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Title: | The Rapid ASKAP Continuum Survey III: Spectra and Polarisation In Cutouts of Extragalactic Sources (SPICE-RACS) first data release | Authors: | Thomson, Alec J. M. McConnell, David Lenc, Emil Galvin, Timothy J. Rudnick, Lawrence Heald, George Hale, Catherine L. Duchesne, Stefan W. Anderson, Craig S. CARRETTI, ETTORE Federrath, Christoph Gaensler, B. M. Harvey-Smith, Lisa Haverkorn, Marijke Hotan, Aidan W. Ki Ma, Yik Murphy, Tara McClure-Griffiths, N. M. Moss, Vanessa A. O’Sullivan, Shane P. Raja, Wasim Seta, Amit Van Eck, Cameron L. West, Jennifer L. Whiting, Matthew T. Wieringa, Mark H. |
Issue Date: | 2023 | Journal: | PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF AUSTRALIA | Number: | 40 | Abstract: | The Australian SKA Pathfinder (ASKAP) radio telescope has carried out a survey of the entire Southern Sky at 887.5 MHz. The wide area, high angular resolution, and broad bandwidth provided by the low-band Rapid ASKAP Continuum Survey (RACS-low) allow the production of a next-generation rotation measure (RM) grid across the entire Southern Sky. Here we introduce this project as Spectral and Polarisation in Cutouts of Extragalactic sources from RACS (SPICE-RACS). In our first data release, we image 30 RACS-low fields in Stokes I, Q, U at 25" angular resolution, across 744-1032 MHz with 1 MHz spectral resolution. Using a bespoke, highly parallelised, software pipeline we are able to rapidly process wide-area spectro-polarimetric ASKAP observations. Notably, we use `postage stamp' cutouts to assess the polarisation properties of 105912 radio components detected in total intensity. We find that our Stokes Q and U images have an rms noise of ∼ 80 μJy PSF-1, and our correction for instrumental polarisation leakage allows us to characterise components with ≳ 1% polarisation fraction over most of the field of view. We produce a broadband polarised radio component catalogue that contains 5818 RM measurements over an area of ∼ 1300 deg2 with an average error in RM of 1.6+1.1-1.0 rad m-2, and an average linear polarisation fraction 3.4+3.0-1.6%. We determine this subset of components using the conditions that the polarised signal-to-noise ratio is > 8, the polarisation fraction is above our estimated polarised leakage, and the Stokes I spectrum has a reliable model. Our catalogue provides an areal density of 4±2 RMs deg-2; an increase of ∼ 4 times over the previous state-of-the-art (Taylor, Stil, Sunstrum <xref rid="ref94" ref-type="bibr">2009</xref>, ApJ, 702, 1230). Meaning that, having used just 3% of the RACS-low sky area, we have produced the 3rd largest RM catalogue to date. This catalogue has broad applications for studying astrophysical magnetic fields; notably revealing remarkable structure in the Galactic RM sky. We will explore this Galactic structure in a follow-up paper. We will also apply the techniques described here to produce an all-Southern-sky RM catalogue from RACS observations. Finally, we make our catalogue, spectra, images, and processing pipeline publicly available. | URI: | http://hdl.handle.net/20.500.12386/34371 | URL: | https://arxiv.org/abs/2307.07207 https://www.cambridge.org/core/journals/publications-of-the-astronomical-society-of-australia/article/rapid-askap-continuum-survey-iii-spectra-and-polarisation-in-cutouts-of-extragalactic-sources-spiceracs-first-data-release/7355C6B8459B29E3F838B6DEF4CFAE3B |
ISSN: | 1448-6083 | DOI: | 10.1017/pasa.2023.38 | Bibcode ADS: | 2023PASA...40...40T | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
Files in This Item:
File | Description | Size | Format | |
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PASA 2307.07207.pdf | preprint | 7.28 MB | Adobe PDF | View/Open |
1_the-rapid-askap-continuum-survey-iii-spectra-and-polarisation-in-cutouts-of-extragalactic-sources-spice-racs-first-data-release.pdf | [Administrators only] | 9.72 MB | Adobe PDF | |
2_the-rapid-askap-continuum-survey-iii-spectra-and-polarisation-in-cutouts-of-extragalactic-sources-spice-racs-first-data-release.pdf | [Administrators only] | 9.76 MB | Adobe PDF | |
3_the-rapid-askap-continuum-survey-iii-spectra-and-polarisation-in-cutouts-of-extragalactic-sources-spice-racs-first-data-release.pdf | [Administrators only] | 4.3 MB | Adobe PDF | |
4_the-rapid-askap-continuum-survey-iii-spectra-and-polarisation-in-cutouts-of-extragalactic-sources-spice-racs-first-data-release.pdf | [Administrators only] | 6.44 MB | Adobe PDF |
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