H. A. Holties
A5057977098- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Antenna Design and Optimization
- Distributed and Parallel Computing Systems
- Methane Hydrates and Related Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Radio Wave Propagation Studies
- Medical Imaging Techniques and Applications
- Railway Engineering and Dynamics
- Adaptive optics and wavefront sensing
- Solar and Space Plasma Dynamics
- Magnetic confinement fusion research
- Advanced Data Storage Technologies
- Scientific Research and Discoveries
- Geological Formations and Processes Exploration
- Advanced Frequency and Time Standards
- Astro and Planetary Science
- Railway Systems and Energy Efficiency
- Neutrino Physics Research
- Particle Accelerators and Free-Electron Lasers
Netherlands Institute for Radio Astronomy
2010-2023
AstroTec Holding (Netherlands)
2023
Astronomy and Space
2012
Institute for Atomic and Molecular Physics
1994
LOFAR, the LOw-Frequency ARray, is a new-generation radio interferometer constructed in north of Netherlands and across europe. Utilizing novel phased-array design, LOFAR covers largely unexplored low-frequency range from 10-240 MHz provides number unique observing capabilities. Spreading out core located near village Exloo northeast Netherlands, total 40 stations are nearing completion. A further five have been deployed throughout Germany, one station has built each France, Sweden, UK....
Low frequency radio waves, while challenging to observe, are a rich source of information about pulsars. The LOw Frequency ARray (LOFAR) is new interferometer operating in the lowest 4 octaves ionospheric "radio window": 10-240MHz, that will greatly facilitate observing pulsars at low frequencies. Through huge collecting area, long baselines, and flexible digital hardware, it expected LOFAR revolutionize astronomy frequencies visible from Earth. next-generation telescope pathfinder Square...
The low frequency array (LOFAR), is the first radio telescope designed with capability to measure emission from cosmic-ray induced air showers in parallel interferometric observations. In $\sim 2\,\mathrm{years}$ of observing, 405 events energy range $10^{16} - 10^{18}\,\mathrm{eV}$ have been detected band $30 80\,\mathrm{MHz}$. Each these registered up $\sim1000$ independent antennas resulting measurements unprecedented detail. This article describes dataset, as well analysis pipeline, and...
Dispersion in the interstellar medium is a well known phenomenon that follows simple relationship, which has been used to predict time delay of dispersed radio pulses since late 1960s. We performed wide-band simultaneous observations four pulsars with LOFAR (at 40-190 MHz), 76-m Lovell Telescope 1400 MHz) and Effelsberg 100-m 8000 test accuracy dispersion law over broad frequency range. In this paper we present results these show accurate better than 1 part 100000 across our observing band....
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 last observations taken 28 February 2022. The imaging component provides radio continuum, polarization, and spectral line data. Aims. Public release data critical maximizing legacy survey. Toward that end, we describe products from first year operations,...
We describe the APERture Tile In Focus (Apertif) system, a phased array feed (PAF) upgrade of Westerbork Synthesis Radio Telescope that transforms this telescope into 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 sky simultaneously, significantly increasing speed telescope. With upgraded instrument, an covering area 2300 deg 2 is being performed will deliver both continuum...
Cassiopeia A is one of the best-studied supernova remnants. Its shocked ejecta emits brightly in radio and X-rays. unshocked can be studied through infrared emission, radio-active decay $^{44}$Ti, low frequency free-free absorption due to cold gas internal shell. Free-free affected by mass, geometry, temperature, ionisation conditions absorbing gas. Observations at lowest frequencies constrain a combination these properties. We use LOFAR LBA observations 30-77 MHz L-band VLA compare...
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 Burst (FRB) emitters arguably requires good localisation more detections, and broadband studies enabled real-time alerting. We here present Apertif Transient System (ARTS), supercomputing radio-telescope instrument that performs FRB detection on Westerbork Synthesis Telescope (WSRT) interferometer....
