1. Johns Hopkins University Applied Physics Laboratory; Laurel Maryland USA
2. Space Science and Engineering Division; Southwest Research Institute; San Antonio Texas USA
3. Université de Versailles St. Quentin, LATMOS, Pierre et Marie Curie, CNRS; Guyancourt France
4. Institut Universitaire de France; Paris France
5. Department of Physics and Astronomy; University of Kansas; Lawrence Kansas USA
6. Department of Physics and Astronomy; Benedictine College; Atchison Kansas USA