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 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
sq. deg over 4h < RA < 13h, -32.7deg < Dec < -20.7deg. We process twenty
frequency bands sampling 72 - 231 MHz, with a resolution of $2'$ - $45"$, and
produce a wideband source-finding image across 170 - 231MHz with a
root-mean-square noise of $1.27\pm0.15$ mJy/beam. Source-finding yields 78,967
components, of which 71,320 are fitted spectrally. The catalogue has a
completeness of 98% at $\sim50$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 on AAO Data Central, SkyView, and the PASA Datastore. This is
the first in a series of data releases from the GLEAM-X survey.
