Contributed Talk - Splinter RadioSky

Wednesday, 14 September 2022, 17:39   (SFG 1030 / virtual RadioSky)

Asynchronous on-the-fly (OTF) mosaic imaging with MeerKAT

Kristof Rozgonyi, J. Mohr, M. G. santos, K. Grainge, N. Maddox, O. Smirnov
Ludwig-Maximilians-Universitaet , Faculty of Physics; University of Western Cape, Departent of Physica and Astronomy; South African Radio Astronomy Observatory (SARO); The University of Manchester, Jordell Bank Centre for Astrophysics; Rhodes University, Department of Physics and Electronics

Interferometric scanning or ’on-the-fly’ mosaicking (OTFM) mode enables a high survey speed by removing some of the slew-and-settle overhead time from the observations. This mode, in particular, is ideal for multi-epoch, shallow, large-area surveys, carried out with a sensitive interferometer with a small field of view. OTFM also enables commensal single-dish intensity mapping with interferometric observations. However, this mode is only available on the VLA. MeerKAT and the upcoming SKA-mid would greatly benefit from implementing the OTF observing mode for both continuum and spectral-line large-area surveys. Although the current hardware is capable of OTF mode observations, developing a dedicated data reduction and imaging pipeline is required. As such, in the first step towards demonstrating the feasibility of the OTF mode on MeerKAT, we conducted a series of scanning observations to probe cosmology by intensity mapping in autocorrelation mode (standard observing mode) while additionally performing crosscorrelation for a fixed delay centre in the observer’s reference frame. Ergo no geometric delays were introduced to track the dish movements. While such an observation strategy introduces a small phase error on the observed visibilities, synthesis imaging can be carried out by phase-rotating the correlated visibilities to the antenna pointing. In this presentation, we report on the first results from these 'asynchronous' MeerKAT OTF observations. We present the calibration and imaging methods used, and our results from the scans processed to date. Furthermore, we discuss possible synergies with a commensal single-dish intensity mapping experiment.