The LOFAR LBA Sky Survey
Open Research Online - ORO (The Open University)
Abstract
Context. The LOw Frequency ARray (LOFAR) is the only radio telescope that is presently capable of high-sensitivity, high-resolution (i.e. <1 mJy beam−1 and <15") observations at ultra-low frequencies (<100 MHz). To utilise these capabilities, the LOFAR Surveys Key Science Project is undertaking a large survey to cover the entire northern sky with Low Band Antenna (LBA) observations. \nAims. The LOFAR LBA Sky Survey (LoLSS) aims to cover the entire northern sky with 3170 pointings in the frequency range between 42−66 MHz, at a resolution of 15" and at a sensitivity of 1 mJy beam−1 (1σ). In this work, we outline the survey strategy, the observational status, and the calibration techniques. We also briefly describe several of our scientific motivations and present the preliminary public data release. \nMethods. The preliminary images were produced using a fully automated pipeline aimed at correcting all direction-independent effects in the data. Whilst the direction-dependent effects, such as those from the ionosphere, have not yet been corrected, the images presented in this work are still ten times more sensitive than previous available surveys at these low frequencies. \nResults. The preliminary data release covers 740 deg2 around the HETDEX spring field region at an angular resolution of 47" with a median noise level of 5 mJy beam−1. The images and the catalogue of 25 247 sources have been publicly released. We demonstrate that the system is capable of reaching a root mean square (rms) noise of 1 mJy beam−1 and an angular resolution of 15" once direction-dependent effects are accounted for. \nConclusions. LoLSS will provide the ultra-low-frequency information for hundreds of thousands of radio sources, providing critical spectral information and producing a unique data set that can be used for a wide range of science topics, such as the search for high redshift galaxies and quasars, the study of the magnetosphere of exoplanets, and the detection of the oldest populations of cosmic-rays in galaxies, clusters of galaxies, as well as those produced by active galactic nuclei.
Authors 41
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Universität Hamburg · Istituto di Radioastronomia di Bologna
Affiliation as printed
Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
INAF – Istituto di Radioastronomia, via P. Gobetti 101, 40129 Bologna, Italy
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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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Royal Observatory · University of Edinburgh
Affiliation as printed
Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
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Affiliation as printed
Hamburger Sternwarte, Universität 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
Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
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Netherlands Institute for Radio Astronomy
Affiliation as printed
ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, 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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Netherlands Institute for Radio Astronomy
Affiliation as printed
ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands
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Netherlands Institute for Radio Astronomy
Affiliation as printed
ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands
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Leiden University · Leiden Observatory · Netherlands Institute for Radio Astronomy
Affiliation as printed
ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands
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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Affiliation as printed
Ruhr-Universität Bochum, Universitätsstr 150/NA7, 44801 Bochum, Germany
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Istituto di Radioastronomia di Bologna · University of Bologna
Affiliation as printed
DIFA – Universitá di Bologna, via Gobetti 93/2, 40129 Bologna, Italy
INAF – Istituto di Radioastronomia, via P. Gobetti 101, 40129 Bologna, Italy
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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 · Netherlands Institute for Radio Astronomy
Affiliation as printed
ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands
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
Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244 Kraków, Poland
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Leiden University · National Radio Astronomy Observatory · Leiden Observatory
Affiliation as printed
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475, USA
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Affiliation as printed
Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
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Affiliation as printed
Department of Astrophysics/IMAPP, Radboud University, PO Box 9010, 6500 GL Nijmegen, 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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Affiliation as printed
Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
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Netherlands Institute for Radio Astronomy
Affiliation as printed
ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, 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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Affiliation as printed
Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Emil-Fischer-Str. 31, 97074 Würzburg, Germany
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National Centre for Nuclear Research
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National Centre for Nuclear Research, ul. Pasteura 7, 02-093 Warsaw, Poland
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Netherlands Institute for Radio Astronomy
Affiliation as printed
ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands
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Leiden University · Leiden Observatory
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Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
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Affiliation as printed
School of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
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Affiliation as printed
Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham DH1 3LE, UK
Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK
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Royal Observatory · University of Edinburgh
Affiliation as printed
Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
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University of Groningen · Netherlands Institute for Radio Astronomy
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ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands
Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
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Netherlands Institute for Radio Astronomy
Affiliation as printed
ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands
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Netherlands Institute for Radio Astronomy
Affiliation as printed
ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, 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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Leiden University · Leiden Observatory · University of Amsterdam
Affiliation as printed
Anton Pannekoek Institute for Astronomy, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam, The Netherlands
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
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Centre National de la Recherche Scientifique · Rhodes University · Observatoire de Paris · Galaxies, Etoiles, Physique et Instrumentation · Université Paris Diderot
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Centre for Radio Astronomy Techniques and Technologies, Rhodes University, Grahamstown 6140, South Africa
GEPI&USN, Observatoire de Paris, CNRS, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France
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Istituto di Radioastronomia di Bologna · University of the Western Cape
Affiliation as printed
Dep. of Physics & Astronomy, University of the Western Cape, Robert Sobukwe Road, 7535 Bellville, Cape Town, South Africa
INAF – Istituto di Radioastronomia, via P. Gobetti 101, 40129 Bologna, Italy
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Centre National de la Recherche Scientifique · Observatoire de Paris · Laboratoire d’études spatiales et d’instrumentation en astrophysique
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LESIA, UMR CNRS 8109, Observatoire de Paris, 92195 Meudon, France
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Leiden University · Leiden Observatory
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Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
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