[1] Lockheed Martin Solar & Astrophys Lab, 3251 Hanover St, Palo Alto, CA 94304 USA
[2] Natl Astron Observ Japan, 2-21-1 Osawa, Mitaka, Tokyo 1818588, Japan
[3] Univ Coll London, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England
[4] Hungarian Acad Sci, Res Ctr Astron & Earth Sci, Konkoly Observ, Budapest, Hungary
[5] Univ Paris Diderot, Observ Paris, LESIA, CNRS,UPMC, F-92195 Meudon, France
[6] Natl Solar Observ, 3665 Discovery Dr, Boulder, CO 80303 USA
[7] Natl Ctr Atmospher Res, POB 3000, Boulder, CO 80307 USA