[1] Max-Planck-Institut für Astronomie (MPIA), Königstuhl 17, 69117 Heidelberg, Germany
[2] University of Kiel, Institute of Theoretical Physics and Astrophysics, Leibnizstrasse 15, 24098 Kiel, Germany
[3] Research and Scientific Support Department, ESA/ESTEC, 2201 AZ Noordwijk, Netherlands
[4] California Institute of Technology, Department of Astronomy, MS 105-24, Pasadena, CA 91125, United States
[5] Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, United States
[6] Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 169-506, Pasadena, CA 91109, United States