[1] Univ Melbourne, Sch Phys, Parkville, Vic 3010, Australia
[2] Space Telescope Sci Inst, Baltimore, MD 21218 USA
[3] European So Observ, D-85748 Garching, Germany
[4] CSIRO, Australia Telescope Natl Facil, Epping, NSW 1710, Australia
[5] Univ Queensland, Dept Phys, St Lucia, Qld 4072, Australia
[6] Swinburne Univ Technol, Ctr Astrophys & Supercomp, Hawthorn, Vic 3122, Australia
[7] Univ Manchester, Jodrell Bank Observ, Macclesfield SK11 9DL, Cheshire, England
[8] Univ Western Sydney Macarthur, Dept Phys, Campbelltown, NSW 2560, Australia
[9] Univ Wales Coll Cardiff, Dept Phys & Astron, Cardiff CF2 3YB, S Glam, Wales
[10] Mt Stromlo & Siding Spring Observ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia
[11] Univ Technol Sydney, Sydney, NSW 2007, Australia
[12] Univ New Mexico, Inst Astrophys, Albuquerque, NM 87131 USA
[13] WIYN Inc, Tucson, AZ USA
[14] ASTRON, NL-7990 AA Dwingeloo, Netherlands
[15] Univ Colorado, CASA, Boulder, CO 80309 USA
[16] Anglo Australian Observ, Epping, NSW 1710, Australia
[17] Univ Sydney, Sch Phys, Sydney, NSW 2006, Australia
[18] Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England