1. Departement Physik, Universität Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
2. Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA.
3. Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia.
4. European Southern Observatory (ESO), Karl-Schwarschild-Strasse 1, 85748 Garching bei München, Germany.