ATLAS 1.4 GHz Data Release 2 - I. Observations of the CDF-S and ELAIS-S1 fields and methods for constructing differential number counts

Abstract

This is the first of two papers describing the second data release (DR2) of\nthe Australia Telescope Large Area Survey (ATLAS) at 1.4 GHz, which comprises\ndeep wide-field observations in total intensity, linear polarization, and\ncircular polarization over the Chandra Deep Field-South and European Large Area\nInfrared Space Observatory Survey-South 1 regions. DR2 improves upon the first\ndata release by maintaining consistent data reductions across the two regions,\nincluding polarization analysis, and including differential number counts in\ntotal intensity and linear polarization. Typical DR2 sensitivities across the\nmosaicked multi-pointing images are 30 uJy/beam at approximately 12"x6"\nresolution over a combined area of 6.4 square degrees. In this paper we present\ndetailed descriptions of our data reduction and analysis procedures, including\ncorrections for instrumental effects such as positional variations in image\nsensitivity, bandwidth smearing with a non-circular beam, and polarization\nleakage, and application of the BLOBCAT source extractor. We present the DR2\nimages and catalogues of components (discrete regions of radio emission) and\nsources (groups of physically associated radio components). We describe new\nanalytic methods to account for resolution bias and Eddington bias when\nconstructing differential number counts of radio components.\n