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This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Context. Apertif is a multi-beam receiver system for the Westerbork Synthesis Radio Telescope that operates at 1.1–1.5 GHz, which overlaps with various radio services, resulting in contamination of astronomical signals with radio-frequency interference (RFI). Aims. We analyse approaches to mitigate Apertif interference and design an automated detection procedure for its imaging mode. Using this approach, we present long-term RFI detection results of over 300 Apertif observations. Methods. Our approach is based on the AOFlagger detection approach. We introduce several new features, including ways to deal with ranges of invalid data (e.g. caused by shadowing) in both the SumThreshold and scale-invariant rank operator steps; pre-calibration bandpass calibration; auto-correlation flagging; and HI flagging avoidance. These methods have been implemented in a new framework that uses the Lua language for scripting, which is new in AOFlagger version 3. Results. Our approach removes RFI fully automatically, and it is robust and effective enough for further calibration and (continuum) imaging of these data. The analysis of 304 observations shows an average of 11.1% of lost data due to RFI with a large spread. We observe 14.6% RFI in auto-correlations. Computationally, AOFlagger achieves a throughput of 370 MB/s on a single computing node. Compared to published machine learning results, the method is one to two orders of magnitude faster. © The Authors 2023., This work makes use of data from the Apertif system installed at the Westerbork Synthesis Radio Telescope owned by ASTRON. ASTRON, the Netherlands Institute for Radio Astronomy, is an institute of the Dutch Research Council (de Nederlandse Organisatie voor Wetenschappelijk Onderzoek, NWO). B.A. acknowledges funding from the German Science Foundation DFG, within the Collaborative Research Center SFB1491 “Cosmic Interacting Matters – From Source to Signal”. E.A.K.A. is supported by the WISE research programme, which is financed by NWO. J.M.vd.H. and K.M.H., acknowledge funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement No. 291531 (‘HIStoryNU’). Jv.L., Y.M. and L.C.O. acknowledge funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement No. 617199 (‘ALERT’; PI: JvL). K.M.H. further acknowledges financial support from the State Agency for Research of the Spanish Ministry of Science, Innovation and Universities through the “Center of Excellence Severo Ochoa” awarded to the Instituto de Astrofísica de Andalucía (SEV-2017-0709) from the coordination of the participation in SKA-SPAIN, funded by the Ministry of Science and innovation (MICIN) and grant RTI2018-096228-B-C31 (MCIU/AEI/FEDER,UE). Jv.L. further acknowledges funding from Vici research programme ‘ARGO’ with project number 639.043.815, financed by NWO. D.V. acknowledges support from the Netherlands eScience Center (NLeSC) under grant ASDI.15.406., With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).

Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Context. Phased array feeds (PAFs) are multi-element receivers in the focal plane of a telescope that make it possible to simultaneously form multiple beams on the sky by combining the complex gains of the individual antenna elements. Recently, the Westerbork Synthesis Radio Telescope (WSRT) was upgraded with PAF receivers to carry out several observing programs, including two imaging surveys and a time-domain survey. The Apertif imaging surveys use a configuration of 40 partially overlapping compound beams (CBs) simultaneously formed on the sky and arranged in an approximately rectangular shape. Aims. This work is aimed at characterising the response of the 40 Apertif CBs to create frequency-resolved I, XX, and YY polarization empirical beam shapes. The measured CB maps can be used for the image deconvolution, primary beam correction, and mosaicking processes of Apertif imaging data. Methods. We used drift scan measurements to measure the response of each of the 40 Apertif CBs. We derived beam maps for all individual beams in I, XX, and YY polarisation in 10 or 18 frequency bins over the same bandwidth as the Apertif imaging surveys. We sampled the main lobe of the beams and the side lobes up to a radius of 0.6 degrees from the beam centres. In addition, we derived beam maps for each individual WSRT dish. Results. We present the frequency and time dependence of the beam shapes and sizes. We compared the compound beam shapes derived with the drift scan method to beam shapes derived with an independent method using a Gaussian Process Regression comparison between the Apertif continuum images and the NRAO VLA Sky Survey (NVSS) catalogue. We find a good agreement between the beam shapes derived with the two independent methods. © H. Dénes et al. 2022., This work makes use