Tammo Jan Dijkema
A5051290644- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- Image and Signal Denoising Methods
- Space Satellite Systems and Control
- Gamma-ray bursts and supernovae
- Planetary Science and Exploration
- Astronomy and Astrophysical Research
- Solar and Space Plasma Dynamics
- Spacecraft Design and Technology
- Geophysics and Gravity Measurements
- Stellar, planetary, and galactic studies
- Antenna Design and Optimization
- Astrophysical Phenomena and Observations
- Impact of Light on Environment and Health
- Advanced Computational Techniques in Science and Engineering
- Calibration and Measurement Techniques
- Advanced Numerical Methods in Computational Mathematics
- Atmospheric aerosols and clouds
- Atmospheric Ozone and Climate
- Telecommunications and Broadcasting Technologies
- Superconducting and THz Device Technology
- Radio Wave Propagation Studies
Netherlands Institute for Radio Astronomy
2016-2023
Campo Arqueologico de Mertola
2022-2023
AstroTec Holding (Netherlands)
2020
Utrecht University
2005-2010
The LOFAR Two-metre Sky Survey (LoTSS) is a deep 120-168 MHz imaging survey that will eventually cover the entire Northern sky. Each of 3170 pointings be observed for 8 hrs, which, at most declinations, sufficient to produce ~5arcsec resolution images with sensitivity ~0.1mJy/beam and accomplish main scientific aims which are explore formation evolution massive black holes, galaxies, clusters galaxies large-scale structure. Due compact core long baselines LOFAR, provide excellent both highly...
The LOFAR Two-metre Sky Survey (LoTSS) is an ongoing sensitive, high-resolution 120-168MHz survey of the entire northern sky for which observations are now 20% complete. We present our first full-quality public data release. For this release 424 square degrees, or 2% eventual coverage, in region HETDEX Spring Field (right ascension 10h45m00s to 15h30m00s and declination 45$^\circ$00$'$00$''$ 57$^\circ$00$'$00$''$) were mapped using a fully automated direction-dependent calibration imaging...
In this data release from the LOFAR Two-metre Sky Survey (LoTSS) we present 120-168MHz images covering 27% of northern sky. Our coverage is split into two regions centred at approximately 12h45m +44$^\circ$30' and 1h00m +28$^\circ$00' spanning 4178 1457 square degrees respectively. The were derived 3,451hrs (7.6PB) High Band Antenna which corrected for direction-independent instrumental properties as well direction-dependent ionospheric distortions during extensive, but fully automated,...
We present the first wide area (19 deg$^2$), deep ($\approx120-150$ {\mu}Jy beam$^{-1}$), high resolution ($5.6 \times 7.4$ arcsec) LOFAR High Band Antenna image of Bo\"otes field made at 130-169 MHz. This is least an order magnitude deeper and 3-5 times higher in angular than previously achieved for this low frequencies. The observations data reduction, which includes full direction-dependent calibration, are described here. a radio source catalogue containing 6276 sources detected over...
We present deep LOFAR observations between 120-181 MHz of the "Toothbrush" (RX J0603.3+4214), a cluster that contains one brightest radio relic sources known. Our exploit new and novel calibration scheme to probe 10 times deeper than any previous study in this relatively unexplored part spectrum. The observations, when combined with VLA, GMRT, Chandra X-ray data, provide information about nature merger shocks their role re-accelerating relativistic particles. derive spectral index $\alpha =...
ABSTRACT 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 low-frequency sky. At same time also provides excellent short baseline coverage to map diffuse extended emission. However, producing high-quality deep images challenging due presence direction-dependent calibration errors, caused by imperfect knowledge station beam shapes ionosphere. Furthermore, large data volume clock errors...
We present the discovery of PSR J0250+5854, a radio pulsar with spin period 23.5 s. This is slowest-spinning known. J0250+5854 was discovered by LOFAR Tied-Array All-Sky Survey (LOTAAS), an all-northern-sky survey for pulsars and fast transients at central observing frequency 135 MHz. subsequently detected pulsations from in interferometric images Two-meter Sky Survey, allowing subarcsecond localization. This, along pre-discovery detection 2 years prior, allowed us to measure spin-period...
Context: New generation low-frequency telescopes are exploring a new parameter space in terms of depth and resolution. The data taken with these interferometers, for example the LOw Frequency ARray (LOFAR), often calibrated low signal-to-noise ratio regime removal critical systematic effects is challenging. process requires an understanding their origin properties. Aim: In this paper we describe major inherent to next telescopes, such as LOFAR. With knowledge, introduce processing pipeline...
The Global Meteor Network (GMN) utilizes highly sensitive low-cost CMOS video cameras which run open-source meteor detection software on Raspberry Pi computers. Currently, over 450 GMN in 30 countries are deployed. main goal of the network is to provide long-term characterization radiants, flux, and size distribution annual showers outbursts optical mass range. rapid 24-hour publication cycle orbital data will enhance public situational awareness near-Earth meteoroid environment. also aims...
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,...
Adaptive tensor product wavelet methods are applied for solving Poisson's equation, as well anisotropic generalizations, in high space dimensions. It will be demonstrated that the resulting approximations converge energy norm with same rate best from span of N wavelets, where moreover constant factor we may lose is independent dimension n. The cost producing these proportional to their length a grow n, but only linearly.
Ultra-low frequency observations (<100 MHz) are particularly challenging because they usually performed in a low signal-to-noise ratio regime due to the high sky temperature and of ionospheric disturbances whose effects inversely proportional observing frequency. Nonetheless, these crucial study emission from low-energy populations cosmic rays. We aim obtain first thermal-noise limited (~ 1.5 mJy/beam) deep continuum radio map using LOFAR Low Band Antenna (LBA) system. Our demonstration...
We construct a wavelet basis on the unit interval with respect to which both (infinite) mass and stiffness matrix corresponding one-dimensional Laplacian are (truly) sparse boundedly invertible. As consequence, n-dimensional box n-fold tensor product is also This greatly simplifies implementation improves quantitative properties of an adaptive scheme solve multi-dimensional Poisson equation. The results extend any second order partial differential operator constant coefficients that defines...
abstract Producing ultra-deep high-angular-resolution images with current and next-generation radio interferometers introduces significant computational challenges. In particular, the imaging is so demanding that processing large datasets, accumulated over hundreds of hours on same pointing, likely infeasible in data reduction schemes. this paper, we revisit a solution to problem was considered past but not being used modern software: sidereal visibility averaging (SVA). This technique...
Abstract As a part of China’s Chang’e-4 lunar far side mission, two microsatellites for low frequency radio astronomy, amateur and education, Longjiang-1 Longjiang-2, were launched as secondary payloads on 20 May 2018 together with the Queqiao L2 relay satellite. On 25 2018, Longjiang-2 successfully inserted itself into elliptical orbit 357 km × 13,704 km, became smallest spacecraft which entered its own propulsion system. The satellite carried first communication system operating in orbit,...
We report on simultaneous 30 - 60 MHz LOFAR / AARTFAAC12 radio observations and CAMS low-light video of +4 to -10 magnitude meteors at the peak Perseid meteor shower August 12/13, 2020. 204 trains were imaged in both optical domain. Aside from scattered artificial sources, we identify broadband emission many persistent trains, one which lingered for up 6 minutes. Unexpectedly, fewer recorded when experiment was repeated during 2020 Geminids 2021 Quadrantids. Intrinsic reported earlier by...