Deconvolution of interferometric observations by MIM

Abstract

We derive deconvolution equations - dirty map and dirty beam - without use of Fourier transforms. We thus avoid interpolation of observed complex visibilities (CVs) as well as aliasing eects. MIM (= minimum in- formation method) implies the modication of the dirty beam such that a straightforward deconvolution without constraints gives a smoothed result. Smoothing can be di- minished at edges and point sources by modication of the dirty map near these features. We give test examples in which we discuss in detail the Gibbs phenomenon en- countered in any smoothed deconvolution of sharp fea- tures. Finally, we deconvolve old VLBI observations of 3C 309.1.