1. University of Arizona, Tucson, AZ 85721.
2. U.S. Geological Survey, Flagstaff, AZ 86001.
3. New Mexico State University, Las Cruces, NM 88003.
4. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109.
5. NASA Headquarters, Washington, DC 20546.
6. Observatoire de Paris, Meudon, Paris, France.
7. Center for Astrophysics, Cambridge, MA 02138.
8. NASA Ames Research Center, Moffett Field, CA 94035.
9. California Institute of Technology, Pasadena, CA 91125.
10. Rand Corporation, Santa Monica, CA 90406.
11. Imperial College, London, England.
12. University of Wisconsin, Madison, WI 53706.
13. University of Hawaii, Honolulu, HI 96822.
14. State University of New York, Stony Brook, NY 11794.
15. Cornell University, Ithaca, NY 14853.