1. Institute of Astronomy, Madingley Rd, Cambridge CB3 0HA, UK
2. Department of Astronomy, University of Maryland, College Park, Maryland 20742-2421, USA
3. European Space Agency (ESA), European Space Astronomy Centre (ESAC), E-28691 Villanueva de la Cañada, Madrid, Spain
4. Montana State University, PO Box 173840 Bozeman, MT 59717-3840, USA
5. Astronomical Institute ‘Anton Pannekoek’, University of Amsterdam, Science Park 904, NL-1098XH Amsterdam, the Netherlands
6. Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305, USA
7. Nicolaus Copernicus Astronomical Centre of the Polish Academy of Sciences, ul. Bartycka 18, PL-00-716 Warszawa, Poland
8. Department of Physics & Astronomy, Wayne State University, 666 W. Hancock St, Detroit, MI 48201, USA
9. Department of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ, UK
10. Department of Astronomy and Physics, Saint Mary’s University, 923 Robie Street, Halifax, NS B3H 3C 3, Canada
11. Department of Astronomy, University of Michigan, 1085 S. University, Ann Arbor, MI 48109, USA
12. Centro de Astrobiología (CSIC–INTA), Dep. de Astrofísica; ESAC campus, E-28692 Villanueva de la Cañada, Spain
13. Astronomical Institute of the Czech Academy of Sciences, CZ-14100 Prague, Czech Republic
14. H. H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, UK