1. Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
2. Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands
3. Cahill Center for Astrophysics, California Institute of Technology, 1216 East California Boulevard, Pasadena, CA 91125, USA
4. Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE UK
5. Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
6. Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, P-1749-016 Lisbon, Portugal
7. Department of Physics and Astronomy, University of California, 900 University Ave., Riverside, CA 92521, USA
8. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching, Germany