Broadband Photometry of 2012 LZ1: A Large, Dark Potentially Hazardous Asteroid
ATel #4252; M. Hicks (JPL/Caltech), W. Smythe (JPL/Caltech), T. Davtyan (LACC), D. Dombroski (LACC), C. Strojia (VVC), S. Teague (VCC)
on 11 Jul 2012; 23:09 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
2012 LZ1 was discovered on June 10, 2012 by R. McNaught (MPEC 2012-L30). The NEO passed within 0.0364 AU of the Earth on June 14.96 2012 and has been designated as a Potentially Hazardous Asteroid (PHA) by the IAU Minor Planet Center. We obtained 5 nights of time-resolved photometry at the JPL Table Mountain Observatory (TMO) 0.6-m telescope, as summarized in Table 1. Due to a high rate of motion and background star density it was necessary to minimize contamination by creating a running sky background template using adjacent frames and subtracting this template from each R-band frame, as shown in
Figure 1.
Correcting for geometry, we generated the solar phase curve shown in
Figure 2
(H_R = 19.04 mag, G = 0.05). The steep solar phase behavior suggests that 2012 LZ1 is a low albedo asteroid.
The measured colors (B-R=1.115+/-0.033 mag; V-R=0.386+/-0.017 mag; R-I=0.408+/-0.043 mag) were compatible with a X-type spectral classification (Table 2 and
Figure 3). The X-complex (Tholen Taxonomy) consists of 3 spectrally degenerate classes (E, high albedo; M, moderate albedo; P, low albedo). The asteroid's solar phase behavior implies that 2012 LZ1 is a P-type asteroid, also consistent with its relatively low Tisserand Invariant T=3.05. We estimate an absolute magnitude H_V=19.43+/-0.05 mag and size D=0.77+/-0.02 km, assuming an albedo rho=0.05. Fourier analysis was able to constrain a likely rotational period between 5 and 16 hours (Figure 4).
Copyright 2012. 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 0852088 to Cal State LA.
able 1: Observational Circumstances.
UT Time r (AU) delta phase V Filters Observers
[AU] [AU] [deg] [mag]
2012 06 15.40 1.046 0.037 33.3 14.1 R Smythe
2012 06 16.38 1.045 0.039 41.8 14.5 BVRI Teague, Strojia
2012 06 17.38 1.043 0.043 50.5 15.0 BVRI Dombroski, Davtyan
2012 06 19.41 1.043 0.057 63.3 15.9 BVRI Davtyan, Dombroski
2012 06 21.40 1.038 0.073 70.4 16.7 BVRI Dombroski, Davtyan
Table 2: Best-fit SMASS II spectral analogs.
TAXONOMIC CLASS
MISFIT OBJECT NAME (THOLEN) (BUS)
0.529 3533 Toyota Xk
0.768 363 Padua XC X
0.836 507 Laodica X
0.856 216 Kleopatra M Xe
0.892 55 Pandora M X
