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14th of May 2020
PKS B1934-638
by Heywood et al.
The radio source PKS B1934-638 is a Giga-hertz Peaked Spectrum source that is widely used a primary calibrator source for radio interferometers in the southern hemisphere, as it is extremely stable, compact, and effectively unpolarized. Observations with radio interfereometers will usually include an observation of PKS B1934-638 to be used for flux density and bandpass calibration. However, the wide field-of-view and high sensitivity of modern interferometers means that additional sources are often also detected, which can introduce errors into bandpass corrections and subsequently the target data if not properly accounted for. Heywood et al. demonstrate that calibration pipelines should routinely employ complete field models, rather than the standarda assumption of a single point source, to remove this potentially destructive contaminant from the data.

The left image above shows an ASKAP BETA (6-antenna test array) image of the PKS B1934-638 field out to the nominal 10% radius of the primary beam at 863 MHz. The dashed circle shows the equivalent extent of the ATCA primary beam, and the right image shows an ATCA image of that area. Seven sources that are not well characterised by single point or Gaussian components are marked A–G. Development of a complete field model for accurate flux density and bandpass calibration requires accurate modelling of these more complicated sources. More details are given in the paper, published in Monthly Notices of the Royal Astronomical Society.

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