1. Department of Physics, University of California , Santa Barbara, Santa Barbara, CA 93106, USA
2. Department of Astronomy, The University of Texas at Austin , Austin, TX 78712, USA
3. Institute for Astronomy, University of Edinburgh, Royal Observatory , Blackford Hill, Edinburgh EH9 3HJ, UK
4. Astronomy & Astrophysics Department, University of California , Santa Cruz, CA 95064, USA
5. Department of Physics and Astronomy, University of California , Los Angeles, 475 Portola Plaza, Los Angeles, CA 90025, USA
6. American Museum of Natural History , New York, NY 10023, USA
7. Department of Physics and Astronomy, The University of Texas at San Antonio , San Antonio, TX 78249, USA
8. Sub-department of Astrophysics, Department of Physics, University of Oxford , Keble Road, Oxford OX1 3RH, UK