Broadband photometry of 11284 Belenus: A large low delta-V near-Earth Asteroid.

ATel #4969; M. Hicks (JPL/Caltech), M. Brewer (VCC), A. Carcione (Moorpark College), S. Ebelhar (PCC), R. Borlase (PCC)
on 11 Apr 2013; 19:06 UT
Credential Certification: Michael D. Hicks (Michael.Hicks@jpl.nasa.gov)

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The Near-Earth Object (NEO) 11284 Belenus (1990 BA) was discovered on January 21 1990 by Alain Maury at the Observatoire de la Cote d'Azur (IAUC 4951 ). The spacecraft rendezvous potential of any small solar system body can be quantified, to first order, by the delta-V (dV) required to match the target's orbit. Using the method described by Shoemaker & Helin (1978; N7829022) and assuming a massless rendezvous target, a dV of 6.29 km/s is required to reach the orbit of Mars. Objects with dV < 6.29 km/s can therefor be considered low dV targets: 2151 NEOs currently meet this criteria. 11284 Belenus has a dV of 5.77 km/s and is shown as a red symbol in Figure 1. With an absolute magnitude H = 17.8 (Lowell Astorb Database), the object is in the top 0.986 percentile in terms of expected size.

We obtained two nights of Bessel R photometry (March 24+25, 2013) and one night of Bessel BVRI photometry (March 31, 2013) at the JPL Table Mountain 0.6-m telescope. The observational circumstances are listed in Table 1. The rotationally averaged colors (B-R = 1.367+/-0.165 mag; V-R = 0.470+/-0.052 mag; R-I = 0.330+/-0.014 mag) were found most consistent with an S-type spectral classification (Bus taxonomy), an association obtained through a comparison of our colors with the 1341 asteroid spectra in the SMASS II database (Bus & Binzel 2002) [Figure 2 and Table 2]. Assuming a solar phase parameter g=0.15 and our V-R color, we measured an absolute magnitude H_V=18.42+/-0.06 mag. Fourier analysis of the March 24+25 photometry yielded a rotational period P_syn=5.43+/-0.02 hr, with a modest lightcurve amplitude of ~0.4 mag [ [Figure 3].

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   Exp.    
   UT DATE       r    delta  Phase    V   
                [AU]   [AU]  [deg]  [mag] 
2013 03 24.31  1.318  0.323    6.0   16.4 
2013 03 25.31  1.322  0.327    6.5   16.5 
2013 03 31.24  1.347  0.355   10.3   16.9 
 
 
 
Table 2:  Best-fit SMASS II spectral analogs.  
 
                         Taxonomic Class 
Misfit  Object Name      (Tholen)  (Bus) 
 
0.123 3701 Purkyne                   S 
0.230 5008 Miyazawakenji             S 
0.256 5196 Bustelli                  S 
0.276   60 Echo              S       S 
0.289  797 Montana           S       S