of data from the Apertif system installed at the Westerbork Synthesis Radio Telescope owned by ASTRON. ASTRON, the Netherlands Institute for Radio Astronomy, is an institute of the Dutch Research Council (“De Nederlandse Organisatie voor Wetenschappelijk Onderzoek, NWO). K.M.H. acknowledges financial support from the State Agency for Research of the Spanish Ministry of Science, Innovation and universities through the “Center of Excellence Severo Ochoa” awarded to the Instituto de Astrofísica de Andalucía (SEV-2017-0709) from the coordination of the participation in SKA-SPAIN, funded by the Ministry of Science and innovation (MICIN). EAKA is supported by the WISE research programme, which is financed by the Netherlands Organization for Scientific Research (NWO). J.M.vd.H. and K.M.H. acknowledge funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement No. 291531 (‘HIStoryNU’). B.A. acknowledges funding from the German Science Foundation DFG, within the Collaborative Research Center SFB1491 “Cosmic Interacting Matters - From Source to Signal”. Y.M., L.C.O., and R.S. acknowledge funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement No. 617199. J.vL. acknowledges funding from Vici research programme ‘ARGO’ with project number 639.043.815, financed by the Dutch Research Council (NWO). D.V. acknowledges support from the Netherlands eScience Center (NLeSC) under grant ASDI.15.406. This research has made use of NUMPY (van der Walt et al. 2011), SCIPY (Virtanen et al. 2020), ASTROPY, a community-developed core PYTHON package for Astronomy (Astropy Collaboration 2013, 2018; http://www.astropy.org), and scikit-learn (Pedregosa et al. 2011). Data availability: The FITS format CB maps generated from the drift scan observations are available from zenodo as two data sets. Frequency setting 1130-1430 MHz DOI: https://doi.org/10.5281/zenodo.6615555, 1220–1520 MHz DOI: https://doi.org/10.5281/zenodo.6544109. The raw drift scan data are stored on the Apertif Long Term Storage and can be requested for further analysis trough the ASTRON helpdesk (https://support.astron.nl/sdchelpdesk). The observation taskIDs used for the individual drift scan beam maps are listed within aperPB (https://github.com/apertif/aperPB, https://doi.org/10.5281/zenodo.6544109) in the task_id_lists directory with the following file names: task_ids_{beamID}.txt. The GP CB maps are available within the Apertif DR1, trough the ASTRON Virtual Observatory (https://vo.astron.nl/; detailed documentation on the Apertif DR1 is available here: http://hdl.handle.net/21.12136/B014022C-978B-40F6-96C6-1A3B1F4A3DB0).

Full list of authors: Kutkin, A. M.; Oosterloo, T. A.; Morganti, R.; Adams, E. A. K.; Mancini, M.; Adebahr, B.; de Blok, W. J. G.; Denes, H.; Hess, K. M.; van der Hulst, J. M.; Lucero, D. M.; Moss, V. A.; Berger, A.; van den Brink, R.; van Cappellen, W. A.; Connor, L.; Damstra, S.; Loose, G. M.; van Leeuwen, J.; Maan, Y.; Mika, A.; Norden, M. J.; Offringa, A. R.; Oostrum, L. C.; van der Schuur, D.; Vohl, D.; Wijnholds, S. J.; Ziemke, J.--This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., The first data release from Apertif survey contains 3074 radio continuum images, covering a thousand square degrees of the sky. The observations were performed between August 2019 and July 2020. The continuum images were produced at a central frequency 1355 MHz, with a bandwidth of ~150 MHz and angular resolution of up to 10″. In this work, we introduce and apply a new method to obtain a primary beam model based on a machine-learning approach, namely, Gaussian process regression. The primary beam models obtained with this method have been published, along with the data products for the first Apertif data release. We applied the method to the continuum images, carried out a mosaicking process on their basis, and extracted the source catalog. The catalog contains 249672 radio sources, many of which have been detected for the first time at these frequencies. We cross-matched the coordinates with the NVSS, LOFAR/DR1/value-added, and LOFAR/DR2 catalogs – resulting in 44523, 22825, and 152824 common sources, respectively. The first sample provides a unique opportunity for detecting long-term transient sources, which have significantly changed their flux density over the past 25 yr. A combination of the second and the third samples provides valuable information on the spectral properties of the sources in addition to redshift estimates. © A. M. Kutkin et al. 2022., This work makes use of data from the Apertif system installed at the Westerbork Synthesis Radio Telescope owned by ASTRON. ASTRON, the Netherlands Institute for Radio Astronomy, is an institute of the Dutch Science Organisation (De Nederlandse Organisatie voor Wetenschappelijk Onderzoek, NWO). Apertif was partly financed by the NWO Groot projects Apertif (175.010.2005.015) and Apropos (175.010.2009.012). This research made use