[1] Max Planck Inst Astron, D-69117 Heidelberg, Germany
[2] Leiden Observ, NL-2300 RA Leiden, Netherlands
[3] Max Planck Inst Extraterr Phys, D-85748 Garching, Germany
[4] Yale Univ, Dept Astron, New Haven, CT 06520 USA
[5] Univ Calif Santa Cruz, Univ Calif Observ, Lick Observ, Santa Cruz, CA 95064 USA
[6] Univ Calif Santa Cruz, Dept Astron, Santa Cruz, CA 95064 USA
[7] Carnegie Inst Washington Observ, Pasadena, CA 91101 USA
[8] European So Observ, D-85748 Garching, Germany
[9] Natl Opt Astron Observ, Tucson, AZ 85719 USA