The meteor radar response function: Theory and application to narrow beam MST radar

The meteor radar response function is an important tool for analyzing meteor backscatter observed by radar systems. We extend previous work on the development of the response function to include a non-uniform meteor ionization profile, provided by meteor ablation theory, in contrast to what has been assumed in the past. This has the advantage that the height distribution of meteors expected to be observed by a radar meteor system may be accurately modeled. Such modeling leads to meteor height distributions that have implications for the composition of those meteoroids ablating at high altitudes which may be observed by “non-traditional” meteor radars operating at MF/HF. The response function is then employed to investigate meteor backscatter observed by narrow beam MST radars which in recent years have been used increasingly to observe meteors.     

A Method for Determining the Coordinates of Meteor Shower Radiants from Meteor Radar Goniometric Data

We discuss a new method for measuring the coordinates of meteor shower radiants from meteor radar data. The method uses a high accuracy of radar goniometer measurements of one of the angular coordinates for meteor radiants and collective properties of incident meteor showers. It is based on a computer technology of searching for the coordinates of radiants using the intersections of meteor position lines on the celestial sphere and filtering nonrandom combinations of these intersections. The method allows the following: to detect meteor showers with a rate of more than 5 per day of observations and to separate meteor groups from different meteor showers with different radiants and velocities. The method makes it possible to increase the angular resolution from 10° × 10° achieved with a quasi-tomographic technique to 2° × 2°, with a prospect of a further increase in the accuracy through the individual reduction of separated meteor groups. We use the reduction of one-day-long observations during maximum activity of the Geminids meteor shower in 1993 to illustrate the potentialities of the method. We show an example of detecting a weak meteor shower that was active during December 1993.     

The Composition of the Y2K Meteor

During the Leonid meteor shower of November 1999 a very bright meteor train, subsequently called the Y2K meteor, was observed. Analysis of the trajectory of the meteor suggests that it was composed of two distinct materials. The bulk of the meteor was composed of a comet-like material, while a much smaller fraction was of a denser carbonaceous material. A simple model is used to analytically determine the mass of the meteor fragments. This revised version was published online in July 2006 with corrections to the Cover Date.     

Determining the influx rate of meteoric material to the Earth based on measurements with a patrol TV camera from a single station

We propose a technique for reducing the number of meteors observed at a single ground-based station to estimate the influx rate of meteoric material to the Earth (MAI—meteor activity index). We derive a formula that allows the meteor activity to be objectively estimated from the results of meteor detection by assuming that each meteor belongs to a stream with a uniform spatial particle distribution. As an example, we give meteor activity estimates obtained from the results of meteor detection by a patrol TV camera located at a single station.     

Methods and statistics of TV observations of telescopic meteors

A review of TV and telescopic methods of meteor observations and of the problems of meteor astronomy addressed using these methods is presented. A meteor patrol developed at the Astronomical Observatory of Odessa National University and based on a Schmidt telescope and a TV detector is described. The meteor patrol allows meteor events to be recorded with a time resolution of 0.04 s. The investigated characteristics of the patrol are reported, and some aspects of the methods of observations and reduction employed are considered. The results of observations made during the period 2003–2004 are reported. A total of 368 meteors were recorded on 1093 individual frames during a total patrol time of 679 hours within a 36′ × 48′ field of view. The statistical data for meteor observations are reported, and classification of meteor images is presented. The specific features of some recorded meteor events are analyzed.     

A low cost meteor observation system using radio forward scattering and the interferometry technique

We present a low cost meteor observation system based on the radio forward scattering and interferometry technique at Kochi University of Technology (KUT). The system can be a suitable model for low budget educational institutes that target practical learning of astronomical objects and upper atmospheric characteristics. The system methodology for the automatic counting of meteor echoes, filtering noise and detecting meteor echo directions is described. Detection of the meteor echo directions, which is the basic element for determining the meteor trajectories and the orbital parameters of parent comets, is based on a software system developed for analysis of phase differences detected by interferometry. Randomly selected observation samples measured by the radio interferometer are compared to simultaneous optical observations by video cameras to verify the system accuracy. Preliminary error analysis revealed that the system accuracy is directly related to the duration of observed meteor echoes. Eighty percent of meteor echo samples with durations longer than 3 s showed agreement in azimuth and elevation angles measurements to within a 10° error range, while meteor echo samples with shorter durations showed lower agreement levels probably due to the low system sampling resolution of 0.1 s. The reasonable agreement level of meteor echoes with duration longer than 3 s demonstrated the applicability of the system methodology. Accurate observation of shorter duration meteor echoes could possibly be achieved by improving the system resolution.     

