2025MNRAS.541.3894Z

Deep imaging of structures from the Cosmic Dawn (CD) and the Epoch of Reionization (EoR) in five targeted fields is one of the highest priority scientific objectives for the Square Kilometre Array (SKA). Selecting 'quiet' fields, which allow deep imaging, is critical for future SKA CD/EoR observations. Pre-observations using existing radio facilities will help estimate the computational capabilities required for optimal data quality and refine data reduction techniques. In this study, we utilize data from the Murchison Widefield Array Phase II extended array for a selected field to study the properties of foregrounds. We conduct deep imaging across two frequency bands: 72-103 and 200-231 MHz. We identify up to 2576 radio sources within a 5-degree radius of the image centre (at RA (J2000) 8$^h$, Dec (J2000) 5$^\circ$), achieving approximately 80 per cent completeness at 7.7 mJy and 90 per cent at 10.4 mJy for 216 MHz, with a total integration time of 4.43 h and an average RMS of 1.80 mJy. Additionally, we apply a foreground removal algorithm using Principal Component Analysis (PCA) and calculate the angular power spectra of the residual images. Our results indicate that nearly all resolved radio sources can be successfully removed using PCA, leading to a reduction in foreground power. However, the angular power spectra of the residual map remains over an order of magnitude higher than the theoretically predicted CD/EoR 21 cm signal. Further improvements in data reduction and foreground subtraction techniques will be necessary to enhance these results.