GaLactic and Extragalactic All-sky Murchison Widefield Array survey eXtended (GLEAM-X) I: Survey description and initial data release

We describe a new low-frequency wideband radio survey of the southern sky. Observations covering 72 - 231 MHz and Declinations south $+30^\circ$ have been performed with Murchison Widefield Array "extended" Phase II configuration over 2018 2020 will be processed to form data products including continuum polarisation images mosaics, multi-frequency catalogues, transient search data, ionospheric measurements. From pilot field described in this work, we publish an initial release 1,447 sq. deg 4h < RA 13h, -32.7deg Dec -20.7deg. process twenty frequency bands sampling MHz, resolution $2'$ $45"$, produce source-finding image across 170 231MHz root-mean-square noise $1.27\pm0.15$ mJy/beam. Source-finding yields 78,967 components, which 71,320 are fitted spectrally. The catalogue has completeness 98% at $\sim50$mJy, reliability 98.2% $5\sigma$ rising 99.7% $7\sigma$. A is available from Vizier; made on AAO Data Central, SkyView, PASA Datastore. This first series releases GLEAM-X survey.