Explanipedia

Deeper multi-redshift upper limits on the epoch of reionisation 21 cm signal power spectrum from LOFAR between z = 8.3 and z = 10.1 Open

Florent Mertens, M. Mevius, L. V. E. Koopmans, A. R. Offringa, Saleem Zaroubi , et al. · 2025

We present new upper limits on the 21 cm signal power spectrum from the epoch of reionisation (EoR), at redshifts z ≈10.1,9.1, and 8.3, based on reprocessed observations from the Low-Frequency Array (LOFAR). The analysis incorporates signi…

First upper limits on the 21-cm signal power spectrum of neutral hydrogen at $z=9.16$ from the LOFAR 3C196 field Open

E Ceccotti, A. R. Offringa, Florent Mertens, L. V. E. Koopmans, S. Munshi , et al. · 2025

The redshifted 21-cm signal of neutral hydrogen from the Epoch of Reionization (EoR) can potentially be detected using low-frequency radio instruments such as the Low-Frequency Array (LOFAR). So far, LOFAR upper limits on the 21-cm signal …

Freedom of Expression, Assembly, and Association Open

V. N. Pandey · 2025

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…

Transient RFI environment of LOFAR-LBA at 72–75 MHz Open

B. K. Gehlot, L. V. E. Koopmans, S. A. Brackenhoff, E Ceccotti, S. Ghosh , et al. · 2023

Context. Measurement of the highly redshifted and faint 21-cm signal of neutral hydrogen from the Cosmic Dawn and Epoch of Reionisation promises to unveil a wealth of information about the astrophysical processes that governed the structur…

A novel radio imaging method for physical spectral index modelling Open

E Ceccotti, A. R. Offringa, L. V. E. Koopmans, R. Timmerman, S. A. Brackenhoff , et al. · 2023

We present a new method, called ‘forced-spectrum fitting’, for physically based spectral modelling of radio sources during deconvolution. This improves upon current common deconvolution fitting methods, which often produce inaccurate spect…

A novel radio imaging method for physical spectral index modelling Open

E Ceccotti, A. R. Offringa, L. V. E. Koopmans, R. Timmerman, S. A. Brackenhoff , et al. · 2023

We present a new method, called "forced-spectrum fitting", for physically-based spectral modelling of radio sources during deconvolution. This improves upon current common deconvolution fitting methods, which often produce inaccurate spect…

Astronomical data organization, management and access in Scientific Data Lakes Open

Y. G. Grange, V. N. Pandey, Xavier Espinal, R. Di Maria, A.P. Millar · 2022

The data volumes stored in telescope archives is constantly increasing due to the development and improvements in the instrumentation. Often the archives need to be stored over a distributed storage architecture, provided by independent co…

A numerical study of 21-cm signal suppression and noise increase in direction-dependent calibration of LOFAR data Open

M. Mevius, Florent Mertens, L. V. E. Koopmans, A. R. Offringa, S. Yatawatta , et al. · 2021

We investigate systematic effects in direction-dependent gain calibration in the context of the Low-Frequency Array (LOFAR) 21-cm Epoch of Reionization (EoR) experiment. The LOFAR EoR Key Science Project aims to detect the 21-cm signal of …

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 …

Sub-arcsecond imaging with the International LOFAR Telescope Open

N. Jackson, Shruti Badole, John Morgan, R. 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…

Wide-field LOFAR-LBA power-spectra analyses: impact of calibration, polarization leakage, and ionosphere Open

B. K. Gehlot, L. V. E. Koopmans, A. G. de Bruyn, Saleem Zaroubi, M. A. Brentjens , et al. · 2018

Contamination due to foregrounds (Galactic and Extra-galactic), calibration\nerrors and ionospheric effects pose major challenges in detection of the cosmic\n21 cm signal in various Epoch of Reionization (EoR) experiments. We present the\n…

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 (…

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…

Upper Limits on the 21 cm Epoch of Reionization Power Spectrum from One Night with LOFAR Open

A. H. Patil, S. Yatawatta, L. V. E. Koopmans, A. G. de Bruyn, M. A. Brentjens , et al. · 2017

We present the first limits on the Epoch of Reionization 21 cm H i power spectra, in the redshift range z = 7.9–10.6, using the Low-Frequency Array (LOFAR) High-Band Antenna (HBA). In total, 13.0 hr of data were used from observations cent…

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

Correction: Corrigendum: 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

Linear polarization structures in LOFAR observations of the interstellar medium in the 3C 196 field Open

Vibor Jelić, A. G. de Bruyn, V. N. Pandey, M. Mevius, M. Haverkorn , et al. · 2015

This study aims to characterize linear polarization structures in LOFAR\nobservations of the interstellar medium (ISM) in the 3C196 field, one of the\nprimary fields of the LOFAR-Epoch of Reionization key science project. We have\nused the…

Galactic interstellar filaments as probed by LOFAR and Planck Open

Saleem Zaroubi, Vibor Jelić, A. G. de Bruyn, F. Boulanger, A. Bracco , et al. · 2015

Recent Low-Frequency Array (LOFAR) observations at 115–175 MHz of a field at medium Galactic latitudes (centred at the bright quasar 3C196) have shown striking filamentary structures in polarization that extend over more than 4° across the…

The LOFAR Multifrequency Snapshot Sky Survey (MSSS) Open

G. Heald, R. Pizzo, E. Orrú, R. P. Breton, D. Carbone , et al. · 2015

\n Contains fulltext :\n 150947.pdf (Publisher’s version ) (Open Access)\n

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. · 2015

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…

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