1. L. A. Frank, W. R. Paterson, K. L. Ackerson, Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, USA.
2. V. M. Vasyliunas, Max Planck Institut für Aeronomie, Katlenburg-Lindau, Germany.
3. F. V. Coroniti, Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA.
4. S. J. Bolton, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.