1. School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
2. Department of Physics and Astronomy, Haverford College, 370 Lancaster Ave, Haverford, PA 19041, USA
3. Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487, USA
4. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching, Germany
5. Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
6. Department of Astronomy, University of Wisconsin-Madison, 475N. Charter St., Madison, WI 53703, USA
7. PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
8. McDonald Observatory, The University of Texas at Austin, 1 University Station, Austin, TX 78712, USA
9. Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth PO1 3FX, UK