1. Centro de Rádio Astronomia e Astrofísica Mackenzie, Escola de Engenharia, Universidade Presbiteriana Mackenzie , 01302-907 São Paulo , Brazil
2. SUPA School of Physics and Astronomy, University of Glasgow , Glasgow G12 8QQ , UK
3. Rosseland Centre for Solar Physics, University of Oslo , PO Box 1029 Blindern, NO-0315 Oslo , Norway
4. Space Sciences Laboratory, University of California , Berkeley, CA 94720 , USA
5. NASA Goddard Space Flight Center, Heliophysics Science Division , Code 671, 8800 Greenbelt Rd., Greenbelt, MD 20771 , USA
6. Department of Physics, Catholic University of America , 620 Michigan Avenue, Northeast, Washington, DC 20064 , USA
7. Department of Physics, Southern Illinois University Carbondale , IL 62901 , USA