The Rapid ASKAP Continuum Survey Paper II: First Stokes I Source Catalogue Data Release

The Rapid ASKAP ContinuumSurvey (RACS) is the first large sky survey using the Australian Square Kilometre Array Pathfinder (ASKAP), covering the sky south of +41 degrees declination. With ASKAP's large, instantaneous field of view, similar to 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 '', covering a large contiguous region in the declination range delta=-80 degrees to +30 degrees. The catalogue provides an important tool for both the preparation of future ASKAP surveys and for scientific research. It consists of similar to 2.1 million sources and excludes the vertical bar b vertical bar < 5 degrees region around the Galactic plane. This provides a first extragalactic catalogue with ASKAP covering the majority of the sky (delta <+30 degrees). 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 similar to 5 mJy. Assuming a typical sky source distribution model, this suggests an overall 95% point source completeness at an integrated flux density similar to 3 mJy. The catalogue will be available through the CSIRO ASKAP Science Data Archive (CASDA).