Explanipedia

LOFAR discovery of a quiet emission mode in PSR B0823+26 Open

C. Sobey, Neil J. Young, J. W. T. Hessels, P. Weltevrede, A. Noutsos , et al. · 2024

PSR B0823+26, a 0.53-s radio pulsar, displays a host of emission phenomena over time-scales of seconds to (at least) hours, including nulling, subpulse drifting, and mode-changing. Studying pulsars like PSR B0823+26 provides further insigh…

Apertif 1.4 GHz continuum observations of the Boötes field and their combined view with LOFAR Open

A. M. Kutkin, Tom Oosterloo, R. Morganti, A. R. Offringa, Elizabeth A. K. Adams , et al. · 2023

We present a new image of a 26.5 square degrees region in the Boötes constellation obtained at 1.4 GHz using the Aperture Tile in Focus (Apertif) system on the Westerbork Synthesis Radio Telescope. We use a newly developed processing pipel…

Apertif 1.4 GHz continuum observations of the Boötes field and their combined view with LOFAR Open

A. M. Kutkin, Tom Oosterloo, R. Morganti, A. R. Offringa, Elizabeth A. K. Adams , et al. · 2023

We present a new image of a 26.5 square degree region in the Boötes constellation obtained at 1.4 GHz using the Aperture Tile in Focus (Apertif) system on the Westerbork Synthesis Radio Telescope. We use a newly developed processing pipeli…

First release of Apertif imaging survey data Open

Elizabeth A. K. Adams, B. Adebahr, W. J. G. de Blok, Helga Dénes, Kelley M. Hess , et al. · 2022

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 …

\nApertif: Phased array feeds for the Westerbork Synthesis Radio Telescope Open

W. A. van Cappellen, Tom Oosterloo, Marc Verheijen, Elizabeth A. K. Adams, B. Adebahr , et al. · 2022

\n Contains fulltext :\n 247390.pdf (Publisher’s version ) (Open Access)\n

Apertif: Phased array feeds for the Westerbork Synthesis Radio Telescope Open

Wiggert A. van Cappellen, Tom Oosterloo, Marc Verheijen, Elizabeth A. K. Adams, B. Adebahr , et al. · 2021

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…

Sub-arcsecond imaging with the International LOFAR Telescope I. Foundational calibration strategy and pipeline Open

L. K. Morabito, N. Jackson, S. Mooney, Frits Sweijen, Shruti Badole , et al. · 2021

[abridged] The International LOFAR Telescope is an interferometer with stations spread across Europe. With baselines of up to ~2,000 km, LOFAR has the unique capability of achieving sub-arcsecond resolution at frequencies below 200 MHz, al…

Sub-arcsecond imaging with the International LOFAR Telescope: II. Completion of the LOFAR Long-Baseline Calibrator Survey Open

N. Jackson, Shruti Badole, John Morgan, Rajan Chhetri, K. Prūsis , et al. · 2021

The Low-Frequency Array (LOFAR) Long-Baseline Calibrator Survey (LBCS) was conducted between 2014 and 2019 in order to obtain a set of suitable calibrators for the LOFAR array. In this paper we present the complete survey, building on the …

Mid Frequency Aperture Array Architectural Design Document Open

A. W. Gunst, A. J. Faulkner, Stefan J. Wijnholds, Rik Jongerius, S. Torchinsky , et al. · 2020

The Square Kilometre Array (SKA) is the next generation radio telescope. Aperture Arrays (AA) are considered for SKA-2 for frequencies up to 1.4 GHz (SKA-1 uses AAs up to 350 MHz). This document presents design considerations of this Mid-F…

A LOFAR Observation of Ionospheric Scintillation from Two Simultaneous\n Travelling Ionospheric Disturbances Open

R. A. Fallows, Biagio Forte, I. Astin, Tom Allbrook, Alex Arnold , et al. · 2020

This paper presents the results from one of the first observations of\nionospheric scintillation taken using the Low-Frequency Array (LOFAR). The\nobservation was of the strong natural radio source Cas A, taken overnight on\n18-19 August 2…

Cassiopeia A, Cygnus A, Taurus A, and Virgo A at ultra-low radio frequencies Open

F. de Gasperin, Jacco Vink, J. P. McKean, A. Asgekar, I. M. Avruch , et al. · 2020

Context. The four persistent radio sources in the northern sky with the highest flux density at metre wavelengths are Cassiopeia A, Cygnus A, Taurus A, and Virgo A; collectively they are called the A-team. Their flux densities at ultra-low…

A LOFAR observation of ionospheric scintillation from two simultaneous travelling ionospheric disturbances Open

R. A. Fallows, Biagio Forte, I. Astin, Tom Allbrook, Alex Arnold , et al. · 2020

This paper presents the results from one of the first observations of ionospheric scintillation taken using the Low-Frequency Array (LOFAR). The observation was of the strong natural radio source Cassiopeia A, taken overnight on 18–19 Augu…

Ever growing sensitivities Open

J. A. Bregman, Bou Schipper, Wout Beerekamp, A. van Ardenne, T. Grit , et al. · 2019

Ever growing sensitivities Chapter 10.1: - Ever growing sensitivities - Multiplying in Cotton - Fixing the Mesh: “Het Boutjesproject” - Mr. Correlator - Controlling the WSRT - Developments in programming; Encapsulating legacy sotftware Cha…

Needle-like structures discovered on positively charged lightning branches Open

B. M. Hare, O. Schölten, J. R. Dwyer, T. N. G. Trinh, S. Buitink , et al. · 2019

ASTRON Open Source Policy Open

Tammo Jan Dijkema, Y. G. Grange, A. W. Gunst, Ronald Halfwerk, T. Jürges , et al. · 2018

