1. Lockheed Martin, Palo Alto, California, United States
2. NASA Goddard Space Flight Center, Greenbelt, Maryland, United States
3. Università degli Studi di Palermo, Dipartimento di Fisica e Chimica “E. Segré,” Palermo, Italy
4. University of Geneva, Department of Astronomy, Versoix, Switzerland
5. University College London, Department of Physics and Astronomy, London, United Kingdom
6. Center for Astrophysics, Harvard & Smithsonian, Cambridge, Massachusetts, United States
7. Dublin Institute for Advanced Studies, School of Cosmic Physics, DIAS Dunsink Observatory, Dublin, Ireland