Broad-band photometry of NHATS target 387733 (2003 GS)
ATel #6090; M. Hicks (JPL/Caltech), J. Frederick (PCC), I. Harley (PCC)
on 23 Apr 2014; 17:57 UT
Credential Certification: Michael D. Hicks (Michael.Hicks@jpl.nasa.gov)
Subjects: Optical, Asteroid, Planet (minor), Solar System Object, Near-Earth Object
The near-Earth asteroid (2003 GS) was discovered by the LONEOS Sky Survey on April 12, 2003 (MPEC 2003-G25). The object passed within 0.0875 AU on April 12, 2014 and is scheduled to be observed at radar wavelength at Arecibo on April 18-20 (E. Howell, personal communication). 2003 GS has been flagged by NASA's Near-Earth Object Human Space Flight Accessible Targets Study (NHATS) as a potentially attractive mission target. Though close to full moon, we took advantage of the object's 2014 apparition to obtain three partial nights of time-resolved photometry (April 12-14 2014 UT) at the JPL Table Mountain Observatory 0.6-m telescope, as summarized in Table 1 and Figures 1-3
The rotationally averaged colors of the asteroid (B-R=1.233+/-0.012 mag; V-R=0.466+/-0.012 mag; R-I=0.361+/-0.034 mag) were found most compatible with an S-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
and Table 2]. As shown in Figure
, our solar phase coverage allow the determination of absolute magnitude (H_R=18.50 mag) and solar phase parameter g=0.17, consistent with an S-Family taxonomic classification. Using our V-R color, we measured an absolute magnitude in the V band H_V=18.97+/-0.02 mag.
After converting our observed flux to normalized flux, we performed a rotational period search using standard Fourier techniques. Figure
plots chi-squared 2nd and 3rd order Fourier model misfit as a function of assumed rotation period, with a clear minimum near 2.5 hr. Assuming a double-peaked lightcurve, we found a best-fit synodic period P_syn = 2.469+/-0.001 hr, as shown in Figure
. The rapid rotation and low lightcurve amplitude suggests a potential binary NEO system; there was no clear evidence of a two-period system in our data.
Copyright 2014. 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 summary.
Solar Lunar .
UT Date r delta Phase V Elong. Filters Observers
[AU] [AU] [deg] [mag] [deg]
Apr 12.40 1.087 0.087 15.0 14.7 41.6 BVRI Hicks
Apr 13.31 1.086 0.088 16.7 14.8 31.1 R Harley, Frederick, Hicks
Apr 14.26 1.086 0.088 18.7 14.9 23.6 R Hicks
Table 2: Best-fit SMASS II spectral analogs.
MISFIT OBJECT NAME (THOLEN) (BUS)
1.983 39 Laetitia S S
2.988 3198 Wallonia S
3.037 1351 Uzbekistania Xk
3.218 6704 1988 CJ K
3.449 56 Melete P Xk