Adaptive Deconvolution of Astronomical Radio Images

Abstract

The novel image-forming methods used in the Molonglo Observatory Synthesis Telescope (MOST) are not amenable to a direct application of the self-calibration techniques that have been so effective in improving the performance of many other aperture synthesis radio telescopes. Specifically, self-calibration of antenna-based errors and the use of phase closure conditions is not possible because vital antenna-based information is lost irretrievably as the MOST forms interferometer beams in real time. However, it is shown in this paper that suitable models of errors introduced by the atmosphere and telescope can be adaptively constructed from the properties of synthesised images. These models can then be used iteratively with standard deconvolution methods to improve significantly the fidelity of MOST images. The method would have general application to tomographic imaging systems in which non-ideal behaviour could be represented by a small number of unknown parameters.