1. Department of Physics and Astronomy, University of Leicester, Leicester, UK.
2. Birkeland Centre for Space Sciences, University of Bergen, Bergen, Norway.
3. Belgian Institute for Space Aeronomy, Brussels, Belgium.
4. Mullard Space Science Laboratory, University College London, Dorking, UK.
5. Institut de Recherche en Astrophysique et Planétologie (IRAP), UMR 5277, Université Paul Sabatier–Observatoire Midi-Pyrénées, University of Toulouse, Toulouse, France.
6. IRAP, CNRS, Toulouse, France.
7. Space Sciences Laboratory, University of California Berkeley, Berkeley, CA 94720, USA.