Nanosecond Sampling of the Radio Sky with I-LOFAR's Transient Buffer Boards (TBB)
The LOw Frequency ARray (LOFAR) is an interferometeric array that operates at 10-240 MHz, with a ... more The LOw Frequency ARray (LOFAR) is an interferometeric array that operates at 10-240 MHz, with a central hub in the Netherlands and 13 international stations across Europe [1]. LOFAR's Transient Buffer Boards (TBBs) allow upwards of 5 s of data to be recorded at a temporal resolution of ~5.12 ns. Here, we described the development of a data acquisition system to capture TBB observations of solar variability from the Irish LOFAR station (I-LOFAR) at Birr Castle in the Irish Midlands. The system consists of a head node controlling 4 processing nodes offering 64 GB of RAM, as well as an initial 48 TB RAID6 storage node. We present first-light TBB time series data, along with all-sky observations data from a subset of I-LOFAR's Low Band Antennas (LBAs). We also discuss the development of a software based beamformer for TBB data with plans to observe the sun with dynamic spectra using nanosecond time resolution. This could give a new insight into rapidly varying phenomena in the ...
Plenary talk at the 17th RHESSI Workshop at Trinity College Dublin (http:rhessi17.lofar.ie) on Ju... more Plenary talk at the 17th RHESSI Workshop at Trinity College Dublin (http:rhessi17.lofar.ie) on June 18-23, 2018. Describes the construction, operation and first results from the Irish LOFAR radio telescope.
The discovery of the ubiquity of habitable extrasolar planets, combined with revolutionary advanc... more The discovery of the ubiquity of habitable extrasolar planets, combined with revolutionary advances in instrumentation and observational capabilities, have ushered in a renaissance in the millenia-old quest to answer our most profound question about the Universe and our place within it - Are we alone? The Breakthrough Listen Initiative, announced in July 2015 as a 10-year 100M USD program, is the most comprehensive effort in history to quantify the distribution of advanced, technologically capable life in the universe. In this white paper, we outline the status of the on-going observing campaign with our primary observing facilities, as well as planned activities with these instruments over the next few years. We also list collaborative facilities which will conduct searches for technosignatures in either primary observing mode, or commensally. We highlight some of the novel analysis techniques we are bringing to bear on multi-petabyte data sets, including machine learning tools we ...
Multiple Regions of Shock Accelerated Particles in the Solar Corona
Poster at European Space Weather Week, November 2018. <br>The Sun is an active star that ca... more Poster at European Space Weather Week, November 2018. <br>The Sun is an active star that can launch large eruptions of magnetised plasma into the heliosphere, called coronal mass ejections. These ejections can drive shocks that accelerate particles to high energies, often resulting in radio emission at low frequencies (<200 MHz). To date, the relationship between the expansion of coronal mass ejections, shocks and particle acceleration is not well understood, partially due to difficulties associated with radio imaging at low frequencies. Here, we report unique radio, whitelight and ultraviolet imaging of the second largest flare in the current solar cycle and associated very fast coronal mass ejection (~3000km/s). For the first time, we identify the location of a multitude of radio shock signatures, called herringbones, and find evidence for shock accelerated electron beams at multiple locations along an expanding coronal mass ejection, supporting theories of non-uniform, r...
