1. Space Sciences Institute, University of Southern California Tucson Laboratories, Tucson, Arizona 85713
2. Service D'Aeronomie du CNRS, Paris, France
3. Kitt Peak National Observatory, Tucson, Arizona 85726
4. Jet Propulsion Laboratory, Pasadena, California 91103
5. Planetary Science Institute, Pasadena, California 91101
6. University of Michigan, Ann Arbor 48109
7. Johns Hopkins University, Baltimore, Maryland 21218
8. Naval Research Laboratory, Washington, D.C. 20375
9. York University, Ontario, Canada M3J 1P3
10. Harvard University, Cambridge, Massachusetts 02138
11. Brookhaven National Laboratories, Upton, New York 11973