1. Graduate Institute of Astronomy, National Central University , 300 Zhongda Rd., Zhongli, Taoyuan 32001 , Taiwan (R.O.C.)
2. Institute of Astronomy and Astrophysics, Academia Sinica , Taipei 10617 , Taiwan (R.O.C.)
3. Finnish Centre for Astronomy with ESO (FINCA), University of Turku , FI-20014 Turku , Finland
4. Aalto University Metsähovi Radio Observatory , Metsähovintie 114, FI-02540 Kylmälä , Finland
5. Institute of Astrophysics, Foundation for Research and Technology-Hellas , GR-71110 Heraklion , Greece
6. Department of Physics, University of Crete , GR-70013 Heraklion , Greece
7. Owens Valley Radio Observatory, California Institute of Technology , Pasadena, CA 91125 , USA
8. Departamento de Astronomía, Universidad de Chile , Camino El Observatorio 1515, Las Condes, Santiago , Chile
9. Departamento de Astronomía, Universidad de Concepción , Concepción , Chile