1. Instituto de Astronomía, Universidad Nacional Autónoma de México, A.P. 70-264, 04510 CDMX, Mexico
2. Max Planck Institute for Astronomy, Konigstuhl 17, D-69117 Heidelberg, Germany
3. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching b. Munchen, Germany
4. LERMA, CNRS UMR 8112, Observatoire de Paris, 61 Avenue de l’Observatoire, F-75014 Paris, France
5. Instituto de Astrofísica de Andalucía (CSIC), PO Box 3004, E-18080 Granada, Spain