1. Department of Astronomy, University of California , Berkeley, CA 94720-3411 , USA
2. European Organisation for Astronomical Research in the Southern Hemisphere (ESO) , Karl-Schwarzschild-Str. 2, D-85748 Garching b. München , Germany
3. Department of Physics, Florida State University , Tallahassee, FL 32306-4350 , USA
4. Department of Physics and Astronomy, University of Sheffield , Hicks Building, Hounsfield Road, Sheffield S3 7RH , UK
5. George P. and Cynthia Woods Mitchell Institute for Fundamental Physics & Astronomy, Texas A&M University , 4242 TAMU, College Station, TX 77843 , USA
6. Department of Astronomy, University of Texas , Austin, TX 78712 , USA