1. Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, E-08193 Bellaterra (Barcelona), Spain
2. Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, E-08193 Barcelona, Spain
3. Institut d’Estudis Espacials de Catalunya (IEEC), E-08034 Barcelona, Spain
4. Institute for Particle Physics and Astrophysics, ETH Zürich, Wolfgang-Pauli-Str 27, CH-8093 Zürich, Switzerland
5. Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Avenida Complutense 40, E-28040 Madrid (Madrid), Spain
6. Instituto de Fisica Teorica (IFT-UAM/CSIC), Universidad Autonoma de Madrid, E-28049 Madrid, Spain
7. Argelander-Institut für Astronomie, Auf dem Hügel 71, D-53121 Bonn, Germany
8. Leiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333CA Leiden, the Netherlands
9. Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK
10. Institute for Computational Cosmology and Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham DH1 3LE, UK
11. Institució Catalana de Recerca i Estudis Avançats (ICREA), E-08010 Barcelona, Spain