[1] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA
[2] Canada France Hawaii Telescope Corp, Kamuela, HI 96743 USA
[3] CALTECH, Pasadena, CA 91125 USA
[4] NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA
[5] Columbia Univ, Dept Astron, New York, NY 10027 USA
[6] Observ Carnegie Inst Washington, Pasadena, CA 91101 USA
[7] CNRS, Astrophys Lab, F-13388 Marseille 13, France
[8] Yonsei Univ, Ctr Space Astrophys, Seoul 120749, South Korea
[9] Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA