Deconvolution of interferometric observations by MIM

Institut für Astronomie der Leopold-Franzens-Universität Innsbruck, Technikerstraße 25, A–6020 Innsbruck, Austria

Received: 23 May 1997
Accepted: 6 October 1997

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 effects. MIM (= minimum information method) implies the modification of the dirty beam such that a straightforward deconvolution without constraints gives a smoothed result. Smoothing can be diminished at edges and point sources by modification of the dirty map near these features. We give test examples in which we discuss in detail the Gibbs phenomenon encountered in any smoothed deconvolution of sharp features. Finally, we deconvolve old VLBI observations of 3C 309.1.