Apercal - The Apertif calibration pipeline
Journal article, 2022

Apertif (APERture Tile In Focus) is one of the Square Kilometre Array (SKA) pathfinder facilities. The Apertif project is an upgrade to the 50-year-old Westerbork Synthesis Radio Telescope (WSRT) using phased-array feed technology. The new receivers create 40 individual beams on the sky, achieving an instantaneous sky coverage of 6.5 square degrees. The primary goal of the Apertif Imaging Survey is to perform a wide survey of 3500 square degrees (AWES) and a medium deep survey of 350 square degrees (AMES) of neutral atomic hydrogen (up to a redshift of 0.26), radio continuum emission and polarisation. Each survey pointing yields 4.6 TB of correlated data. The goal of Apercal is to process this data and fully automatically generate science ready data products for the astronomical community while keeping up with the survey observations. We make use of common astronomical software packages in combination with Python based routines and parallelisation. We use an object oriented module-based approach to ensure easy adaptation of the pipeline. A Jupyter notebook based framework allows user interaction and execution of individual modules as well as a full automatic processing of a complete survey observation. If nothing interrupts processing, we are able to reduce a single pointing survey observation on our five node cluster with 24 physical cores and 256 GB of memory each within 24 h keeping up with the speed of the surveys. The quality of the generated images is sufficient for scientific usage for 44% of the recorded data products with single images reaching dynamic ranges of several thousands. Future improvements will increase this percentage to over 80%. Our design allowed development of the pipeline in parallel to the commissioning of the Apertif system.

Pipelines

Surveys

Data reduction

Techniques

Telescopes

Image processing

Author

B. Adebahr

Netherlands Institute for Radio Astronomy (ASTRON)

Ruhr-Universität Bochum

R. Schulz

Netherlands Institute for Radio Astronomy (ASTRON)

T. J. Dijkema

Netherlands Institute for Radio Astronomy (ASTRON)

V. A. Moss

Netherlands Institute for Radio Astronomy (ASTRON)

The University of Sydney

Commonwealth Scientific and Industrial Research Organisation (CSIRO)

A. R. Offringa

Netherlands Institute for Radio Astronomy (ASTRON)

University of Groningen

A. M. Kutkin

Netherlands Institute for Radio Astronomy (ASTRON)

Russian Academy of Sciences

J. M. van der Hulst

University of Groningen

B. S. Frank

University of Cape Town

South African Radio Astronomy Observatory (SARAO)

University of the Western Cape

N. Vilchez

Netherlands Institute for Radio Astronomy (ASTRON)

J. Verstappen

University of Groningen

Netherlands Institute for Radio Astronomy (ASTRON)

E. K. Adams

University of Groningen

Netherlands Institute for Radio Astronomy (ASTRON)

W.J.G. de Blok

Netherlands Institute for Radio Astronomy (ASTRON)

University of Groningen

University of Cape Town

H. Dénes

Netherlands Institute for Radio Astronomy (ASTRON)

K. M. Hess

Netherlands Institute for Radio Astronomy (ASTRON)

University of Groningen

Institute of Astrophysics of Andalusia (IAA)

D. M. Lucero

Virginia Polytechnic Institute and State University

R. Morganti

University of Groningen

Netherlands Institute for Radio Astronomy (ASTRON)

T. Oosterloo

Netherlands Institute for Radio Astronomy (ASTRON)

University of Groningen

D. J. Pisano

West Virginia University

Marianna Ivashina

Chalmers, Electrical Engineering, Communication, Antennas and Optical Networks, Antennas

W. van Cappellen

Netherlands Institute for Radio Astronomy (ASTRON)

L. Connor

University of Amsterdam

Netherlands Institute for Radio Astronomy (ASTRON)

A. H.W.M. Coolen

Netherlands Institute for Radio Astronomy (ASTRON)

Sieds Damstra

Netherlands Institute for Radio Astronomy (ASTRON)

G. M. Loose

Netherlands Institute for Radio Astronomy (ASTRON)

Y. Maan

Netherlands Institute for Radio Astronomy (ASTRON)

F. M. Maccagni

INAF Osservatorio Astronomico di Cagliari

Mika

Netherlands Institute for Radio Astronomy (ASTRON)

H. Mulder

Netherlands Institute for Radio Astronomy (ASTRON)

L. C. Oostrum

Netherlands eScience Center

Netherlands Institute for Radio Astronomy (ASTRON)

University of Amsterdam

E. Orrú

Netherlands Institute for Radio Astronomy (ASTRON)

R. Smits

Netherlands Institute for Radio Astronomy (ASTRON)

D. Van Der Schuur

Netherlands Institute for Radio Astronomy (ASTRON)

J. van Leeuwen

University of Amsterdam

Netherlands Institute for Radio Astronomy (ASTRON)

D. Vohl

Netherlands Institute for Radio Astronomy (ASTRON)

S. J. Wijnholds

Netherlands Institute for Radio Astronomy (ASTRON)

J. Ziemke

Netherlands Institute for Radio Astronomy (ASTRON)

University of Groningen

Astronomy and Computing

2213-1337 (ISSN)

Vol. 38 100514

Subject Categories

Other Computer and Information Science

Software Engineering

Media Engineering

DOI

10.1016/j.ascom.2021.100514

More information

Latest update

12/7/2021