1. Institute for Space Research of the Russian Academy of Science, 117997 Moscow, Russia.
2. University of Arizona, Tucson, AZ, USA.
3. NASA Goddard Space Flight Center, Greenbelt, MD, USA.
4. Computer Science Corporation, Greenbelt, MD, USA.
5. Department of Physics, University of Maryland, College Park, MD, USA.
6. Sternberg Astronomical Institute of Moscow State University, Moscow, Russia.
7. Joint Institute of Nuclear Research, Dubna, Russia.
8. Massachusetts Institute of Technology, Cambridge, MA, USA.
9. Catholic University, Washington, DC, USA.
10. Department of Astronomy, University of Maryland, College Park, MD, USA.