of Python programming language with its standard and external libraries/packages including numpy (Harris et al. 2020), scipy (Virtanen et al. 2020), scikit-learn (Pedregosa et al. 2011), matplotlib (Hunter 2007), pandas (McKinney 2010) etc. This research made use of Astropy, (http://www.astropy.org) a community-developed core Python package for Astronomy (Astropy Collaboration 2013, Astropy Collaboration 2018). The radio_beam and reproject python packages are used for manipulations with restoring beam and reprojecting/mosaicking of the images. This research has made use of “Aladin sky atlas” developed at CDS, Strasbourg Observatory, France (Bonnarel et al. 2000; Boch & Fernique 2014). E.A.K.A. is supported by the WISE research programme, which is financed by the Netherlands Organization for Scientific Research (NWO) B.A. acknowledges funding from the German Science Foundation DFG, within the Collaborative Research Center SFB1491 “Cosmic Interacting Matters – From Source to Signal”. T.A.O. acknowledges funding from NWO via grant TOP1EW.14.105. K.M.H. acknowledges financial support from the State Agency for Research of the Spanish Ministry of Science, Innovation and Universities through the “Center of Excellence Severo Ochoa” awarded to the Instituto de Astrofísica de Andalucía (SEV-2017-0709), from the coordination of the participation in SKA-SPAIN, funded by the Ministry of Science and Innovation (MCIN). K.M.H. and J.M.vdH. acknowledge funding from the Europeaní Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC Grant Agreement No. 291531 (‘HIStoryNU’). L.C. and L.C.O. acknowledge funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC Grant Agreement No. 617199. J.vL. acknowledges funding from Vici research programme “ARGO” with project number 639.043.815, financed by the Dutch Research Council (NWO). D.V. acknowledges support from the Netherlands eScience Center (NLeSC) under grant ASDI.15.406.

Full list of authors: Adams, E. A. K.; Adebahr, B.; de Blok, W. J. G.; Denes, H.; Hess, K. M.; van der Hulst, J. M.; Kutkin, A.; Lucero, D. M.; Morganti, R.; Moss, V. A.; Oosterloo, T. A.; Orru, E.; Schulz, R.; van Amesfoort, A. S.; Berger, A.; Boersma, O. M.; Bouwhuis, M.; van den Brink, R.; van Cappellen, W. A.; Connor, L.; Coolen, A. H. W. M.; Damstra, S.; van Diepen, G. N. J.; Dijkema, T. J.; Ebbendorf, N.; Grange, Y. G.; de Goei, R.; Gunst, A. W.; Holties, H. A.; Hut, B.; Ivashina, M., V; Jozsa, G. I. G.; van Leeuwen, J.; Loose, G. M.; Maan, Y.; Mancini, M.; Mika, A.; Mulder, H.; Norden, M. J.; Offringa, A. R.; Oostrum, L. C.; Pastor-Marazuela, I; Pisano, D. J.; Ponomareva, A. A.; Romein, J. W.; Ruiter, M.; Schoenmakers, A. P.; van der Schuur, D.; Sluman, J. J.; Smits, R.; Stuurwold, K. J. C.; Verstappen, J.; Vilchez, N. P. E.; Vohl, D.; Wierenga, K. J.; Wijnholds, S. J.; Woestenburg, E. E. M.; Zanting, A. W.; Ziemke, J.--Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Context. Apertif is a phased-array feed system for the Westerbork Synthesis Radio Telescope, providing forty instantaneous beams over 300 MHz of bandwidth. A dedicated survey program utilizing this upgrade started on 1 July 2019, with the last observations taken on 28 February 2022. The imaging survey component provides radio continuum, polarization, and spectral line data. Aims. Public release of data is critical for maximizing the legacy of a survey. Toward that end, we describe the release of data products from the first year of survey operations, through 30 June 2020. In particular, we focus on defining quality control metrics for the processed data products. Methods. The Apertif imaging pipeline, Apercal, automatically produces non-primary beam corrected continuum images, polarization images and cubes, and uncleaned spectral line and dirty beam cubes for each beam of an Apertif imaging observation. For this release, processed data products are considered on a beam-by-beam basis within an observation. We validate the continuum images by using metrics that identify deviations from Gaussian noise in the residual images. If the continuum image passes validation, we release all processed data products for a given beam. We apply further validation to the polarization and line data products and provide flags indicating the quality of those data products. Results. We release all raw observational data from the first year of survey observations, for a total of 221 observations of 160 independent target fields, covering approximately one thousand square degrees of sky. Images and cubes are released on a per beam basis, and 3374 beams (of 7640 considered) are released. The median noise in the continuum images is 41.4 uJy beam−1, with a slightly lower median noise of 36.9 uJy beam−1 in the Stokes V polarization image. The median angular resolution is 11.6″/sin δ. The median noise for all line cubes, with a spectral resolution of 36.6 kHz, is 1.6 mJy beam−1, corresponding to