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Post Info TOPIC: Murchison Widefield Array


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GLEAM survey
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Title: GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey I: A low-frequency extragalactic catalogue
Author: Natasha Hurley-Walker, Joseph R. Callingham, Paul J. Han****, Thomas M. O. Franzen, Luke Hindson, Anna D. Kapinska, John Morgan, Andre R. Offringa, Randall B. Wayth, Chen Wu, Q. Zheng, Tara Murphy, Martin E. Bell, K. S. Dwarakanath, Bi-Qing For, Bryan M. Gaensler, Melanie Johnston-Hollitt, Emil Lenc, Pietro Procopio, Lister Staveley-Smith, Ron Ekers, Judd D. Bowman, Frank Briggs, R. J. Cappallo, Avinash A. Deshpande, Lincoln Greenhill, Brynah J. Hazelton, David L. Kaplan, Colin J. Lonsdale, S. R. McWhirter, Daniel A. Mitchell, Miguel F. Morales, Edward Morgan, Divya Oberoi, Stephen M. Ord, T. Prabu, N. Udaya Shankar, K. S. Srivani, Ravi Subrahmanyan, Steven J. Tingay, Rachel L. Webster, Andrew Williams, Christopher L. Williams

Using the Murchison Widefield Array (MWA), the low-frequency Square Kilometre Array (SKA1 LOW) precursor located in Western Australia, we have completed the GaLactic and Extragalactic All-sky MWA (GLEAM) survey, and present the resulting extragalactic catalogue, utilising the first year of observations. The catalogue covers 24,831 square degrees, over declinations south of +30 and Galactic latitudes outside 10 of the Galactic plane, excluding some areas such as the Magellanic Clouds. It contains 307,455 radio sources with 20 separate flux density measurements across 72--231MHz, selected from a time- and frequency- integrated image centred at 200MHz, with a resolution of approx 2'. Over the catalogued region, we estimate that the catalogue is 90% complete at 170mJy, and 50% complete at 55mJy, and large areas are complete at even lower flux density levels. Its reliability is 99.97% above the detection threshold of 5sigma, which itself is typically 50mJy. These observations constitute the widest fractional bandwidth and largest sky area survey at radio frequencies to date, and calibrate the low frequency flux density scale of the southern sky to better than 10%. This paper presents details of the flagging, imaging, mosaicking, and source extraction/characterisation, as well as estimates of the completeness and reliability. All source measurements and images are available online. This is the first in a series of publications describing the GLEAM survey results.

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RE: Murchison Widefield Array
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Australian desert telescope views sky in radio technicolour

A telescope located deep in the West Australian outback has shown what the Universe would look like if human eyes could see radio waves.
Published today in the Monthly Notices of the Royal Astronomical Society, the GaLactic and Extragalactic All-sky MWA, or 'GLEAM' survey, has produced a catalogue of 300,000 galaxies observed by the Murchison Widefield Array (MWA), a $50 million radio telescope located at a remote site north-east of Geraldton.

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Posts: 131433
Date:
Murchison Radio-astronomy Observatory
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Upgrade For SKA Precursor Telescope In Australia

On September 4, the first full-size second generation (Mk II) phased array feed (PAF) receiver was installed on an antenna at the Australian SKA site - the Murchison Radio-astronomy Observatory in Western Australia.
This marked a new milestone in the development of CSIRO's Australian SKA Pathfinder (ASKAP) telescope, one of three SKA precursor telescopes.

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RE: Murchison Widefield Array
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Title: Observing the Sun with the Murchison Widefield Array
Author: D. Oberoi (1), R. Sharma (1), S. Bhatnagar (2), C. J. Lonsdale (3), L. D. Matthews (3), I. H. Cairns (4), S. J. Tingay (5), L. Benkevitch (3), A. Donea (6), S. M. White (7), G. Bernardi (8), J. D. Bowman (9), F. Briggs (10), R. J. Cappallo (3), B. E. Corey (3), A. Deshpande (11), D. Emrich (5), B. M. Gaensler (4 and 12), R. Goeke (13), L. J. Greenhill (14), B. J. Hazelton (15), M. Johnston-Hollitt (16), D. L. Kaplan (17), J. C. Kasper (18), E. Kratzenberg (3), M. J. Lynch (5), S. R. McWhirter (3), D. A. Mitchell (19 and 12), M. F. Morales (15), E. Morgan (13), A. R. Offringa (10), S. M. Ord (5), T. Prabu (11), A. E. E. Rogers (3), A. Roshi (20), J. E. Salah (3), N. Udaya Shankar (11), K. S. Srivani (11), R. Subrahmanyan (11 and 12), M. Waterson (5), R. B. Wayth (5), R. L. Webster (21 and 12), et al. (3 additional authors not shown)

The Sun has remained a difficult source to image for radio telescopes, especially at the low radio frequencies. Its morphologically complex emission features span a large range of angular scales, emission mechanisms involved and brightness temperatures. In addition, time and frequency synthesis, the key tool used by most radio interferometers to build up information about the source being imaged is not effective for solar imaging, because many of the features of interest are short lived and change dramatically over small fractional bandwidths.
Building on the advances in radio frequency technology, digital signal processing and computing, the kind of instruments needed to simultaneously capture the evolution of solar emission in time, frequency, morphology and polarization over a large spectral span with the requisite imaging fidelity, and time and frequency resolution have only recently begun to appear. Of this class of instruments, the Murchison Widefield Array (MWA) is best suited for solar observations. The MWA has now entered a routine observing phase and here we present some early examples from MWA observations.

