Speaker
Description
Detecting the redshifted 21-cm signal from the Epoch of Reionization (EoR) and Cosmic Dawn requires extremely precise calibration of low-frequency interferometric arrays. Small errors in the sky model can imprint artificial spectral structure in the gain solutions and leak bright foregrounds into the EoR window of the power spectrum. Wide-area surveys such as TGSS, GLEAM, and GLEAM-X provide a crucial starting point, but their sensitivity, resolution, and spectral-index accuracy are insufficient to meet the requirements of upcoming 21-cm experiments. Motivated by recent deep uGMRT imaging of the HERA calibration field GLEAM 02H, this project targets the MWA EoR fields with the upgraded GMRT Band-2 receiver to build a complementary, high-fidelity sky model optimized for precision calibration. In this work, Band-2 GWB observations of the MWA EoR fields (e.g., EoR0/SKAEoR5) are used, with the 200 MHz instantaneous bandwidth divided into multiple narrower sub-bands to facilitate accurate bandpass and direction-dependent calibration. The data are processed with a SPAM-based pipeline incorporating RFI excision, direction-independent calibration, ionospheric modelling, facet-based self-calibration, and wide-field imaging. The analysis is designed to quantitatively characterize image quality and calibration performance using background RMS maps, dynamic range, and the stability of gain solutions across frequency. The primary goal is to construct a deep source catalogue for these EoR fields with high completeness at faint flux densities, precise astrometry, and reliable integrated fluxes and morphology. This catalogue will be cross-matched with existing low-frequency surveys and then used as an enhanced sky model to simulate visibilities for MWA/HERA-like arrays, enabling a direct comparison between legacy and uGMRT-based calibration models for 21-cm cosmology and informing SKA-era calibration strategies.