a 3-σ H I column density sensitivity of 1.8 × 1020 atoms cm−2 over 20 km s−1 (for a median angular resolution of 24″ × 15″). Line cubes at lower frequency have slightly higher noise values, consistent with the global RFI environment and overall Apertif system performance. We also provide primary beam images for each individual Apertif compound beam. The data are made accessible using a Virtual Observatory interface and can be queried using a variety of standard tools. © E. A. K. Adams et al. 2022., This work makes use of data from the Apertif system installed at the Westerbork Synthesis Radio Telescope owned by ASTRON. ASTRON, the Netherlands Institute for Radio Astronomy, is an institute of the Dutch Research Council (“De Nederlandse Organisatie voor Wetenschappelijk Onderzoek, NWO). Apertif was partly financed by the NWO Groot projects Apertif (175.010.2005.015) and Apropos (175.010.2009.012). This work was partly supported by funding from the European Research Council under the European Union’s Seventh Frame-work Programme (FP/2007-2013), through ERC Grant Agreement No. 291531 (‘HIStoryNU’, PI: JMvdH) and ERC Advanced Grant RADIOLIFE-320745 (PI: RM), in addition to funding from NWO via grant TOP1EW.14.105 (PI: TAO). E.A.K.A. is supported by the WISE research programme, which is financed by NWO. B.A. acknowledges funding from the German Science Foundation DFG, within the Collaborative Research Center SFB1491 “Cosmic Interacting Matters - From Source to Signal”. KMH acknowledges financial support from the State Agency for Research of the Spanish Ministry of Science, Innovation and Universities through the “Center of Excellence Severo Ochoa” awarded to the Instituto de Astrofísica de Andalucía (SEV-2017-0709), from the coordination of the participation in SKA-SPAIN, funded by the Ministry of Science and Innovation (MCIN). OMB and JvL acknowledge funding from NWO under the Vici research program “ARGO” with project number 639.043.815. Y.M., L.C.O., R.S. and J.vL. acknowledge funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement No. 617199 (“ALERT”). IPM acknowledges funding from the Netherlands Research School for Astronomy (grant no. NOVA5-NW3-10.3.5.14). A.A.P. acknowledges support of the STFC consolidated grant ST/S000488/1. DV acknowledges support from the Netherlands eScience Center (NLeSC) under grant ASDI.15.406. This research has made use of NASA’s Astrophysics Data System Bibliographic Services and Astropy, (http://www.astropy.org) a community-developed core Python package for Astronomy (Astropy Collaboration 2013, 2018).

Context. The characteristics of the polarised radio sky are a key ingredient in constraining evolutionary models of magnetic fields in the Universe and their role in feedback processes. The origin of the polarised emission and the characteristics of the intergalactic medium on the line of sight can be investigated using large samples of polarised sources. Ancillary infrared (IR) and optical data can be used to study the nature of the emitting objects. Aims. We analyse five early science datasets from the APERture Tile in Focus (Apertif) phased array feed system to verify the polarisation capabilities of Apertif in view of future larger data releases. We aim to characterise the source population of the polarised sky in the L-Band using polarised source information in combination with IR and optical data. Methods. We use automatic routines to generate full field-of-view Q- and U-cubes and perform rotation measure (RM)-Synthesis, source finding, and cross-matching with published radio, optical, and IR data to generate polarised source catalogues. All sources were inspected individually by eye for verification of their IR and optical counterparts. Spectral energy distribution (SED)-fitting routines were used to determine photometric redshifts, star-formation rates, and galaxy masses. IR colour information was used to classify sources as active galactic nuclei (AGN) or star-forming-dominated and early- or late-type. Results. We surveyed an area of 56 deg2 and detected 1357 polarised source components in 1170 sources. The fraction of polarised sources is 10.57% with a median fractional polarisation of 4.70 ± 0.14%. We confirmed the reliability of the Apertif measurements by comparing them with polarised cross-identified NVSS sources. Average RMs of the individual fields lie within the error of the best Milky Way foreground measurements. All of our polarised sources were found to be dominated by AGN activity in the radio regime with most of them being radio-loud (79%) and of the Fanaroff-Riley (FR)II class (87%). The host galaxies of our polarised source sample are dominated by intermediate disc and star-forming disc galaxies. The contribution of star formation to the radio emission is on the order of a few percent for ≈10% of the polarised sources while for ≈90% it is completely dominated by the AGN. We do not