[1] Space Telescope Sci Inst, Baltimore, MD 21218 USA
[2] Johns Hopkins Univ, Dept Phys & Astron, Bloomberg Ctr 366, Baltimore, MD 21218 USA
[3] Rochester Inst Technol, Ctr Imaging Sci, Rochester, NY 14623 USA
[4] Rochester Inst Technol, Lab Multiwavelength Astrophys, Rochester, NY 14623 USA
[5] NASA, Observat Cosmol Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA
[6] ORAU, Oak Ridge, TN 37831 USA
[7] Space Sci Inst, Boulder, CO 80301 USA
[8] Heidelberg Univ, Inst Theoret Astrophys, Zentrum Astron, D-69120 Heidelberg, Germany