Most ASTRON Software Products are released under an open source license, such that they can be used, modified, and redistributed by external parties. In return, ASTRON wants to get some form of acknowledgement or credit for the de…

Shock location and CME 3D reconstruction of a solar type II radio burst with LOFAR Open

Pietro Zucca, D. E. Morosan, A. P. Rouillard, R. A. Fallows, P. T. Gallagher , et al. · 2018

Context. Type II radio bursts are evidence of shocks in the solar atmosphere and inner heliosphere that emit radio waves ranging from sub-meter to kilometer lengths. These shocks may be associated with coronal mass ejections (CMEs) and rea…

Low-frequency radio absorption in Cassiopeia A Open

M. Arias, Jacco Vink, F. de Gasperin, P. Salas, J. B. R. Oonk , et al. · 2018

Context. Cassiopeia A is one of the best-studied supernova remnants. Its bright radio and X-ray emission is due to shocked ejecta. Cas A is rather unique in that the unshocked ejecta can also be studied: through emission in the infrared, t…

Cas A LOFAR and VLA images Open

M. Arias, Fiamma Capitanio, F. de Gasperin, P.F. de Salas, J. B. R. Oonk , et al. · 2018

LOFAR LBA and VLA L-band images of supernova remnant Cassiopeia A. Data taken in 2015 (LOFAR) and 2017 (VLA). - VLA_lband2017.fits: images made from one night (August 13th) combining the two available continuum spectral windows (…

Tracking of an electron beam through the solar corona with LOFAR Open

G. Mann, F. Breitling, C. Vocks, H. Auraß, Matthias Steinmetz , et al. · 2017

The Sun’s activity leads to bursts of radio emission, among other phenomena. An example is type-III radio bursts. They occur frequently and appear as short-lived structures rapidly drifting from high to low frequencies in dynamic radio spe…

The association of a<i>J</i>-burst with a solar jet Open

D. E. Morosan, P. T. Gallagher, R. A. Fallows, Hamish Reid, G. Mann , et al. · 2017

\n Contains fulltext :\n 178482.pdf (Publisher’s version ) (Open Access)\n

The Association of a J-burst with a Solar Jet Open

D. E. Morosan, P. T. Gallagher, R. A. Fallows, Hamish Reid, G. Mann , et al. · 2017

Context. The Sun is an active star that produces large-scale energetic events such as solar flares and coronal mass ejections and numerous smaller-scale events such as solar jets. These events are often associated with accelerated particle…

LOFAR Bootes and 3C295 field sources Open

R. J. van Weeren, W. L. Williams, C. Tasse, H. J. A. Röttgering, D. A. Rafferty , et al. · 2017

The AARTFAAC All-Sky Monitor: System Design and Implementation Open

Peeyush Prasad, Folkert Huizinga, E. Kooistra, D. van der Schuur, A. W. Gunst , et al. · 2016

The Amsterdam–ASTRON Radio Transients Facility and Analysis Center (AARTFAAC) all-sky monitor is a sensitive, real-time transient detector based on the Low Frequency Array (LOFAR). It generates images of the low frequency radio sky with sp…

SKA Aperture Array Mid Frequency Science Requirements Open

S. Torchinsky, J. W. Broderick, A. W. Gunst, A. J. Faulkner, W. van Cappellen · 2016

This document describes the top level requirements for the SKA-AAMID telescope as determined by the SKA key science projects. These include parameters such as operating frequency range,instantaneous bandwidth (total processed bandwidth), f…

LOFAR tied-array imaging of Type III solar radio bursts Open

D. E. Morosan, P. T. Gallagher, Pietro Zucca, R. A. Fallows, Eoin Carley , et al. · 2016

(Affiliations can be found after the references) Received / Accepted Context. The Sun is an active source of radio emission which is often associated with energetic phenomena such as solar flares and coronal mass ejections (CMEs). At low r…

LBCS: The LOFAR Long-Baseline Calibrator Survey Open

N. Jackson, A. Tagore, Adam T. Deller, J. Moldòn, E. Varenius , et al. · 2016

We outline the LOFAR Long-Baseline Calibrator Survey (LBCS), whose aim is to identify sources suitable for calibrating the highest-resolution observations made with the International LOFAR Telescope, which include baselines >1000 km. Suita…

A large light-mass component of cosmic rays at 1017–1017.5 electronvolts from radio observations Open

S. Buitink, A. Corstanje, H. Falcke, J.R. Hörandel, T. Huege , et al. · 2016

Pulse profiles of 100 radio pulsars Open

M. Pilia, J. W. T. Hessels, B. W. Stappers, V. I. Kondratiev, M. Krämer , et al. · 2016

The observed sample of pulsars was loosely based on a selection of the brightest objects in the LOFAR-visible sky (declination >-30°), using the ATNF Pulsar Catalog1 (Manchester et al., 2005AJ....129.1993M) for guidance. We observed 100 pu…

LOFAR MSSS: detection of a low-frequency radio transient in 400 h of monitoring of the North Celestial Pole Open

A. Stewart, R. P. Fender, J. W. Broderick, T. E. Hassall, T. Muñoz‐Darias , et al. · 2015

We present the results of a four-month campaign searching for low-frequency radio transients near the North Celestial Pole with the Low-Frequency Array (LOFAR), as part of the Multifrequency Snapshot Sky Survey (MSSS). The data were record…

Wide-field LOFAR imaging of the field around the double-double radio galaxy B1834+620 Open

E. Orrú, Sjoert van Velzen, R. Pizzo, S. Yatawatta, R. Paladino , et al. · 2015

The existence of double-double radio galaxies (DDRGs) is evidence for recurrent jet activity in AGN, as expected from standard accretion models. A detailed study of these rare sources provides new perspectives for investigating the AGN dut…

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