Development of an Automatic Echo-counting Program for HROFFT Spectrograms

Radio meteor observations by Ham-band beacon or FM radio broadcasts using “Ham-band Radio meteor Observation Fast Fourier Transform” (HROFFT) an automatic operating software have been performed widely in recent days. Previously, counting of meteor echoes on the spectrograms of radio meteor observation was performed manually by observers. In the present paper, we introduce an automatic meteor echo counting software application. Although output images of the HROFFT contain both the features of meteor echoes and those of various types of noises, a newly developed image processing technique has been applied, resulting in software that enables a useful auto-counting tool. There exists a slight error in the processing on spectrograms when the observation site is affected by many disturbing noises. Nevertheless, comparison between software and manual counting revealed an agreement of almost 90%. Therefore, we can easily obtain a dataset of detection time, duration time, signal strength, and Doppler shift of each meteor echo from the HROFFT spectrograms. Using this software, statistical analyses of meteor activities is based on the results obtained at many Ham-band Radio meteor Observation (HRO) sites throughout the world, resulting in a very useful “standard” for monitoring meteor stream activities in real time.     

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.     

A synthetical index of the potential threats about intense activities of meteors

In the present age, several techniques for the application to the observation of meteors and meteor showers have been developed in modern meteor astronomy. The initial definition for a meteor storm based on the visual observation with a Zenithal Hourly Rate of above 1000 seems insufficient now, since it only means a storm or burst of meteors in numbers and means that an eyewitness could have a chance to see a spectacular meteor show. Up to now, peoples have also recorded the meteoric flashes on the Moon during the Leonid meteor showers. Especially, the increasing activities of mankind in space for scientific, commercial and military purposes, have led to an increase in the problems concerning the safety of the satellites, space stations and astronauts. How the intense activity of a meteor storm is defined and forecast, some new points of view are needed. In this paper, several aspects about the intensity of the meteor storm are analyzed, including the number, mass, impulse, energy, electric charge, different purposes and different physical meanings. Finally, a synthetical index denoting the activity and potential threat of an intense meteor shower is suggested.     

Orthos' meteor showers

Probably the majority of meteor showers has a cometary origin. Investigation of Near-Earth asteroids' orbital evolution to determine whether they have related meteor showers are necessary to determine which asteroids evolved from comets. The results of calculations show that asteroid Orthos' orbit is an octuple Earth-crosser. Therefore, if Orthos has an old meteoroid stream it may produce eight meteor showers observable on the Earth. The existence of four Orthos' Northern meteor showers is confirmed by our search in the published catalogues of meteor radiants and orbits or in the archives of the IAU Meteor Data Center (Lund, Sweden).     

Is 2329 Orthos a dead comet?

Probably most meteor showers have a cometary origin. Investigation of Near-Earth asteroids' orbital evolution to determine whether they have related meteor showers is necessary to determine which asteroids evolved from comets. The results of calculations show that asteroid Orthos' orbit is an octuple Earth-crosser. Therefore, if Orthos has an old meteoroid stream it may produce eight meteor showers observable on the Earth. The existence of four Orthos' Northern meteor showers is confirmed by our search in the published catalogues of meteor radiants and orbits or in the archives of the IAU Meteor Data Center (Lund, Sweden).     

基于嵌入式人工智能设备的流星光学监测系统

流星光学监测网是定位陨石和观测火流星的基础科研设施. 流星光学监测系统利用光学相机高速采集天空图像, 使用嵌入式系统实时处理数据, 能够快速识别流星并获取流星位置和陨石落点信息, 是构成流星监测网的关键仪器. 为提高流星光学监测系统获取信息的实时性及准确性, 提出了一种基于嵌入式人工智能设备的流星光学监测系统. 该系统由软件及硬件部分组成: 硬件部分包括观测设备(商用高空抛物摄像头)以及数据处理设备(嵌入式人工智能设备); 软件部分运行于数据处理设备内, 主要包括控制界面模块、流星监测模块、数据管理模块. 实际工作时, 摄像头采集天空视频信息, 流星监测模块从视频流中实时监测流星并存储包含流星视频的数据, 数据管理模块将流星位置信息实时传回数据中心用于预警. 观测结束后, 将原始观测数据同步至数据中心用于后续科学研究. 在整个系统中, 流星监测模块决定了整个监测系统的实时性及准确性. 该系统采用嵌入式人工智能设备与人工智能算法结合的方法构建流星监测模块. 通过使用实测数据对搭载监测模块性能进行测试, 结果表明: 流星监测模块能够达到0.28%的低误检率以及100%的召回率, 且数据处理速度达到了Mobilenetv2的8倍. 进一步将包含监测模块的整个流星光学监测系统部署于太原理工大学-张壁古堡远程天文台, 通过实测表明流星光学监测系统实用中能达到100%的召回率和较低的误检率.     

