1. Dipartimento di Fisica e Astronomia ‘Galileo Galilei’, Univ. di Padova, Vicolo dell'Osservatorio 3, I-35122 Padova, Italy
2. Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia
3. Istituto Nazionale di Astrofisica – Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monteporzio Catone, Roma, Italy
4. Istituto Nazionale di Astrofisica – Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy
5. Dipartimento di Fisica, Universita’ degli Studi di Cagliari, SP Monserrato-Sestu km 0.7, I-09042 Monserrato, Italy
6. Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
7. Departamento de Fisica y Astronomia, Universidad de La Serena, Av. Juan Cisternas 1200 N, La Serena, Chile
8. Instituto de Investigacion Multidisciplinar en Ciencia y Tecnologia, Universidad de La Serena, Raul Bitran 1305, La Serena, Chile
9. Space Telescope Science Institute, 3800 San Martin Drive, Baltimore, MD 21218, USA
10. Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109, Australia
11. Instituto de Astrofìsica de Canarias, E-38200 La Laguna, Tenerife, Canary Islands, Spain
12. Department of Astrophysics, University of La Laguna, E-38200 La Laguna, Tenerife, Canary Islands, Spain
13. Department of Astronomy, Indiana University, Bloomington, IN 47405, USA