1. Astronomy and Space Physics Department; National Taras Shevchenko University of Kiev; Kiev Ukraine
2. Institut für Geophysik und extraterrestrische Physik; Technische Universität Braunschweig; Braunschweig Germany
3. Max-Planck-Institut für Sonnensystemforschung; Katlenburg-Lindau Germany
4. Department of Earth and Space Sciences; University of California; Los Angeles California USA
5. Space Research Institute; Austrian Academy of Sciences; Graz Austria
6. Space Sciences Laboratory; University of California; Berkeley California USA