The LOFAR Two-metre Sky Survey: V. Second data release
Artikel i vetenskaplig tidskrift, 2022

In this data release from the ongoing LOw-Frequency ARray (LOFAR) Two-metre Sky Survey we present 120a 168 MHz images covering 27% of the northern sky. Our coverage is split into two regions centred at approximately 12h45m +44 30a and 1h00m +28 00a and spanning 4178 and 1457 square degrees respectively. The images were derived from 3451 h (7.6 PB) of LOFAR High Band Antenna data which were corrected for the direction-independent instrumental properties as well as direction-dependent ionospheric distortions during extensive, but fully automated, data processing. A catalogue of 4 396 228 radio sources is derived from our total intensity (Stokes I) maps, where the majority of these have never been detected at radio wavelengths before. At 6a resolution, our full bandwidth Stokes I continuum maps with a central frequency of 144 MHz have: a median rms sensitivity of 83 μJy beama 1; a flux density scale accuracy of approximately 10%; an astrometric accuracy of 0.2a; and we estimate the point-source completeness to be 90% at a peak brightness of 0.8 mJy beama 1. By creating three 16 MHz bandwidth images across the band we are able to measure the in-band spectral index of many sources, albeit with an error on the derived spectral index of > a ±a 0.2 which is a consequence of our flux-density scale accuracy and small fractional bandwidth. Our circular polarisation (Stokes V) 20a resolution 120a168 MHz continuum images have a median rms sensitivity of 95 μJy beama 1, and we estimate a Stokes I to Stokes V leakage of 0.056%. Our linear polarisation (Stokes Q and Stokes U) image cubes consist of 480a A a 97.6 kHz wide planes and have a median rms sensitivity per plane of 10.8 mJy beama 1 at 4a and 2.2 mJy beama 1 at 20a; we estimate the Stokes I to Stokes Q/U leakage to be approximately 0.2%. Here we characterise and publicly release our Stokes I, Q, U and V images in addition to the calibrated uv-data to facilitate the thorough scientific exploitation of this unique dataset.

Techniques: image processing

Surveys

Catalogs

Radio continuum: general

Författare

T. W. Shimwell

Netherlands Institute for Radio Astronomy (ASTRON)

M. J. Hardcastle

University of Hertfordshire

C. Tasse

Observatoire de Paris

P. N. Best

University of Edinburgh

H. J.A. Röttgering

Universiteit Leiden

W. L. Williams

Universiteit Leiden

A. Botteon

Universiteit Leiden

A. Drabent

Thüringer Landessternwarte Tautenburg

A. P. Mechev

Universiteit Leiden

A. Shulevski

Universiteit Leiden

R. van Weeren

Universiteit Leiden

L. Bester

Rhodes University

M. Bruggen

Universität Hamburg

G. Brunetti

Istituto di Radioastronomia

J. R. Callingham

Netherlands Institute for Radio Astronomy (ASTRON)

K.T. Chyz̊y

Uniwersytet Jagiellonski w Krakowie

John Conway

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium

T. J. Dijkema

Netherlands Institute for Radio Astronomy (ASTRON)

K. Duncan

University of Edinburgh

F. De Gasperin

Universität Hamburg

C. Hale

University of Edinburgh

M. Haverkorn

Radboud Universiteit

B. Hugo

Rhodes University

N. Jackson

University of Manchester

M. Mevius

Netherlands Institute for Radio Astronomy (ASTRON)

G. K. Miley

Universiteit Leiden

L. Morabito

Durham University

R. Morganti

Netherlands Institute for Radio Astronomy (ASTRON)

A. R. Offringa

Netherlands Institute for Radio Astronomy (ASTRON)

J. B. R. Oonk

Netherlands Institute for Radio Astronomy (ASTRON)

D. Rafferty

Universität Hamburg

J. Sabater

University of Edinburgh

D.J.B. Smith

University of Hertfordshire

D. J. Schwarz

Universität Bielefeld

O. Smirnov

Rhodes University

S.P. Oasullivan

Dublin City University

Harish K. Vedantham

Netherlands Institute for Radio Astronomy (ASTRON)

