1. M. G. Kivelson, K. K. Khurana, R. J. Walker, J. Warnecke, C. T. Russell, Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, USA.
2. J. A. Linker, Science Applications International Corporation, San Diego, CA 92171, USA.
3. D. J. Southwood, Department of Physics, Imperial College of Science, Technology, and Medicine, London SW7 2BZ, UK.
4. C. Polanskey, Jet Propulsion Laboratory, Pasadena, CA 91109, USA.