GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey III: South Galactic Pole data release

TL;DR

This paper presents the South Galactic Pole data release from the GLEAM survey, providing a large, sensitive radio source catalog at low frequencies with improved calibration and data reduction techniques, enabling advanced extragalactic studies.

Contribution

The paper introduces a new data release with enhanced calibration, automated deconvolution, and accurate flux correction, expanding the GLEAM survey's utility for large-scale extragalactic research.

Findings

Catalog contains 108,851 components above 5σ

77% of sources have spectral indices between 72 and 231 MHz

Typical rms noise is approximately 5 mJy/beam at 216 MHz

Abstract

We present the South Galactic Pole (SGP) data release from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. These data combine both years of GLEAM observations at 72-231 MHz conducted with the Murchison Widefield Array (MWA) and cover an area of 5,113 $\mathrm{deg}^2$ centred on the SGP at 20$^\mathrm{h}$40$^\mathrm{m}$ < RA < 05$^\mathrm{h}$04$^\mathrm{m}$ and $-48\deg$ < Dec < $-2\deg$. At 216 MHz, the typical rms noise is $\approx 5$ mJy/beam and the angular resolution $\approx 2$ arcmin. The source catalogue contains a total of 108,851 components above $5\sigma$, of which 77 per cent have measured spectral indices between 72 and 231 MHz. Improvements to the data reduction in this release include the use of the GLEAM Extragalactic catalogue as a sky model to calibrate the data, a more efficient and automated algorithm to deconvolve the snapshot images, and a more accurate primary beam model to correct the flux scale. This data release enables more sensitive large-scale studies of extragalactic source populations as well as spectral variability studies on a one-year timescale.