| Affiliation: |
| AA(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 ), AB(Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-264, 04510 México DF, Mexico; American Museum of National History, Central Park West at 79th Street, New York, NY 10024-5192.), AC(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 ), AD(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 ), AE(American Museum of National History, Central Park West at 79th Street, New York, NY 10024-5192; Max-Planck-Institut für Radioastronomie, auf dem Hügel 69, Bonn D-53121, Germany), AF(Department of Physics, University of Cincinnati, Cincinnati, OH 45221-0011.) |