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Palomar Spectroscopy of the Potentially Hazardous Asteroids 2010 MF1 and 138404 (2000 HA24)

ATEL # 2822; M.Hicks (JPL/CalTech), B. Buratti (JPL/CalTech)
on 30 Aug 2010; 22:40 UT
Password Certification: Michael D. Hicks (Michael.Hicks@jpl.nasa.gov)

Subjects: Optical, Asteroids, Solar System Objects

We obtained long-slit CCD spectrograms of the near-Earth asteroids 2010 MF1 and 138404 (2000 HA24) using the Palomar 5-m Hale Telescope equipped with the facility dual-channel spectrometer on August 10 2010. 2010 MF1 was discovered June 18 2010 by the Siding Spring Survey (MPEC 2010-M28) while 2000 HA24 was discovered by the LINEAR NEO survey on April 28 2000 (MPEC 2000-J10). Both minor planets have been designated as Potentially Hazardous Asteroids by the Minor Planets Center, although they currently pose no significant impact threat. We note that the delta-V requirements for a spacecraft rendezvous with 2000 HA24 are modest (dV = 5.80 km/sec).

Table 1 summarizes our observational circumstances, with the expected V magnitude computed assuming a phase parameter G=0.15 using the orbital elements and Absolute Magnitude H_V maintained by the JPL HORIZONS database. Table 2 lists the solar analog stars used to generate the composite normalized reflectance spectra, as shown in Figures 1-2 [1][2].

A comparison of our optical spectra with the 1341 asteroid spectra archived in the SMASS II database (Bus & Binzel 2002) was used to determine taxonomy. Table 3 list the five best-fit SMASS II analogs for each object. We identify 2010 MF1 as a new Vestoid, with a spectrum best matched by the main-belt asteroid 4 Vesta, and we assign a K-type classification (a subset of the S-family which may suggest a highly weathered surface) for 2000 HA24.

Both asteroids are well placed for further physical characterization, particularly rotational lightcurve studies. 2010 MF1 remains at a high northerly declination and brighter than V~19 though October 14 2010, while 2000 HA24 remains near Dec = -11 deg and brighter than V~19 though October 22 2010. Collaborations with other observers are welcome.

Copyright 2010. California Institute of Technology. Government sponsorship acknowledged.

   Table 1: Observational Circumstances.      Object Name   r (AU)  delta (AU)  phase (deg)  H (mag)  V (mag)  Exp Time (min)   2010 FM1      1.025     0.132        81.5       19.5     18.0       30.0   2000 HA24     1.296     0.288        10.1       20.9     19.0       35.0   


   Table 2:  Solar Analog Stars      Object Name      Solar Analog Stars   2010 MF1         16 Cyg B, 115-268   2000 HA24        115-268   


   Table 3:  Best-fit SMASS II spectral analogs.                                            TAXONOMIC CLASS   MISFIT  OBJECT NAME        (THOLEN) (BUS)          - for 2010 MF1 -   1.802     4 Vesta             V       V   2.009  3498 Belton                    V   2.160  3265 Fletcher                  V   2.175  1324 Knysna                    Sq   2.182  4051 Hatanaka                  Sq          - for 2000 HA24-   0.863   606 Brangane         TSD      K   0.899  2271 Kiso                      T   0.907   559 Nanon             C       Xk   0.914  2724 Orlov                     K   0.940  2929 Harris                    T   



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