Broadband Photometry of the Potentially Hazardous Asteroid 2013 RH74

ATel #5562; M. Hicks (JPL/Caltech), S. Ebelhar (PCC)
on 9 Nov 2013; 02:02 UT
Credential Certification: Michael D. Hicks (Michael.Hicks@jpl.nasa.gov)

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The Near-Earth Asteroid (NEA) 2013 RH74 was discovered by the Catalina Sky Survey on September 15 2013 (MPEC 2013-S15) and has been designated as a Potentially Hazardous Asteroid (PHA) by the Minor Planet Center. We obtained six partial nights of broadband Bessel BVRI photometry at the JPL Table Mountain 0.6-m telescope (TMO), as summarized in Table 1. This object was detected by planetary radar soon after discovery (http://echo.jpl.nasa.gov/asteroids/index.html).

The rotationally averaged colors of the asteroid (B-R=1.196+/-0.029 mag; V-R=0.409+/-0.013 mag; R-I=0.251+/-0.035 mag) were found most compatible with an Sq-type spectral classification, an association obtained through a comparison of our colors with the 1341 asteroid spectra in the SMASS II database (Bus & Binzel 2002) [ [Figure 1] and Table 2]. As shown in Figure 2 , our solar phase coverage allow the determination of absolute magnitude (H_R=20.35 mag) and solar phase parameter g=0.05. This is a steeper solar phase curve than what is typical for S-family asteroids and implies a relative low albedo rho~0.1. Using our V-R color, we measured an absolute magnitude in the V band H_V=20.76+/-0.02 mag.

We performed a rotational period search using standard Fourier techniques. Figure 3 plots chi-squared 3rd order Fourier model misfit as a function of assumed rotation period. Assuming a double-peaked lightcurve, we found a best-fit synodic period P_syn = 5.38+/-0.02 hr, as shown in Figure 4.

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. The student participation was supported by the National Science Foundation under REU grant AST-1156756 to Los Angeles City College.

 

Table 1:   Observational circumstances. 
 
                               Solar Expected  Gal.  Lunar 
   UT DATE       r     delta   Phase    V      Lat.  Elong. Filters   Observer 
                [AU]    [AU]   [deg]  [mag]   [deg]  [deg] 
2013 10 12.38  1.051   0.063   32.8    16.5    -30    120    BVRI     Hicks 
2013 10 13.35  1.045   0.060   37.0    16.5    -27    112    BVRI     Hicks 
2013 10 15.33  1.033   0.054   47.6    16.5    -19     97      R      Hicks 
2013 10 16.34  1.022   0.053   53.8    16.7    -13     90      R      Ebelhar 
2013 10 17.35  1.021   0.053   60.4    16.8     -8     84      R      Hicks 
2013 10 18.44  1.016   0.053   67.2    17.0     -2     77      R      Hicks 
 
 
 
Table 2:  Best-fit SMASS II spectral analogs. 
 
                           TAXONOMIC CLASS 
MISFIT    OBJECT NAME      (THOLEN)  (BUS) 
0.738   1324 Knysna                   Sq 
1.463   7728 Giblin                   Sq 
1.501   4051 Hatanaka                 Sq 
1.724   1653 Yakhontovia      (C)     X 
2.227   4261 Gekko                    Sq