MeqTrees and direction-dependent effects

TL;DR

This paper demonstrates how MeqTrees can effectively correct direction-dependent effects in radio telescope data, using experiments with deliberately introduced pointing errors to compare different correction methods.

Contribution

It introduces a novel application of MeqTrees for correcting DDEs through differential gain and direct pointing solutions, validated by controlled WSRT observations.

Findings

MeqTrees successfully corrected DDEs in simulated and real data.

Differential gain and direct pointing solutions show comparable effectiveness.

The approach improves calibration accuracy for high-frequency radio observations.

Abstract

Direction-dependent effects (DDEs) represent a major challenge both for calibration of new radio telescopes, and for advancing the state of the art of existing ones. Various approaches to the problem are currently in development. This paper describes several WSRT observations where a pointing error -- commonly thought to be a major contributor to DDEs at higher frequencies -- was deliberately introduced. These observations were reduced using the MeqTrees package, using two different approaches to correct for DDEs: differential gain solutions, and a direct solution for pointing errors. The results of this are analysed and compared.