The data reductions and analyses were carried out on workstations provided by the Alfried Krupp von Bohlen und Halbach Stiftung through a joint grant to the Max-Planck-Institut für Radioastronomie and the Institut für Theoretische Astrophysik. This support is greatfully acknowledged. We thank the director of the Max-Planck-Institut für Astronomie for the generous allocation of observing time at the ESO-MPG telescope. We benefitted much from discussions with P.L. Biermann, A. Eckart, M. McCaughrean, I.S. Glass and J. Najarro.
© European Southern Observatory (ESO) 1999
Online publication: August 13, 199