1. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München, Germany
2. Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany
3. Department of Physics, Broida Hall, University of California, Santa Barbara, CA 93106-9530, USA
4. Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064, USA
5. University of California Observatories, Lick Observatory, 1156 High Street, Santa Cruz, CA 95064, USA
6. Institute for Astronomy, University of Edinburgh, Royal Observatory Blackford Hill, Edinburgh EH9 3HJ, UK
7. Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
8. Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK