1. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109.
2. Massachusetts Institute of Technology, Cambridge, MA 02139.
3. Observatory, Westford, MA 01886.
4. Goddard Space Flight Center, Greenbelt, MD 20771.
5. Bendix Field Engineering Corporation, Seabrook, MD 20706.
6. TRW Space and Technology Group, Las Cruces, NM 88004.
7. Division of Radiophysics, Commonwealth Scientific and Industrial Research Organization, Canberra, Australian Capital Territory 2601, Australia.
8. Mount Stromlo Observatory, Australian National University, Canberra, Australian Capital Territory 2606, Australia.
9. Institute for Space and Astronautical Science, Tokyo, 153, Japan.
10. Nobeyama Radio Observatory, Nobeyama, 384-13, Japan.
11. Radio Research Laboratory, Kashima, 314, Japan.