The Rapid ASKAP Continuum Survey Paper II: First Stokes I Source
  Catalogue Data Release
  The Rapid ASKAP Continuum Survey (RACS) is the first large sky survey using
the Australian Square Kilometre Array Pathfinder (ASKAP), covering the sky
south of +41$^\circ$ declination. With ASKAP's large, instantaneous field of
view, $\sim 31$ deg$^2$, RACS observed the entire sky at a central frequency of
887.5 MHz using 903 individual pointings with 15 minute observations. This has
resulted in the deepest radio survey of the full Southern sky to date at these
frequencies. In this paper, we present the first Stokes I catalogue derived
from the RACS survey. This catalogue was assembled from 799 tiles that could be
convolved to a common resolution of 25$^{\prime\prime}$, covering a large
contiguous region in the declination range $\delta=-$80$^\circ$ to +30$^\circ$.
The catalogue provides an important tool for both the preparation of future
ASKAP surveys and for scientific research. It consists of $\sim$2.1 million
sources and excludes the $|b|<5^\circ$ region around the Galactic plane. This
provides a first extragalactic catalogue with ASKAP covering the majority of
the sky ($\delta<+30^\circ$). We describe the methods to obtain this catalogue
from the initial RACS observations and discuss the verification of the data, to
highlight its quality. Using simulations, we find this catalogue detects 95% of
point sources at an integrated flux density of $\sim$5 mJy. Assuming a typical
sky source distribution model, this suggests an overall 95% point source
completeness at an integrated flux density $\sim$3 mJy. The catalogue will be
available through the CSIRO ASKAP Science Data Archive (CASDA).
