The SARAO MeerKAT Galactic Plane Survey extended source catalogue

¹ INAF-Osservatorio Astrofisico di Catania, Via Santa Sofia 78, 95123 Catania, Italy
² Department of Electrical, Electronic and Computer Engineering, University of Catania, Viale Andrea Doria 6, 95125 Catania, Italy
³ South African Radio Astronomy Observatory, 2 Fir Street, Observatory 7925, South Africa
⁴ National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
⁵ School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
⁶ SARAO/Hartebeesthoek Radio Astronomy Observatory, PO Box 443, Krugersdorp 1740, South Africa
⁷ Department of Physics and Astronomy, York University, Toronto, M3J 1P3, Ontario, Canada
⁸ SKA Observatory, 2 Fir Street, Observatory 7925, South Africa
⁹ Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506, USA
¹⁰ Adjunct Astronomer at the Green Bank Observatory, PO Box 2, Green Bank, WV 24944, USA
¹¹ Center for Gravitational Waves and Cosmology, West Virginia University, Chestnut Ridge Research Building, Morgantown, WV 26505, USA
¹² Department of Mathematical Sciences, University of South Africa, Cnr Christian de Wet Rd and Pioneer Avenue, Florida Park, 1709 Roodepoort, South Africa
¹³ Department of Physics and Astronomy, Faculty of Physical Sciences, University of Nigeria, Carver Building, 1 University Road, Nsukka 410001, Nigeria
¹⁴ Department of Physics, Aberystwyth University, Ceredigion, Cymru SY23 3BZ, UK

^★ Corresponding authors; cristobal.bordiu@inaf.it, simone.riggi@inaf.it

Received: 12 April 2024
Accepted: 31 January 2025

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 deg² across the first, third, and fourth Galactic quadrants, the catalogue includes 16 534 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.