1. AWE plc, Aldermaston, Reading RG7 4PR, UK
2. Department of Astronomy, University of Virginia, Charlottesville, VA 22904, USA
3. Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching, Germany
4. Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ, UK
5. Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2, Ireland
6. Centre for AstroParticle Physics and Astrophysics, DIAS Dunsink Observatory, Dunsink Lane, Dublin 15, Ireland