University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242, USA
CNRS/Universite Paul Sabatier, Centre d-Etude Spatiale des Rayonnements, Toulouse, 31062, France
University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242, USA
University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242, USA
University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242, USA
Charles University, Faculty of Mathematics and Physics, Prague, CZ-18000, Czech Republic; Czech Academy of Sciences, Institute of Atmospheric Physics, Prague, 14133, Czech Republic