1. Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi 830011, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
3. Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Urumqi 830011, China
4. Key Laboratory of Xinjiang Radio Astrophysics, Urumqi 830011, China
5. School of Physics and Technology, Xinjiang University, Urumqi 830046, China