GLEAM : The GaLactic and Extragalactic All-sky MWA survey
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Author
Wayth, R. B.
Lenc, E.
Bell, M. E.
Callingham, J. R.
Dwarakanath, K. S.
Franzen, T. M. O.
For, B. -Q.
Gaensler, B.
Hancock, P.
Hindson, L.
Hurley-Walker, N.
Jackson, C. A.
Johnston-Hollitt, M.
Kapinska, A. D.
McKinley, B.
Morgan, J.
Offringa, A. R.
Procopio, P.
Staveley-Smith, L.
Wu, C.
Zheng, Q.
Trott, C. M.
Bernardi, G.
Bowman, J. D.
Briggs, F.
Cappallo, R. J.
Corey, B. E.
Deshpande, A. A.
Emrich, D.
Goeke, R.
Greenhill, L. J.
Hazelton, B. J.
Kaplan, D. L.
Kasper, J. C.
Kratzenberg, E.
Lonsdale, C. J.
Lynch, M. J.
McWhirter, S. R.
Mitchell, D. A.
Morales, M. F.
Morgan, E.
Oberoi, D.
Ord, S. M.
Prabu, T.
Rogers, A. E. E.
Roshi, A.
Shankar, N. Udaya
Srivani, K. S.
Subrahmanyan, R.
Tingay, S. J.
Waterson, M.
Webster, R. L.
Whitney, A. R.
Williams, A.
Williams, C. L.
Attention
2299/18919
Abstract
GLEAM, the GaLactic and Extragalactic All-sky MWA survey, is a survey of the entire radio sky south of declination +25 deg at frequencies between 72 and 231 MHz, made with the Murchison Widefield Array (MWA) using a drift scan method that makes efficient use of the MWA's very large field-of-view. We present the observation details, imaging strategies and theoretical sensitivity for GLEAM. The survey ran for two years, the first year using 40 kHz frequency resolution and 0.5 s time resolution; the second year using 10 kHz frequency resolution and 2 s time resolution. The resulting image resolution and sensitivity depends on observing frequency, sky pointing and image weighting scheme. At 154 MHz the image resolution is approximately 2.5 x 2.2/cos(DEC+26.7) arcmin with sensitivity to structures up to ~10 deg in angular size. We provide tables to calculate the expected thermal noise for GLEAM mosaics depending on pointing and frequency and discuss limitations to achieving theoretical noise in Stokes I images. We discuss challenges, and their solutions, that arise for GLEAM including ionospheric effects on source positions and linearly polarised emission, and the instrumental polarisation effects inherent to the MWA's primary beam.