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Broad-Band Photometry of 52762 (1998 MT24)

ATel #5306; M. Hicks (JPL/Caltech), S. Ebelhar (PCC), R. Borlase (PCC), A. Carcione (Moorpark)
on 21 Aug 2013; 17:52 UT
Credential Certification: Michael D. Hicks (Michael.Hicks@jpl.nasa.gov)

Subjects: Optical, Asteroid, Solar System Object, Near-Earth Object

Referred to by ATel #: 5311

The Near-Earth Object (NEO) 52762 (1998 MT24) was discovered by the LINEAR asteroid survey on June 19, 1998 (MPEC 1998-N06). As tabulated in the DLR EARN database, thermal flux observations by the WISE spacecraft coupled with optical observations (Pravec at al. 2012) have measured a low albedo (rho=0.054), while R. Whiteley (2001) determined a spectral X-type classification. The Ondrejov NEO Photometric Program Webpage has reported a rotational period of 12.066 hr. With a Jupiter Tisserand Invariant T=3.01, the orbit of 1998 MT24 is closely related to the Jupiter-family comets.

We obtained four nights of Bessel BVRI photometry at the JPL 0.6-m telescope of 1998 MT24, with observational circumstances as generated by HORIZONS listed in Table 1. Our rotationally averaged colors (B-V=1.123+/-0.038 mag; V-R+/-0.030 mag; I-R=0.401+/-0.016 mag) yielded an X-family classification and absolute magnitude H_V=14.61+/-0.03 mag [Table 2 and Figure 1 ], assuming solar phase parameter g=0.05. No cometary activity was apparent in our images.

Though our data is sparse, an application of Fourier analysis to our reduced R photometry suggests three best-fit synodic periods (near 4.82/6.04/12.08 hr), as shown in Figure 2. The two shorter periods yield single-peaked lightcurves and can be rejected. Our measured rotational period P=12.08+/-0.02 hr [Figure 3] is consistent with the value obtained by previous observers.

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. 
   UT DATE       r     delta   Phase   V        Observers 
                [AU]    [AU]   [deg]  [mag] 
2013 08 01.41  1.914   0.926   10.0   16.6      Ebelhar, Borlase 
2013 08 15.26  2.031   1.036    7.4   16.9      Borlase, Ebelhar 
2013 08 16.24  2.039   1.046    7.7   16.9      Ebelhar, Carcione 
2013 08 17.27  2.048   1.057    8.1   17.0      Carcione, Borlase 
Table 2:  Best-fit SMASS II spectral analogs. 
                           TAXONOMIC CLASS 
0.723  1104 Syringa                    Xk 
0.786   627 Charis            XB:      X 
0.816   547 Praxedis          XD:      Xk 
0.943    83 Beatrix           X        X 
0.943    87 Sylvia            P        X