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    Quantifying ionospheric effects on time-domain astrophysics with the Murchison Widefield Array

    234780_234780.pdf (2.687Mb)
    Access Status
    Open access
    Authors
    Loi, S.
    Murphy, T.
    Bell, M.
    Kaplan, D.
    Lenc, E.
    Offringa, A.
    Hurley-Walker, Natasha
    Bernardi, G.
    Bowman, J.
    Briggs, F.
    Cappallo, R.
    Corey, B.
    Deshpande, A.
    Emrich, David
    Gaensler, B.
    Goeke, R.
    Greenhill, L.
    Hazelton, B.
    Johnston-Hollitt, M.
    Kasper, J.
    Kratzenberg, E.
    Lonsdale, C.
    Lynch, Mervyn
    McWhirter, S.
    Mitchell, D.
    Morales, M.
    Morgan, E.
    Oberoi, D.
    Ord, Stephen
    Prabu, T.
    Rogers, A.
    Roshi, A.
    Udaya Shankar, N.
    Srivani, K.
    Subrahmanyan, R.
    Tingay, Steven
    Waterson, M.
    Wayth, Randall
    Webster, R.
    Whitney, A.
    Williams, Andrew
    Williams, C.
    Date
    2015
    Type
    Journal Article
    
    Metadata
    Show full item record
    Citation
    Loi, S. and Murphy, T. and Bell, M. and Kaplan, D. and Lenc, E. and Offringa, A. and Hurley-Walker, N. et al. 2015. Quantifying ionospheric effects on time-domain astrophysics with the Murchison Widefield Array. Monthly Notices of the Royal Astronomical Society. 453 (3): pp. 2731-2746.
    Source Title
    Monthly Notices of the Royal Astronomical Society
    DOI
    10.1093/mnras/stv1808
    ISSN
    0035-8711
    School
    Department of Physics and Astronomy
    Remarks

    This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

    URI
    http://hdl.handle.net/20.500.11937/28456
    Collection
    • Curtin Research Publications
    Abstract

    © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Refraction and diffraction of incoming radio waves by the ionosphere induce time variability in the angular positions, peak amplitudes and shapes of radio sources, potentially complicating the automated cross-matching and identification of transient and variable radio sources. In this work, we empirically assess the effects of the ionosphere on data taken by the Murchison Widefield Array (MWA) radio telescope. We directly examine 51 h of data observed over 10 nights under quiet geomagnetic conditions (global storm index Kp < 2), analysing the behaviour of short-time-scale angular position and peak flux density variations of around ten thousand unresolved sources. We find that while much of the variation in angular position can be attributed to ionospheric refraction, the characteristic displacements (10-20 arcsec) at 154 MHz are small enough that search radii of 1-2 arcmin should be sufficient for crossmatching under typical conditions. By examining bulk trends in amplitude variability, we place upper limits on the modulation index associated with ionospheric scintillation of 1-3 per cent for the various nights. For sources fainter than ~1 Jy, this variation is below the image noise at typical MWA sensitivities. Our results demonstrate that the ionosphere is not a significant impediment to the goals of time-domain science with the MWA at 154 MHz.

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