Related papers: Probing Ionospheric Structures using the LOFAR rad…
We present the first deep polarimetric study of Galactic synchrotron emission at low radio frequencies. Our study is based on 21 observations of the European Large Area Infrared Space Observatory Survey-North 1 (ELAIS-N1) field using the…
The ionosphere introduces chromatic distortions on low frequency radio waves, and thus poses a hurdle for 21-cm cosmology. In this paper we introduce time-varying chromatic ionospheric effects on simulated antenna temperature data of a…
Very Low Frequency, VLF and Low Frequency, LF signal perturbations were examined to study ionospheric disturbances induced by solar X-ray flares. The aim was to understand processes in propagation VLF/LF radio signals over short paths, and…
Energy consumption and hardware cost of signal digitization together with the management of the resulting data volume form serious issues for high-rate measurement systems with multiple sensors. Switching to binary sensing front-ends…
Many aspects of our societies now depend upon satellite telecommunications, such as those requiring Global Navigation Satellite Systems (GNSS). GNSS is based on radio waves that propagate through the ionosphere and experience complicated…
The 21-cm emission line from neutral hydrogen during the cosmic Dark Ages can be a powerful probe of cosmological models and early universe physics. This work provides a quantitative forecast for the design requirements of a lunar far-side…
The O I 1355{\AA} spectral line is one of the only optically thin lines that are both routinely observed and thought to be formed in the chromosphere. We present analysis of a variety of observations of this line with the Interface Region…
We present the final 6'' resolution data release of the ELAIS-N1 field from the LOw-Frequency ARray (LOFAR) Two-metre Sky Survey Deep Fields project (LoTSS Deep). The 144MHz images are the most sensitive achieved to date at this frequency…
LOFAR is a leading aperture synthesis telescope operated in the Netherlands with stations across Europe. The LOFAR Two-meter Sky Survey (LoTSS) will produce more than 3000 14 TB data sets, mapping the entire northern sky at low frequencies.…
Due to their steep spectra, low-frequency observations of FR II radio galaxies potentially provide key insights in to the morphology, energetics and spectrum of these powerful radio sources. However, limitations imposed by the previous…
We describe a method for spectral cleaning and timing calibration of short voltage time series data from individual radio interferometer receivers. It makes use of the phase differences in Fast Fourier Transform (FFT) spectra across antenna…
We modelled the two major layer of Earth's ionosphere, the F-layer and the D-layer, by a simplified spatial model with temporal variance to study the chromatic ionospheric effects on global 21-cm observations. From the analyses, we found…
We present a deep, low-frequency radio continuum study of the nearby Fanaroff--Riley class I (FR I) radio galaxy 3C 31 using a combination of LOw Frequency ARray (LOFAR; 30--85 and 115--178 MHz), Very Large Array (VLA; 290--420 MHz),…
We have developed a three dimensional (3D) interferometric beamforming technique for imaging lightning flashes using Very-High Frequency (VHF) radio data recorded from several hundreds antennas with baselines up to 100~km as offered by the…
The aim of this study is to explore the suitability of chromospheric images for magnetic modeling of active regions. We use high-resolution images (0.1") from the Interferometric Bidimensional Spectrometer (IBIS) in the Ca II 8542 A line,…
The non transparency and severe propagation effects of the terrestrial ionosphere make it impossible for Earth based instruments to study the universe at low radio frequencies. An exploration of the low frequency radio window with the…
In the present work, we study the periodicities of oscillations in dark fine structures using observations of a network and a semi-active region close to the solar disk center. We simultaneously obtained spatially high resolution time…
Interferometric Synthetic Aperture Radar (InSAR) is a powerful tool for monitoring surface deformation with high precision. However, low Signal-to-Noise Ratio (SNR) conditions, common in regions with low backscatter, can degrade phase…
We have observed a complex and continuous change in the integrated pulse profile of PSR B2217+47, manifested as additional components trailing the main peak. These transient components are detected over 6 years at $150$ MHz using the LOw…
We have conducted a deep survey (with a central rms of $55\mu\textrm{Jy}$) with the LOw Frequency ARray (LOFAR) at 120-168 MHz of the Bo\"otes field, with an angular resolution of $3.98^{''}\times6.45^{''}$, and obtained a sample of 10091…