Affiliation: | Cavendish Laboratory, Madingley Road, Cambridge CB3 OHE; Department of Physics, University of Durham, South Road, Durham DH1 3LE; Institute for Astronomy, Department of Physics and Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ; Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT; Observatoire Midi-Pyrénées, 14 Avenue E. Belin, 31400 Toulouse, France |