First release of Apertif imaging survey data

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 \u27\u27/sin delta. 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-sigma H i column density sensitivity of 1.8 x 10(20) atoms cm(-2) over 20 km s(-1) (for a median angular resolution of 24 \u27\u27 x 15 \u27\u27). 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

Revealing personal professional theories

Personal professional theories, Knowledge development, Professional development, Vocational education and training, Concept mapping, Stimulated recall,

Subject-specific lesson coaching during placements

Wiederholt wurde gezeigt, dass Unterrichtspraktika von Lehramtsstudierenden sehr geschätzt werden. Allerdings wissen wir wenig über die Wirkung unterschiedlicher Unterstützungsformen in Praktika auf das Lernen zukünftiger Lehrpersonen. Ein Modell zur Förderung von Praktikanten ist das fachspezifische Unterrichtscoaching. In einer quasi-experimentellen Interventionsstudie wurde dessen Wirksamkeit basierend auf Fragebogen, Videoaufzeichnungen und Interviews mit Dyaden von Praxislehrpersonen und ihren Praktikanten untersucht. Ergebnisse der Studie zeigen, dass in fachspezifischem Unterrichtscoaching weitergebildete Praxislehrpersonen (Interventionsgruppe, NIG = 16) wesentliche Elemente dieses Modells in ihr Handlungsrepertoire aufnahmen. Ihre Unterstützungspraxis unterscheidet sich signifikant von jener der Kontrollgruppe (NKG = 16), welche die Praktikanten auf traditionelle Weise unterstützen. Indikatoren für Lernen im Kontext von Unterrichtsbesprechungen belegen weiter, dass die Praktikanten der Interventionsgruppe signifikant mehr Lernerträge erzielten als die traditionell unterstützten Praktikanten. Auch die anhand von Videoaufnahmen vorgenommene Einschätzung der Unterrichtsqualität fiel für die Interventionsgruppe signifikant besser aus als für die Kontrollgruppe. It has been repeatedly shown that teaching placements are highly valued by student teachers. However, there is very little knowledge on the impact of different forms of support for placements on the learning of future teachers. One model to support placements is Content-Focused CoachingSM. In a quasi-experimental intervention study, we investigated the impact of this form of support using questionnaires, video recordings and interviews with dyads of practical teaching staff and their placement students. The results of the survey show that practical teaching staff trained in Content-Focused CoachingSM (intervention group NIG = 16) integrated basic elements of this model into their repertoire and that their teaching practice is significantly different to that in the control group (NKG = 16), which supports placement students in the traditional way. Indicators for learning in the context of lesson meetings, furthermore, give evidence that placement students in the intervention group achieve significantly better learning results than their counterparts supported in the traditional manner. The assessment of teaching quality, based on the video recordings, was also significantly better than for the control group

The Apertif Radio Transient System (ARTS): Design, Commissioning, Data Release, and Detection of the first 5 Fast Radio Bursts

Fast Radio Bursts must be powered by uniquely energetic emission mechanisms. This requirement has eliminated a number of possible source types, but several remain. Identifying the physical nature of Fast Radio Burst (FRB) emitters arguably requires good localisation of more detections, and broadband studies enabled by real-time alerting. We here present the Apertif Radio Transient System (ARTS), a supercomputing radio-telescope instrument that performs real-time FRB detection and localisation on the Westerbork Synthesis Radio Telescope (WSRT) interferometer. It reaches coherent-addition sensitivity over the entire field of the view of the primary dish beam. After commissioning results verified the system performed as planned, we initiated the Apertif FRB survey (ALERT). Over the first 5 weeks we observed at design sensitivity in 2019, we detected 5 new FRBs, and interferometrically localised each of these to 0.4--10 sq. arcmin. All detections are broad band and very narrow, of order 1 ms duration, and unscattered. Dispersion measures are generally high. Only through the very high time and frequency resolution of ARTS are these hard-to-find FRBs detected, producing an unbiased view of the intrinsic population properties. Most localisation regions are small enough to rule out the presence of associated persistent radio sources. Three FRBs cut through the halos of M31 and M33. We demonstrate that Apertif can localise one-off FRBs with an accuracy that maps magneto-ionic material along well-defined lines of sight. The rate of 1 every ~7 days next ensures a considerable number of new sources are detected for such study. The combination of detection rate and localisation accuracy exemplified by the 5 first ARTS FRBs thus marks a new phase in which a growing number of bursts can be used to probe our Universe

First release of Apertif imaging survey data

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 beama 1, with a slightly lower median noise of 36.9 uJy beama 1 in the Stokes V polarization image. The median angular resolution is 11.6a3;/sin δ. The median noise for all line cubes, with a spectral resolution of 36.6 kHz, is 1.6 mJy beama 1, corresponding to a 3-ÏÃ Â H i column density sensitivity of 1.8 A-1020 atoms cma 2 over 20 km sa 1 (for a median angular resolution of 24a 3-15a3). 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

Episode-centered guidelines for teacher belief change toward technology integration

Teachers' episodic memories influence their beliefs. The investigation of episodic memories can help identify the teacher beliefs that limit technology-integration. We propose the Episode-Centered Belief Change (ECBC) model that utilizes teachers' episodic memories for changing beliefs impeding effective technology integration. We also propose guidelines for using ECBC model in professional development to promote teacher belief change for effective technology integration. A preliminary study was conducted to apply the ECBC model in a teacher education course. The findings suggest that the ECBC model was effective in changing teacher beliefs regarding technology integration. Finally, the implications of the ECBC model and guidelines for research and practice are discussed

Apertif: Phased array feeds for the Westerbork Synthesis Radio Telescope

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