A5004518641- Astro and Planetary Science
- Planetary Science and Exploration
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Radio Astronomy Observations and Technology
- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Astrophysics and Cosmic Phenomena
- Space Satellite Systems and Control
- Astronomical Observations and Instrumentation
- GNSS positioning and interference
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- Geology and Paleoclimatology Research
- Space Exploration and Technology
- Fire effects on ecosystems
- earthquake and tectonic studies
- Soil Moisture and Remote Sensing
- CCD and CMOS Imaging Sensors
- Biofuel production and bioconversion
- Lightning and Electromagnetic Phenomena
- Geophysics and Gravity Measurements
- Particle Accelerators and Free-Electron Lasers
Netherlands Institute for Radio Astronomy
2016-2024
Jacobs (United States)
2015-2019
Wheaton College - Illinois
2019
Marshall Space Flight Center
2013-2017
Army Logistics University
2017
Dynetics (United States)
2013-2014
Western University
2011
Abstract Fast radio bursts (FRBs) are extremely energetic, millisecond-duration flashes that reach Earth from extragalactic distances. Broadly speaking, FRBs can be classified as repeating or (apparently) non-repeating. It is still unclear, however, whether the two types share a common physical origin and differ only in their activity rate. Here we report on an observing campaign targeted one hyperactive source, FRB 20201124A, for more than 2,000 h using four 25–32 m class telescopes. We...
Very long baseline interferometric (VLBI) localisations of repeating fast radio bursts (FRBs) have demonstrated a diversity local environments: from nearby star-forming regions to globular clusters. Here we report the VLBI localisation FRB 20201124A using an ad-hoc array dishes that also participate in European Network (EVN). In our campaign, detected 18 total at two separate epochs. By combining visibilities both observing epochs, were able localise with 1-$\sigma$ error 4.5 milliarcseconds...
(abridged). We outline LBCS (the LOFAR Long-Baseline Calibrator Survey), whose aim is to identify sources suitable for calibrating the highest-resolution observations made with International Telescope, which include baselines >1000 km. Suitable must contain significant correlated flux density (50-100mJy) at frequencies around 110--190~MHz on scales of a few hundred mas. At least 200--300-km international baselines, we find 1 calibrator source per square degree over large part northern...
The low-frequency radio spectra of the hotspots within powerful galaxies can provide valuable information about physical processes operating at site jet termination. These are responsible for dissipation kinetic energy, particle acceleration, and magnetic-field generation. Here, we report new observations galaxy Cygnus A using Low Frequency Array (LOFAR) between 109 183 MHz, an angular resolution ∼3.5 arcsec. emission lobes is found to have a complex spectral index distribution, with...
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...
The mass distribution index of the Geminid, Quadrantid, Arietid, Eta Aquariid, Orionid and South Delta Aquariid meteor showers have been measured using data from 2007 to 2010 Canadian Meteor Orbit Radar (CMOR). Single-station 29.85-MHz system were used find as a function solar longitude, compare separate years showers. variation in with longitude can provide information on structure stream how changes time. Geminids Quadrantids most prominent seen by CMOR, had peak indices 1.65 1.55,...
The mass distribution index of sporadic meteors and the indices specific sources have been measured using data from 2007 to 2010 Canadian Meteor Orbit Radar. Single-station 29.85-MHz system were used trends throughout year are examined. We find that average values for approximately equal, but annual variation each source is unique. overall 2.17 ± 0.07, less than frequently cited 2.34. in can provide information about meteoroid populations Earth encountering at different parts its orbit.
Type II radio bursts are evidence of shocks in the solar atmosphere and inner heliosphere that emit waves ranging from sub-meter to kilometer lengths. These may be associated with CMEs reach speeds higher than local magnetosonic speed. Radio imaging decameter wavelengths (20-90 MHz) is now possible LOFAR, opening a new window which study coronal leave corona enter interplanetary medium understand their association CMEs. To this end, we shock CME type burst determine locations at emission...
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 complete survey, building on preliminary analysis published 2016 which covered approximately half survey area. final catalogue consists 30006 observations 24713 sources northern sky, selected combination high low-frequency radio flux density flat spectral index using existing surveys (WENSS,...
The four persistent radio sources in the northern sky with highest flux density at metre wavelengths are Cassiopeia A, Cygnus Taurus and Virgo A; collectively they called A-team. Their densities ultra-low frequencies (<100 MHz) can reach several thousands of janskys, often contaminate observations low-frequency by interfering image processing. Furthermore, these foreground objects for all-sky hampering study faint signals, such as cosmological 21 cm line from epoch reionisation. We aim to...
Multi-aperture photometry of Comet 29P/Schwassmann-Wachmann 1 was conducted on Johnson–Cousins R-band observations spanning 2011 May 1–9 and 2012 June 6–July 3. The comet observed in outburst 3 July 1, during which its brightness increased by 2.2 2.1 mag, respectively, as measured through a 10 arcsec aperture. Dust production before after each is calculated using the parameter Af ρ, converted to lower limit dust rate based models derived nuclear properties from other studies. Both outbursts...
The bulk density of a meteoroid affects its dynamics in space, ablation the atmosphere, and damage it does to spacecraft lunar or planetary surfaces. Meteoroid densities are also notoriously difficult measure, we typically forced assume attempt measure via proxy. In this paper, construct distribution for sporadic meteoroids based on existing measurements. We considered two possible proxies density: KB parameter introduced by Ceplecha Tisserand parameter, TJ. Although is frequently cited as...
This paper outlines new methods to measure optical meteor fluxes for showers and sporadic sources. Many past approaches have found the collecting area of a detector at fixed 100 km altitude, but this approach considers full volume, finding in 2 height intervals based on position shower or source radiant population's velocity. Here, stellar limiting magnitude is every 10 min during clear periods converted having measured, which then mass. The final output mass-limited flux Presented are...
Abstract We present the localization and host galaxy of FRB 20190208A, a repeating source fast radio bursts (FRBs) discovered using CHIME/FRB. As part Pinpointing REpeating ChIme Sources with EVN dishes repeater program on European VLBI Network (EVN), we monitored 20190208A for 65.6 hr at ∼1.4 GHz detected single burst, which led to its very long baseline interferometry 260 mas uncertainty (2 σ ). Follow-up optical observations MMT Observatory ( i ≳ 25.7 mag (AB)) found no visible position....
Context. The Sun is an active star that produces large-scale energetic events such as solar flares and coronal mass ejections numerous smaller-scale jets. These are often associated with accelerated particles can cause emission at radio wavelengths. reconfiguration of the magnetic field in corona believed to be majority particles. Aims. Here, we investigate a bright J-burst was jet possible mechanism causing these two phenomena. Methods. We used data from Solar Dynamics Observatory (SDO)...
Fast radio bursts (FRBs) are extremely energetic, millisecond-duration flashes that reach Earth from extragalactic distances. Broadly speaking, FRBs can be classified as repeating or (apparently) non-repeating. It is still unclear, however, whether the two types share a common physical origin, differing only in their activity rate. Here we report on an unprecedented observing campaign targeted one hyperactive source, FRB 20201124A, for more than $2000~\mathrm{hr}$ using four...
The Chelyabinsk superbolide of February 15, 2013, was caused by the atmospheric entry a ~19 m asteroid with kinetic energy 500 kT TNT just south city Chelyabinsk, Russia. It rare event; impacts similar occur on Earth only few times per century. Impacts this near such large urban area are expected 10 000 years. A number video records obtained casual eyewitnesses, dashboard cameras in cars, security, and traffic were made publicly available their authors Internet. These represent rich...