Meteor Tracks Research Articles

Neural Network Based Approach to Recognition of Meteor Tracks in the Mini-EUSO Telescope Data

Mini-EUSO is a wide-angle fluorescence telescope that registers ultraviolet (UV) radiation in the nocturnal atmosphere of Earth from the International Space Station. Meteors are among multiple phenomena that manifest themselves not only in the visible range but also in the UV. We present two simple artificial neural networks that allow for recognizing meteor signals in the Mini-EUSO data with high accuracy in terms of a binary classification problem. We expect that similar architectures can be effectively used for signal recognition in other fluorescence telescopes, regardless of the nature of the signal. Due to their simplicity, the networks can be implemented in onboard electronics of future orbital or balloon experiments.

Physical bases of meteor registration methods and the instrument complex of the NKU Observatory

One of the actual directions of studying the physical characteristics of near–Earth space is the assessment of the concentration of meteoroids in it, and the time change of this parameter. In this regard, the principles of setting and implementing meteor observations at the observatory of the North Kazakhstan university named after Manash Kozybayev are considered in chronological order. Meteor observations were carried out on the basis of an integrated approach, including the use of meteor patrols, an All Sky camera, a system for recording radio wave reflections from a remote station from meteor tracks, and a camera based on an optical image intensifier.  Based on the analysis of the practical experience of using this equipment, the advantages and disadvantages of each of the methods of meteor registration are revealed. It is shown that the use of the latest image brightness amplifiers and wide–angle cameras with the highest possible sensor sensitivity is the most progressive for their optical observations. The closest attention is paid to the analysis of the experience of implementing the registration of plasma meteor tracks in the radio range. The method is based on the selection of reflected (scattered) musical–speech signals of a remote radio station having a specific pulse structure. Comparison of the obtained results on the frequency of meteor phenomena with the data of known observation points allows us to speak about the effective operation of the newly created meteor monitoring system in the radio range. In the final part of the work, ways to improve the efficiency of recording meteor phenomena in the optical range based on the use of the latest radiation receivers are considered.

Scientific goals of optical instruments of the National Heliogeophysical Complex

Studies of the upper atmosphere have to be performed using optical photometric and spectrometric means. Modern devices allow precise photometry of the glow of the night atmosphere — airglow — with high temporal spatial and spectral resolution. As a result, the obtained airglow parameters make it possible to determine the physicochemical properties of the upper atmosphere and observe their variation under the influence of various factors. The National Heliogeophysical Complex, which is being created in Eastern Siberia, is therefore to include a certain set of modern optical instruments. The paper presents the main phenomena that will be investigated by the optical instruments of the complex, provides information on their composition and scientific goals, presents the results of preliminary studies performed using a prototype of the instruments. As a result of the studies, the presence of a significant (about 10 m/sec) vertical wind at various altitudes (100 and 250 km) was established, the importance of taking into account the vertical wind to study the vertical dynamics of the charged component was demonstrated. The long-term dynamics of the vertical wind at an altitude of about 100 km has a pronounced seasonal variations and the absence of diurnal variations, whereas the dynamics of the vertical wind at an altitude of 250 km has a pronounced diurnal variations, which is mostly clearly defined in winter. This suggests the presumed presence of vertical circulation cells at various altitude levels. The possibilities of optical stereoscopy and differential image analysis methods are demonstrated, as applied to the study of fast luminous formations and conducting active ground and space experiments to modify Earth's ionosphere. We report the results of the determination of a three-dimensional picture of a long-lived meteor track with the use of two wide-angle cameras. We propose an algorithm that allows us to get a stereo image of events occurring in the upper atmosphere, recorded simultaneously from different observation points. The joint work of the tools of this complex and the development of cooperation with third-party organizations are shown to be a good enough direction for further study of the vertical dynamics of Earth’s upper atmosphere and space weather phenomena.

