1. Physics Department, University of Surrey, Guildford GU2 7XH, UK
2. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
3. Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, CA 90095, USA
4. Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l’Université, F-67000 Strasbourg, France
5. Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany
6. Dalhousie University Department of Physics and Atmospheric Science, Coburg Road, Halifax B3H1A6, Canada
7. Department of Physics & Astronomy, Bloomberg Center for Physics and Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, UK