1. Physics and Astronomy, University of Southampton, Southampton, Hampshire SO17 1BJ, UK
2. Instituto de Astrofísica de Canarias (IAC), Vía Láctea s/n, La Laguna, E-38205 S/C de Tenerife, Spain
3. Departamento de Astrofísica, Universidad de La Laguna, La Laguna, E-38205 S/C de Tenerife, Spain
4. Kapteyn Astronomical Institute, University of Groningen, PO Box 800, NL-9700 AV Groningen, the Netherlands
5. Extreme Natural Phenomena RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
6. Eureka Scientific, Inc., 2452 Delmer Street, Oakland, CA 94602, USA
7. SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, NL-3584 CA Utrecht, the Netherlands
8. MIT Kavli Institute for Astrophysics and Space Research, MIT, 70 Vassar Street, Cambridge, MA 02139, USA
9. Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, NL-1098 XH Amsterdam, the Netherlands
10. Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
11. Dipartimento di Fisica, Università degli Studi di Cagliari, SP Monserrato-Sestu km 0.7, I-09042 Monserrato, Italy
12. Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
13. Department of Physics, Villanova University, Villanova, PA 19085, USA
14. Department of Physics, University of Rome ‘Tor Vergata’, Via della Ricerca Scientifica 1, I-00133 Rome, Italy
15. Department of Astronomy, University of Maryland, College Park, MD 20742, USA
16. INAF Osservatorio Astronomico di Roma, Via Frascati 33, I-00078 Monte Porzio Catone (Rome), Italy