Научные задачи оптических инструментов Национального гелиогеофизического комплекса

Studies of the upper atmosphere have to be performed using optical photometric and spectrometric means. Modern devices allow precise photometry of the glow of the night atmosphere — airglow — with high temporal spatial and spectral resolution. As a result, the obtained airglow parameters make it possible to determine the physicochemical properties of the upper atmosphere and observe their variation under the influence of various factors. The National Heliogeophysical Complex, which is being created in Eastern Siberia, is therefore to include a certain set of modern optical instruments. The paper presents the main phenomena that will be investigated by the optical instruments of the complex, provides information on their composition and scientific goals, presents the results of preliminary studies performed using a prototype of the instruments. As a result of the studies, the presence of a significant (about 10 m/sec) vertical wind at various altitudes (100 and 250 km) was established, the importance of taking into account the vertical wind to study the vertical dynamics of the charged component was demonstrated. The long-term dynamics of the vertical wind at an altitude of about 100 km has a pronounced seasonal variations and the absence of diurnal variations, whereas the dynamics of the vertical wind at an altitude of 250 km has a pronounced diurnal variations, which is mostly clearly defined in winter. This suggests the presumed presence of vertical circulation cells at various altitude levels. The possibilities of optical stereoscopy and differential image analysis methods are demonstrated, as applied to the study of fast luminous formations and conducting active ground and space experiments to modify Earth's ionosphere. We report the results of the determination of a three-dimensional picture of a long-lived meteor track with the use of two wide-angle cameras. We propose an algorithm that allows us to get a stereo image of events occurring in the upper atmosphere, recorded simultaneously from different observation points. The joint work of the tools of this complex and the development of cooperation with third-party organizations are shown to be a good enough direction for further study of the vertical dynamics of Earth’s upper atmosphere and space weather phenomena.

Experience of registration of reflection of radio signals from plasma meteor tracks in the observatory of SKSU

One of the actual problems of astrophysical studies of The solar system bodies is the registration of meteor phenomena occurring in the upper layers of The earth’s atmosphere. Statistics of such events allow to obtain averaged estimates of the concentration of meteoroids in near-earth space. These data have an important practical application on the security of space infrastructure development. In this paper, it is shown that optical methods of meteor registration, despite their diversity, suffer from limitations associated with the influence of atmospheric meteorology, daylight and anthropogenic illumination of the sky. In this regard, the transition to the use of methods of registration of meteors based on the property of formed or plasma tracks to reflect radio waves is relevant.The results of work on the development of the material base and methods of radio observations of meteors in the center of astrophysical research of North Kazakhstan state University are presented. The approach of registration of the radio signal reflected from the plasma meteor track of the remote station is applied. Information processing was carried out online using standard software. Comparison of the obtained results with the published data on the application of the method showed a high degree of similarity of the amplitude-time structure of the signal with typical for the applied method. The daily frequency distribution of meteor events is also quite realistic. Thus, we can state the creation in the Republic of Kazakhstan of the first point for registration of meteors in the radio range.

Selected catalog of highly eccentric orbits of meteoroids from archived data of radio observations of faint meteors in Kharkiv, Ukraine

Full Kharkiv archival data from 1972 to 1978 have a volume of almost 250 thousand meteor orbits. Of these, we used a sample of sporadic meteoroids with a volume of 159319 orbits. We selected 214 meteor orbits with the aphelia exceeding 100 AU. The greatest aphelion distance for them was 1997.7 (near 2000) AU. At the same time, meteoroids in these orbits invaded the Earth’s atmosphere and burned, creating ionized meteor tracks. The sensitivity of the Kharkiv orbital radar made it possible to record radio meteors up to +12 ​M from meteoroids in the mass range 10−3-10−6 g. Thus, the selected catalog of 214 meteor orbits represents a kind of toolkit for testing remote areas of the Solar system associated with objects called sednoids. The selected catalog of 214 highly eccentric orbits of weak radio meteors up to +12 ​M is presented in the form of tables with a description of the data. Distributions by various parameters for 214 orbits and 159319 orbits are given.The mapping of the annual cycle of observations may be obtained across a catalog of 6743 sporadic meteor orbits, which were published by Voloshchuk, Kolomiyets, and Cherkas in 2018. It is planned to transfer the Kharkiv archived meteor radar data to the IAU Meteor Data Center using experience of transferring archived data of radio observations of past years, received at the Hissar Observatory in Tajikistan which was published by Narziev in 2018.

Advances in the meteor image processing chain using fast algorithms, deep learning, and empirical fitting

The processing pipeline for both video meteor detection and track analysis has evolved to embrace several new algorithms, which have improved the efficiency and performance of various steps in the meteor image processing chain. With the advent of larger pixel count digital sensors, the image processing techniques have needed to keep up with the computational load by not only employing higher end processors, but developing faster thresholding, clustering, and tracking algorithms for detection. In addition, machine learning methods employing both recurrent and convolutional deep neural networks have helped remove the human-in-loop false alarm mitigation step inherent in many meteor collection processing streams. The application of a matched filtering algorithm has helped to refine the measurement positional accuracy of propagating meteor tracks for post-detection analysis. The use of improved multi-site track aggregation has dramatically reduced the occurrence of mis-associating unrelated tracks during the combination into a single trajectory. When coupled with an improved minimization metric in the multi-parameter fitting method for trajectory estimation, this yields better meteor orbital solutions. Finally, proposed concepts in using a convolutional neural network as a meteor detector and performing trajectory fitting with an empirically based propagation model, show promise for more robust meteor image processing and analysis in the near future.

