High accuracy wide field imaging method in radio interferometry

TL;DR

This paper introduces a new wide-field imaging algorithm for radio interferometry that significantly improves accuracy over existing methods by employing least-misfit optimal gridding, enabling high-precision imaging with reduced computational cost.

Contribution

The paper presents a novel wide-field imaging algorithm based on W-stacking that achieves higher accuracy through least-misfit optimal gridding, outperforming traditional methods.

Findings

Achieves the smallest approximation error relative to direct Fourier transform.

Capable of single-precision accuracy with specific parameters.

Reduces computational cost while maintaining high accuracy.

Abstract

With the development of modern radio interferometers, wide-field continuum surveys have been planned and undertaken, for which accurate wide-field imaging methods are essential. Based on the widely-used W-stacking method, we propose a new wide-field imaging algorithm that can synthesize visibility data from a model of the sky brightness via degridding, able to construct dirty maps from measured visibility data via gridding. Results carry the smallest approximation error yet achieved relative to the exact calculation involving the direct Fourier transform. In contrast to the original W-stacking method, the new algorithm performs least-misfit optimal gridding (and degridding) in all three directions, and is capable of achieving much higher accuracy than is feasible with the original algorithm. In particular, accuracy at the level of single precision arithmetic is readily achieved by choosing a least-misfit convolution function of width W=7 and an image cropping parameter of x0=0.25. If the accuracy required is only that attained by the original W-stacking method, the computational cost for both the gridding and FFT steps can be substantially reduced using the proposed method by making an appropriate choice of the width and image cropping parameters.