M.B. and D.D. acknowledge financial support from the the European Union as an EU Fellow under contract ERBCHBGCT920212. The WSRT is operated by the Netherlands Foundation for Research in Astronomy with the financial support of the of the Netherlands Organization for Scientific Research (NWO). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
© European Southern Observatory (ESO) 1997
Online publication: April 28, 1998