¹ Department of Physics and Astronomy, Iowa State University, Ames, IA 50011
² Now at NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771
³ Department of Physics, University of Leeds, Leeds, LS2 9JT Yorkshire, England, UK
⁴ Department of Physics, Washington University, St. Louis, MO 63130
⁵ Department of Physics, Purdue University, West Lafayette, IN 47907
⁶ Physics Department, Grinnell College, Grinnell, IA 50112
⁷ Physics Department, National University of Ireland, Belfield, Dublin 4, Ireland
⁸ Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645
⁹ Department of Physics, University of Arizona, Tucson, AZ 85721
¹⁰ High Energy Astrophysics Institute, University of Utah, Salt Lake City, UT 84112
¹¹ Department of Physics and Astronomy, University of Arkansas, Little Rock, AR 72204
¹² Physics Department, De Pauw University, Greencastle, IN, 46135
¹³ School of Science, Galway-Mayo Institute of Technology, Galway, Ireland
¹⁴ Enrico Fermi Institute, University of Chicago, Chicago, IL 60637
¹⁵ Department of Physics, University of California, Los Angeles, CA 90095
¹⁶ Department of Physics, Kansas State University, Manhattan, KS 66506
¹⁷ Department of Physics, Cork Institute of Technology, Cork, Ireland