1. Department of Astronomy, Yale University, PO Box 208101, New Haven, CT 06520, USA
2. Laboratoire Lagrange, Observatoire de la Côte d'Azur, CNRS, Blvd de l'Observatoire, CS 34229, F-06304 Nice cedex 4, France
3. University Observatory Munich (USM), Scheinerstr. 1, D-81679 Munich, Germany
4. Associated Scientist, Max-Planck-Institute for Extraterrestrial Physics (MPE), Giessenbachstr. 1, D-85748 Garching, Germany