The non-coplanar baselines effect in radio interferometry: The W-Projection algorithm

TL;DR

The paper introduces W-projection, a novel algorithm that effectively corrects for non-coplanar baselines in radio interferometry, offering significant speed improvements and accuracy for next-generation radio telescopes.

Contribution

The paper presents W-projection, a new algorithm that outperforms existing methods in speed and accuracy for handling non-coplanar baselines in radio interferometry.

Findings

W-projection is up to ten times faster than facet-based algorithms.

W-projection maintains high accuracy regardless of computation time.

The algorithm has significant implications for future radio telescope design.

Abstract

We consider a troublesome form of non-isoplanatism in synthesis radio telescopes: non-coplanar baselines. We present a novel interpretation of the non-coplanar baselines effect as being due to differential Fresnel diffraction in the neighborhood of the array antennas. We have developed a new algorithm to deal with this effect. Our new algorithm, which we call "W-projection", has markedly superior performance compared to existing algorithms. At roughly equivalent levels of accuracy, W-projection can be up to an order of magnitude faster than the corresponding facet-based algorithms. Furthermore, the precision of result is not tightly coupled to computing time. W-projection has important consequences for the design and operation of the new generation of radio telescopes operating at centimeter and longer wavelengths.