The MeerKLASS On-the-Fly continuum survey: pipeline design and validation

Suman Chatterjee; Mario G. Santos; Kristof Rozgonyi; Keith Grainge; Sarvesh Mangla; Joseph J. Mohr; Sourabh Paul; Yvette Perrott; Oleg M. Smirnov; Cyril Tasse; Laura Wolz

arXiv · 2512.11978

The MeerKLASS On-the-Fly continuum survey: pipeline design and validation

Suman Chatterjee·Mario G. Santos·Kristof Rozgonyi·Keith Grainge·Sarvesh Mangla·Joseph J. Mohr·Sourabh Paul·Yvette Perrott·Oleg M. Smirnov·Cyril Tasse·Laura Wolz

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Abstract

The MeerKAT Large Area Synoptic Survey (MeerKLASS) is designed to map large areas of the Southern sky for cosmology using the single-dish HI intensity mapping (IM) technique, while simultaneously delivering a wide, high angular-resolution interferometric survey. We present the design and first results of the MeerKLASS On-the-Fly (OTF) continuum data, which exploits the visibilities recorded during fast, constant-elevation scans. This observing mode enables fast commensal imaging over several hundred of square degrees on a nightly basis. We describe the OTF survey strategy and pipeline, focusing on handling challenges introduced by the current MeerKAT fixed-delay correlation observing mode, which causes decorrelation (smearing). We implement a correction scheme based on time-dependent phase rotation, direction-dependent PSF modeling, and wide-band faceted deconvolution with \texttt{DDFacet}. Using UHF-band and pilot L-band data, we demonstrate the recovery of high-quality 2-second snapshot images and deep mosaics over hundreds of square degrees. After smearing correction we are able to achieve a resolution of $23.3$arcsec and $14$ arcsec with an rms sensitivity of $35 \mu {\rm Jy\,beam}^{-1}$ and $ 33 \mu {\rm Jy\,beam}^{-1}$ in the UHF and L-band respectively. The full survey will cover $10,000 \, {\rm deg}^{2}$ at 544-1088 MHz, and after the delay tracking fix implemented we expect to reach $\sim 25 \mu {\rm Jy\,beam}^{-1}$ at $14$ arcsec resolution. The continuum OTF data products will support diverse science goals, including galaxy and AGN evolution, diffuse cluster emission, large-scale structure and cosmology, rotation-measure synthesis, and transient searches. MeerKLASS-OTF thus establishes an efficient path to wide-area commensal surveys with MeerKAT and provides a key technical precursor for SKA-Mid.

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Suman Chatterjee, Mario G. Santos, Kristof Rozgonyi, Keith Grainge, Sarvesh Mangla, Joseph J. Mohr, Sourabh Paul, Yvette Perrott, Oleg M. Smirnov, Cyril Tasse, Laura Wolz. 2025-12-12. The MeerKLASS On-the-Fly continuum survey: pipeline design and validation. https://arxiv.org/abs/2512.11978

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