GaLactic and Extragalactic All-sky Murchison Widefield Array survey eXtended (GLEAM-X) I: Survey description and initial data release. (23rd August 2022) - Hurley-Walker, N.
Abstract: We describe a new low-frequency wideband radio survey of the southern sky. Observations covering 72–231 MHz and Declinations south of $+30^\circ$ have been performed with the Murchison Widefield Array "extended" Phase II configuration over 2018–2020 and will be processed to form data products including continuum and polarisation images and mosaics, multi-frequency catalogues, transient search data, and ionospheric measurements. From a pilot field described in this work, we publish an initial data release covering 1, 447 $\mathrm{deg}^2$ over $4\, \mathrm{h}\leq \mathrm{RA}\leq 13\, \mathrm{h}$, $-32.7^\circ \leq \mathrm{Dec} \leq -20.7^\circ$ . We process twenty frequency bands sampling 72–231 MHz, with a resolution of 2′–45 ′′, and produce a wideband source-finding image across 170–231 MHz with a root mean square noise of $1.27\pm0.15\, \mathrm{mJy\, beam}^{-1}$ . Source-finding yields 78, 967 components, of which 71, 320 are fitted spectrally. The catalogue has a completeness of 98% at ${{\sim}}50\, \mathrm{mJy}$, and a reliability of 98.2% at $5\sigma$ rising to 99.7% at $7\sigma$ . A catalogue is available from Vizier; images are made available via the PASA datastore, AAO Data Central, and SkyView. This is the first in a series of data releases from the GLEAM-X survey.