The LOFAR Two-meter Sky Survey: Deep Fields Data Release 1
Astronomy and Astrophysics, vol. 648, pp. A1
Abstract
The Low Frequency Array (LOFAR) is an ideal instrument to conduct deep extragalactic surveys. It has a large field of view and is sensitive to large-scale and compact emission. It is, however, very challenging to synthesize thermal noise limited maps at full resolution, mainly because of the complexity of the low-frequency sky and the direction dependent effects (phased array beams and ionosphere). In this first paper of a series, we present a new calibration and imaging pipeline that aims at producing high fidelity, high dynamic range images with LOFAR High Band Antenna data, while being computationally efficient and robust against the absorption of unmodeled radio emission. We apply this calibration and imaging strategy to synthesize deep images of the Boötes and Lockman Hole fields at ~150 MHz, totaling ~80 and ~100 h of integration, respectively, and reaching unprecedented noise levels at these low frequencies of ≲30 and ≲23μJy beam−1in the inner ~3 deg2. This approach is also being used to reduce the LOTSS-wide data for the second data release.
Authors 32
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Centre National de la Recherche Scientifique · Rhodes University · Université Paris Sciences et Lettres · Observatoire de Paris · Galaxies, Etoiles, Physique et Instrumentation · Université Paris Diderot
Affiliation as printed
Centre for Radio Astronomy Techniques and Technologies, Department of Physics and Electronics, Rhodes University, Grahamstown 6140, South Africa
GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France
USN, Observatoire de Paris, CNRS, PSL, UO, Nançay, France
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Leiden University · Leiden Observatory · Netherlands Institute for Radio Astronomy
Affiliation as printed
ASTRON, Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, 7991 PD, Dwingeloo, The Netherlands
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
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Affiliation as printed
Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
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Affiliation as printed
School of Physical Sciences and Centre for Astrophysics & Relativity, Dublin City University, Glasnevin, D09 W6Y4, Ireland
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Leiden University · Leiden Observatory
Affiliation as printed
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
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Affiliation as printed
SUPA, Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK
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Rhodes University · South African Radio Astronomy Observatory
Affiliation as printed
Centre for Radio Astronomy Techniques and Technologies, Department of Physics and Electronics, Rhodes University, Grahamstown 6140, South Africa
South African Radio Astronomy Observatory, Observatory 7925, Cape Town, South Africa
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Rhodes University · South African Radio Astronomy Observatory
Affiliation as printed
Centre for Radio Astronomy Techniques and Technologies, Department of Physics and Electronics, Rhodes University, Grahamstown 6140, South Africa
South African Radio Astronomy Observatory, Observatory 7925, Cape Town, South Africa
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Rhodes University · South African Radio Astronomy Observatory
Affiliation as printed
Centre for Radio Astronomy Techniques and Technologies, Department of Physics and Electronics, Rhodes University, Grahamstown 6140, South Africa
South African Radio Astronomy Observatory, Observatory 7925, Cape Town, South Africa
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Affiliation as printed
SUPA, Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK
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Affiliation as printed
European Southern Observatory, Karl-Schwarzchild-Strasse 2, 85748 Garching bei München, Germany
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Affiliation as printed
Hamburger Sternwarte, University of Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
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Affiliation as printed
Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham, DH1 3LE, UK
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Leiden University · Leiden Observatory
Affiliation as printed
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
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Leiden University · Leiden Observatory
Affiliation as printed
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
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Istituto di Radioastronomia di Bologna · Osservatorio Astronomico di Padova · National Institute for Astrophysics
Affiliation as printed
INAF – Istituto di Radioastronomia, Via P. Gobetti 101, 40129 Bologna, Italy
INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122, Padova, Italy
Italian ALMA Regional Centre, Via Gobetti 101, 40129 Bologna, Italy
INAF – Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122, Padova, Italy
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Istituto di Radioastronomia di Bologna
Affiliation as printed
INAF – Istituto di Radioastronomia, Via P. Gobetti 101, 40129 Bologna, Italy
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Leiden University · Istituto di Radioastronomia di Bologna · Leiden Observatory
Affiliation as printed
INAF – Istituto di Radioastronomia, Via P. Gobetti 101, 40129 Bologna, Italy
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
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Affiliation as printed
Hamburger Sternwarte, University of Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
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Istituto di Radioastronomia di Bologna
Affiliation as printed
INAF – Istituto di Radioastronomia, Via P. Gobetti 101, 40129 Bologna, Italy
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Affiliation as printed
Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244 Kraków, Poland
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Leiden University · University of Manchester · Leiden Observatory
Affiliation as printed
Jodrell Bank Centre for Astrophysics, University of Manchester, Alan Turing Building, Oxford Road, M13 9PL, UK
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
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Commonwealth Scientific and Industrial Research Organisation
Affiliation as printed
CSIRO Astronomy and Space Science, PO Box 1130, Bentley WA 6102, Australia
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University of Oxford · University of the Western Cape
Affiliation as printed
Astrophysics, Department of Physics, Keble Road, Oxford, OX1 3RH, UK
Department of Physics & Astronomy, University of the Western Cape, Private Bag X17, Bellville, Cape Town 7535, South Africa
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Affiliation as printed
SUPA, Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK
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Leiden University · Leiden Observatory
Affiliation as printed
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
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Istituto di Radioastronomia di Bologna
Affiliation as printed
INAF – Istituto di Radioastronomia, Via P. Gobetti 101, 40129 Bologna, Italy
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Affiliation as printed
Institute of Sensors, Signals and Systems, Heriot-Watt University, Edinburgh EH14 4AS, UK
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Affiliation as printed
Astrophysics & Cosmology Research Unit, School of Mathematics, Statistics & Computer Science, University of KwaZulu-Natal, Durban 3690, South Africa
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Affiliation as printed
Fakultät für Physik, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany
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Affiliation as printed
Anton Pannekoek Institute for Astronomy, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam, The Netherlands
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Affiliation as printed
Institute of Sensors, Signals and Systems, Heriot-Watt University, Edinburgh EH14 4AS, UK
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