The LOFAR Two-metre Sky Survey (LoTSS) III. First Data Release: optical/IR identifications and value-added catalogue
Abstract
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 https://lofar-surveys.org/, as part of this data release.
Keywords
Cite
@article{arxiv.1811.07927,
title = {The LOFAR Two-metre Sky Survey (LoTSS) III. First Data Release: optical/IR identifications and value-added catalogue},
author = {W. L. Williams and M. J. Hardcastle and P. N. Best and J. Sabater and J. H. Croston and K. J. Duncan and T. W. Shimwell and H. J. A. Röttgering and D. Nisbet and G. Gürkan and L. Alegre and R. K. Cochrane and A. Goyal and C. L. Hale and N. Jackson and M. Jamrozy and R. Kondapally and M. Kunert-Bajraszewska and V. H. Mahatma and B. Mingo and L. K. Morabito and I. Prandoni and C. Roskowinski and A. Shulevski and D. J. B. Smith and C. Tasse and S. Urquhart and B. Webster and G. J. White and R. J. Beswick and J. R. Callingham and K. T. Chyży and F. de Gasperin and J. J. Harwood and M. Hoeft and M. Iacobelli and J. P. McKean and A. P. Mechev and G. K. Miley and D. J. Schwarz and R. J. van Weeren},
journal= {arXiv preprint arXiv:1811.07927},
year = {2019}
}
Comments
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 https://lofar-surveys.org/ upon publication in the journal