Direction Dependent Effects In Wide-Field Wideband Full Stokes Radio Imaging

TL;DR

This paper investigates the impact of direction-dependent effects on wide-field, wideband full Stokes radio imaging, highlighting errors in deconvolution caused by uncorrected antenna gain variations and proposing high-performance computing solutions.

Contribution

It analyzes the errors from direction-dependent gains in radio imaging and demonstrates the need for parallel computing approaches for correction in large-scale surveys.

Findings

Uncorrected DD effects cause significant imaging errors.

Simulations with VLA data quantify these errors.

Parallel computing is essential for feasible DD corrections.

Abstract

Synthesis imaging in radio astronomy is affected by instrumental and atmospheric effects which introduce direction-dependent (DD) gains.The antenna power pattern varies both as a function of time and frequency. The broad band time varying nature of the antenna power pattern when not corrected leads to gross errors in full Stokes imaging and flux estimation. In this poster we explore the errors that arise in image deconvolution while not accounting for the time and frequency dependence of the antenna power pattern. Simulations were conducted with the wide-band full Stokes power pattern of the Karl G. Jansky Very Large Array (VLA) antennas to demonstrate the level of errors arising from direction-dependent gains and their non-neglegible impact on upcoming sky surveys such as the VLASS. DD corrections through hybrid projection algorithms are computationally expensive to perform. A highly parallel implementation through high performance computing architectures is the only feasible way of applying these corrections to the large data sizes of these upcoming surveys.