Institution: | (1) Joint Institute for Laboratory Astrophysics, Univ. of Colorado, 80302 Boulder, Colo., U.S.A.;(2) Present address: Dept. of Atomic Physics, The University, Newcastle upon Tyne, England;(3) Present address: Ionospheric Prediction Service Division, Commonwealth Centre, 2000 Sydney, New South Wales, Australia;(4) Present address: United Aircraft Research Laboratories, 06108 East Hartford, Conn., U.S.A. |