The LOFAR Two-metre Sky Survey

VII. Third Data Release

¹ ASTRON, The Netherlands Institute for Radio Astronomy Postbus 2 NL-7990 AA Dwingeloo, The Netherlands
² Leiden Observatory, Leiden University PO Box 9513 2300 RA Leiden, The Netherlands
³ Centre for Astrophysics Research, University of Hertfordshire, Hatfield Herts AL10 9AB, UK
⁴ LUX, Observatoire de Paris, Université PSL, CNRS 792190 Meudon, France
⁵ Centre for Radio Astronomy Techniques and Technologies (RATT), Department of Physics and Electronics, Rhodes University Makhanda 6140, South Africa
⁶ Observatoire Radioastronomique de Nancçay, Observatoire de Paris, CNRS, PSL, UO Nancçay, France
⁷ Thüringer Landessternwarte Sternwarte 5 D-07778 Tautenburg, Germany
⁸ INAF-Istituto di Radioastronomia Via P. Gobetti 101 40129 Bologna, Italy
⁹ SKA Observatory, Jodrell Bank Lower Withington Macclesfield SK11 9FT, United Kingdom
¹⁰ School of Physics and Astronomy, Institute for Astronomy, University of Edinburgh, Royal Observatory Blackford Hill EH9 3HJ Edinburgh, UK
¹¹ Hamburger Sternwarte, University of Hamburg Gojenbergsweg 112 21029 Hamburg, Germany
¹² Anton Pannekoek Institute for Astronomy, University of Amsterdam Postbus 94249 1090 GE Amsterdam, The Netherlands
¹³ Astronomical Observatory of the Jagiellonian University Orla 171 PL-30-244 Krakow, Poland
¹⁴ Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory SE-439 92 Onsala, Sweden
¹⁵ Department of Astrophysics/IMAPP, Radboud University, Nijmegen P.O. Box 9010 6500 GL Nijmegen, The Netherlands
¹⁶ JBCA, Department of Physics and Astronomy, University of Manchester Oxford Road Manchester M13 9PL, UK
¹⁷ Centre for Extragalactic Astronomy, Department of Physics, Durham University Durham DH1 3LE, UK
¹⁸ Institute for Computational Cosmology, Department of Physics, Durham University South Road Durham DH1 3LE, UK
¹⁹ Kapteyn Astronomical Institute, University of Groningen PO Box 800 9700 AV Groningen, The Netherlands
²⁰ Departamento de Física de la Tierra y Astrofísica & IPARCOS-UCM, Universidad Complutense de Madrid 28040 Madrid, Spain
²¹ Fakultät für Physik, Universität Bielefeld Postfach 100131 33501 Bielefeld, Germany
²² Department of Physics & Astronomy, The Open University Milton Keynes MK7 6AA, UK
²³ RAL Space, UKRI STFC Rutherford Appleton Laboratory, Chilton Didcot Oxfordshire OX11 0QX, UK
²⁴ INAF – Osservatorio Astrofisico di Torino Strada Osservatorio 20 10025 Pino Torinese, Italy
²⁵ Dipartimento di Fisica, Università degli Studi di Torino Via P. Giuria 1 10125 Torino, Italy
²⁶ INFN – Sezione di Torino Via P. Giuria 1 10125 Torino, Italy
²⁷ Center for Theoretical Physics, Polish Academy of Sciences 32/46 Al. Lotników 02-668 Warsaw, Poland
²⁸ Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute (AIRUB) 44780 Bochum, Germany
²⁹ Dipartimento di Fisica e Astronomia, Università di Bologna Via P. Gobetti 93/2 40129 Bologna, Italy
³⁰ Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, Allée Geoffroy Saint-Hilaire 33615 Pessac, France
³¹ National Centre for Nuclear Research Pasteura 7 02-093 Warsaw, Poland
³² Jülich Supercomputing Centre, Forschungszentrum Jülich Wilhelm-Johnen-Straße Jülich 52428 NRW, Germany
³³ CSIRO Space and Astronomy, ATNF PO Box 1130 Bentley WA 6102, Australia
³⁴ Department of Geodesy, Faculty of Geoengineering, University of Warmia and Mazury ul. Oczapowskiego 2 10-719 Olsztyn, Poland
³⁵ Astrophysics, Department of Physics, University of Oxford Keble Road Oxford OX1 3RH, UK
³⁶ Astrophysics Group, Cavendish Laboratory, University of Cambridge JJ Thomson Ave Cambridge CB3 0HE, UK
³⁷ Department of Physics and Astronomy, University of the Western Cape Robert Sobukwe Road 7535 Bellville Cape Town, South Africa
³⁸ Ruđer Bošković Institute Bijenička cesta 54 10000 Zagreb, Croatia
³⁹ Julius-Maximilians-Universität Würzburg, Fakultät für Physik und Astronomie, Institut für Theoretische Physik und Astrophysik, Lehrstuhl für Astronomie Emil-Fischer-Str. 31 D-97074 Würzburg, Germany
⁴⁰ Toruń Centre for Astronomy, Faculty of Physics, Astronomy and Informatics, NCU Grudziądzka 5/7 87-100 Toruń, Poland
⁴¹ INAF – IAPS Via Fosso del Cavaliere 100 00133 Roma, Italy
⁴² South African Radio Astronomy Observatory (SARAO), P.O. Box 443, Krugersdorp 1740, South Africa; Department of Physics, University of Pretoria Lynnwood Road Hatfield Pretoria 0083, South Africa
⁴³ Instituto de Astrofísica de Andalucía, IAA-CSIC Glorieta de la Astronomía s/n 18008 Granada, Spain
⁴⁴ Astronomy Department, Universidad de Concepción Casilla 160-C Concepción, Chile
⁴⁵ Max Planck Institute for Radio Astronomy Auf dem Hügel 69 53121 Bonn, Germany
⁴⁶ Center for Astrophysics Harvard & Smithsonian 60 Garden Street Cambridge MA 02138, USA
⁴⁷ Ruhr Astroparticle and Plasma Physics Center (RAPP Center) 44780 Bochum, Germany
⁴⁸ Waterloo Centre for Astrophysics, University of Waterloo 200 University Ave W Waterloo ON N2L 3G1, Canada
⁴⁹ Department of Physics & Astronomy, University of Waterloo Waterloo ON N2L 3G1, Canada
⁵⁰ Center for Advanced Interdisciplinary Research, Ss. Cyril and Methodius University in Skopje Skopje, Macedonia
⁵¹ Inter-University Institute for Data Intensive Astronomy, Department of Astronomy, University of Cape Town 7701 Rondebosch Cape Town, South Africa
⁵² Inter-University Institute for Data Intensive Astronomy, Department of Physics and Astronomy, University of the Western Cape 7535 Bellville Cape Town, South Africa

