1. ITAMP, Harvard-Smithsonian Center for Astrophysics Harvard University 60 Garden St. Cambridge MA 02138 USA
2. Physics Department University of Connecticut, Storrs CT 06269-3046 USA
3. Department of Physics The United States Naval Academy Annapolis Maryland 21402 USA
4. University of Oklahoma Homer L. Dodge Department of Physics and Astronomy Norman Oklahoma 73072 USA