Apertif: Phased array feeds for the Westerbork Synthesis Radio Telescope

System overview and performance characteristics

¹ ASTRON, the Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands
e-mail: cappellen@astron.nl
² Kapteyn Astronomical Institute, PO Box 800 9700 AV Groningen, The Netherlands
³ Astronomisches Institut der Ruhr-Universität Bochum (AIRUB), Universitätsstrasse 150, 44780 Bochum, Germany
⁴ SKA Organization, Jodrell Bank, Lower Withington, Macclesfield, Cheshire SK11 9DL, UK
⁵ Anton Pannekoek Institute, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam, The Netherlands
⁶ CSIRO Astronomy and Space Science, Australia Telescope National Facility, PO Box 76 Epping, NSW 1710, Australia
⁷ Sydney Institute for Astronomy, School of Physics, University of Sydney, Sydney, NSW 2006, Australia
⁸ South African Radio Astronomy Observatory (SARAO), 2 Fir Street, Observatory 7925, South Africa
⁹ Department of Physics and Electronics, Rhodes University, PO Box 94 Makhanda 6140, South Africa
¹⁰ Argelander-Institut für Astronomie, Auf dem Hügel 71, 53121 Bonn, Germany
¹¹ Dept. of Electrical Engineering, Chalmers University of Technology, Gothenburg, Sweden
¹² The Inter-University Institute for Data Intensive Astronomy (IDIA), and University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
¹³ Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
¹⁴ Department of Physics, McGill University, 3600 Rue University, Montreal, QC H3A 2T8, Canada
¹⁵ Tricas Industrial Design & Engineering, Zwolle, The Netherlands
¹⁶ Netherlands eScience Center, Science Park 140, 1098 XG Amsterdam, The Netherlands
¹⁷ Astro Space Center of Lebedev Physical Institute, Profsoyuznaya Str. 84/32, 117997 Moscow, Russia
¹⁸ ASML Netherlands B.V., De Run 6501, 5504 DR Veldhoven, The Netherlands
¹⁹ Cahill Center for Astronomy, California Institute of Technology, Pasadena, CA, USA
²⁰ Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
²¹ Joint Institute for VLBI ERIC, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands
²² INAF, Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius, CA, Italy
²³ Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411 007, India
²⁴ NYU Abu Dhabi, PO Box 129188 Abu Dhabi, UAE
²⁵ Center for Astro, Particle, and Planetary Physics (CAP 3), NYU Abu Dhabi, PO Box 129188 Abu Dhabi, UAE
²⁶ NIKHEF, National Institute for Subatomic Physics, 1098 XG Amsterdam, The Netherlands
²⁷ Department of Astrophysics/IMAPP, Radboud University, PO Box 9010 6500 GL Nijmegen, The Netherlands
²⁸ West Virginia University, White Hall, Box 6315 Morgantown, WV 26506, USA
²⁹ Department of Physics, Virginia Polytechnic Institute and State University, 50 West Campus Drive, Blacksburg, VA 24061, USA
³⁰ University of Oslo Center for Information Technology, PO Box 1059 0316 Oslo, Norway

Received: 7 July 2021
Accepted: 17 September 2021

Abstract

We describe the APERture Tile In Focus (Apertif) system, a phased array feed (PAF) upgrade of the Westerbork Synthesis Radio Telescope that transforms this telescope into a high-sensitivity, wide-field-of-view L-band imaging and transient survey instrument. Using novel PAF technology, up to 40 partially overlapping beams are formed on the sky simultaneously, significantly increasing the survey speed of the telescope. With this upgraded instrument, an imaging survey covering an area of 2300 deg² is being performed that will deliver both continuum and spectral line datasets, of which the first data have been publicly released. In addition, a time domain transient and pulsar survey covering 15 000 deg² is in progress. An overview of the Apertif science drivers, hardware, and software of the upgraded telescope is presented, along with its key performance characteristics.