The FHD Polarized Imaging Pipeline: A New Approach to Widefield Interferometric Polarimetry

TL;DR

This paper introduces a novel polarized imaging pipeline for widefield interferometric polarimetry, utilizing optimal mapmaking, a new calibration method, and a specialized polarization basis to improve image reconstruction accuracy.

Contribution

It presents a new polarized imaging pipeline based on optimal mapmaking, a specialized polarization basis, and a widefield calibration approach for improved interferometric polarimetry.

Findings

Effective horizon-to-horizon image reconstruction in all polarization modes.

Accurate calibration leveraging widefield effects.

Implementation in the FHD software package.

Abstract

We describe a new polarized imaging pipeline implemented in the FHD software package. The pipeline is based on the optimal mapmaking imaging approach and performs horizon-to-horizon image reconstruction in all polarization modes. We discuss the formalism behind the pipeline's polarized analysis, describing equivalent representations of the polarized beam response, or Jones matrix. We show that, for arrays where antennas have uniform polarization alignments, defining a non-orthogonal instrumental polarization basis enables accurate and efficient image reconstruction. Finally, we present a new calibration approach that leverages widefield effects to perform fully-polarized calibration. This analysis pipeline underlies the analysis of Murchison Widefield Array (MWA) data in Byrne et al. (2022, MNRAS, 510, 2011).