The Westerbork Radio Observatory is operated by the Netherlands Foundation for Research in Astronomy (NFRA), with financial support from NWO. We thank Prof. A. Blaauw and Prof. R.G. Strom for discussions about supernova remnants and pulsars, and Dr. B.P. Wakker for providing Fig. 5.
© European Southern Observatory (ESO) 1998
Online publication: September 8, 1998