The SARAO MeerKAT Galactic Plane survey compact source catalogue

ABSTRACT We present a catalogue of compact sources detected in the SARAO (South African Radio Astronomy Observatory) MeerKAT 1.3 GHz Galactic Plane Survey (SMGPS). We extract 510 599 compact sources, with areas less than five 8 arcsec beams, from the survey maps covering the regions $252^{\circ } < l < 358^{\circ }$ and $2^{\circ } < l < 61^{\circ }$ at $|b| \le 1.5^{\circ }$, which have an angular resolution of 8 arcsec and a sensitivity of $\sim$10–30 $\mu$Jy beam$^{-1}$. In this paper, we describe the source identification and characterization methods, present the quality assurance of the catalogue, explore the nature of the catalogue sources, and present initial science highlights. We limit our catalogue to sources with a signal-to-noise ratio $\ge 5$, as the catalogue is $\sim$90 per cent complete, and has a false positive rate of less than 1 per cent at this threshold. The bulk of the catalogue sources are previously unknown to the literature, with the majority of unknown sources at sub-mJy levels. Initial science highlights from the catalogue include the detection of 213 radio quiet Wide-field Infrared Survey Explorer (WISE) H ii region candidates, previously undetected in radio continuum studies. We show images that compare the SMGPS compact sources to CORNISH (Coordinated Radio and Infrared Survey for High-Mass Star Formation) ultracompact H ii regions, thus highlighting the sensitivity and unprecedented uv-coverage of the SMGPS, and the potential synergy of the SMGPS with other surveys.