1. Laboratory for Extraterrestrial Physics, Goddard Space Flight Center, Greenbelt, MD 20771
2. Astronomy Department, Cornell University, Ithaca, NY 14853
3. Paris Observatory, 92190 Meudon, France
4. Ames Research Center, Moffett Field, CA 94035
5. Jet Propulsion Laboratory, Pasadena, CA 91109
6. Department of Meteorology, University of Maryland, College Park, MD 20472