Background: The detection of pathogens in complex sample backgrounds has been revolutionized by w... more Background: The detection of pathogens in complex sample backgrounds has been revolutionized by wide access to next-generation sequencing (NGS) platforms. However, analytical methods to support NGS platforms are not as uniformly available. Pathosphere (found at Pathosphere.org) is a cloud-based open-sourced community tool that allows for communication, collaboration and sharing of NGS analytical tools and data amongst scientists working in academia, industry and government. The architecture allows for users to upload data and run available bioinformatics pipelines without the need for onsite processing hardware or technical support. Results: The pathogen detection capabilities hosted on Pathosphere were tested by analyzing pathogen-containing samples sequenced by NGS with both spiked human samples as well as human and zoonotic host backgrounds. Pathosphere analytical pipelines developed by Edgewood Chemical Biological Center (ECBC) identified spiked pathogens within a common sample analyzed by 454, Ion Torrent, and Illumina sequencing platforms. ECBC pipelines also correctly identified pathogens in human samples containing arenavirus in addition to animal samples containing flavivirus and coronavirus. These analytical methods were limited in the detection of sequences with limited homology to previous annotations within NCBI databases, such as parvovirus. Utilizing the pipeline-hosting adaptability of Pathosphere, the analytical suite was supplemented by analytical pipelines designed by the United States Army Medical Research Insititute of Infectious Diseases and Walter Reed Army Institute of Research (USAMRIID-WRAIR). These pipelines were implemented and detected parvovirus sequence in the sample that the ECBC iterative analysis previously failed to identify. Conclusions: By accurately detecting pathogens in a variety of samples, this work demonstrates the utility of Pathosphere and provides a platform for utilizing, modifying and creating pipelines for a variety of NGS technologies developed to detect pathogens in complex sample backgrounds. These results serve as an exhibition for the existing pipelines and web-based interface of Pathosphere as well as the plug-in adaptability that allows for integration of newer NGS analytical software as it becomes available.
Geomagnetically induced currents (GICs) are a well-known terrestrial space weather hazard. They o... more Geomagnetically induced currents (GICs) are a well-known terrestrial space weather hazard. They occur in power transmission networks and are known to have adverse effects in both high-latitude and midlatitude countries. Here we study GICs in the Irish power transmission network (geomagnetic latitude 54.7–58.5∘N) during five geomagnetic storms (6–7 March 2016, 20–21 December 2015, 17–18 March 2015, 29–31 October 2003, and 13–14 March 1989). We simulate electric fields using a plane wave method together with two ground resistivity models, one of which is derived from magnetotelluric measurements (magnetotelluric (MT) model). We then calculate GICs in the 220, 275, and 400 kV transmission network. During the largest of the storm periods studied, the peak electric field was calculated to be as large as 3.8 V km−1, with associated GICs of up to 23 A using our MT model. Using our homogenous resistivity model, those peak values were 1.46 V km−1 and 25.8 A. We find that three 400 and 275 kV...
Modern radio interferometers such as the LOw Frequency ARray (LOFAR) are capable of producing dat... more Modern radio interferometers such as the LOw Frequency ARray (LOFAR) are capable of producing data at hundreds of gigabits to terabits per second. This high data rate makes the analysis of radio data cumbersome and computationally expensive. While high performance computing facilities exist for large national and international facilities, that may not be the case for instruments operated by a single institution or a small consortium. Data rates for next generation radio telescopes are set to eclipse those currently in operation, hence local processing of data will become all the more important. Here, we introduce the REAL-time Transient Acquisition backend (REALTA), a computing backend at the Irish LOFAR station (I-LOFAR) which facilitates the recording of data in near real-time and post-processing. We also present first searches and scientific results of a number of radio phenomena observed by I-LOFAR and REALTA, including pulsars, fast radio bursts, rotating radio transients, the ...
Experimental study of the phase and amplitude observations of sub-ionospheric very low and low fr... more Experimental study of the phase and amplitude observations of sub-ionospheric very low and low frequency signals is performed to analyze the response of the lower ionosphere during the August 21, 2017 total solar eclipse in the United States of America. Three subionospheric wave paths have been investigated. The length of the paths varied from 2200 to 6500 km, signal frequencies were 21.4 kHz, 25.2 kHz and 40.8 kHz. Two paths crossed the region of total eclipse and the third path was in the region of 40-60% of obscuration. None of the signals revealed any noticeable amplitude changes during the eclipse while negative phase anomalies (from-35° to-95°) were detected for all three paths. It was shown that the effective reflection height of the ionosphere in low and middle latitudes has been increased by 3.5-5 km during the eclipse.
Surface electric fields and geomagnetically induced currents (GIC) were simulated in the Irish po... more Surface electric fields and geomagnetically induced currents (GIC) were simulated in the Irish power network for five geomagnetic events. • A multi-layered resistivity model to a depth of 200 km was made using magnetotelluric measurements for use in GIC simulations in Ireland. • GICs have been replicated for Kp6 and Kp7 storms, and predicted for Kp9 storms in Ireland.
