Determining ideal fields for Epoch of Reionisation science using the 21 cm line

Abstract The upcoming Square Kilometre Array Low Frequency (SKA-Low) interferometer will have the required sensitivity to detect the 21 cm line from neutral hydrogen during the Epoch of Reionisation (EoR). In preparation, we investigated the suitability of different fields for EoR science with the 21 cm line, using existing observations of candidate fields from the Murchison Widefield Array (MWA). Various image and calibration metrics were extracted from archival MWA observations centred on $z \sim 6.8$ . We explore the usefulness of these metrics and compare their behaviour between different fields of interest. In addition, a theoretical approach to quantifying the impact of different fields on the power spectrum is also provided. Gain uncertainties were calculated based on the positions of the calibrators within the beam. These uncertainties were then propagated into visibilities to produce cylindrical power spectra for various fields. Using these metrics in combination with the power spectra, we confirm that EoR0 ( $\text{R.A.} = 0\,\mathrm{deg}$ , $\text{Dec} = {-}27.0\,\mathrm{deg}$ ) is an ideal EoR field and discuss the interesting behaviour of other fields.