1. NASA Goddard Space Flight Center , Greenbelt, MD 20771 , USA
2. Center for Space Sciences and Technology, University of Maryland , Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 , USA
3. Max-Planck-Institut für Astronomie , Königstuhl 17, D-69117 Heidelberg , Germany
4. Zentrum für Astronomie, Institut für theoretische Astrophysik, Universität Heidelberg , Albert-Ueberle-Str 2, D-69120 Heidelberg , Germany
5. Center for Astrophysics I Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138 , USA
6. Deparment of Astronomy, University of Maryland , College Park, MD 20742-2421 , USA
7. CASA, Department of Astrophysical and Planetary Sciences, University of Colorado , 389 UCB, Boulder, CO 80309 , USA
8. Department of Physics, Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139 , USA
9. Joint Space-Science Institute, University of Maryland , College Park, MD 20742 , USA
10. Astronomy Department, University of Massachusetts , Amherst, MA 01003 , USA
11. Department of Theoretical Physics and Astrophysics, Faculty of Science, Masaryk University , Kotlářská 2, CZ-611 37 Brno , Czech Republic
12. Department of Astronomy and Astrophysics, The University of Chicago , Chicago, IL 60637 , USA