Affiliation: | Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany;MERLIN/VLBI National Facility, Jodrell Bank Observatory, University of Manchester, Macclesfield, Cheshire SK11 9DL;Department of Physics, University of California, Davis, CA 95616, USA;Kapteyn Astronomical Institute, Postbus 800, NL-9700 AV Groningen, the Netherlands |