Efficient correction for both direction-dependent and baseline-dependent effects in interferometric imaging: An A-stacking framework

¹ Department of Electrical and Electronic EngineeringStellenbosch University, 7599 Stellenbosch, South Africa
e-mail: ayoung.at.sun@gmail.com
² Netherlands Institute for Radio Astronomy (ASTRON), 7990AA Dwingeloo, The Netherlands
³ Department of Earth and Space Sciences, Chalmers University of Technology, 412 58 Gothenburg, Sweden
⁴ Department of Signals and Systems, Chalmers University of Technology, 412 58 Gothenburg, Sweden

Received: 10 December 2014
Accepted: 23 February 2015

Abstract

A general framework is presented for modeling direction-dependent effects that are also baseline-dependent, as part of the calibration and imaging process. Within this framework such effects are represented as a parametric linear model in which basis functions account for direction dependence, whereas expansion coefficients account for the baseline dependence. This separation enables the use of a multiple fast Fourier transform-based implementation of the forward calculation (sky to visibility) in a manner similar to the W-stacking solution for non-coplanar baselines, and offers a potential improvement in computational efficiency in scenarios where the gridding operation in a convolution-based approach to direction-dependent effects may be too costly. Two novel imaging approaches that are possible within this framework are also presented.