1. National Solar Observatory, 3665 Discovery Drive, Boulder, Colorado 80303, United StatesbKiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, D-79104 Freiburg, GermanycUniversity of Hawaii, Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, Hawaii 96822, United States
2. University of Hawaii, Institute for Astronomy Maui, 34 Ohia Ku Street, Pukalani, Hawaii 96768, United States
3. IRAP CNRS, UMR 5277, 14, Avenue E Belin, Toulouse, France