University of Hertfordshire

From the same journal

From the same journal

By the same authors


  • 1811.07927v1

    Accepted author manuscript, 2.16 MB, PDF document

  • W. L. Williams
  • P. N. Best
  • J. Sabater
  • J. H. Croston
  • K. J. Duncan
  • T. W. Shimwell
  • H. J. A. Röttgering
  • D. Nisbet
  • G. Gürkan
  • L. Alegre
  • R. K. Cochrane
  • A. Goyal
  • C. L. Hale
  • N. Jackson
  • M. Jamrozy
  • R. Kondapally
  • M. Kunert-Bajraszewska
  • V. H. Mahatma
  • B. Mingo
  • L. K. Morabito
  • I. Prandoni
  • C. Roskowinski
  • A. Shulevski
  • C. Tasse
  • S. Urquhart
  • B. Webster
  • G. J. White
  • R. J. Beswick
  • J. R. Callingham
  • K. T. Chyży
  • F. de Gasperin
  • M. Hoeft
  • M. Iacobelli
  • J. P. McKean
  • A. P. Mechev
  • G. K. Miley
  • D. J. Schwarz
  • R. J. van Weeren
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Original languageEnglish
Article numberA2
Pages (from-to)1-23
Number of pages23
JournalAstronomy & Astrophysics
Early online date9 Nov 2018
Publication statusE-pub ahead of print - 9 Nov 2018


The LOFAR Two-metre Sky Survey (LoTSS) is an ongoing sensitive, high-resolution 120-168 MHz survey of the Northern sky with diverse and ambitious science goals. Many of the scientific objectives of LoTSS rely upon, or are enhanced by, the association or separation of the sometimes incorrectly catalogued radio components into distinct radio sources, and the identification and characterisation of the optical counterparts to these sources. Here we present the source associations and optical and/or IR identifications for sources in the first data release, which are made using a combination of statistical techniques and visual association and identification. We document in detail the colour- and magnitude-dependent likelihood ratio method used for statistical identification as well as the Zooniverse project, called LOFAR Galaxy Zoo, used for the visual classification. We describe the process used to select which of these two different methods is most appropriate for each LoTSS source. The final LoTSS-DR1-IDs value-added catalogue presented contains 318,520 radio sources, of which 231,716 (73%) have optical and/or IR identifications in Pan-STARRS and WISE. The value-added catalogue is available online at, as part of this data release.


8 figures, 5 tables and 23 pages. This paper is part of the LOFAR surveys data release 1 and has been accepted for publication in a special edition of A&A that will appear in Feb 2019, volume 622. The catalogues and images from the data release will be publicly available at upon publication in the journal. Reproduced with permission from Astronomy & Astrophysics. © 2019 ESO.

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