1. DIRAC Institute, Department of Astronomy, University of Washington , 3910 15th Avenue NE, Seattle, WA 98195, USA
2. Division of Physics, Mathematics, and Astronomy, California Institute of Technology , Pasadena, CA 91125, USA
3. Astrophysics Research Institute, Liverpool John Moores University , IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UK
4. The Oskar Klein Centre, Department of Physics, Stockholm University , SE-106 91 Stockholm, Sweden
5. The Oskar Klein Centre, Department of Astronomy, Stockholm University , SE-106 91 Stockholm, Sweden
6. E.O. Lawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, CA 94720, USA
7. Department of Astronomy, University of California , Berkeley, CA 94720-3411, USA
8. Institute of Astronomy and Kavli Institute for Cosmology, University of Cambridge , Madingley Road, Cambridge CB3 0HA, UK
9. Institute of Physics, Humboldt-Universität zu Berlin , Newtonstrasse 15, D-12489 Berlin, Germany
10. Center for Interdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern University , 1800 Sherman Ave, Evanston, IL 60201, USA
11. The Adler Planetarium , Chicago, IL 60605, USA
12. Department of Physical Sciences, Arkansas Tech University , 1701 N. Boulder Avenue, Russellville, AR 72801, USA
13. Université de Lyon, Université Claude Bernard Lyon 1, CNRS, IP2I Lyon/IN2P3, IMR 5822 , F-69622 Villeurbanne, France
14. Caltech Optical Observatories, California Institute of Technology , Pasadena, CA 91125, USA