1. SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
2. Space Sciences Laboratory, UC Berkeley, 94720 CA, USA
3. Centro de Rádio Astronomia e Astrofísica Mackenzie, Escola de Engenharia, Universidade Presbiteriana Mackenzie, São Paulo 01302, Brazil
4. Rosseland Centre for Solar Physics, University of Oslo, PO Box 1029 Blindern, NO-0315 Oslo, Norway
5. Solar Physics Laboratory, Code 671, Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA