368 citations · 1.3k across the 13 of their papers we have counts for
13 papers
Precision requirements for interferometric gridding in 21-cm power spectrum analysis
A. R. Offringa, F. Mertens, S. van der Tol +4
We analyse the accuracy of radio interferometric gridding of visibilities with the aim to quantify the Epoch of Reionization (EoR) 21-cm power spectrum bias caused by gridding, ult…
Probing Ionospheric Structures using the LOFAR radio telescope
M. Mevius, S. van der Tol, V. N. Pandey +24
LOFAR is the LOw Frequency Radio interferometer ARray located at mid-latitude (). Here, we present results on ionospheric structures derived from 29 LOFAR nighttim…
LOFAR, VLA, and Chandra observations of the Toothbrush galaxy cluster
R. J. van Weeren, G. Brunetti, M. Brüggen +39
We present deep LOFAR observations between 120-181 MHz of the "Toothbrush" (RX J0603.3+4214), a cluster that contains one of the brightest radio relic sources known. Our LOFAR obse…
LOFAR facet calibration
R. J. van Weeren, W. L. Williams, M. J. Hardcastle +39
LOFAR, the Low-Frequency Array, is a powerful new radio telescope operating between 10 and 240 MHz. LOFAR allows detailed sensitive high-resolution studies of the low-frequency rad…
Polarization leakage in Epoch of Reionization windows: I. LOFAR observations of the 3C196 field
K. M. B. Asad, L. V. E. Koopmans, V. Jelić +25
Detection of the 21-cm signal coming from the epoch of reionization (EoR) is challenging especially because, even after removing the foregrounds, the residual Stokes maps conta…
M87 at metre wavelengths: the LOFAR picture
F. de Gasperin, E. Orru', M. Murgia +92
M87 is a giant elliptical galaxy located in the centre of the Virgo cluster, which harbours a supermassive black hole of mass 6.4x10^9 M_sun, whose activity is responsible for the…
First LOFAR results on galaxy clusters
C. Ferrari, I. van Bemmel, A. Bonafede +21
Deep radio observations of galaxy clusters have revealed the existence of diffuse radio sources related to the presence of relativistic electrons and weak magnetic fields in the in…
First LOFAR observations at very low frequencies of cluster-scale non-thermal emission: the case of Abell 2256
R. J. van Weeren, H. J. A. Rottgering, D. A. Rafferty +79
Abell 2256 is one of the best known examples of a galaxy cluster hosting large-scale diffuse radio emission that is unrelated to individual galaxies. It contains both a giant radio…
LOFAR: Recent imaging results & future prospects
George Heald, Michael R. Bell, Andreas Horneffer +27
The Low Frequency Array (LOFAR) is under construction in the Netherlands and in several surrounding European countries. In this contribution, we describe the layout and design of t…
LOFAR: Early imaging results from commissioning for Cygnus A
John McKean, Louise Ker, Reinout J. van Weeren +19
The Low Frequency Array (LOFAR) will operate between 10 and 250 MHz, and will observe the low frequency Universe to an unprecedented sensitivity and angular resolution. The constru…
Progress with the LOFAR Imaging Pipeline
George Heald, John McKean, Roberto Pizzo +14
One of the science drivers of the new Low Frequency Array (LOFAR) is large-area surveys of the low-frequency radio sky. Realizing this goal requires automated processing of the int…
Calibration Challenges for Future Radio Telescopes
Stefan J. Wijnholds, Sebastiaan van der Tol, Ronald Nijboer +1
Instruments for radio astronomical observations have come a long way. While the first telescopes were based on very large dishes and 2-antenna interferometers, current instruments…
Ionospheric Calibration of Low Frequency Radio Interferometric Observations using the Peeling Scheme: I. Method Description and First Results
H. T. Intema, S. van der Tol, W. D. Cotton +3
Calibration of radio interferometric observations becomes increasingly difficult towards lower frequencies. Below ~300 MHz, spatially variant refractions and propagation delays of…