Monitoring and Modelling Geomagnetic Storms in Ireland
<p>Poster given at ESWW11 in Liege.</p> <p> </p> <p>November 2014&l... more <p>Poster given at ESWW11 in Liege.</p> <p> </p> <p>November 2014</p
Solubility of Mo 6 S 4.5 I 4.5 Nanowires in Common Solvents: A Sedimentation Study
The Journal of Physical Chemistry B, 2005
Due to their ease of fabrication and monodisperse, metallic nature, molybdenum-sulfur-iodine nano... more Due to their ease of fabrication and monodisperse, metallic nature, molybdenum-sulfur-iodine nanowires are an interesting alternative to carbon nanotubes for some applications. However very little is known about the solubility of these materials. In this work we have investigated the solubility of Mo(6)S(4.5)I(4.5) nanowire soot in a range of common solvents by performing sedimentation studies and microscopic and spectroscopic characterization. A sedimentation equation was derived showing that the concentration of any insoluble dispersed phase decreases exponentially with time. We find that in all solvents, Mo(6)S(4.5)I(4.5) nanowire soot contains three phases, two of which are insoluble with one stable phase. Microscopy and spectroscopy show that the first insoluble phase is associated mainly with spherical impurities and sediments rapidly out of solution resulting in purification. The second phase appears to consist of insoluble nanowire bundles and sediments more slowly, eventually leaving a stable dispersion of nanowire bundles. The stably dispersed bundles tend to be smaller than their insoluble counterparts. The best solvents studied were 2-propanol and dimethylformamide. Microscopy studies showed that, in the case of 2-propanol, sonication significantly reduced the bundle size relative to the unsonicated bulk. However, during sedimentation, large quantities of bundles were observed to reaggregate to form larger bundles which subsequently sedimented out of solution. In general, the sedimentation properties of the various phases did not vary significantly with concentration indicating that the insoluble nanowires are intrinsically insoluble. However, the diameter of the stably dispersed bundles decreased with concentration, until very small bundles consisting of only two or three nanowires were observed at concentrations below 0.003 mg/mL. In addition, stable composite dispersions were produced by mixing the nanowires with poly(vinylpyrrolidone) in 2-propanol opening the way for the formation of polymer/inorganic nanowire composites.
Initial Irish light pollution measurements and a new Sky Quality Meter-based data logger
Lighting Research & Technology, 2014
In the Celtic Tiger years, Ireland underwent an explosive growth in housing and an increase in li... more In the Celtic Tiger years, Ireland underwent an explosive growth in housing and an increase in light pollution, nationally. We outline work undertaken towards the first ever ground-based survey of light pollution in the island of Ireland and illustrate this with some representative data taken between 2009 and the present. The aim of our work is to establish a database to serve as a reference to monitor future changes, to compare with in-orbit measurements, to study the potential impact on the environment and to permit the calculation of the effects of future changes in lighting usage and patterns. We also report the development of a microcontroller-based data-logging instrument based on a Unihedron Sky Quality Meter-LR detector, which can be used by amateurs or can serve as a stand-alone instrument for night-sky brightness surveys.
The Low Frequency Array (LOFAR) is an international radio telescope array, consisting of 38 stati... more The Low Frequency Array (LOFAR) is an international radio telescope array, consisting of 38 stations in the Netherlands and 14 international stations spread over Europe. Here we present an observation method to study the jovian decametric radio emissions from several LOFAR stations (here DE604, FR606 and IE613), at high temporal and spectral resolution. This method is based on prediction tools, such as radio emission simulations and probability maps, and data processing. We report an observation of Io-induced decametric emission from June 2021, and a first case study of the substructures that compose the macroscopic emissions (calledmillisecond bursts). The study of these bursts make it possible to determine the electron populations at the origin of these emissions. We then present several possible future avenues for study based on these observations. The methodology and study perspectives described in this paper can be applied to new observations of jovian radio emissions induced b...
