1. Department of Physics; University of Oslo; Oslo Norway
2. Department of Physics; University of Bergen; Bergen Norway
3. Space Sciences Laboratory; University of California; Berkeley California USA
4. Center for Space Plasma and Astronomy Research; University of Alabama in Huntsville; Huntsville Alabama USA
5. Space and Atmospheric Sciences; Los Alamos National Laboratory; Los Alamos New Mexico USA
6. Space Science Department; Southwest Research Institute; San Antonio Texas USA
7. Space and Atmospheric Physics; Imperial College London; London UK
8. Centre d'Etude Spatiale des Rayonnements; Toulouse France
9. Space Science Center; University of New Hampshire; Durham New Hampshire USA