Deep Learning Algorithms Applied to the Classification of Video Meteor Detections

Abstract The application of a class of advanced machine learning techniques, namely deep learning, has been applied to automating the confirmation/classification of potential meteor tracks in video imagery. Deep learning is shown to perform remarkably well, even surpassing human performance, and will likely supplant the need for human visual inspection and review of collected meteor imagery. When applied to time series measurements of meteor track centroid positions and integrated intensities obtained from each video frame, a recurrent neural network (RNN) has achieved 98.1 per cent recall, which is defined as the number of true meteors properly classified as meteors. The RNN allowed only 2.1 per cent leakage, defined herein as the number of false positives that were incorrectly identified as meteors. The desire is to maximize recall to avoid missed orbit estimations, while also minimizing false alarms leaking through to the next processing stage of multi-site trajectory and orbit estimation. When two-dimensional spatial imagery is available or the temporal image sequence can be reconstructed, these results climb to 99.94 per cent recall and only 0.4 per cent leakage when employing a convolutional neural network (CNN). This has been further generalized from a baseline of interleaved analog video to modern progressive scan digital imagery with equivalent results. The trained CNN, nicknamed MeteorNet, will be used for post-detection automated screening of potential meteor tracks and explored in the future as a potential upstream meteor detector.

Fast meteor tracking in noisy video sequences

AbstractMeteor recording, detection, and analysis is one of the traditional topics of astronomy. This paper deals with fast‐tracking of faint meteors and meteor showers in video sequences with high frame rates. Since meteors are fast optical events, the utilization of cameras with high frame rates and short exposure times is the standard technique of meteor tracks capture. Low efficiency of such camera systems is typically compensated with image intensifiers, mostly based on the microchannel plate (MCP). In this work, we use image data captured with the meteor automatic imager and analyzer, double‐station system dedicated for observing faint meteor showers. The system works with minimal human interaction, and it is necessary to automatically process (i.e., identify all meteor candidates) all captured data as fast as possible. Results show possible speed‐up of the image processing method when fluctuations of MCP are reduced.

Linear feature detection algorithm for astronomical surveys – II. Defocusing effects on meteor tracks

Given the current limited knowledge of meteor plasma micro-physics and its interaction with the surrounding atmosphere and ionosphere, meteors are a highly interesting observational target for high-resolution wide-field astronomical surveys. Such surveys are capable of resolving the physical size of meteor plasma heads, but they produce large volumes of images that need to be automatically inspected for possible existence of long linear features produced by meteors. Here we show how big aperture sky survey telescopes detect meteors as defocused tracks with a central brightness depression. We derive an analytic expression for a defocused point source meteor track and use it to calculate brightness profiles of meteors modeled as uniform brightness disks. We apply our modeling to meteor images as seen by the SDSS and LSST telescopes. The expression is validated by Monte Carlo ray-tracing simulations of photons traveling through the atmosphere and the LSST telescope optics. We show that estimates of the meteor distance and size can be extracted from the measured FWHM and the strength of the central dip in the observed brightness profile. However, this extraction becomes difficult when the defocused meteor track is distorted by the atmospheric seeing or contaminated by a long lasting glowing meteor trail. The FWHM of satellites tracks is distinctly narrower than meteor values, which enables removal of a possible confusion between satellites and meteors.

The Method of Measurements of Celestial Coordinates in Wide-Field TV-Frames

We present a method for calculations of equatorial coordinates of any point in the single frame of the wide-field TV systems. This method can be applying for the different television systems [wide-field cameras, all-sky cameras, the cameras with the hybrid TV-system (the system with coupled of the Image Intensifier) et al.]. In that system the calculations of distortions are difficult. Therefore, we devised this method which helps decrease errors (due to distortion and the electro-optical system).The method can be used for measuring of equatorial coordinates of meteor tracks under difficult conditions during the observations such as partial cloudiness, small number of stars and large distortions of the coordinate grid in the frame. These restrictions cannot be overcome by other methods. In the case of the small number of stars the present method using of the reference stars received on a series of frames during the observation period. The accuracy of the method has been estimated to be 4′–8′ (for cameras with fov 50° × 40° at the CCD 720 × 576 pixels) for maximum number of reference points in the frame. The method used 3 reference points for calculation of the equatorial coordinates of the object. One can use this method if the camera was re-oriented as well. We use this method for our wide field of view cameras.