Nanosecond Sampling of the Radio Sky with I-LOFAR's Transient Buffer Boards (TBB)
The LOw Frequency ARray (LOFAR) is an interferometeric array that operates at 10-240 MHz, with a ... more The LOw Frequency ARray (LOFAR) is an interferometeric array that operates at 10-240 MHz, with a central hub in the Netherlands and 13 international stations across Europe [1]. LOFAR's Transient Buffer Boards (TBBs) allow upwards of 5 s of data to be recorded at a temporal resolution of ~5.12 ns. Here, we described the development of a data acquisition system to capture TBB observations of solar variability from the Irish LOFAR station (I-LOFAR) at Birr Castle in the Irish Midlands. The system consists of a head node controlling 4 processing nodes offering 64 GB of RAM, as well as an initial 48 TB RAID6 storage node. We present first-light TBB time series data, along with all-sky observations data from a subset of I-LOFAR's Low Band Antennas (LBAs). We also discuss the development of a software based beamformer for TBB data with plans to observe the sun with dynamic spectra using nanosecond time resolution. This could give a new insight into rapidly varying phenomena in the ...
Plenary talk at the 17th RHESSI Workshop at Trinity College Dublin (http:rhessi17.lofar.ie) on Ju... more Plenary talk at the 17th RHESSI Workshop at Trinity College Dublin (http:rhessi17.lofar.ie) on June 18-23, 2018. Describes the construction, operation and first results from the Irish LOFAR radio telescope.
The discovery of the ubiquity of habitable extrasolar planets, combined with revolutionary advanc... more The discovery of the ubiquity of habitable extrasolar planets, combined with revolutionary advances in instrumentation and observational capabilities, have ushered in a renaissance in the millenia-old quest to answer our most profound question about the Universe and our place within it - Are we alone? The Breakthrough Listen Initiative, announced in July 2015 as a 10-year 100M USD program, is the most comprehensive effort in history to quantify the distribution of advanced, technologically capable life in the universe. In this white paper, we outline the status of the on-going observing campaign with our primary observing facilities, as well as planned activities with these instruments over the next few years. We also list collaborative facilities which will conduct searches for technosignatures in either primary observing mode, or commensally. We highlight some of the novel analysis techniques we are bringing to bear on multi-petabyte data sets, including machine learning tools we ...
Multiple Regions of Shock Accelerated Particles in the Solar Corona
Poster at European Space Weather Week, November 2018. <br>The Sun is an active star that ca... more Poster at European Space Weather Week, November 2018. <br>The Sun is an active star that can launch large eruptions of magnetised plasma into the heliosphere, called coronal mass ejections. These ejections can drive shocks that accelerate particles to high energies, often resulting in radio emission at low frequencies (<200 MHz). To date, the relationship between the expansion of coronal mass ejections, shocks and particle acceleration is not well understood, partially due to difficulties associated with radio imaging at low frequencies. Here, we report unique radio, whitelight and ultraviolet imaging of the second largest flare in the current solar cycle and associated very fast coronal mass ejection (~3000km/s). For the first time, we identify the location of a multitude of radio shock signatures, called herringbones, and find evidence for shock accelerated electron beams at multiple locations along an expanding coronal mass ejection, supporting theories of non-uniform, r...
