1 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, China
2 Max-Planck-Institute for Astronomy, K?nigstuhl 17, D-69117 Heidelberg, Germany
3 Graduate School of Chinese Academy of Sciences, Beijing 100039, China
4 LESIA - Observatoire de Paris, 77, Avenue Denfert-Rochereau, 75014 Paris, France
5 Max Planck Institute for Extraterrestrial Physics, Postfach 1312, 85741 Garching, Germany
6 Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, China