1. ESA European Space Research and Technology Centre, Noordwijk, The Netherlands
2. University of Leicester, Department of Physics and Astronomy, Leicester, United Kingdom
3. Center for Astrophysics, Harvard and Smithsonian, Cambridge, Massachusetts, United States
4. Max-Planck-Institut für extraterrestrische Physik, Garching bei München, Germany
5. NWO-I/SRON, Netherlands Institute for Space Research, Leiden, The Netherlands
6. European Space Agency (ESA), European Space Astronomy Centre, Madrid, Spain
7. INAF, IAPS, Rome, Italy