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Received: 18 October 2025
Accepted: 13 January 2026

Abstract

We present the third data release of the LOFAR Two-metre Sky Survey (LoTSS-DR3). The survey images cover 88% of the northern sky and were created from 12 950 h of data (18.6 PB) accumulated over 10.5 years. Producing the images took 20 million core hours of processing through direction-independent and direction-dependent calibration pipelines that correct for instrumental effects as well as spatially and temporally varying ionospheric distortions. In our 120–168 MHz continuum mosaic images with an angular resolution of 6″ (9″ below declination 10°) we catalogue 13 667 877 sources, formed from 16 943 656 Gaussian components. The scatter in the astrometric precision approximately follows the expected noise-like behaviour but with an additional systematic component of at least 0.24″ that is likely due to calibration imperfections. The random flux density scale error is 6%, while the systematic offset was previously shown to be within 2%. The median sensitivity of our mosaics is 92 μJy beam⁻¹, improving to 68 μJy beam⁻¹ at high observing elevations, but degrading to 183 μJy beam⁻¹ at the celestial equator due to station area projection effects. Completeness simulations, accounting for realistic source models, time- and bandwidth-smearing effects, and astrometric errors, indicate that we detect more than 95% of compact sources with integrated flux densities exceeding 9 times the local root mean square (RMS) noise. However, the recovered source counts in a particular integrated flux density bin do not match the injected counts until flux densities exceed 45 times the local RMS noise. The Euclidean-normalised differential source counts derived from the survey constrain the radio source population over five orders of magnitude and are in good agreement with previous deep and wide-area surveys. All data products are publicly available, including catalogues, individual-field Stokes I, Q, U, and V images, mosaicked Stokes I images, and uv data with associated direction-dependent calibration solutions.