The calculation of meteor motion parameters based on the single station TV observations

Recently, television observations of meteors have steadily replaced photographic observations. Television recording with short exposures is a close analog of a photographic survey with a rotary shutter in the form of a system of set time marks on the meteor track. Each meteoric event is a series of recordings of separate phases of the motion of a meteor. This allows for the use of the geometric method for the determination of the motion parameters of meteors. In this work, a critique is given regarding the concept proposed by K.P. Stanyukovich in 1932–1939, and a mathematical justification of the geometric method of the analysis of the television images of meteors is given.

The Churchill kimberlite field, Nunavut, Canada: petrography, mineral chemistry, and geochronology

Seventy-nine kimberlite intrusions have been identified in the Churchill Province, Nunavut, the result of an aggressive diamond exploration program by Shear Minerals Ltd. and their partners. This is one of Canada’s newest and largest kimberlite districts, situated immediately west of Hudson Bay between the communities of Rankin Inlet and Chesterfield Inlet. This study documents the occurrence of bonafide kimberlite rocks, classified as mainly sparsely macrocrystic, oxide-rich calcite evolved hypabyssal kimberlite and macrocrystic oxide-rich monticellite phlogopite hypabyssal kimberlite. Electron microprobe analyses of olivine, phlogopite, spinel, and perovskite support this petrographical classification. Low 87Sr/86Sr isotopic compositions determined from perovskite indicate a group I affinity. In addition, 27 precise U–Pb perovskite and Rb–Sr phlogopite emplacement ages have been determined for the Churchill kimberlites, indicating that magmatism spans ∼45 million years (225–170 Ma). The Churchill kimberlites belong to the NW–SE-trending corridor of Jurassic–Triassic kimberlite magmatism in eastern North America, which includes the Kirkland Lake, Timiskaming, and Attawapiskat kimberlite fields. Churchill kimberlites extend this corridor ∼800 km northwest, suggesting that the corridor may continue northwest with older kimberlites. This corridor is interpreted as the continental expression of magmatism linked to either a single or multiple mantle-plume hotspot track(s), a pattern geographically coincident with independent estimates for the timing and location of the continental extension of both the Great Meteor and Verde hotspot tracks.

Algorithms and Software for Meteor Detection

An ever increasing variety of electronic instrumentation is being brought to bear in meteor studies and analysis, with unique meteor detection challenges arising from the attempt to do automated and near real-time processing of the imagery. Recent algorithm developments in the literature have been applied and implemented in software to provide reliable meteor detection in all-sky imagers, wide-field intensified video, and narrow field-of-view telescopic systems. The algorithms that have been employed for meteor streak detection include Hough transforms with phase coded disk, localized Hough transforms with matched filtering, and fast moving cluster detection. They have found application in identifying meteor tracks in the Spanish Fireball Network all-sky images, detailed analysis of video recordings during the recent Leonid meteor storms, and development of a detection/cueing technology system for rapid slew and tracking of meteors.

Lithospheric variations across the Superior Province, Ontario, Canada: Evidence from tomography and shear wave splitting

The Superior Province of the Canadian Shield is the largest contiguous region of the Archean crust. A combination of data from multiple experiments is used to obtain shear wave splitting parameters and a three‐dimensional tomographic velocity model beneath a large portion of the Superior, corresponding approximately to the province of Ontario. Shear wave splits are obtained at 24 sites across the Superior, displaying strong (averaging 1.34 s) ENE‐WSW splitting at stations west of 86°W and weaker (0.67 s) E‐W splitting in the east. The fast direction is subparallel to both absolute plate motion and tectonic belt boundaries. The recovered tomographic velocity model shows a major boundary oriented NNW‐SSE, separating high velocities in the western Superior (WS) from low velocities in the east and coinciding with the divide between weak and strong shear wave splits. Other features include a 200‐km‐thick low‐velocity anomaly corresponding to the Nipigon Embayment, a 1.0‐Ga failed‐rift branch; and a linear low‐velocity anomaly in the east, attributed to the Great Meteor hot spot track. The Nipigon anomaly, in the western portion of the model, is probably in situ, while the Great Meteor track is displaced from crustal features associated with the hot spot. We interpret this displacement as evidence that the eastern lithosphere has been deformed by basal drag, while the western lithosphere has remained stable, and propose that the east‐west lithospheric boundary we have detected represents a change in mechanical properties, between stronger, higher velocity western material with consistent anisotropic fabric, and weaker eastern material with more variable fabric.

