Spatially constrained direction dependent calibration

TL;DR

This paper introduces a method to improve direction dependent calibration in radio interferometry by incorporating spatial smoothness constraints, leading to better systematic error correction across the sky.

Contribution

It proposes a novel calibration approach that enforces spatial smoothness constraints, enhancing multi-frequency calibration accuracy in widefield radio interferometers.

Findings

Spatial constraints improve calibration performance.

Method reduces systematic errors caused by ionosphere and beam shape.

Simulations confirm enhanced calibration accuracy.

Abstract

Direction dependent calibration of widefield radio interferometers estimates the systematic errors along multiple directions in the sky. This is necessary because with most systematic errors that are caused by effects such as the ionosphere or the receiver beam shape, there is significant spatial variation. Fortunately, there is some deterministic behavior of these variations in most situations. We enforce this underlying smooth spatial behavior of systematic errors as an additional constraint onto spectrally constrained direction dependent calibration. Using both analysis and simulations, we show that this additional spatial constraint improves the performance of multi-frequency direction dependent calibration.