Background: The detection of pathogens in complex sample backgrounds has been revolutionized by w... more Background: The detection of pathogens in complex sample backgrounds has been revolutionized by wide access to next-generation sequencing (NGS) platforms. However, analytical methods to support NGS platforms are not as uniformly available. Pathosphere (found at Pathosphere.org) is a cloud-based open-sourced community tool that allows for communication, collaboration and sharing of NGS analytical tools and data amongst scientists working in academia, industry and government. The architecture allows for users to upload data and run available bioinformatics pipelines without the need for onsite processing hardware or technical support. Results: The pathogen detection capabilities hosted on Pathosphere were tested by analyzing pathogen-containing samples sequenced by NGS with both spiked human samples as well as human and zoonotic host backgrounds. Pathosphere analytical pipelines developed by Edgewood Chemical Biological Center (ECBC) identified spiked pathogens within a common sample analyzed by 454, Ion Torrent, and Illumina sequencing platforms. ECBC pipelines also correctly identified pathogens in human samples containing arenavirus in addition to animal samples containing flavivirus and coronavirus. These analytical methods were limited in the detection of sequences with limited homology to previous annotations within NCBI databases, such as parvovirus. Utilizing the pipeline-hosting adaptability of Pathosphere, the analytical suite was supplemented by analytical pipelines designed by the United States Army Medical Research Insititute of Infectious Diseases and Walter Reed Army Institute of Research (USAMRIID-WRAIR). These pipelines were implemented and detected parvovirus sequence in the sample that the ECBC iterative analysis previously failed to identify. Conclusions: By accurately detecting pathogens in a variety of samples, this work demonstrates the utility of Pathosphere and provides a platform for utilizing, modifying and creating pipelines for a variety of NGS technologies developed to detect pathogens in complex sample backgrounds. These results serve as an exhibition for the existing pipelines and web-based interface of Pathosphere as well as the plug-in adaptability that allows for integration of newer NGS analytical software as it becomes available.
Geomagnetically induced currents (GICs) are a well-known terrestrial space weather hazard. They o... more Geomagnetically induced currents (GICs) are a well-known terrestrial space weather hazard. They occur in power transmission networks and are known to have adverse effects in both high-latitude and midlatitude countries. Here we study GICs in the Irish power transmission network (geomagnetic latitude 54.7–58.5∘N) during five geomagnetic storms (6–7 March 2016, 20–21 December 2015, 17–18 March 2015, 29–31 October 2003, and 13–14 March 1989). We simulate electric fields using a plane wave method together with two ground resistivity models, one of which is derived from magnetotelluric measurements (magnetotelluric (MT) model). We then calculate GICs in the 220, 275, and 400 kV transmission network. During the largest of the storm periods studied, the peak electric field was calculated to be as large as 3.8 V km−1, with associated GICs of up to 23 A using our MT model. Using our homogenous resistivity model, those peak values were 1.46 V km−1 and 25.8 A. We find that three 400 and 275 kV...
Modern radio interferometers such as the LOw Frequency ARray (LOFAR) are capable of producing dat... more Modern radio interferometers such as the LOw Frequency ARray (LOFAR) are capable of producing data at hundreds of gigabits to terabits per second. This high data rate makes the analysis of radio data cumbersome and computationally expensive. While high performance computing facilities exist for large national and international facilities, that may not be the case for instruments operated by a single institution or a small consortium. Data rates for next generation radio telescopes are set to eclipse those currently in operation, hence local processing of data will become all the more important. Here, we introduce the REAL-time Transient Acquisition backend (REALTA), a computing backend at the Irish LOFAR station (I-LOFAR) which facilitates the recording of data in near real-time and post-processing. We also present first searches and scientific results of a number of radio phenomena observed by I-LOFAR and REALTA, including pulsars, fast radio bursts, rotating radio transients, the ...
Experimental study of the phase and amplitude observations of sub-ionospheric very low and low fr... more Experimental study of the phase and amplitude observations of sub-ionospheric very low and low frequency signals is performed to analyze the response of the lower ionosphere during the August 21, 2017 total solar eclipse in the United States of America. Three subionospheric wave paths have been investigated. The length of the paths varied from 2200 to 6500 km, signal frequencies were 21.4 kHz, 25.2 kHz and 40.8 kHz. Two paths crossed the region of total eclipse and the third path was in the region of 40-60% of obscuration. None of the signals revealed any noticeable amplitude changes during the eclipse while negative phase anomalies (from-35° to-95°) were detected for all three paths. It was shown that the effective reflection height of the ionosphere in low and middle latitudes has been increased by 3.5-5 km during the eclipse.
Surface electric fields and geomagnetically induced currents (GIC) were simulated in the Irish po... more Surface electric fields and geomagnetically induced currents (GIC) were simulated in the Irish power network for five geomagnetic events. • A multi-layered resistivity model to a depth of 200 km was made using magnetotelluric measurements for use in GIC simulations in Ireland. • GICs have been replicated for Kp6 and Kp7 storms, and predicted for Kp9 storms in Ireland.
