1. Smithsonian Astrophysical Observatory (United States)
2. Univ. of Michigan (United States)
3. SRON (Netherlands)
4. Astronomisches Institut der Univ. Erlangen-Nürnberg (Germany)
5. Johns Hopkins Univ. (United States)
6. Univ. of Leicester (United Kingdom)
7. Massachusetts Institute of Technology (United States)
8. Max-Planck-Institut für extraterrestrische Physik (Germany)
9. NASA Ames Research Ctr. (United States)
10. Pennsylvania State Univ. (United States)
11. Queen's Univ. Belfast (United Kingdom)
12. The Univ. of Iowa (United States)
13. Univ. of Maryland, College Park (United States)