1. Hermanus Magnetic Observatory; Hermanus South Africa
2. School of Physics; University of KwaZulu-Natal; Durban South Africa
3. Space Research Group; Eötvös University; Budapest Hungary
4. Physical Sciences Division; British Antarctic Survey; Cambridge UK
5. Department of Physics; University of Otago; Dunedin New Zealand
6. Research Group for Geology, Geophysics and Space Sciences, Hungarian Academy of Sciences; Eötvös University; Budapest Hungary