Monitoring and Modelling Geomagnetic Storms in Ireland
<p>Poster given at ESWW11 in Liege.</p> <p> </p> <p>November 2014&l... more <p>Poster given at ESWW11 in Liege.</p> <p> </p> <p>November 2014</p
Solubility of Mo 6 S 4.5 I 4.5 Nanowires in Common Solvents: A Sedimentation Study
The Journal of Physical Chemistry B, 2005
Due to their ease of fabrication and monodisperse, metallic nature, molybdenum-sulfur-iodine nano... more Due to their ease of fabrication and monodisperse, metallic nature, molybdenum-sulfur-iodine nanowires are an interesting alternative to carbon nanotubes for some applications. However very little is known about the solubility of these materials. In this work we have investigated the solubility of Mo(6)S(4.5)I(4.5) nanowire soot in a range of common solvents by performing sedimentation studies and microscopic and spectroscopic characterization. A sedimentation equation was derived showing that the concentration of any insoluble dispersed phase decreases exponentially with time. We find that in all solvents, Mo(6)S(4.5)I(4.5) nanowire soot contains three phases, two of which are insoluble with one stable phase. Microscopy and spectroscopy show that the first insoluble phase is associated mainly with spherical impurities and sediments rapidly out of solution resulting in purification. The second phase appears to consist of insoluble nanowire bundles and sediments more slowly, eventually leaving a stable dispersion of nanowire bundles. The stably dispersed bundles tend to be smaller than their insoluble counterparts. The best solvents studied were 2-propanol and dimethylformamide. Microscopy studies showed that, in the case of 2-propanol, sonication significantly reduced the bundle size relative to the unsonicated bulk. However, during sedimentation, large quantities of bundles were observed to reaggregate to form larger bundles which subsequently sedimented out of solution. In general, the sedimentation properties of the various phases did not vary significantly with concentration indicating that the insoluble nanowires are intrinsically insoluble. However, the diameter of the stably dispersed bundles decreased with concentration, until very small bundles consisting of only two or three nanowires were observed at concentrations below 0.003 mg/mL. In addition, stable composite dispersions were produced by mixing the nanowires with poly(vinylpyrrolidone) in 2-propanol opening the way for the formation of polymer/inorganic nanowire composites.
Initial Irish light pollution measurements and a new Sky Quality Meter-based data logger
Lighting Research & Technology, 2014
In the Celtic Tiger years, Ireland underwent an explosive growth in housing and an increase in li... more In the Celtic Tiger years, Ireland underwent an explosive growth in housing and an increase in light pollution, nationally. We outline work undertaken towards the first ever ground-based survey of light pollution in the island of Ireland and illustrate this with some representative data taken between 2009 and the present. The aim of our work is to establish a database to serve as a reference to monitor future changes, to compare with in-orbit measurements, to study the potential impact on the environment and to permit the calculation of the effects of future changes in lighting usage and patterns. We also report the development of a microcontroller-based data-logging instrument based on a Unihedron Sky Quality Meter-LR detector, which can be used by amateurs or can serve as a stand-alone instrument for night-sky brightness surveys.
The Low Frequency Array (LOFAR) is an international radio telescope array, consisting of 38 stati... more The Low Frequency Array (LOFAR) is an international radio telescope array, consisting of 38 stations in the Netherlands and 14 international stations spread over Europe. Here we present an observation method to study the jovian decametric radio emissions from several LOFAR stations (here DE604, FR606 and IE613), at high temporal and spectral resolution. This method is based on prediction tools, such as radio emission simulations and probability maps, and data processing. We report an observation of Io-induced decametric emission from June 2021, and a first case study of the substructures that compose the macroscopic emissions (calledmillisecond bursts). The study of these bursts make it possible to determine the electron populations at the origin of these emissions. We then present several possible future avenues for study based on these observations. The methodology and study perspectives described in this paper can be applied to new observations of jovian radio emissions induced b...
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