1. Planetary Geosciences Division, University of Hawaii, Honolulu,HI 96822 and Visiting Astronomers at the Infrared Telescope Facility, operated by the University of Hawaii under contract to the National Aeronautics and Space Administration
2. Jet Propulsion Laboratory and California Institute of Technology, Mail Stop 169-237, 4800 Oak Grove Drive, Pasadena, CA 91109
3. Institute for Astronomy, University of Hawaii, Honolulu, HI 96822