[1] Max Planck Inst Kernphys, D-69117 Heidelberg, Germany
[2] Yerevan Phys Inst, Yerevan, Armenia
[3] CNRS UPS, Ctr Etud Spatiale Rayonnements, Toulouse, France
[4] Univ Hamburg, Inst Expt Phys, Hamburg, Germany
[5] Humboldt Univ, Inst Phys, D-1086 Berlin, Germany
[6] Univ Paris 07, LUTH, Observ Paris, CNRS, Meudon, France
[7] CE Saclay, DAPNIA DSM CEA, Gif Sur Yvette, France
[8] Univ Durham, Dept Phys, Durham DH1 3HP, England
[9] NW Univ, Unit Space Phys, Potchefstroom, South Africa
[10] CNRS IN2P3, Lab Leprince Ringuet, Ecole Polytech, Palaiseau, France
[11] CNRS IN2P3, Lab Annecy Le Vieux Phys Particules, Annecy Le Vieux, France
[12] Univ Paris 07, CNRS, APC, Paris, France
[13] Univ Paris 07, UMR 7164, CNRS, CEA,Observ Paris, F-75221 Paris 05, France
[14] Dublin Inst Adv Studies, Dublin, Ireland
[15] Univ Heidelberg, Landessternwarte Konigstuhl, Konigstuhl, Germany
[16] Univ Montpellier 2, Lab Phys Theor & Astroparticules, CNRS IN2P3, Montpellier, France
[17] Univ Erlangen Nurnberg, Inst Phys, D-8520 Erlangen, Germany
[18] Univ Grenoble 1, Astrophys Lab, INSU CNRS, Grenoble, France
[19] Univ Tubingen, Inst Astron & Astrophys, D-72074 Tubingen, Germany
[20] Univ Paris 06, LPNHE, CNRS IN2P3, Paris, France
[21] Univ Paris 07, LPNHE, CNRS IN2P3, Paris, France
[22] Charles Univ Prague, Inst Nucl & Particle Phys, CR-18000 Prague 8, Czech Republic
[23] Ruhr Univ Bochum, Inst Theoret Phys, Lehrstuhl 4, D-4630 Bochum, Germany
[24] Univ Namibia, Windhoek, Namibia
[25] Univ Jagiellonski, Astron Observ, Krakow, Poland
[26] Nicolaus Copernicus Astron Ctr, Warsaw, Poland
[27] Univ Leeds, Sch Phys & Astron, Leeds LS2 9JT, W Yorkshire, England
[28] Univ Adelaide, Sch Chem & Phys, Adelaide, SA 5005, Australia
[29] Nicholas Copernicus Univ, Torun Ctr Astron, Torun, Poland
[30] CNRS & MPG, European Associated Lab Gamma Ray Astron, F-75700 Paris, France
[31] Stanford Univ, HEPL & KIPAC, Stanford, CA 94305 USA