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
Image processing
Techniques
Data reduction
Telescopes
Author
B. Adebahr
Ruhr-Universität Bochum
Netherlands Institute for Radio Astronomy (ASTRON)
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
University of Groningen
Netherlands Institute for Radio Astronomy (ASTRON)
A. M. Kutkin
Russian Academy of Sciences
Netherlands Institute for Radio Astronomy (ASTRON)
J. M. van der Hulst
University of Groningen
B. S. Frank
University of Cape Town
University of the Western Cape
South African Radio Astronomy Observatory (SARAO)
N. Vilchez
Netherlands Institute for Radio Astronomy (ASTRON)
J. Verstappen
University of Groningen
Netherlands Institute for Radio Astronomy (ASTRON)
E. K. Adams
Netherlands Institute for Radio Astronomy (ASTRON)
University of Groningen
W.J.G. de Blok
University of Cape Town
Netherlands Institute for Radio Astronomy (ASTRON)
University of Groningen
H. Dénes
Netherlands Institute for Radio Astronomy (ASTRON)
K. M. Hess
University of Groningen
Spanish National Research Council (CSIC)
Netherlands Institute for Radio Astronomy (ASTRON)
D. M. Lucero
Virginia Polytechnic Institute and State University
R. Morganti
Netherlands Institute for Radio Astronomy (ASTRON)
University of Groningen
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
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
Istituto nazionale di astrofisica (INAF)
Mika
Netherlands Institute for Radio Astronomy (ASTRON)
H. Mulder
Netherlands Institute for Radio Astronomy (ASTRON)
L. C. Oostrum
Netherlands Institute for Radio Astronomy (ASTRON)
Netherlands eScience Center
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
University of Groningen
Netherlands Institute for Radio Astronomy (ASTRON)
Astronomy and Computing
2213-1337 (ISSN)
Vol. 38 100514Subject Categories (SSIF 2011)
Other Computer and Information Science
Software Engineering
Media Engineering
DOI
10.1016/j.ascom.2021.100514