First release of Apertif imaging survey data
Artikel i vetenskaplig tidskrift, 2022

Context. Apertif is a phased-array feed system for the Westerbork Synthesis Radio Telescope, providing forty instantaneous beams over 300 MHz of bandwidth. A dedicated survey program utilizing this upgrade started on 1 July 2019, with the last observations taken on 28 February 2022. The imaging survey component provides radio continuum, polarization, and spectral line data. Aims. Public release of data is critical for maximizing the legacy of a survey. Toward that end, we describe the release of data products from the first year of survey operations, through 30 June 2020. In particular, we focus on defining quality control metrics for the processed data products. Methods. The Apertif imaging pipeline, Apercal, automatically produces non-primary beam corrected continuum images, polarization images and cubes, and uncleaned spectral line and dirty beam cubes for each beam of an Apertif imaging observation. For this release, processed data products are considered on a beam-by-beam basis within an observation. We validate the continuum images by using metrics that identify deviations from Gaussian noise in the residual images. If the continuum image passes validation, we release all processed data products for a given beam. We apply further validation to the polarization and line data products and provide flags indicating the quality of those data products. Results. We release all raw observational data from the first year of survey observations, for a total of 221 observations of 160 independent target fields, covering approximately one thousand square degrees of sky. Images and cubes are released on a per beam basis, and 3374 beams (of 7640 considered) are released. The median noise in the continuum images is 41.4 uJy beam(-1), with a slightly lower median noise of 36.9 uJy beam(-1) in the Stokes V polarization image. The median angular resolution is 11.6 ''/sin delta. The median noise for all line cubes, with a spectral resolution of 36.6 kHz, is 1.6 mJy beam(-1), corresponding to a 3-sigma H i column density sensitivity of 1.8 x 10(20) atoms cm(-2) over 20 km s(-1) (for a median angular resolution of 24 '' x 15 ''). Line cubes at lower frequency have slightly higher noise values, consistent with the global RFI environment and overall Apertif system performance. We also provide primary beam images for each individual Apertif compound beam. The data are made accessible using a Virtual Observatory interface and can be queried using a variety of standard tools.

radio lines

galaxies

galaxies

surveys

radio continuum

ISM

polarization

galaxies

Författare

E. A. K. Adams

Netherlands Institute for Radio Astronomy (ASTRON)

Kapteyn Astronomical Institute

B. Adebahr

Ruhr-Universität Bochum

W. J. G. de Blok

Netherlands Institute for Radio Astronomy (ASTRON)

University of Cape Town

Kapteyn Astronomical Institute

H. Denes

Netherlands Institute for Radio Astronomy (ASTRON)

K. M. Hess

Kapteyn Astronomical Institute

Instituto de Astrofisica de Andalucía (IAA)

Netherlands Institute for Radio Astronomy (ASTRON)

J. M. van der Hulst

Kapteyn Astronomical Institute

A. Kutkin

Russian Academy of Sciences

Netherlands Institute for Radio Astronomy (ASTRON)

D. M. Lucero

Virginia Polytechnic Institute and State University

R. Morganti

Kapteyn Astronomical Institute

Netherlands Institute for Radio Astronomy (ASTRON)

V. A. Moss

Commonwealth Scientific and Industrial Research Organisation (CSIRO)

Netherlands Institute for Radio Astronomy (ASTRON)

The University of Sydney

T. A. Oosterloo

Netherlands Institute for Radio Astronomy (ASTRON)

Kapteyn Astronomical Institute

E. Orru

Netherlands Institute for Radio Astronomy (ASTRON)

R. Schulz

Netherlands Institute for Radio Astronomy (ASTRON)

A. S. van Amesfoort

Netherlands Institute for Radio Astronomy (ASTRON)

A. Berger

Ruhr-Universität Bochum

O. M. Boersma

Universiteit Van Amsterdam

M. Bouwhuis

National Institute for Subatomic Physics (NIKHEF)

R. van den Brink

Netherlands Institute for Radio Astronomy (ASTRON)

