| Affiliation: | Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT;Laboratory for High Energy Astrophysics, Code 660, Goddard Space Flight Centre, NASA, Greenbelt, MD 20770, USA;Department of Astronomy, University of Maryland, College Park, MD 20742, USA;Laboratory for High Energy Astrophysics, Mail Code 662, NASA Goddard Space Flight Centre, Greenbelt, MD 20771, USA;Observatoire Astronomique de Strasbourg, 11 rue de l'Observatoire, F-67000 Strasbourg, France |
