Fast and Reproducible LOFAR Workflows with AGLOW

Mechev, A. P.; Oonk, Raymond; Shimwell, T. W.; Plaat, Aske; Intema, H. T.; Rottgerin, Huub

doi:10.1109/escience.2018.00029

Cited by 1 publication

(2 citation statements)

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“…This builds significantly upon our previous work by making use of our enhanced direction dependent calibration and imaging processing pipeline (see Tasse et al 2021) as well as improved processing efficiency and automation (see e.g. Drabent et al 2019 andMechev et al 2018). These improvements enable us to present images spanning 5,634 square degrees (27%) of the Northern sky, and a catalogue containing 4,396,228 radio sources -the largest catalogue of radio sources released to date.…”

Section: Introductionmentioning

confidence: 73%

“…Finally, the LOFAR surveys are also having a large technical impact with studies of calibration and imaging techniques (e.g. de Gasperin et al 2019, Morabito et al 2021, efficient distributed processing (Drabent et al 2019 andMechev et al 2018), photometric redshift estimators (Duncan et al 2019) and automated source classification (e.g. Mostert et al 2021 andMingo et al 2019).…”

Section: Introductionmentioning

confidence: 99%

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The LOFAR Two-metre Sky Survey

Shimwell

Hardcastle

Tasse

et al. 2022

A&A

289

108

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In this data release from the ongoing LOw-Frequency ARray (LOFAR) Two-metre Sky Survey (LoTSS) we present 120-168 MHz images covering 27% of the northern sky. Our coverage is split into two regions centred at approximately 12h45m +44 • 30 and 1h00m +28 • 00 and spanning 4178 and 1457 square degrees respectively. The images were derived from 3,451 hrs (7.6 PB) of LOFAR High Band Antenna data which were corrected for the direction-independent instrumental properties as well as direction-dependent ionospheric distortions during extensive, but fully automated, data processing. A catalogue of 4,396,228 radio sources is derived from our total intensity (Stokes I) maps, where the majority of these have never been detected at radio wavelengths before. At 6 resolution, our full bandwidth Stokes I continuum maps with a central frequency of 144 MHz have: a median rms sensitivity of 83 µJy/beam; a flux density scale accuracy of approximately 10%; an astrometric accuracy of 0.2 ; and we estimate the point-source completeness to be 90% at a peak brightness of 0.8 mJy/beam. By creating three 16 MHz bandwidth images across the band we are able to measure the in-band spectral index of many sources, albeit with an error on the derived spectral index of > ±0.2 which is a consequence of our flux-density scale accuracy and small fractional bandwidth. Our circular polarisation (Stokes V) 20 resolution 120-168 MHz continuum images have a median rms sensitivity of 95 µJy/beam, and we estimate a Stokes I to Stokes V leakage of 0.056%. Our linear polarisation (Stokes Q and Stokes U) image cubes consist of 480 × 97.6 kHz wide planes and have a median rms sensitivity per plane of 10.8 mJy/beam at 4 and 2.2 mJy/beam at 20 ; we estimate the Stokes I to Stokes Q/U leakage to be approximately 0.2%. Here we characterise and publicly release our Stokes I, Q, U and V images in addition to the calibrated uv-data to facilitate the thorough scientific exploitation of this unique dataset.

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Section: Introductionmentioning

confidence: 73%