[1] Swinburne Univ Technol, Ctr Astrophys & Supercomp, Hawthorn, Vic 3122, Australia
[2] Swinburne Univ Technol, ARC Ctr All Sky Astrophys CAASTRO, Hawthorn, Vic 3122, Australia
[3] Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA
[4] Univ Manchester, Jodrell Bank Ctr Astrophys, Sch Phys & Astron, Manchester M13 9PL, Lancs, England
[5] CALTECH, Caltech Opt Observ, Pasadena, CA 91125 USA
[6] Osservatorio Astron Cagliari, Ist Nazl Astrofis, I-09012 Capoterra, Italy
[7] Commonwealth Sci & Ind Res Org CSIRO Astron & Spa, Australia Telescope Natl Facil, Epping, NSW 1710, Australia
[8] Max Planck Inst Radioastron, D-53121 Bonn, Germany
[9] Univ Cagliari, Dipartimento Fis, I-09042 Monserrato, CA, Italy