The Rapid ASKAP Continuum Survey IV: continuum imaging at 1367.5 MHz and the first data release of RACS-mid

Abstract

The Australian SKA Pathfinder (ASKAP) is being used to undertake a campaign to rapidly survey the sky in three frequency bands across its operational spectral range. The first pass of the Rapid ASKAP Continuum Survey (RACS) at 887.5 MHz in the low band has already been completed, with images, visibility datasets, and catalogues made available to the wider astronomical community through the CSIRO ASKAP Science Data Archive (CASDA). This work presents details of the second observing pass in the mid band at 1367.5 MHz, RACS-mid, and associated data release comprising images and visibility datasets covering the whole sky south of $\delta_{\text{J2000}}=+49^\circ$ . This data release incorporates selective peeling to reduce artefacts around bright sources, as well as accurately modelled primary beam responses. The Stokes I images reach a median noise of 198 $\mu$ Jy PSF $^{-1}$ with a declination-dependent angular resolution of 8.1–47.5 arcsec that fills a niche in the existing ecosystem of large-area astronomical surveys. We also supply Stokes V images after application of a widefield leakage correction, with a median noise of 165 $\mu$ Jy PSF $^{-1}$ . We find the residual leakage of Stokes I into V to be $\lesssim 0.9$ – $2.4$ % over the survey. This initial RACS-mid data release will be complemented by a future release comprising catalogues of the survey region. As with other RACS data releases, data products from this release will be made available through CASDA.

Survey and monitoring of ASKAP’s RFI environment and trends I: Flagging statistics

“…2021; Duchesne et al. 2023), the ASKAP survey for Variables and Slow Transients (VAST) (Murphy et al. 2013, 2021), the POlarisation Sky Survey of the Universe’s Magnetism (POSSUM) (Anderson et al.…”

Powerful Radio Sources in the Southern Sky. III. First Results of the Optical Spectroscopic Campaign

“…Table 1 shows the log of our observations. Sources are listed there using their G4Jy name but we also report a common name if present in the NASA/IPAC Extragalactic Database (NED) 23 21 We remark that not all radio observations of the Rapid ASKAP Continuum Survey (McConnell et al 2020;Hale et al 2021;Duchesne et al 2023) had been released when Paper I was in preparation; therefore, these data sets were not included/used there. However, we are currently carrying out an additional investigation on all archival radio observations for the whole G4Jy-3CRE sample that will be presented together with observations recently obtained in a forthcoming paper (F. The optical spectra presented here were collected at the Víctor Blanco Telescope, the New Technology Telescope (NTT), the Southern Astrophysical Research (SOAR) Telescope, and the 2.1 m Telescope of the Observatorio Astronómico Nacional located at San Pedro Mártir, Mexico (OAN-SPM).…”

Prototype Faraday Rotation Measure Catalogs from the Polarisation Sky Survey of the Universe’s Magnetism (POSSUM) Pilot Observations

“…The formed beams have an approximately Gaussian response and peak sensitivity near the center, and the response becomes distorted toward the edges (Duchesne et al 2023;Thomson et al 2023). Mosaicking the beams helps achieve approximately uniform sensitivity across the majority of the image by overlapping the lower-sensitivity regions of two beams to increase the overall sensitivity to that of the central beam.…”