1. NASA Ames Research Center, Moffett Field, California 94035
2. University of Arizona, Tucson 85721
3. Service d'Aeronomie du Centre National de la Recherche Scientifique, 91 Verrieres, France
4. Particle Measuring Systems, Inc., Boulder, Colorado 80301
5. University of Colorado, Boulder 80309
6. NASA Goddard Institute for Space Studies, New York 10025