1. Instituto de Geofísica; Universidad Nacional Autónoma de México; Mexico City Mexico
2. Max-Planck-Institut für Sonnensystemforschung; Göttingen Germany
3. Instituto de Geofísica, Unidad Michoacán; Universidad Nacional Autónoma de México; Morelia Mexico
4. Institute of Geophysics and Planetary Physics; University of California; Los Angeles California USA
5. NASA Goddard Space Flight Center; Greenbelt Maryland USA
6. Astronomy Department; University of Maryland; College Park Maryland USA
7. Space Sciences Laboratory; University of California; Berkeley California USA