1. Instituto de Astrofísica de Canarias (IAC), E-38205 La Laguna, Tenerife, Spain
2. Departamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain
3. South African Astronomical Observatory, PO Box 9, Observatory 7935, Cape Town, South Africa
4. Department of Physics & Astronomy, University of Southampton, Southampton SO17 1BJ, UK
5. European Southern Observatory (ESO), Alonso de Córdova 3107, Vitacura, Casilla 19, Santiago, Chile
6. Pontificia Universidad Católica de Chile, Vicuña-Mackenna 4860, Macul, Santiago, Chile
7. Astrophysics, Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK
8. Istituto di Astrofisica e Planetologia Spaziali (INAF-IAPS), Via Fosso del Cavaliere 100, I-00133 Roma, Italy
9. Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, UK
10. INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (LC), Italy
11. Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, D-85748, Garching, Germany