1. Physics Department and Tsinghua Centre for Astrophysics (THCA), Tsinghua University, Beijing 100084, China
2. Bejing Planetarium, Beijing Academy of Science and Technology, Beijing 100044, China
3. Department of Optics and Quantum Electronics, University of Szeged, 6720 Szeged, Hungary
4. Department of Astronomy, Beijing Normal University, Beijing 100875, China
5. Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216, China
6. Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming 650216, China
7. Center for Astronomical Mega-Science, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012, China
8. Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019, USA
9. Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 10101, China
10. School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 101408, China
11. DiRAC Institute, Department of Astronomy, University of Washington, Box 351580, U.W., Seattle, WA 98195, USA
12. Department of Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China