1. P. D. Nicholson and C. A. McGhee are with the Astronomy Department, Cornell University, Ithaca, NY 14853-6801, USA.
2. M. R. Showalter is at the Center for Radar Astronomy, Stanford University, Stanford, CA 94305, USA.
3. L. Dones is with the San Jose State University Foundation, San Jose, CA 95172-0130, USA.
4. R. G. French is with the Astronomy Department, Wellesley College, Wellesley, MA 02181-8286, USA.
5. S. M. Larson is with the Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA.
6. J. J. Lissauer is with the Astronomy Program, Department of Earth and Space Sciences, State University of New York, Stony Brook, NY 11794-2100, USA.
7. P. Seitzer is with the Department of Astronomy, University of Michigan, Ann Arbor, MI 48109-1090, USA.
8. B. Sicardy is with the Observatoire de Paris, IUF/Université Paris 6, 92195 Meudon Cédex, France.
9. G. E. Danielson is at 170-25 California Institute of Technology, Pasadena, CA 91125, USA.