1. Enrico Fermi Institute, University of Chicago, 933 East 56 Street, Chicago, IL 60637
2. Herzberg Institute for Astrophysics, National Research Council of Canada, Ottawa, Canada, K1A OR6
3. Blackett Laboratory, Imperial College of Science and Technology, Prince Consort Road, London, SW7 2BZ, United Kingdom
4. Centre d'Etudes Nucléaires de Saclay, Service d'Astrophysique, Bat. 528, 91191 Gif-sur-Yvette, Cedex, France
5. Institut für Reine und Angewandte Kernphysik, Universität Kiel, Olshausenstrasse 40-60, D-2300, Kiel 1, Germany
6. Space Science Department of the European Space Agency, European Space Research and Technology Center, Postbus 299, 2200 AG, Noordwijk, Holland
7. European Space Agency at Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109