The ASKAP Variables and Slow Transients (VAST) Pilot Survey
Publications of the Astronomical Society of Australia Cambridge University Press 38 (2021) e054
Authors:
Tara Murphy, David L Kaplan, Adam J Stewart, Andrew O'Brien, Emil Lenc, Sergio Pintaldi, Joshua Pritchard, Dougal Dobie, Archibald Fox, James K Leung, Tao An, Martin E Bell, Jess W Broderick, Shami Chatterjee, Shi Dai, Daniele d'Antonio, J Gerry Doyle, BM Gaensler, George Heald, Assaf Horesh, Megan L Jones, David McConnell, Vanessa A Moss, Wasim Raja, Gavin Ramsay, Stuart Ryder, Elaine M Sadler, Gregory R Sivakoff, Yuanming Wang, Ziteng Wang, Michael S Wheatland, Matthew Whiting, James R Allison, CS Anderson, Lewis Ball, K Bannister, DC-J Bock, R Bolton, JD Bunton, R Chekkala, AP Chippendale, FR Cooray, N Gupta, DB Hayman, K Jeganathan, B Koribalski, K Lee-Waddell, Elizabeth K Mahony, J Marvil, NM McClure-Griffiths
Abstract:
The Variables and Slow Transients Survey (VAST) on the Australian Square Kilometre Array Pathfinder (ASKAP) is designed to detect highly variable and transient radio sources on timescales from 5 s to ~5 yr. In this paper, we present the survey description, observation strategy and initial results from the VAST Phase I Pilot Survey. This pilot survey consists of ~162 h of observations conducted at a central frequency of 888 MHz between 2019 August and 2020 August, with a typical rms sensitivity of 0.24 mJy beam-1 and angular resolution of 12 – 20 arcseconds. There are 113 fields, each of which was observed for 12 min integration time, with between 5 and 13 repeats, with cadences between 1 day and 8 months. The total area of the pilot survey footprint is 5 131 square degrees, covering six distinct regions of the sky. An initial search of two of these regions, totalling 1 646 square degrees, revealed 28 highly variable and/or transient sources. Seven of these are known pulsars, including the millisecond pulsar J2039–5617. Another seven are stars, four of which have no previously reported radio detection (SCR J0533–4257, LEHPM 2-783, UCAC3 89–412162 and 2MASS J22414436–6119311). Of the remaining 14 sources, two are active galactic nuclei, six are associated with galaxies and the other six have no multi-wavelength counterparts and are yet to be identified.
