The Apertif instrument, significantly increasing the field of view of the Westerbork Synthesis Radio Telescope (WSRT), has been operational since 1 July 2019, undertaking a series of legacy surveys -- a time-domain survey plus wide and medium-deep imaging surveys. The Apertif/ARTS surveys were originally funded through the end of 2020 and extended to the end of 2021 to compensate for delays in the start of operations. The surveys will wrap-up at the end of this year. The WSRT observatory will of course continue to be operated, amongst other activities, as part of the European VLBI network.

Published by the editorial team, 3 June 2021

To date, the wide tier of the Apertif imaging surveys has covered ~2000 square degrees, and the medium-deep tier had collected significant depth over ~120 square degrees. The end of 2020 saw the first release of imaging data, covering ~1000 square degrees from the first year of survey operations. Available data products include continuum images, polarization images and cubes, and line (neutral hydrogen) data cubes, available via We look forward to future data releases, both of additional sky coverage and also of higher quality data products with improved processing. The legacy from the imaging surveys will extend for many years to come.

The time-domain survey detected several dozen new Fast Radio Bursts (FRBs) up to now, in real time. It discovered FRBs that skewered the halo of M33; it found that some repeating FRBs originate from very clean environments, important for cosmological applications. It links in real-time to facilities at other wavelengths. Time-series data from all survey pointings is and/or will be publicly available, as are the high-resolution data of all detections. Real-time public alerts for FRB detections continue until the end of 2021.


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