Wide field imaging for the Square Kilometre Array

TL;DR

This paper introduces a hybrid imaging algorithm called w snapshots for wide-field radio interferometry, combining w projection and snapshot imaging to improve efficiency and accuracy for the Square Kilometre Array.

Contribution

The paper proposes a novel hybrid algorithm, w snapshots, that enhances wide-field imaging by reducing memory and computation compared to existing methods.

Findings

w snapshots reduces memory usage compared to pure w projection

w snapshots is more accurate than pure snapshot imaging

w snapshots converges to w projection and snapshot at asymptotes

Abstract

Wide-field radio interferometric telescopes such as the Square Kilometre Array now being designed are subject to a number of aberrations. One particularly pernicious aberration is that due to non-coplanar baselines whereby long baselines incur a quadratic image-plane phase error. There are numerous algorithms for dealing with the non-coplanar baselines effect. As a result of our experience with developing processing software for the Australian Square Kilometre Array Pathfinder, we advocate the use of a hybrid algorithm, called w snapshots, based on a combination of w projection and snapshot imaging. This hybrid overcomes some of the deficiencies of each and has advantages from both. Compared to pure w projection, w snapshots uses less memory and execution time, and compared to pure snapshot imaging, w snapshots uses less memory and is more accurate. At the asymptotes, w snapshots devolves to w projection and to snapshots.