Patterns of primary beam non-redundancy in close-packed 21 cm array observations
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Date
2021
Journal Title
Journal ISSN
Volume Title
Publisher
Oxford University Press
Abstract
Radio interferometer arrays such as HERA consist of many close-packed dishes arranged in a regular pattern, giving rise to a
large number of ‘redundant’ baselines with the same length and orientation. Since identical baselines should see an identical sky
signal, this provides a way of finding a relative gain/bandpass calibration without needing an explicit sky model. In reality, there
are many reasons why baselines will not be exactly identical, giving rise to a host of effects that spoil the redundancy of the array
and induce spurious structure in the calibration solutions if not accounted for. In this paper, we seek to build an understanding
of how differences in the primary beam response between antennas affect redundantly calibrated interferometric visibilities
and their resulting frequency (delay-space) power spectra. We use simulations to study several generic types of primary beam
variation, including differences in the width of the main lobe, the angular and frequency structure of the sidelobes, and the beam
ellipticity and orientation.
Description
Keywords
Astrophysics, Astronomy, Dark ages, Reionization, Radiation, Radio interferometer arrays
Citation
Choudhuri, S. et al. (2021). Patterns of primary beam non-redundancy in close-packed 21 cm array observations. Monthly Notices of the Royal Astronomical Society, 506(2), 2066–2088. https://doi.org/10.1093/mnras/stab1795