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Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/6390
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dc.contributor.authorLoi, Shyeh Tjing-
dc.contributor.authorMurphy, Tara-
dc.contributor.authorDeshpande, A.A.-
dc.contributor.authorPrabu, T.-
dc.contributor.authorUdaya Shankar, N.-
dc.contributor.authorSrivani, K.S.-
dc.contributor.authorSubrahmanyan, Ravi-
dc.contributor.author+28 Co-authors-
dc.date.accessioned2016-09-21T06:05:03Z-
dc.date.available2016-09-21T06:05:03Z-
dc.date.issued2015-11-
dc.identifier.citationMonthly Notices of the Royal Astronomical Society , 2015, Vol. 453, p 2731-2746en_US
dc.identifier.issn1365-2966 - (online)-
dc.identifier.issn0035-8711-
dc.identifier.urihttp://hdl.handle.net/2289/6390-
dc.descriptionOpen Accessen_US
dc.description.abstractRefraction 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 cross-matching 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.en_US
dc.language.isoenen_US
dc.publisherOxford University Press for the RASen_US
dc.relation.urihttp://adsabs.harvard.edu/abs/2015MNRAS.453.2731Len_US
dc.relation.urihttp://arxiv.org/abs/1508.00965en_US
dc.relation.urihttp://dx.doi.org/ 10.1093/mnras/stv1808en_US
dc.rights2015 The authors & the Royal Astronomical Society.en_US
dc.subjectinterferometersen_US
dc.subjectradio continuumen_US
dc.titleQuantifying ionospheric effects on time-domain astrophysics with the Murchison Widefield arrayen_US
dc.typeArticleen_US
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