Description: | The above image shows a simulated WSRT observation of a field of 9 regularly-spaced point sources with the same flux, arranged in the shape of a cross. The outer sources are attenuated by the primary beam of the 25m dish. Each source is multiplied with a so-called point-spread-function (PSF) which in the case of the WSRT consists of a series of concentric rings. The interaction of these rings from the various sources produces a pretty pattern, which changes as we vary the observing frequency. |