1. Department of Physics and Astronomy, University of Alabama in Huntsville, Huntsville, AL 35899, USA
2. Deutsches Elektronen Synchrotron (DESY), Platanenallee 6, D-15738 Zeuthen, Germany
3. Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street S.E., Minneapolis, MN 55455, USA
4. Department of Astronomy, University of Virginia, 530 McCormick Rd., Charlottesville, VA 22904, USA
5. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
6. Optical and Infrared Astronomy Division, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan
7. Aix-Marseille Univ., CNRS, CNES, LAM, Marseille 13013, France
8. Institute for Computational Cosmology and Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
9. Universitá di Milano-Bicocca, piazza della scienza 3, I-20100, Milano, Italy