¹ Institute for Nuclear and Particle Astrophysics, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720
² European Southern Observatory, La Silla, Chile
³ Institute of Astronomy, Cambridge, England, UK
⁴ Department of Astronomy, University of Barcelona, Barcelona, Spain
⁵ Isaac Newton Group, La Palma, Spain
⁶ Department of Astronomy, Yale University, New Haven, CT
⁷ Anglo-Australian Observatory, Sydney, Australia
⁸ Department of Astronomy, University of California, Berkeley, CA
⁹ Space Telescope Science Institute, Baltimore, MD
¹⁰ Fermi National Laboratory, Batavia, IL
¹¹ University of New South Wales, Sydney, Australia
¹² Center for Particle Astrophysics, University of California, Berkeley, California
¹³ Instituto Superior Técnico, Lisbon, Portugal
¹⁴ LPNHE, CNRS-IN2P3, and University of Paris VI and VII, Paris, France
¹⁵ Department of Physics, University of Stockholm, Stockholm, Sweden
¹⁶ European Southern Observatory, Munich, Germany
¹⁷ PCC, CNRS-IN2P3, and Collège de France, Paris, France
¹⁸ Institute of Astronomy, Cambridge, England, UK
¹⁹ Space Sciences Laboratory, University of California, Berkeley, California
²⁰ Space Sciences Department, European Space Agency