| Affiliation: |
| AA(Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK; .), AB(Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK; .), AC(Department of Physics, University of Padova, Via Marzolo 8, I-35131 Padua, Italy; .), AD(INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padua, Italy; .), AE(Department of Physics and Mathematics, Universitá dell'Insubria, Via Valleggio 11, I-22100 Como, Italy; , .; Institut für Theoretische Physik der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.), AF(Smithsonian Astrophysical Observatory, Mail Stop 3, 60 Garden Street, Cambridge, MA 02138; .), AG(Department of Physics and Mathematics, Universitá dell'Insubria, Via Valleggio 11, I-22100 Como, Italy; , .) |