[1] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA
[2] Inst Astrophys, CNRS, F-75014 Paris, France
[3] CALTECH, Pasadena, CA 91125 USA
[4] Lab Astrophys Marseille, F-13376 Marseille 12, France
[5] Yonsei Univ, Ctr Space Astrophya, Seoul 120749, South Korea
[6] Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA
[7] Observ Carnegie Inst Washington, Pasadena, CA 91101 USA
[8] NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA
[9] Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA
[10] Columbia Univ, Dept Astron, New York, NY 10027 USA