1. Department of Physics, University of Bath , Claverton Down, Bath BA2 7AY , UK
2. Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo , Sayo, Hyogo 679-5313 , Japan
3. Department of Astronomy, University of Tokyo , Hongo, Tokyo 113-0033 , Japan
4. Department of Astronomy, School of Physics and Astronomy, and Shanghai Key Laboratory for Particle Physics and Cosmology, Shanghai Jiao Tong University , Shanghai 200240 , China
5. Institute for Computational Astrophysics and Department of Astronomy and Physics, Saint Mary’s University , 923 Robie Street, Halifax, Nova Scotia B3H 3C3 , Canada
6. Observatório Nacional , Rua José Cristino, 77. CEP 20921-400, São Cristóvão, Rio de Janeiro-RJ , Brazil
7. Astronomical Institute, Tohoku University , 6-3, Aramaki, Aoba, Sendai, Miyagi 980-8578 , Japan
8. Research Center for Space and Cosmic Evolution, Ehime University , 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577 , Japan
9. H H Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristo, BS8 1TL , UK
10. Institute for Cosmic Ray Research, The University of Tokyo , 5-1-5 Kashiwa-no-Ha, Kashiwa, Chiba 277-8582 , Japan
11. Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA) , Taipei 10617 , Taiwan