1. Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
2. Academia Sinica Institute of Astronomy and Astrophysics, No. 1, Section 4, Roosevelt Rd., Taipei 10617, Taiwan
3. University of Leicester, Physics and Astronomy, University Road, Leicester LE1 7RH, UK
4. Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802, USA
5. Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA 16802, USA
6. Department of Physics, 104 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802, USA
7. Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 3J5, Canada
8. European Southern Observatory, Karl Schwarzschild Strasse 2, D-85748 Garching, Germany
9. Instituto de Astrofísica de Canarias (IAC), E-38205 La Laguna, Tenerife, Spain
10. Universidad de La Laguna, Dpto. Astrofsica, E-38206 La Laguna, Tenerife, Spain
11. Leiden Observatory, Leiden University, PO Box 9513, NL- 2300 RA Leiden, the Netherlands
12. Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
13. Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala, Sweden
14. Department of Physics and Astronomy, 6224 Agricultural Road, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
15. Jodrell Bank Centre for Astrophysics, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
16. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany