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
Credential Certification: Michael D. Hicks (Michael.Hicks@jpl.nasa.gov)

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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