[1] Princeton Univ Observ, Princeton, NJ 08544 USA
[2] Univ Washington, Dept Astron, Seattle, WA 98195 USA
[3] Max Planck Inst Extraterr Phys, D-85750 Garching, Germany
[4] Fermilab Natl Accelerator Lab, Batavia, IL 60510 USA
[5] Apache Point Observ, Sunspot, NM 88349 USA
[6] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA
[7] CALTECH, Dept Astron, Pasadena, CA 91125 USA
[8] Eotvos Lorand Univ, Dept Phys Complex Syst, H-1117 Budapest, Hungary
[9] Univ Tokyo, Sch Sci, Dept Astron, Tokyo 1130033, Japan
[10] Univ Chicago, Ctr Astron & Astrophys, Chicago, IL 60637 USA
[11] Univ Tokyo, Inst Cosm Ray Res, Tanashi, Tokyo 1888502, Japan
[12] Inst Adv Study, Princeton, NJ 08540 USA
[13] USN Observ, Washington, DC 20392 USA
[14] Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA
[15] USN Observ, Flagstaff Stn, Flagstaff, AZ 86002 USA
[16] Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA
[17] Univ Tokyo, Sch Sci, Res Ctr Early Universe, Tokyo 1130033, Japan