1. Department of Physics and Astronomy; University of Leicester; Leicester UK
2. Skobeltsyn Institute of Nuclear Physics; Lomonosov Moscow State University; Moscow Russia
3. Mullard Space Science Laboratory; University College London; Dorking UK
4. Space and Atmospheric Physics, Blackett Laboratory; Imperial College; London UK
5. Center for Space Physics; Boston University; Boston Massachusetts USA
6. Institute of Geophysics and Planetary Physics; University of California; Los Angeles California USA