1. Max-Planck-Institut für Kernphysik, Heidelberg, 6900 Heidelberg, Germany.
2. National Aeronautics and Space Administration, Johnson Space Center, Houston, TX 77058.
3. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91103.
4. Lund Observatory, 221 Lund, Sweden.
5. Max-Planck-lnstitut für Aeronomie, 3411 Katlenburg-Undau, Germany.
6. University of Kent, Canterbury, CT2 7NR, United Kingdom.
7. Max-Planck-Institut für Extraterrestrische Physik, 8046 Garching, Germany.
8. European Space Agency European Space Technology Center, 2200 AG Noordwijk, The Netherlands.