[1] Universität Hamburg, Institut für Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg, Germany
[2] Laboratoire Univers et Particules de Montpellier, Université Montpellier 2, CNRS/IN2P3, CC 72, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
[3] Max-Planck-Institut für Kernphysik, PO Box 103980, 69029 Heidelberg, Germany
[4] Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2, Ireland
[5] National Academy of Sciences of the Republic of Armenia, Yerevan, Armenia
[6] Yerevan Physics Institute, 2 Alikhanian Brothers St., 375036 Yerevan, Armenia
[7] Universität Erlangen-Nürnberg, Physikalisches Institut, Erwin-Rommel-Str. 1, 91058 Erlangen, Germany
[8] University of Durham, Department of Physics, South Road, Durham DH1 3LE, United Kingdom
[9] Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warsaw, Poland
[10] CEA Saclay, DSM/IRFU, 91191 Gif-Sur-Yvette Cedex, France
[11] APC, AstroParticule et Cosmologie, Université Paris Diderot, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France
[12] Laboratoire Leprince-Ringuet, École Polytechnique, CNRS/IN2P3, 91128 Palaiseau, France
[13] Institut für Theoretische Physik, Lehrstuhl IV Weltraum und Astrophysik, Ruhr-Universität Bochum, 44780 Bochum, Germany
[14] Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
[15] LUTH, Observatoire de Paris, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France
[16] LPNHE, Université Pierre et Marie Curie Paris 6, Université Denis Diderot Paris 7, 4 place Jussieu, 75252 Paris Cedex 5, France
[17] Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
[18] Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warsaw, Poland
[19] Unit for SpacePhysics, North-West University, 2520 Potchefstroom, South Africa
[20] Landessternwarte, Universität Heidelberg, Königstuhl, 69117 Heidelberg, Germany
[21] Oskar Klein Centre, Department of Physics, Stockholm University, 10691 Stockholm, Sweden
[22] University of Namibia, Department of Physics, Private Bag 13301, Windhoek, Namibia
[23] UJF-Grenoble 1/CNRS-INSU, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, 38041 Grenoble, France
[24] Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, United Kingdom
[25] Instytut Fizyki Ja¸drowej PAN, ul. Radzikowskiego 152, 31-342 Kraków, Poland
[26] Institut für Astro- und Teilchenphysik, Leopold-Franzens-Universität Innsbruck, 6020 Innsbruck, Austria
[27] Laboratoire d'Annecy-le-Vieux de Physique des Particules, Univ. de Savoie, CNRS/IN2P3, 74941 Annecy-le-Vieux, France
[28] Obserwatorium Astronomiczne, Uniwersytet Jagiellon´ski, ul. Orla 171, 30-244 Kraków, Poland
[29] Torun´ Centre for Astronomy, Nicolaus Copernicus University, ul. Gagarina 11, 87-100 Torun´, Poland
[30] School of Chemistry and Physics, University of Adelaide, Adelaide 5005, Australia
[31] Charles University, Faculty of Mathematics and Physics, Institute of Particle and Nuclear Physics, V Holešovičkách 2, 180 00 Prague 8, Czech Republic
[32] School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
[33] Université Bordeaux 1, CNRS/IN2p3, Centre d'Itudes Nucléaires de Bordeaux Gradignan, 33175 Gradignan, France
[34] European Associated Laboratory for Gamma-Ray Astronomy, United States