1. Harvard-Smithsonian Ctr. for Astrophysics (United States)
2. Cardiff Univ. (United Kingdom)
3. Stanford Univ. (United States)
4. The Univ. of British Columbia (Canada)
5. Univ. of Toronto (Canada)
6. California Institute of Technology (United States)
7. Univ. of Minnesota (United States)
8. National Institute of Standards and Technology (United States)
9. The Univ. of Chicago (United States)
10. Jet Propulsion Lab. (United States)
11. Univ. of Minnesota, Twin Cities (United States)
12. Univ. of California, Berkeley (United States)