34th Meeting of the AAS Division on Dynamical Astronomy, May 2003
6 Poster Papers
Posters, Monday, May 5, 2003, 8:00pm,

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[6.12] Getting Physical: Rotation Rate Determination for PHAs

J. G. Ries, E. S. Barker (UT at Austin, McDonald Observatory), P.J. Shelus, R. L. Ricklefs (UT at Austin, Center for Space Research)

The NASA Near Earth Object (NEO) search efforts have now discovered more than 2300 objects, 500 of which are classified as Potentially Hazardous Asteroids (PHAs). The McDonald Observatory NEO team continues to participate in the astrometric work of NEO confirmations and follow-up observations. While finding and maintaining precise orbits of these objects is essential in assessing the hazards they might pose to Earth, the physical characteristics such as mass, rotation rate and surface properties are important factors in understanding their full dynamical evolution. The efficiency of the proposed process for transporting objects from the Main Asteroid Belt to Earth crossing orbits (i.e., resonances assisted by the YORP effect) depends on the above properties. At the present we lack sufficient information on the physical characteristics of most NEOs.

As a first step, we are attempting to obtain refined absolute magnitudes, rotational periods, and, whenever possible, axis ratios and three-color information for PHAs. Relative photometry has been already carried out for 2002 EZ11 in the Johnson R band, and more are scheduled. The results of these studies will be presented at the meeting.

This research is funded by NASA's NEO Observation Program grants NAG5-6863 and NAG5-10183.

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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.