[1] Max Planck Inst Extraterr Phys, D-85748 Garching, Germany
[2] Univ Portsmouth, Inst Cosmol & Gravitat, Portsmouth PO1 3FX, Hants, England
[3] Univ Sternwarte, D-81679 Munich, Germany
[4] South East Phys Network, SEPNET, Tucson, AZ 85719 USA
[5] Natl Opt Astron Observ, Tucson, AZ 85719 USA
[6] Univ Wisconsin, Dept Astron, Madison, WI 53706 USA
[7] Nanjing Univ, Dept Astron, Nanjing 210093, Jiangsu, Peoples R China
[8] Univ Utah, Dept Phys & Astron, Salt Lake City, UT 84112 USA
[9] Max Planck Inst Astrophys, D-85748 Garching, Germany
[10] Univ Tokyo, Inst Phys & Math Universe, Chiba 2778582, Japan
[11] Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA
[12] Penn State Univ, Inst Gravitat & Cosmos, University Pk, PA 16802 USA
[13] Univ Calif San Diego, Ctr Astrophys & Space Sci, Dept Phys, San Diego, CA 92093 USA
[14] Open Univ, Dept Phys Sci, Milton Keynes MK7 6AA, Bucks, England
[15] Apache Point Observ, Sunspot, NM 88349 USA