Speaker
Description
The MeerKLASS survey uses MeerKAT in single-dish autocorrelation mode to map the large-scale neutral-hydrogen sky over hundreds of square degrees, with the long-term goal of contributing a low-redshift, radio-frequency view of cosmic structure to the broader multi-wavelength sky-modelling effort. Reaching the required sensitivity demands gain calibration that is stable and absolute to a level well beyond what is needed for typical radio imaging, and that can be propagated cleanly into an end-to-end analysis alongside foreground and systematics models. In this poster I present recent progress within the MuSEEK pipeline on tying together the two principal calibration handles available to a single-dish experiment: bright astronomical point sources (Hydra A, Pictor A) observed at the start and end of each scan, and the injected noise diode firings that bracket every dump. Point-source calibration provides an absolute temperature anchor through a physical model combining the primary beam, atmospheric opacity, receiver temperature, and ground spillover, while the noise diode tracks the bandpass and short-timescale gain drifts between calibrator visits. I show the level of consistency between the two approaches across the MeerKAT UHF band (~580–1015 MHz), the residual spectral structure that limits their agreement, and the implications for the per-dish gain solutions propagated downstream into map-making. A persistent obstacle to both calibration paths is low-level RFI that survives conventional flagging and biases gain estimates in subtle, frequency-dependent ways — a systematic that directly leaks into any global model built on these data. As part of an ongoing effort within the MeerKLASS collaboration to harden the calibration chain, I am evaluating a number of recently developed tools against real UHF observations, including a moment-based RFI detection scheme (momentRFI) intended to complement AOFlagger by exploiting higher-order statistics of the visibility distribution to catch contamination that escapes amplitude-threshold flaggers. I report on its impact, and that of related improvements, on the recovered gain solutions and on the noise-diode-derived bandpass, and close with an outlook on folding the most promising of these into the standard MeerKLASS calibration chain and on how the resulting data products are intended to interface with end-to-end Bayesian analyses of the kind central to the Cosmoglobe programme.