Tricas Industrial Design & Engineering

W. A. van Cappellen

Netherlands Institute for Radio Astronomy (ASTRON)

L. Connor

Universiteit Van Amsterdam

California Institute of Technology (Caltech)

A. H. W. M. Coolen

Netherlands Institute for Radio Astronomy (ASTRON)

S. Damstra

Netherlands Institute for Radio Astronomy (ASTRON)

G. N. J. van Diepen

Netherlands Institute for Radio Astronomy (ASTRON)

T. J. Dijkema

Netherlands Institute for Radio Astronomy (ASTRON)

N. Ebbendorf

Netherlands Institute for Radio Astronomy (ASTRON)

Y. G. Grange

Netherlands Institute for Radio Astronomy (ASTRON)

R. de Goei

Netherlands Institute for Radio Astronomy (ASTRON)

A. W. Gunst

Netherlands Institute for Radio Astronomy (ASTRON)

H. A. Holties

Netherlands Institute for Radio Astronomy (ASTRON)

B. Hut

Netherlands Institute for Radio Astronomy (ASTRON)

Marianna Ivashina

Chalmers, Elektroteknik, Kommunikation, Antenner och Optiska Nätverk

G. I. G. Jozsa

Max-Planck-Gesellschaft

Rhodes University

J. van Leeuwen

Netherlands Institute for Radio Astronomy (ASTRON)

Universiteit Van Amsterdam

G. M. Loose

Netherlands Institute for Radio Astronomy (ASTRON)

Y. Maan

Tata Institute of Fundamental Research

Netherlands Institute for Radio Astronomy (ASTRON)

M. Mancini

Netherlands Institute for Radio Astronomy (ASTRON)

A. Mika

Netherlands Institute for Radio Astronomy (ASTRON)

H. Mulder

Netherlands Institute for Radio Astronomy (ASTRON)

M. J. Norden

Netherlands Institute for Radio Astronomy (ASTRON)

A. R. Offringa

Netherlands Institute for Radio Astronomy (ASTRON)

Kapteyn Astronomical Institute

L. C. Oostrum

Universiteit Van Amsterdam

Netherlands Institute for Radio Astronomy (ASTRON)

Netherlands eScience Center

I Pastor-Marazuela

Netherlands Institute for Radio Astronomy (ASTRON)

Universiteit Van Amsterdam

D. J. Pisano

West Virginia University

University of Cape Town

A. A. Ponomareva

University of Oxford

J. W. Romein

Netherlands Institute for Radio Astronomy (ASTRON)

M. Ruiter

Netherlands Institute for Radio Astronomy (ASTRON)

A. P. Schoenmakers

Netherlands Institute for Radio Astronomy (ASTRON)

D. van der Schuur

Netherlands Institute for Radio Astronomy (ASTRON)

J. J. Sluman

Netherlands Institute for Radio Astronomy (ASTRON)

R. Smits

Netherlands Institute for Radio Astronomy (ASTRON)

K. J. C. Stuurwold

Netherlands Institute for Radio Astronomy (ASTRON)

J. Verstappen

Netherlands Institute for Radio Astronomy (ASTRON)

Kapteyn Astronomical Institute

N. P. E. Vilchez

Netherlands Institute for Radio Astronomy (ASTRON)

D. Vohl

Universiteit Van Amsterdam

Netherlands Institute for Radio Astronomy (ASTRON)

K. J. Wierenga

Netherlands Institute for Radio Astronomy (ASTRON)

S. J. Wijnholds

Netherlands Institute for Radio Astronomy (ASTRON)

E. E. M. Woestenburg

Netherlands Institute for Radio Astronomy (ASTRON)

A. W. Zanting

Netherlands Institute for Radio Astronomy (ASTRON)

J. Ziemke

Netherlands Institute for Radio Astronomy (ASTRON)

Universitetet i Oslo

Astronomy and Astrophysics

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

Vol. 667 A38

Ämneskategorier

Fjärranalysteknik

Datorseende och robotik (autonoma system)

Medicinsk bildbehandling

DOI

10.1051/0004-6361/202244007

Mer information

Senast uppdaterat

2023-10-10