“The Rapid ASKAP Continuum Survey I: Design and First Results”

Recently, Dr. Buzz Aldrin featured a FACEBOOK post of a SPACE.COM article on this Australian research paper (below). It raised many questions amongst his readers, not the least of which, “where is American leadership in this rapidly developing science?”

What this shows is when a country – in this case Australia – is determined to be a leader in science, results in academia and in space exploration will result.

Buzz’ post is below –

“Intriguing…” with 11K likes and Loves and Wows, over 1.1K comments and shares…

From Buzz => https://www.space.com/fastest-all-sky-map-ever-askap?fbclid=IwAR1G1yVsxcVZ5gRgTCRAf2s05EMsqhqN4qWMAQGfH_9h5vZfdv5hu_ipSNY

“Scientists just mapped 1 million new galaxies, in 300 hours”

By Brandon Specktor 6 days ago

All-sky surveys usually take years. This one took weeks.

The ASKAP radio telescope array, located in the Australian outback, just mapped 3 million galaxies in less than a month.
The ASKAP radio telescope array, located in the Australian outback, just mapped 3 million galaxies in less than a month. (Image: © CSIRO)

D. McConnell1 , C. L. Hale2, E. Lenc1 , J. K. Banfield1, George Heald2, A. W. Hotan2 , James K. Leung1,3, Vanessa A. Moss1, Tara Murphy3, Andrew O’Brien1,4,5 , Joshua Pritchard1,3, Wasim Raja1, Elaine M. Sadler1,3, Adam Stewart3, Alec J. M. Thomson2, M. Whiting1, James R. Allison6, S. W. Amy1, C. Anderson2,7 , Lewis Ball1,8, Keith W. Bannister1, Martin Bell1,9, Douglas C.-J. Bock1, Russ Bolton1, J. D. Bunton1, A. P. Chippendale1, J. D. Collier1,5,10, F. R. Cooray1, T. J. Cornwell1,11, P. J. Diamond1,8, P. G. Edwards1, N. Gupta1,12, Douglas B. Hayman1, Ian Heywood6,13, C. A. Jackson1,14, Bärbel S. Koribalski1, Karen Lee-Waddell1, N. M. McClure-Griffiths15, Alan Ng1, Ray P. Norris1,5, Chris Phillips1, John E. Reynolds1, Daniel N. Roxby1, Antony E. T. Schinckel1, Matt Shields1, Chenoa Tremblay2, A. Tzioumis1, M. A. Voronkov1 and Tobias Westmeier16

1 CSIRO Astronomy and Space Science, PO Box 76, Epping, NSW 1710 Australia, 2 CSIRO Astronomy and Space Science, PO Box 1130, Bentley, WA 6102, Australia, 3 Sydney Institute for Astronomy, School of Physics, University of Sydney, Sydney, NSW 2006, Australia, 4 Center for Gravitation, Cosmology, and Astrophysics, Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA, 5 Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia, 6 Sub-dept of Astrophysics, Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH, UK, 7 Jansky fellow of the National Radio Astronomy Observatory, NRAO, 1003 Lopezville Rd, Socorro, NM 87801 USA, 8 SKA Organisation, Jodrell Bank, Lower Withington, Macclesfield, Cheshire SK11 9FT, UK, 9 University of Technology Sydney, 15 Broadway, Ultimo, NSW 2007, Australia, 10 Department of Astronomy, The Inter-University Institute for Data Intensive Astronomy (IDIA), University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa, 11 Tim Cornwell Consulting, 17 Elgan Crescent, Sandbach CW111LD,
UK, 12 Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007, India, 13 Department of Physics & Electronics, Rhodes University, Makhanda, 6140, South Africa, 14 ASTRON, The Netherlands Institute for Radio Astronomy, Oude Hoogeveensdijk 4, Dwingeloo 7991 PD, Netherlands, 15 Research School of Astronomy & Astrophysics, Australian National University, Canberra 2611, Australia and 16 ICRAR, M468, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia

The Cambridge Press publication may be downloaded here…

Abstract

“The Rapid ASKAP Continuum Survey (RACS) is the first large-area survey to be conducted with the full 36-antenna Australian Square Kilometre Array Pathfinder (ASKAP) telescope. RACS will provide a shallow model of the ASKAP sky that will aid the calibration of future deep ASKAP surveys. RACS will cover the whole sky visible from the ASKAP site in Western Australia and will cover the full ASKAP band of 700–1800 MHz. The RACS images are generally deeper than the existing NRAO VLA Sky Survey and Sydney University Molonglo Sky Survey radio surveys and have better spatial resolution. All RACS survey products will be public, including radio images (with ∼ 15 arcsec resolution) and catalogues of about three million source components with spectral index and polarisation information. In this paper, we present a description of the RACS survey and the first data release of 903 images covering the sky south of declination +41◦ made over a 288-MHz band centred at 887.5 MHz.

