[1] Space Telescope Sci Inst, Baltimore, MD 21218 USA
[2] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA
[3] Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA
[4] Inst Astrophys, CNRS, F-75014 Paris, France
[5] European So Observ, D-85748 Garching, Germany
[6] Yale Univ, Dept Astron, New Haven, CT 06520 USA
[7] CALTECH, Palomar Observ, Pasadena, CA 91125 USA
[8] Osserv Astron Trieste, Ist Nazl Astrofis, I-34131 Trieste, Italy
[9] NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA
[10] CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA
[11] Max Planck Inst Astrophys, D-85748 Garching, Germany
[12] Univ Calif Davis, Dept Phys, Davis, CA 95616 USA
[13] European Space Agcy, Space Telescope Div, F-75738 Paris 15, France
[14] European So Observ, Space Telescope European Coordinating Facil, D-85748 Garching, Germany
[15] Univ Calif Santa Cruz, Dept Astron & Astrophys, Santa Cruz, CA 95064 USA
[16] Univ Arizona, Steward Observ, Tucson, AZ 85721 USA
[17] Univ Bonn, Inst Astrophys & Extraterr Forsch, D-53121 Bonn, Germany
[18] Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA
[19] Univ Oxford, Dept Phys, Oxford OX1 3RH, England