[1] Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA
[2] Princeton Univ, Dept Astrophys Sci, Princeton, NJ 08544 USA
[3] Univ Oxford, Subdept Astrophys, Oxford OX1 3RH, England
[4] Univ Paris Diderot, APC, Observ Paris, CNRS,IN2P3,CEA,IRFU, Sorbonne Paris Cite, France
[5] Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA
[6] Univ Roma La Sapienza, Dept Phys, I-00185 Rome, Italy
[7] Apache Point Observ, Sunspot, NM 88349 USA
[8] Univ Toronto, Canadian Inst Theoret Astrophys, Toronto, ON M5S 3H8, Canada
[9] Univ Pittsburgh, Dept Phys & Astron, Pittsburgh, PA 15260 USA
[10] Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA
[11] Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA
[12] Univ Utah, Dept Phys & Astron, Salt Lake City, UT 84112 USA
[13] Univ Penn, Dept Phys & Astron, Philadelphia, PA 19104 USA
[14] Pontificia Univ Catolica Chile, Dept Astron & Astrofis, Santiago 22, Chile
[15] Harvard Coll Observ, Cambridge, MA 02138 USA
[16] NIST Quantum Devices Grp, Boulder, CO 80305 USA
[17] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA
[18] Univ British Columbia, Dept Phys & Astron, Vancouver, BC V6T 1Z4, Canada
[19] Univ Nottingham, Sch Phys & Astron, Nottingham NG7 2RD, England
[20] Princeton Univ, Joseph Henry Labs Phys, Princeton, NJ 08544 USA
[21] Rutgers State Univ, Dept Phys & Astron, Piscataway, NJ 08854 USA
[22] Univ Pittsburgh, Pittsburgh Particle Phys Astrophys & Cosmol Ctr, Pittsburgh, PA 15260 USA
[23] Acad Sinica, Inst Astron & Astrophys, Taipei 115, Taiwan
[24] Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA
[25] Univ KwaZulu Natal, Sch Math Sci, Astrophys & Cosmol Res Unit, ZA-4041 Durban, South Africa
[26] CEA, Ctr Saclay, IRFU, F-91191 Gif Sur Yvette, France
[27] Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA
[28] Penn State Univ, Inst Gravitat & Cosmos, University Pk, PA 16802 USA
[29] NYU, Ctr Cosmol & Particle Phys, New York, NY 10003 USA
[30] NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA