1. Institute of Geophysics and Planetary Physics; University of California, Los Angeles; Los Angeles California USA
2. Department of Physics, Imperial College of Science; Technology and Medicine; London UK
3. CESR/CNRS; Toulouse France
4. Mullard Space Science Laboratory, Department of Space and Climate Physics; University College London, Holmbury St. Mary, Dorking; Surrey UK
5. Space Science Center, Science and Engineering Research Center; University of New Hampshire; Durham New Hampshire USA