Temperature Changes in the Higher Atmosphere

UNTIL some years ago, it was generally thought that the temperature of the stratosphere was practically uniform, and of the order of 220° K. A radical change in such notions was first effected by Lmdemann and Dobson who, in 1922, from their study of meteor tracks, showed that the temperature at levels above 60 km. was even higher than that at ground-level. Their conclusions have been adequately confirmed recently in experiments on the anomalous propagation of acoustic waves, on the vertical distribution of ozone with height and, to some extent, by direct temperature measurements in high balloon ascents. There is, then, trustworthy evidence that solar radiation does not pass through the middle part of the atmosphere without warming it, so that we are led to examine, in this connexion, the evidence relating to still higher atmospheric levels, where such heating might be expected to be especially pronounced, since the solar radiation is there most intense and the thermal capacity of the transmission medium least.

The Meteors of April 20th

BETWEEN ten and twelve o'clock on the night of April 18th, Mr. W. L. Taylor, a member of the junior class in the State University, with several other gentlemen, observed an unusual number of shooting-stars. These gentlemen were returning in an open waggon from Ellettsville, eight miles north of Bloom-ington. No count was kept of the number of meteors observed, but the appearance was so frequent as to attract the attention of all the company. Mr. Taylor thinks the number noticed could not have been less than twelve or fifteen. From the descriptions given of the meteor tracks, I find that they were nearly conformable to the radiant of the Lyraids. The meteors were remarkably brilliant, apparently equal to stars of the first or second magnitude.

The British Association

REPORTS.Report of the Committee on Luminous Meteors, by Mr. James Glaisher.-The report related, as usual, to meteors doubly observed, and to aerolites, the portion having reference to the latter being the more interesting, as the falls of aërolites which have been placed on record since the last report were more than ordinarily numerous and interesting. A mass of meteoric iron fell on Aug. 24, 1873, at Maysville, California, and is one of the very few metallic irons the actual descent of which has been witnessed. In the following month a number of meteorites fell near Khairpur, in the Punjaub; and it is also related that in the month of December, when the British army halted on the banks of the Prah, an aërolite fell in the market-place of Coomassie, and was regarded by the native population as a portent of evil. On the 14th and 20th of May, 1874, aërolites fell at Castalia, in North Carolina. The last stone-fall of the past year took place near Iowa city on the 12th of February, 1875, and of this meteorite also special analyses were made in the United States, of which some unforeseen results were lately announced by their author, Mr. A. W. Wright. In England no detonating meteor has been observed this year; and the brightest meteor recorded since the last report occurred on the 1st of September last, taking its course over the north of England, or Scotland, where clouded skies must have prevailed, as its flash was like that of lightning. Other bright meteors occurred on the 2nd and 16th of September, 11th of October, 17th of December, 9th of March, 12th of April, and 2nd and 4th of May in this year. A meteor burst with a loud detonation over Paris and its neighbourhood on the 10th of February; it was of great size and brilliancy, and left a cloud-like streak of light on its track for more than half an hour. No duplicate observation of it was obtained in England. Another fireball fell at Orleans on the 9th of March, and of this two good observations appeared to have been obtained in England, which may assist to determine its real height. During the annual meteor showers of the past year very unfavourable weather generally prevailed for recording meteor tracks, and few meteors were seen on those nights when the usual expectations of their appearance were entertained. A thorough examination of all the observations collected by the committee since the publication of the Meteor Atlas in 1867, with the view of extending and correcting the list of general and occasional meteoric showers which it embraced, has been continued with satisfactory results I under the direction of Mr. Greg. The report also contained a résumé of the contents of the recent publications on the subject of meteoric astronomy. Mr. Glaisher remarked that the report was the result of considerable labour performed by Prof. A. S. Herschel, but he pointed out that the work of properly treating meteor observations had now become so great as to be beyond the power of the Association to grapple with, and alluded with satisfaction to the arrangements being carried out by M. Leverrier. A discussion took place on the connection of comets and meteors, in the course of which Sir William Thomson said that there was nothing to justify the assertion that the mass of comets was so small as was sometimes supposed, and he considered there was good evidence for believing that the comet's tail was really a train of meteors.