see any change in fractional polarisation for different star-formation rates of the AGN host galaxies. Conclusions. The Apertif system is suitable for large-area high-sensitivity polarised sky surveys. The data products of the polarisation analysis pipeline can be used to investigate the Milky Way magnetic field on projected scales of several arcminutes as well as the origin of the polarised emission in AGN and the properties of their host galaxies. © ESO 2022., This research made use of Montage. It is funded by the National Science Foundation under Grant Number ACI-1440620, and was previously funded by the National Aeronautics and Space Administration’s Earth Science Technology Office, Computation Technologies Project, under Cooperative Agreement Number NCC5-626 between NASA and the California Institute of Technology. The Montage distribution includes an adaptation of the MOPEX algorithm developed at the Spitzer Science Center. BA and AB acknowledge funding from the German Science Foundation DFG, within the Collaborative Research Center SFB1491 “Cosmic Interacting Matters - From Source to Signal”. EAKA is supported by the WISE research programme, which is financed by the Dutch Research Council (NWO). K.M.H. acknowledges funding from the State Agency for Research of the Spanish Ministry of Science, Innovation and Universities through the “Center of Excellence Severo Ochoa” awarded to the Instituto de Astrofísica de Andalucía (SEV-2017-0709); from grant RTI2018-096228-B-C31 (Ministry of Science, Innovation and Universities/State Agency for Research/European Regional Development Funds, European Union); and from the coordination of the participation in SKA-SPAIN, funded by the Ministry of Science and innovation (MICIN). J.M.vdH. and K.M.H. acknowledge funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement No. 291531 (‘HIStoryNU’). J.vL. acknowledges funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC Grant Agreement no. 617199 (‘ALERT’), and from Vici research programme ‘ARGO’ with project number 639.043.815, financed by the Dutch Research Council (NWO). DV acknowledges support from the Netherlands eScience Center (NLeSC) under grant ASDI.15.406. RS acknowledges funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC Grant Agreement No. 617199. LCO acknowledges funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC Grant Agreement No. 617199.

يهدف البحث الى تحديد المعايير الرئيسية والفرعية لتقييم قطاعات السوق الصناعي واقتراح نموذج لترتيب تلك المعايير حسب الاولوية ومعرفة المعيار الاعلى من ناحية الاهمية النسبية في الشركة العامة لتجارة السيارات والمكائن، ولغرض انشاء هذا النموذج تم اعتماد الخبرات في الشركة المعنية ، وتقترح هذه الدراسة نموذج قرار متعدد المعايير وفق طريقة التحليل الهرمي الضبابي الموسع FEAHP يمكن الشركة التجارية من وضع سياسات استراتيجية واضحة يعتمد عليها نظام إدارة الشركة في تحديد معايير تقييم واختيار قطاعات السوق واتخاذ القرارات الملائمة في تحديد المعايير ذات الاولوية تجاه تحقيق اهداف الشركة ومتطلباتها ، والنتائج الرئيسية تثبت كفاءة النموذج المقترح في تحديد الاهمية النسبية للمعيار الفرعي جودة وميزة المنافسة في المرتبة الاولى من بين المعايير الفرعية البالغ عددها 22 معيار كونه المعيار الذي يلبي متطلبات الشركة ويلبي متطلبات اسواقها حسب نتائج المنهجية المطبقة ، وهذا سيمكن متخذي القرار في الشركة من تحديد اولويات الاجراءات التسويقية وتحديد العوامل التي تؤثر على تحسين كفاءة الشركة ضمن ذلك المعيار.

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.

PSR B0950+08 is a bright non-recycled pulsar whose single-pulse fluence variability is reportedly large. Based on observations at two widely separated frequencies, 55 MHz (NenuFAR) and 1.4 GHz (Westerbork Synthesis Radio Telescope), we review the properties of these single pulses. We conclude that they are more similar to ordinary pulses of radio emission than to a special kind of short and bright Giant Pulses, observed from only a handful of pulsars. We argue that temporal variation of properties of interstellar medium along the line of sight to this nearby pulsar, namely the fluctuating size of decorrelation bandwidth of diffractive scintillation makes important contribution to observed single-pulse fluence variability. We further present interesting structures in the low-frequency single-pulse spectra that resemble the "sad trombones" seen in Fast Radio Bursts (FRBs); although for PSR B0950+08 the upward frequency drift is also routinely present. We explain these spectral features with radius-to-frequency mapping, similar to the model developed by Wang et al. (2019) for FRBs. Finally, we speculate that microsecond-scale fluence variability of the general pulsar population remains poorly known, and that its further study may bring important clues about the nature of FRBs., Accepted by A&A. This version includes a number of minor corrections, including corrected FRB luminosities on the time-luminosity phase-space plot for radio pulses from neutron stars and repeating FRBs