[1] Curtin Univ, Int Ctr Radio Astron Res, Perth, WA 6845, Australia
[2] San Diego State Univ, Dept Astron, San Diego, CA 92182 USA
[3] Monash Univ, Sch Phys & Astron, Clayton, Vic 3800, Australia
[4] OzGrav Australian Res Council Ctr Excellence Grav, Hawthorn, Vic 3122, Australia
[5] Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England
[6] Chinese Acad Sci, Key Lab Computat Astrophys, Natl Astron Observ, Beijing 100012, Peoples R China
[7] Univ Chinese Acad Sci, Beijing 100012, Peoples R China
[8] Texas Tech Univ, Dept Phys & Astron, Lubbock, TX 79409 USA
[9] Nicolaus Copernicus Astron Ctr, PL-00716 Warsaw, Poland
[10] Harvard & Smithsonian, Ctr Astrophys, Cambridge, MA 02138 USA
[11] Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 XH Amsterdam, Netherlands
[12] Korea Astron & Space Sci Inst, Daejeon 34055, South Korea
[13] Univ Sci & Technol, Daejeon 34113, South Korea
[14] Univ Western Australia, Int Ctr Radio Astron Res, Crawley, WA 6009, Australia
[15] Univ Tubingen, Inst Astron & Astrophys, D-72076 Tubingen, Germany
[16] European Res Infrastruct Consortium, Joint Inst Very Long Baseline Interferometry, NL-7991 PD Dwingeloo, Netherlands
[17] Univ Amsterdam, Gravitat & Astroparticle Phys Amsterdam Inst, NL-1098 XH Amsterdam, Netherlands
[18] CSIRO, Astron & Space Sci, Perth, WA 6102, Australia
[19] Inst Geog Nacl Expanol, Observ Astronom Nacl, Madrid 28014, Spain
[20] Univ Oxford, Dept Phys, Astrophys, Oxford OX1 3RH, England
[21] Univ Southampton, Sch Phys & Astron, Southampton SO17 1BJ, Hants, England
[22] New York Univ Abu Dhabi, Ctr Astro Particle & Planetary Phys, Abu Dhabi, U Arab Emirates
[23] Univ Alberta, Centennial Ctr Interdisciplinary Sci, Dept Phys, Edmonton, AB T6G 2E1, Canada
[24] East Asian Observ, Hilo, HI 96720 USA
[25] Inst Space Sci, Bucharest 077125, Romania
[26] Friedrich Alexander Univ Erlangen Nurnberg, Dr Karl Remeis Sternwarte & Erlangen Ctr Astropar, D-96049 Bamberg, Germany
[27] Max Planck Inst Extraterr Phys, D-85748 Garching, Germany