Institution: | 1South African Astronomical Observatory, PO Box 9, Observatory, 7935 Cape, South Africa; 2Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, 3001 Heverlee, Belgium; 3Observatoire de Genève, 1290 Sauverny, Switzerland; 4Princeton University Observatory, Princeton, NJ 08544, USA |