1. Introduction

“The Rapid ASKAP Continuum Survey (RACS) is a shallow all-sky precursor to the full, multi-year surveys to be conducted with the Australian SKAa Pathfinder (ASKAP; Johnston et al. 2007; Hotan et al. submitted). It will image the entire sky south of declination δ = +51◦ over representative bands within ASKAP’s operating frequency range of 700–1800 MHz. The aims of this survey are to generate reference images to aid ASKAP’s future operation, to exercise the newly commissioned instrument ahead of the commencement of its full scientific operations and to provide a valuable astronomical resource.

“ASKAP was designed to be a survey instrument capable of quickly observing the whole accessible sky. It is located at the Murchison Radio-astronomy Observatory (MRO) in Western Australia and is operated by the Commonwealth Scientific and Industrial Research Organisation (CSIRO). ASKAP is an array of 36 12-m prime focus antennas; each is equipped with a phased array feed (PAF) that enables the simultaneous digital formation of 36 dual-polarisation beams to sample its 31 deg2 field of view. It has an instantaneous bandwidth of 288 MHz. A full descrip- tion of ASKAP is in preparation (Hotan et al. submitted), but descriptions of the PAFs, beam formation, and telescope operation exist in Hotan et al. (2014) and McConnell et al. (2016).

“The data gathering capacity of ASKAP, equal to 36 simultaneous 630-baseline synthesis arrays, presented a software development challenge: how to develop calibration and imaging software that could run in less time than the time taken to make the observations. In addition to the use of highly parallel supercomputers, the solution relied upon the availability of a model of the sky that could provide the properties of all the major sources in any field being observed (Cornwell et al. 2011b). The aim was to construct this model [the Global Sky Model (GSM)] from short observations made with ASKAP itself, and that all subsequent observations would contribute to its improvement. Although the early operation of ASKAP makes no attempt to form images in real time, the availability of a sky model will assist data calibration and reduce reliance on time-consuming observations of calibration sources. The survey we describe here will allow the initialisation of the GSM.

“RACS will be a valuable resource and will complement other all-sky radio surveys. Table 1 gives a comparison of the RACS survey parameters with other comparable radio surveys with sub- stantial Southern-sky coverage in the metric and decimetric bands: Very Large Array Low-frequency Sky Survey Redux (VLSSr; Lane et al. 2014), Galactic and Extragalactic All-sky Murchison Widefield Array survey (GLEAM; Wayth et al. 2015; Hurley- Walker et al. 2017; Lenc et al. 2018), TIFR GMRT Sky Survey (TGSS-ADR1; Intema et al. 2017), NRAO VLA Sky Survey (NVSS; Condon et al. 1998), Sydney University Molonglo Sky Survey (SUMSS; Mauch et al. 2003), Molonglo Galactic Plane Survey (MGPS-2; Murphy et al. 2007), and the VLA Sky Survey (VLASS; Lacy et al. 2020). Together, NVSS in the north and SUMSS and MGPS-2 in the south cover the whole sky and have been the primary reference for radio sources at gigahertz frequencies. It is clear from Table 1 that RACS fills a critical niche connecting low-frequency surveys at metre wavelength to existing and forth- coming decimetric surveys. Sensitive wideband coverage in this intermediate regime strengthens efforts to understand the broad- band spectra of the radio source population (e.g., Callingham et al. 2017; de Gasperin, Intema, & Frail 2018). RACS also establishes a solid reference catalogue against which to assess radio source variability and transient candidates as future surveys emerge from ASKAP, MeerKAT, and the SKA.

“This paper is a companion to the first RACS data release of 903 images made at a centre frequency of 887.5 MHz and covering the sky south of δ = +41◦ (83% of the celestial sphere). We outline the survey design in Section 2 and how it uses the established capabili- ties of the telescope. In Section 3, we describe the specific approach taken with the first epoch of observations and present their results. We discuss image quality and describe some extra steps taken to optimise the scientific utility of the RACS data products. Section 4 lists the products to be released and gives some examples of RACS images. In Section 5, we summarise the the current state of the survey and our plans for its future…”

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