The Impact of Tandem Redundant/Sky-Based Calibration in MWA Phase II Data Analysis

Abstract

Precise instrumental calibration is of crucial importance to 21-cm cosmology experiments. The Murchison Widefield Array's (MWA) Phase II compact configuration offers us opportunities for both redundant calibration and sky-based calibration algorithms; using the two in tandem is a potential approach to mitigate calibration errors caused by inaccurate sky models. The MWA Epoch of Reionization (EoR) experiment targets three patches of the sky (dubbed EoR0, EoR1, and EoR2) with deep observations. Previous work in \cite{Li_2018} and \cite{Wenyang_2019} studied the effect of tandem calibration on the EoR0 field and found that it yielded no significant improvement in the power spectrum over sky-based calibration alone. In this work, we apply similar techniques to the EoR1 field and find a distinct result: the improvements in the power spectrum from tandem calibration are significant. To understand this result, we analyze both the calibration solutions themselves and the effects on the power spectrum over three nights of EoR1 observations. We conclude that the presence of the bright radio galaxy Fornax A in EoR1 degrades the performance of sky-based calibration, which in turn enables redundant calibration to have a larger impact. These results suggest that redundant calibration can indeed mitigate some level of model-incompleteness error.

arXiv comment20 pages, 11 figures, accepted for publication in PASA

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Cited by in corpus (8)

• A new MWA limit on the 21 cm Power Spectrum at Redshifts $\sim$ 13 $-$ 17
• A Unified Calibration Framework for 21 cm Cosmology
• A Map of Diffuse Radio Emission at 182 MHz to Enhance Epoch of Reionization Observations in the Southern Hemisphere
• Probing early universe through redshifted 21-cm signal: Modelling and observational challenges
• The Role of the Instrumental Response in 21 cm EoR Power Spectrum Gridding Analyses
• Delay-Weighted Calibration: Precision Calibration for 21 cm Cosmology with Resilience to Sky Model Error
• Epoch of Reionization Power Spectrum Limits from Murchison Widefield Array Data Targeted at EoR1 Field
• The Correlation Calibration of PAPER-64 data