[1] Inst Space & Astronaut Sci, Kanagawa 2298510, Japan
[2] Natl Astron Observ, Tokyo 1818588, Japan
[3] Univ Guanajuato, Guanajuato, Mexico
[4] Commun Res Labs, Mito, Ibaraki 3108512, Japan
[5] Kagoshima Univ, Kagoshima 8900064, Japan
[6] CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA
[7] Natl Radio Astron Observ, Socorro, NM 87801 USA
[8] Natl Radio Astron Observ, Green Bank, WV 24944 USA
[9] Natl Res Council Canada, Herzberg Inst Astrophys, Dominion Radio Astrophys Observ, Penticton, BC V2A 6K3, Canada
[10] Australia Telescope Natl Facil, Epping, NSW 2122, Australia
[11] Univ Calgary, Calgary, AB T2N 1N4, Canada
[12] Univ Tasmania, Hobart, Tas 7000, Australia
[13] York Univ, Ctr Res Earth & Space Technol, Downsview, ON M3J 3K1, Canada
[14] Joint Inst VLBI Europe, NL-7991 PD Dwingeloo, Netherlands
[15] PN Lebedev Phys Inst, Ctr Astro Space, Moscow 117810, Russia
[16] Chalmers, Onsala Space Observ, S-43662 Onsala, Sweden