOID=0.010 AU, the object has been designated as a Potentially Hazardous Asteroid (PHA) by the Minor Planet Center. 2009 KC3 has an orbit similar to many Jupiter-family comets (Tisserand Invariant T=2.73), implying a possible cometary past. We obtained Bessel BVRI colors over the course of two partial nights at the JPL Table Mountain Observatory (TMO) 0.6-m telescope (Figure 1 and Table 1).

We compared our averaged broad-band colors (B-R=1.130+/-0.027 mag; V-R=0.388+/-0.014 mag; I-R=0.338+/-0.025 mag) with 1341 asteroid spectra collected by the SMASS II survey (Bus & Binzel 2002) and found the colors best matched by the C-type asteroid 1716 Peter (Figure 2 and Table 2). However, our colors were also consistent with the Xe-type asteroids 396 Aeolia and 2001 Einstein. This is problematic for resolving any possible asteroid-comet connection: C-type asteroids have low albedos, similar to the primitive surfaces of cometary nuclei, while Xe asteroids tend to have moderate to high albedos, consistent with a more evolved mineralogy. Thermal observations and/or optical/near-IR spectroscopy would be required to resolve this ambiguity.

Copyright 2009. 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.

Table 1: TMO observational summary.

UT Date r (AU) delta (AU) phase (deg) Num. Exp. Observers
Sep 20.46 1.11 0.18 50.4 13 A. McAuley
Sep 24.19 1.14 0.21 45.4 82 T. Barajas

Table 2: Top 5 spectral matches in the SMASS II database.

Misfit Asteroid Name Taxonomic Class
    (Tholen) (Bus)
0.159 1716 Peter   C
0.267 1396 Aeolia   Xe
0.358 2001 Einstein X Xe
0.596 783 Nora   C
0.649 1517 Beograd   X

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