a) An image constructed from the average flux densities of the input sources to the simulation. b) The dirty image. c) The result of 5000 cycles of Högbom clean at a gain of 0.01. d) Shows the distribution of the zeroth component of a Sault-Wieringa clean, with similar gain and number of clean cycles, using the two-beam decomposition as described in the text. The unsaturated brightness scale was  − 0.005 to +0.005 for a) and d),  − 0.05 to +0.05 for b) and c). The grey scale is reversed for all images.