G.J. White

STFC Rutherford Appleton Laboratory

J.G. Albert

Universiteit Leiden

L. Alegre

University of Edinburgh

B. Asabere

Netherlands Institute for Radio Astronomy (ASTRON)

D.J. Bacon

University of Portsmouth

A. Bonafede

Universität Hamburg

E. Bonnassieux

Universita di Bologna

M. Brienza

Istituto di Radioastronomia

M. Bilicki

Polish Academy of Sciences

M. Bonato

Istituto di Radioastronomia

G. Calistro Rivera

European Southern Observatory (ESO)

R. Cassano

Istituto di Radioastronomia

R. Cochrane

Harvard-Smithsonian Center for Astrophysics

J. H. Croston

Open University

V. Cuciti

Universität Hamburg

D. Dallacasa

Istituto di Radioastronomia

A. Danezi

SURFnet

R. -J. Dettmar

Ruhr-Universität Bochum

G. Di Gennaro

Universität Hamburg

H.W. Edler

Universität Hamburg

T.A. Enalin

Max-Planck-Gesellschaft

K.L. Emig

National Radio Astronomy Observatory

T. M.O. Franzen

Netherlands Institute for Radio Astronomy (ASTRON)

C. García-Vergara

Universiteit Leiden

Y. G. Grange

Netherlands Institute for Radio Astronomy (ASTRON)

G. Gurkan

Thüringer Landessternwarte Tautenburg

M. Hajduk

Radboud Universiteit

G. Heald

Commonwealth Scientific and Industrial Research Organisation (CSIRO)

V. Heesen

Universität Hamburg

D. N. Hoang

Universität Hamburg

M. Hoeft

Thüringer Landessternwarte Tautenburg

Cathy Horellou

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

M. Iacobelli

Netherlands Institute for Radio Astronomy (ASTRON)

M. Jamrozy

Uniwersytet Jagiellonski w Krakowie

V. Jelia

Ruder Boskovic Institute

R. Kondapally

University of Edinburgh

P. Kukreti

Netherlands Institute for Radio Astronomy (ASTRON)

M. Kunert-Bajraszewska

Uniwersytet Mikolaja Kopernika

M. Magliocchetti

Istituto nazionale di astrofisica (INAF)

V. Mahatma

Thüringer Landessternwarte Tautenburg

K. Maaek

Narodowe Centrum Badan Jadrowych

S. Mandal

Universiteit Leiden

F. Massaro

Universita degli Studi di Torino

Z. Meyer-Zhao

Netherlands Institute for Radio Astronomy (ASTRON)

B. Mingo

Open University

R.I.J. Mostert

Netherlands Institute for Radio Astronomy (ASTRON)

Dhanya G. Nair

Joint Institute for VLBI in Europe (JIVE)

S.J. Nakoneczny

Narodowe Centrum Badan Jadrowych

B. Nikiel-Wroczyaski

Uniwersytet Jagiellonski w Krakowie

E. Orrú

Netherlands Institute for Radio Astronomy (ASTRON)

U. Pajdosz-Amierciak

Uniwersytet Jagiellonski w Krakowie

T. Pasini

Universität Hamburg

I. Prandoni

Istituto di Radioastronomia

H.E. Van Piggelen

SURFnet

K. Rajpurohit

Istituto di Radioastronomia

E. Retana-Montenegro

University of KwaZulu-Natal

C. J. Riseley

Istituto di Radioastronomia

A. Rowlinson

Netherlands Institute for Radio Astronomy (ASTRON)

A. Saxena

University College London (UCL)

C. Schrijvers

SURFnet

F. Sweijen

Universiteit Leiden

T.M. Siewert

Universität Bielefeld

R. Timmerman

Universiteit Leiden

M. Vaccari

Istituto di Radioastronomia

J. Vink

Anton Pannekoek Institute for Astronomy

Jennifer L. West

University of Toronto

A. Woaowska

Commonwealth Scientific and Industrial Research Organisation (CSIRO)

X. Zhang

Universiteit Leiden

J. Zheng

University of Portsmouth

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 659 A1

Ämneskategorier

Geofysik

Signalbehandling

Medicinsk bildbehandling

DOI

10.1051/0004-6361/202142484

Mer information

Senast uppdaterat

2022-03-22