1. X-Ray and Observational Astronomy Group, School of Physics & Astronomy, University of Leicester, Leicester LE1 7RH, UK
2. Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
3. Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800, USA
4. Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
5. European Space Astronomy Centre, E-28692 Villanueva de la Cañada, Madrid, Spain
6. INAF – Osservatorio di Padova, Vicolo Osservatorio 5, I-35122 Padova, Italy
7. Department of Astronomy, University of Wisconsin, 475 N. Charter St., Madison, WI 53706, USA
8. Center for Data Intensive and Time Domain Astronomy, Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
9. Sternberg Astronomical Institute, Moscow State University, Universitetskii pr. 13, 119992 Moscow, Russia