BVRI photometry of the Potentially Hazardous Asteroid 285263 (1998 QE2).
ATel #5121; M. Hicks (JPL/Caltech), B. BurattJPL/Caltech), P. Dalba (JPL/Caltech)
on 10 Jun 2013; 22:23 UT
Credential Certification: Michael D. Hicks (Michael.Hicks@jpl.nasa.gov)
Subjects: Optical, Asteroid, Planet (minor), Solar System Object, Near-Earth Object, Potentially Hazardous Asteroid, Asteroid (Binary)
The Near-Earth asteroid 285263 (1998 QE2) was discovered by LINEAR on August 19, 1998 (MPEC 1998-Q19). The object passed within 15 lunar distances (0.039 AU) on May 31, 2013 and was a strong target for radar observation at both Arecibo and Goldstone. With a Minimum Orbit Intersection Distance (MOID) of 0.035 AU and diameter D = 2.7km (Trilling et al., 2010), this object has been flagged as a Potentially Hazardous Asteroid (PHA) by the Minor Planet Center. We recently obtained two partial nights of Bessel BVRI photometry at the JPL Table Mountain 0.6-m telescope (TMO), as summarized in Table 1.
The rotationally averaged colors of 1998 QE2 (B-R = 1.059 +/- 0.011 mag; V-R = 0.353 +/- 0.015 mag; R-I = 0.365 +/- 0.015 mag) where found most consistent with a Ch-type classification (Bus taxonomy), compatible with the low albedo measured by Spitzer (Trilling et al. 2010). Taxonomy was determined through a comparison of our colors with the 1341 asteroid spectra in the SMASS II database (Bus & Binzel 2002) [
Figure 1
and Table 2].
After converting the photometry from magnitude to flux units and correcting for observational geometry, we found a best-fit synodic period P_syn = 5.39+/-0.02 hr [Figure 2] using standard Fourier techniques. Assuming a solar phase parameter g=0.05 and our measured colors, our photometry yields an absolute magnitude H_V = 16.98 +/- 0.02 mag, implying an effective diameter D~2.2 km (rho = 0.06), slightly smaller than the D=2.7 km diameter estimated by Spitzer (Trilling et al. 2010). Continuing observation at TMO through June and July 2013 should allow us to measure the solar phase parameter g directly and refine our estimate of 1998 QE2's absolute magnitude. Collaborations are welcome.
Copyright 2013. 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: Observational circumstances.
UT DATE r delta Phase V Observers
[AU] [AU] [deg] [mag]
2013 06 02.24 1.052 0.040 18.4 11.1 Hicks, Buratti, Dalba
2013 06 03.22 1.054 0.042 17.1 11.2 Hicks, Buratti
Table 2: Best-fit SMASS II spectral analogs.
TAXONOMIC CLASS
MISFIT OBJECT NAME (THOLEN) (BUS)
0.299 200 Dynamene C Ch
0.579 1360 Tarka Ch
1.065 109 Felicitas GC Ch
1.128 997 Priska Ch
1.534 868 Lova C: Ch
