1. Instituto de Geofísica; Universidad Nacional Autónoma de México; Coyoacán D.F. Mexico
2. University of California, Los Angeles; Institute of Geophysics and Planetary Physics; Los Angeles California USA
3. University of Maryland; College Park Maryland USA
4. NASA Goddard Space Flight Center; Greenbelt Maryland USA
5. Space Science Laboratory; University of California; Berkeley California USA
6. Space Science Center; University of New Hampshire; Durham New Hampshire USA