1. European Southern Observatory, Alonso de Córdova 3107, Casilla 19001, Santiago, Chile
2. Institute of Astrophysics, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile
3. European Southern Observatory, Karl-Schwarzschild-Straße 2, D-85748 Garching bei München, Germany