Radio Echo Observations of Meteors

Prentice, Jonah; Lovell, A. C. B.; Banwell, C. J.

doi:10.1093/mnras/107.2.155

Cited by 26 publications

(4 citation statements)

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“…The meteor striking the atmosphere generates a plasma, which acts as a reflector for an over the horizon analog TV transmitter at 55.25 MHz, illuminating the plasma line. This is in fact virtually identical to the methodology of studying meteor events using radar (Prentice et al 1947). Studies of reflections such as these provide information about the speed of the neutral wind in the mesosphere and lower thermosphere through the observed Doppler shift of the reflection (Obenberger et al 2014).…”

Section: Detection Of Meteor Transient As Proof Of Conceptmentioning

confidence: 86%

Interferometric Methods

2005

Shock Waves

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Future radio telescopes promise great advances in resolution and sensitivity. These include the Square Kilometer Array, a two array instrument, in South Africa and Australia. Similarly, the next generation Very Large Array (ngVLA) is being designed for construction in North America. These arrays all promise exceptional advances in sensitivity, angular resolution, and survey speed. The SKA and ngVLA are both specified to have sensitivities at the level of µJy's. The SKA-Low instrument will consist of a huge number of dipoles antennas in Australia which is pushing the bounds of current FX correlator technology with O(n 2 ) scaling, where n is the number of antennas. The design proposals for these instruments include a dense core of antennas, necessitating advances in imaging methods for these very dense cores versus more traditionally sparse instruments.Another ambitious experiment is the Hydrogen Epoch of Reionisation Array (HERA) in South Africa which hopes to make the first direct detection of the Epoch of Reionisation through the red-shifted H signal which is a factor of 10 5 smaller than the thermal-like noise.In this thesis, these problems are tackled by re-examining the underlying principles of interferometry. The first working example of a direct imaging correlator is presented which allows images to be formed directly from the voltages off each antenna in a dense array, without an expensive cross-correlation operation as is typically required. A detailed discussion is given of how standard steps in interferometric imaging differ in this new scheme, including calibration. Additionally the first wide field direct imaging correlator is presented, which allows the problems of non-coplanarity to be dealt with for both sparse and dense arrays in a very efficient manner on modern GPU compute hardware. These are, to the best of the authors knowledge, the only working implementations of a direct imaging correlator for generic arrays with no restrictions on the geometry of the array or homogeneity of constituent receiver elements. These new approaches have been published in the scientific literature as discussed in the Declaration.Moving on from this, the closure phase bispectrum is presented as a way of uncovering the cosmological Epoch of Reionisation signal from the H line. This is using the HERA telescope, which consists of a dense core of parabolic antennas in a highly redundant layout. A data iii reduction and processing pipeline for the HERA telescope is constructed and presented, for use with the bispectrum. Initial results towards a cosmologial limit are reported.The HERA telescope relies on redundancy in its antenna elements for its calibration and measurement strategy. The bispectrum with its unique mathematical propeties, in combination with forward modelling, is shown to be a potent tool for probing departures from the assumed reudundancy. It is shown, through this method, that HERA suffers significant directiondependent non-redundancies in the dataset used for our analysis, which are extremely difficul...

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Section: Detection Of Meteor Transient As Proof Of Conceptmentioning

confidence: 86%

Interferometric Methods

2005

Shock Waves

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“…The meteor striking the atmosphere generates a plasma, which acts as a reflector for an over the horizon analog TV transmitter at 55.25 MHz, illuminating the meteor plasma's path. This is almost identical to the methodology of studying meteor events through the use of radar (Prentice et al 1947). Studies of reflections such as these provide information about the speed of the neutral wind in the mesosphere and lower thermosphere through the observed Doppler shift of the reflection (Helmboldt et al 2014).…”

Section: Detection Of Meteor Transient As Proof Of Conceptmentioning

confidence: 90%

A real-time, all-sky, high time resolution, direct imager for the long wavelength array

Kent

Dowell

Beardsley

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The future of radio astronomy will require instruments with large collecting areas for higher sensitivity, wide fields of view for faster survey speeds, and efficient computing and data rates relative to current capabilities. We describe the first successful deployment of the E-field Parallel Imaging Correlator (EPIC) on the LWA station in Sevilleta, New Mexico, USA (LWA-SV). EPIC is a solution to the computational problem of large interferometers. By gridding and spatially Fourier transforming channelised electric fields from the antennas in real-time, EPIC removes the explicit cross multiplication of all pairs of antenna voltages to synthesize an aperture, reducing the computational scaling from O(n 2 a ) to O(n g log 2 n g ), where n a is the number of antennas and n g is the number of grid points. Not only does this save computational costs for dense arrays but it produces very high time resolution images in real time. The GPU-based implementation uses existing LWA-SV hardware and the high performance streaming framework, Bifrost. We examine the practical details of the EPIC deployment and verify the imaging performance by detecting a meteor impact on the atmosphere using continuous all-sky imaging at 50 ms time resolution.

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“…After leaving TRE Banwell helped Bernard Lovell establish a radar meteor observatory at Jodrell Bank (Prentice et al, 1947;Lovell, 1990) (It is interesting that Lovell's earlier history of Jodrell Bank (Lovell, 1968) makes no mention of Banwell). When he returned to NZ Banwell very successfully changed his research field to geophysics, studying the heat flow and related physics of the Wairakei geothermal field.…”

Section: Post-war Scientific Uses Of Radarmentioning

confidence: 99%

The antecedents and subsequent development of scientific radar in New Zealand

Fraser

2005

Journal of Atmospheric and Solar-Terrestrial Physics

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Radio Echo Observations of Meteors

Cited by 26 publications

References 0 publications

Interferometric Methods

Interferometric Methods

A real-time, all-sky, high time resolution, direct imager for the long wavelength array

The antecedents and subsequent development of scientific radar in New Zealand

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