1. Xinjiang Astronomical Observatory, Chinese Academy of Sciences , Urumqi 830011 , China
2. Key Laboratory of Radio Astronomy, Chinese Academy of Sciences , Nanjing 210008 , China
3. Xinjiang Key Laboratory of Radio Astrophysics , Urumqi 830011 , China
4. Chongqing Institute of Engineering , Chongqing 400056 , China
5. Institute of Astrophysics, Central China Normal University , Wuhan 430079 , China
6. Department of Astronomy, School of Physics, Huazhong University of Science and Technology , Wuhan 430074 , China