1. Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
2. European Southern Observatory , Alonso de Cordova 3107, Vitacura, Casilla, 19001 Santiago de Chile, Chile
3. Department of Physics, University of Oxford , Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
4. European Southern Observatory , Karl-Schwarzschild-Strasse 2, Garching bei München, 85748, Germany
5. INAF - Osservatorio Astronomico di Roma , Via Frascati 33 00040, Monte Porzio Catone, Italy
6. INAF - Istituto di Astrofisica Spaziale e Fisica Cosmica Milano , Via A. Corti 12, 20133 Milano, Italy
7. Centro de Astrobiología (CAB) , CSIC–INTA, Ctra. de Ajalvir Km. 4, 28850 Torrejón de Ardoz, Madrid, Spain
8. Scuola Normale Superiore , Piazza dei Cavalieri 7, I-56126 Pisa, Italy
9. INAF - Osservatorio Astrofisico di Arcetri , Largo E. Fermi 5, 50125 Firenze, Italy
10. School of Mathematics, Statistics and Physics, Newcastle University , Newcastle upon Tyne NE1 7RU, UK
11. Dipartimento di Fisica e Astronomia, Universitá di Firenze , Via G. Sansone 1, Sesto Fiorentino, 50019 Firenze, Italy
12. Dipartimento di Fisica, Universitá di Trieste, Sezione di Astronomia , Via G.B. Tiepolo 11, I-34131 Trieste, Italy
13. INAF - Osservatorio Astronomico di Trieste , Via G. Tiepolo 11, I-34143 Trieste, Italy
14. Institute of Theoretical Astrophysics, University of Oslo , PO Box 1029, Blindern 0315, Oslo, Norway
15. Department of Physics & Astronomy, University College London , Gower Street, London WC1E 6BT, UK
16. European Space Agency (ESA), European Space Astronomy Centre (ESAC) , Camino Bajo del Castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain
17. Max-Planck-Institut für Astronomie , Königstuhl 17, D-69117 Heidelberg, Germany
18. Dunlap Institute for Astronomy and Astrophysics, University of Toronto , 50 St George Street, Toronto ON M5S 3H4, Canada
19. Department of Physics & Astronomy, University of British Columbia , 6224 Agricultural Road, Vancouver BC V6T 1Z1, Canada
20. School of Physics and Astronomy, Tel-Aviv University , Tel Aviv 69978, Israel
21. Affiliated to INAF-Osservatorio di Astrofisica e Scienza dello Spazio , Via Piero Gobetti 93/3, I-40129 Bologna, Italy
22. Centre for Extragalactic Astronomy, Department of Physics, Durham University , South Road, Durham DH1 3LE, UK
23. Kavli Institute for Cosmology, University of Cambridge , Madingley Road, Cambridge CB3 0HA, UK
24. Cavendish Laboratory - Astrophysics Group, University of Cambridge , 19 JJ Thompson Avenue, Cambridge CB3 0HE, UK
25. Dipartimento di Fisica e Astronomia ‘Augusto Righi’, Universitá degli Studi di Bologna , via P. Gobetti, 93/2, 40129 Bologna, Italy
26. INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna , via Piero Gobetti, 93/3, I-40129 Bologna, Italy