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Early Universe to be revealed

Solar storms, space junk and the formation of the Universe are about to be seen in an entirely new way with the start of operations today by the $51 million Murchison Widefield Array (MWA) radio telescope.
The first of three international precursors to the $2 billion Square Kilometre Array (SKA) telescope, the MWA is located in a remote pocket of outback Western Australia. It is the result of an international project led by Curtin University and was officially turned on this morning by Australias Science and Research Minister, Senator Kim Carr.

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Title: A 189 MHz, 2400 square degree polarization survey with the Murchison Widefield Array 32-element prototype
Authors: G. Bernardi, L.J. Greenhill, D.A. Mitchell, S.M. Ord, B.J. Hazelton, B.M. Gaensler, A. de Oliveira-Costa, M.F. Morales, R. Udaya Shankar, R. Subrahmanyan, R.B. Wayth, E. Lenc, C.L. Williams, W. Arcus, S.A. Balwinder, D.G. Barnes, J.D. Bowman, F.H. Briggs, J.D. Bunton, R.J. Cappallo, B.E. Corey, A. Deshpande, L. deSouza, D. Emrich, R. Goeke, D. Herne, J.N. Hewitt, M. Johnston-Hollitt, D. Kaplan, J.C. Kasper, B.B. Kincaid, R. Koenig, E. Kratzenberg, C.J. Lonsdale, M.J. Lynch, S.R. McWhirter, E. Morgan, D. Oberoi, J. Pathikulangara, T. Prabu, R.A. Remillard, A.E.E. Rogers, A. Roshi, J.E. Salah, R.J. Sault, K.S. Srivani, J. Stevens, S.J. Tingay, M. Waterson, R.L. Webster, A.R. Whitney, A. Williams, J.S.B. Wyithe

We present a Stokes I, Q and U survey at 189 MHz with the Murchison Widefield Array 32-element prototype covering 2400 square degrees. The survey has a 15.6 arcmin angular resolution and achieves a noise level of 15 mJy/beam. We demonstrate a novel interferometric data analysis that involves calibration of drift scan data, integration through the co-addition of warped snapshot images and deconvolution of the point spread function through forward modelling. We present a point source catalogue down to a flux limit of 4 Jy. We detect polarisation from only one of the sources, PMN J0351-2744, at a level of 1.8 0.4%, whereas the remaining sources have a polarisation fraction below 2%. Compared to a reported average value of 7% at 1.4 GHz, the polarisation fraction of compact sources significantly decreases at low frequencies. We find a wealth of diffuse polarised emission across a large area of the survey with a maximum peak of ~13 K, primarily with positive rotation measure values smaller than +10 rad/m. The small values observed indicate that the emission is likely to have a local origin (closer than a few hundred parsecs). There is a large sky area at 2^h30^m where the diffuse polarised emission rms is fainter than 1 K. Within this area of low Galactic polarisation we characterise the foreground properties in a cold sky patch at (\alpha,\delta) = (4^h,-27.6) in terms of three dimensional power spectra

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Title: Science with the Murchison Widefield Array
Authors: Judd D. Bowman, Iver Cairns, David L. Kaplan, Tara Murphy, Divya Oberoi, Lister Staveley-Smith, Wayne Arcus, David G. Barnes, Gianni Bernardi, Frank H. Briggs, Shea Brown, John D. Bunton, Adam J. Burgasser, Roger J. Cappallo, Shami Chatterjee, Brian E. Corey, Anthea Coster, Avinash Deshpande, Ludi deSouza, David Emrich, Philip Erickson, Robert F. Goeke, B. M. Gaensler, Lincoln J. Greenhill, Lisa Harvey-Smith, Bryna J. Hazelton, David Herne, Jacqueline N. Hewitt, Melanie Johnston-Hollitt, Justin C. Kasper, Barton B. Kincaid, Ronald Koenig, Eric Kratzenberg, Colin J. Lonsdale, Mervyn J. Lynch, Lynn D. Matthews, S. Russell McWhirter, Daniel A. Mitchell, Miguel F. Morales, Edward H. Morgan, Stephen M. Ord, Joseph Pathikulangara, Prabu Thiagaraj, Ronald A. Remillard, Timothy Robishaw, Alan E. E. Rogers, et al. (15 additional authors not shown)

Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the Southern Hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21 cm emission from the epoch of reionisation in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.

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Providing a clearer view of our early Universe

The MWA will survey the sky more thoroughly and deeply than ever before in an attempt to detect very faint signals from the Epoch of Reionisation - a little understood early era of the Universe's history, occurring within the first billion years after the Big Bang, when cool atomic hydrogen gas was heated and ionised by the first light-emitting objects in the Universe.
As recently published in The Astrophysical Journal, researcher Dr Cathryn Trott and her team at the International Centre for Radio Astronomy Research have proposed a more accurate method of understanding bright foreground noise that may be obscuring scientists' views of these very faint signals.

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New radio telescope could save world billions

A small pocket of Western Australia's remote outback is set to become the eye on the sky and could potentially save the world billions of dollars. The Murchison Widefield Array (MWA) radio telescope, unveiled today, Friday 30 November, will give the world a dramatically improved view of the Sun and provide early warning to prevent damage to communication satellites, electric power grids and GPS navigation systems.
The $51 million low-frequency radio telescope will be able to detect and monitor massive solar storms, such as the one that cut power to six million people in Canada in 1989 during the last peak in solar activity.

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Australia - New Zealand Square Kilometre Array site is already producing world-class astrophysics

CSIRO's Murchison Radioastronomy Observatory (MRO), located in remote Western Australia, is the site proposed by Australia and New Zealand to host the high-density core of the multi-billion dollar Square Kilometre Array (SKA), and is already producing world-class research that will be described at an international conference in the UK this week.
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