1. Instituto de Astrofísica de Canarias , E-38205 La Laguna, Tenerife, Spain
2. Departamento de Astrofísica, Universidad de La Laguna , E-38206 La Laguna, Tenerife, Spain
3. Space Telescope Science Institute , 3700 San Martin Dr, Baltimore, MD 21218, USA
4. Australian Astronomical Optics, Macquarie University , 105 Delhi Rd, North Ryde, NSW 2113, Australia
5. Department of Astrophysics/IMAPP, Radboud University , PO Box 9010, NL-6500 GL Nijmegen, the Netherlands
6. SRON, Netherlands Institute for Space Research , Niels Bohrweg 4, NL-2333 CA Leiden, the Netherlands