1. Instituto de Astronomia, Geofísica e Ciências Atmosféricas da USP, Rua do Matão 1226, Cidade Universitária São Paulo-SP, 05508-090, Brasil
2. Facultad de Ciencias Astronómicas y Geofísicas – Universidad Nacional de La Plata, Paseo del Bosque S/N – B1900FWA La Plata, Argentina
3. Instituto de Astrofísica de La Plata (CCT La Plata – CONICET/UNLP), B1900FWA, La Plata, Argentina
4. Departamento de Física, Universidade Federal do Rio Grande do Norte, UFRN, CP 1641, Natal, RN, 59072-970, Brazil
5. CRESST II & X-ray Astrophysics Laboratory, Code 662, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
6. Institute for Astrophysics and Computational Sciences, Department of Physics, The Catholic University of America, Washington, DC 20064, USA
7. Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742-5815, USA
8. Laboratory for Extraterrestrial Planets and Stellar Astrophysics, Code 667, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
9. Department of Physics, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
10. Department of Physics and Astronomy & Pittsburgh Particle Physics, Astrophysics, and Cosmology Center (PITT PACC), University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260, USA
11. Instituto Nacional de Pesquisas Espaciais/MCTIC Avenida dos Astronautas 1758, São José dos Campos, SP, 12227-010, Brazil
12. Department of Physics and Astronomy, San José State University, One Washington Square, San José, CA 95192-0106, USA
13. Département de physique and Centre de Recherche en Astrophysique du Québec (CRAQ), Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, QC H3C 3J7, Canada
14. Ritter Observatory, Department of Physics and Astronomy, The University of Toledo, Toledo, OH 43606-3390, USA
15. Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, D-53121 Bonn, Germany