1. Department of Earth and Planetary Sciences, Massachusetts Institute of Technology,
Cambridge 02139
2. Department of Electrical Engineering, Massachusetts Institute of Technology
3. Haystack Observatory, Northeast Radio Observatory Corporation, Westford, Massachusetts
01886
4. Smithsonian Astrophysical Observatory, Cambridge, Massachusetts 02138
5. Goddard Space Flight Center, Greenbelt, Maryland 20771
6. Research Laboratory of Electronics, Massachusetts Institute of Technology