1. Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands
2. Sterrenkundig Instituut Anton Pannekoek, Science Park 904, NL-1098 XH Amsterdam, the Netherlands
3. European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München, Germany
4. Rockhurst University, Department of Physics, 1100 Rockhurst Road, Kansas City MO 64110, USA
5. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, M/S 321-100, Pasadena CA 91109, USA
6. Department of Physics & Astronomy, University of Rochester, Rochester NY 14627, USA
7. IPAC, California Institute of Technology, M/C 100-22, 1200 East California Boulevard, Pasadena CA 91125, USA
8. Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium