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◦declination. With ASKAP’slarge, instantaneous field of view,∼31deg2, RACS observed the entire sky at a central frequency of887.5 MHz using 903 individual pointings with 15 minute observations. This has resulted in the deepestradio 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 thatcould be convolved to a common resolution of 25′′, covering a large contiguous region in the declination range δ=−80◦to +30◦. The catalogue provides an important tool for both the preparation of future ASKAP surveys and for scientific research. It consists of∼2.1 million sources and excludes the|b|<5◦region around the Galactic plane. This provides a first extragalactic catalogue with ASKAP coveringthe majority of the sky (δ <+30◦). We describe the methods to obtain this catalogue from the initialRACS 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∼5 mJy. Assuming atypical sky source distribution model, this suggests an overall 95% point source completeness at anintegrated flux density∼3 mJy. The catalogue will be available through the CSIRO ASKAP ScienceData Archive (CASDA).