1. Department of Physics and Astronomy University of Iowa Iowa City IA USA
2. Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, CNRS/Observatoire de Paris Meudon France
3. Naval Research Laboratory Washington DC USA
4. Department of Physics and Astronomy Middle Tennessee State University Murfreesboro TN USA
5. Space Research Institute Austrian Academy of Sciences Graz Austria
6. Institute of Radio Astronomy National Academy of Sciences of Ukraine Kharkiv Ukraine
7. Poltava Gravimetrical Observatory, S. Subotin Institute of Geophysics National Academy of Sciences of Ukraine Poltava Ukraine
8. Karpenko Physico‐Mechanical Institute National Academy of Sciences of Ukraine Lviv Ukraine