The SARAO MeerKAT Galactic Plane Survey extended source catalogue

TL;DR

This paper presents a comprehensive catalogue of over 16,500 extended radio sources from the MeerKAT Galactic Plane Survey, including their classification, properties, and potential for new discoveries in Galactic and extragalactic astronomy.

Contribution

The paper introduces a large, detailed catalogue of extended radio sources from MeerKAT, including classification and analysis methods, enhancing the understanding of Galactic and extragalactic radio emitters.

Findings

24% of sources are associated with known Galactic objects

33% are candidate extragalactic sources

43% remain unclassified

Abstract

We present a catalogue of extended radio sources from the SARAO MeerKAT Galactic Plane Survey (SMGPS). Compiled from 56 survey tiles and covering approximately 500 deg$^2$ across the first, third, and fourth Galactic quadrants, the catalogue includes 16534 extended and diffuse sources with areas larger than 5 synthesised beams. Of them, 3891 (24\% of the total) are confidently associated with known Galactic radio-emitting objects in the literature, such as HII regions, supernova remnants, planetary nebulae, luminous blue variables, and Wolf-Rayet stars. A significant fraction of the remaining sources, 5462 (33\%), are candidate extragalactic sources, while 7181 (43\%) remain unclassified. Isolated radio filaments are excluded from the catalogue. The diversity of extended sources underscores MeerKAT's contribution to the completeness of censuses of Galactic radio emitters, and its potential for new scientific discoveries. For the catalogued sources, we derived basic positional and morphological parameters, as well as flux density estimates, using standard aperture photometry. This paper describes the methods followed to generate the catalogue from the original SMGPS tiles, detailing the source extraction, characterisation, and crossmatching procedures. Additionally, we analyse the statistical properties of the catalogued populations