We have presented the first installment of the Westerbork Northern Sky Survey and discussed the uncertainties in the resulting catalogue. Reduction of the full WENSS survey should be completed in the summer of 1997. Analysis of the mini-survey has shown that the full WENSS survey will be an important data base for tackling many important astrophysical problems.
A combination of WENSS with existing large sky radio catalogues will produce radio colour-colour and colour-magnitude diagrams over a large area of sky. This will enable us to separate various types of sources to flux-levels fainter by at least an order of magnitude than was previously possible, and should provide new data on the evolution of the space density of distant radio galaxies as a function of spectral index. In addition, WENSS will be used to study large-scale clustering of radio sources taking into account the radio colour discriminant and the optical identification information.
Acknowledgements
We would like to thank Peter Katgert for useful discussions. We acknowledge support from an EU twinning project, funding from the high-z programme subsidy granted by the Netherlands Organization for Scientific Research (NWO), and a NATO research grant. This research was supported by the Netherlands Foundation for Research in Astronomy (NFRA). WENSS is a joint project of the NFRA and Leiden Observatory. The WSRT is operated by the NFRA with financial support from NWO.