1. Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg, Germany
2. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
3. Fakultät für Physik, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
4. School of Physics, Astronomy and Mathematics, University of Hertfordshire, Hatfield AL10 9AB, UK
5. Astronomical Observatory, Jagiellonian University, ul. Orla 171, PL-30-244 Kraków, Poland
6. Jodrell Bank Centre for Astrophysics, Alan Turing Building, Oxford Road, Manchester M13 9PL, UK
7. CSIRO Astronomy and Space Science, 26 Dick Perry Avenue, Kensington, WA 6151, Australia
8. Kapteyn Astronomical Institute, University of Groningen, NL-9700 AV Groningen, the Netherlands
9. School of Mathematics and Statistics, Newcastle University, Newcastle-upon-Tyne NE1 7RU, UK
10. Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala, Sweden
11. Instituto de Astrofísica de Canarias, Vía Láctea S/N, E-38205 La Laguna, Spain
12. Departamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Spain
13. INAF/Istituto di Radioastronomia, via Gobetti 101, I-40129 Bologna, Italy
14. Thüringer Landessternwarte (TLS), Sternwarte 5, D-07778 Tautenburg, Germany
15. Astronomisches Institut der Ruhr-Universität Bochum, D-44780 Bochum, Germany