GaLactic and Extragalactic All-sky Murchison Widefield Array survey eXtended (GLEAM-X) III: Galactic Plane

TL;DR

The GLEAM-X survey's third data release provides extensive low-frequency radio observations of the Galactic Plane, combining new and previous data to produce high-resolution images and a large source catalogue for astrophysical research.

Contribution

This work presents the first combined wide-band, high-resolution radio survey of the Galactic Plane at 72-231 MHz, enhancing sensitivity and source detection over previous surveys.

Findings

98,207 sources detected across the surveyed region

Achieved 90% completeness at 50 mJy flux density

Source position accuracy within 1 arcsecond

Abstract

We present the third data release for the Galactic and Extragalactic All-Sky Murchison Widefield Array eXtended (GLEAM-X) survey, covering = 3800 deg2 of the southern Galactic Plane (GP) with \ang{233} < l < \ang{44} and |b| < \ang{11} across a frequency range of 72 - 231 MHz divided into 20 sub-bands. GLEAM-X observations were taken using the "extended" Phase-II configuration of the Murchison Widefield Array (MWA), which features baselines ranging from approximately 12 m to 5 km. This configuration limits sensitivity to the diffuse structure of the GP, with an angular resolution range of about 45'' to 2'. To achieve lower noise levels while being sensitive to a wide range of spatial scales (45''- \ang{15}), we combined these observations with the previous Galactic and Extragalactic All-Sky Murchison Widefield Array (GLEAM) survey. For the area covered, we provide images spanning the whole frequency range. A wide-band image over 170 - 231 MHz, with RMS noise of = 3 - 6 mJy/beam and source position accuracy within 1 arcseconds, is then used to perform source-finding, which yields 98,207 elements measured across 20 x 7.68 MHz frequency bands. The catalogue is 90% complete at 50 mJy within \ang{233} < l < \ang{324} and at 125 mJy in \ang{290} < l < \ang{44}, while it is 99.3% reliable overall. All the images and the catalogue are available online for download.