The computational and storage demands for the future Square Kilometer Array (SKA) radio telescope are significant. Building on experience gained with collaboration between ASTRON IBM Blue Gene based LOFAR correlator, have now embarked a public-private exascale computing research project aimed at solving SKA challenges. This project, called DOME, investigates novel approaches to computing, focus energy efficient, streaming data processing, storage, nano-photonics. DOME will not only benefit...
We present a new image of 26.5 square degree region in the Bo\"otes constellation obtained at 1.4 GHz using Aperture Tile Focus (Apertif) system on Westerbork Synthesis Radio Telescope. use newly developed processing pipeline which includes direction-dependent self-calibration provides significant improvement quality images compared to those released as part Apertif first data release. For region, we mosaic 187 and extract source catalog. The has an angular resolution 27${\times}$11.5...
Abstract The LOw Frequency ARray (LOFAR) is a European radio telescope operating since 2010 in the frequency bands 10 - 80 MHz and 110 250 MHz. This article provides an analysis of energy consumption carbon footprint LOFAR. approach used Life Cycle Analysis (LCA). We find that one year LOFAR operations requires 3,627 MWh electricity, 48,714 m 3 gas 135,497 liters fuel. associated emission 1,867 tCO2e/year. Results include stemming from all stations central processing, but exclude scientific...
The Low Frequency Array (LOFAR) is a large distributed radio telescope that observes at frequencies from 10 MHz to 240 MHz. LOFAR combines phased array antenna stations in Germany, the UK, France, and Sweden with forty Netherlands. archive of science data products expected grow by five petabyte per year. long-term (LTA) provides an e-Infrastructure for storage, distribution, analysis produced LOFAR. It builds on national international European scale pioneering cyber-infrastructures future...
After its first implementation in 2003 the Astro-WISE technology has been rolled out several European countries and is used for production of KiDS survey data. In multi-disciplinary Target initiative this technology, nicknamed WISE further applied to a large number projects. Here, we highlight data handling other astronomical applications, such as VLT-MUSE LOFAR, together with some non-astronomical applications medical projects Lifelines GLIMPS, MONK handwritten text recognition system,...
It is shown that the conservation of flow circulation along magnetic field lines can be used to improve on δW stability criterion for rotating plasmas by adding energy integral a positive definite term. The improvement most effective ballooning modes in systems with closed-line field. Such are investigated, both when sheared and it unsheared. In unsheared case, instabilities grow exponentially time, while, if sheared, an instability eventually saturates. time-asymptotic behavior such...
The Astro-WISE information system was developed to handle data processing for the KIDS survey. In this paper we describe adaptation of WISE concept allow scaling support archives containing tens petabytes stored and changes introduced accommodate LOFAR Long Term Archive. With provide an example how technology can be adapted a wider range scale data.
In the framework of Dutch program Quiet Train Traffic (Stiller Trein Verkeer) low, close to track barriers and absorptive layers on a slab have been investigated. Following numerical calculations an experimental study has made in order evaluate different solutions. A special test site constructed, which acoustically resembles track. It enables quick mounting dismounting slab. Using reciprocal measurement method acoustical performance (insertion loss) solutions determined. One advantages is...
We present a new image of 26.5 square degree region in the Boötes constellation obtained at 1.4 GHz using Aperture Tile Focus (Apertif) system on Westerbork Synthesis Radio Telescope. use newly developed processing pipeline which includes direction-dependent self-calibration provides significant improvement quality images compared to those released as part Apertif first data release. For region, we mosaic 187 and extract source catalog. The has an angular resolution 27${\times}$11.5...
The LOFAR Long-Term Archive (LTA) is a multi-Petabyte scale data storage for the processed of telescope. We describe adaptation WISE concept implemented by Target consortium LTA and changes we introduced to it accommodate data. This paper describes an example new information system created on basis Astro-WISE wider range