Is 2329 Orthos a dead comet?

Probably most meteor showers have a cometary origin. Investigation of Near-Earth asteroids' orbital evolution to determine whether they have related meteor showers is necessary to determine which asteroids evolved from comets. The results of calculations show that asteroid Orthos' orbit is an octuple Earth-crosser. Therefore, if Orthos has an old meteoroid stream it may produce eight meteor showers observable on the Earth. The existence of four Orthos' Northern meteor showers is confirmed by our search in the published catalogues of meteor radiants and orbits or in the archives of the IAU Meteor Data Center (Lund, Sweden).     

Techniques for positional measurements of telescopic meteor TV images

We present the results of our positional reduction of the observational material obtained using a meteor patrol based on a Schmidt telescope and a TV CCD detector. More that 1000 telescopic meteors were recorded in three years of meteor patrolling. Techniques for the cataloging and positional reduction of 3050 TV images with meteor trails are described. We have developed a technique for measuring the images of reference stars to determine the rectangular coordinates in the image frame. We discuss the achieved accuracy of determining the equatorial coordinates of reference and check stars by Turner’s method (of the order of a few arcseconds). We have developed software that allows the rectangular coordinates of meteor trajectory points to be determined after the meteor image reduction. These coordinates are used to determine the equatorial coordinates of the poles of the great circles of meteor trajectories (the angular length is not less than 15′ with an accuracy of at least 4′. We consider the possibility of using Stanyukovich’s method to determine the equatorial coordinates of radiants for non-basis meteor observations. The accuracy of determining the radiant coordinates has been estimated to be 4′–5′. Prospects for obtaining the kinematic characteristics of meteor particles are discussed.     

A method for the determination of meteor stream membership based on the results of the single-station television observations used at INASAN

Massive television observations of meteors aimed at verifying the existing and finding new meteor streams create the task of the reliable preliminary determination of the detected meteor membership in a particular known stream. The mostly widely used method of meteor identification is connected with the estimation of the distance between the great circle of the meteor and the point of the examined radiant. Often observers perform this estimation without checking the possibility that the same meteor belongs to another stream. When several streams occur simultaneously, many meteors can be members of two or more streams. When the determination of the meteor membership is done in a subjective way, it may lead to an overestimation of strong streams’ and an underestimation of weak streams’ activity. In this work, we describe a method and algorithm for the determination of the meteor membership in known streams which were tested using real television observations and were successfully used at INASAN. This algorithm is almost completely automatic and allows for the obtainment of additional information regarding meteor streams. We also show some results of the processing of 2254 meteors observations obtained with the FAVOR camera from July 31, 2006 to October 21, 2006 using the proposed method. The work is part of the program for the creation of the Verified Catalogue of Meteor Streams.     

Meteor stream activity. III. Measurement of the first in a new series of Leonid outburst

Abstract— In 1994 November, a shower of bright Leonid meteors signaled what is likely the first meteor outburst of Leonids associated with the upcoming return of comet P/Tempel-Tuttle to perihelion. Measurements of meteor activity and the meteor brightness distribution are presented. By comparing the present observation with those of past Leonid returns, a forecast is made of the time, the duration, the intensity, and the mean meteor brightness of Leonid outbursts that may occur if previously observed patterns are repeated in the forthcoming years.     

Periodic Variability of Visual Sporadic Meteor Rates

A long-term variability of visual sporadic meteor hourly rates is studied in the period between 1984 and 2006. The present analysis involves four particular periods of visual sporadic meteor activity in January, March, July and September over two solar cycles, and the results reveal that the observed visual sporadic meteor rates vary periodically in the course of the solar cycle. It is found that the highest sporadic meteor rates are observed in the years near solar activity maxima, and their variability directly correlates with solar activity expressed by International sunspot numbers.     

Associations of Meteor Microshowers or as the Kazan Radar “SEES” Radiants on Northern Celestial Hemisphere

The discrete quasitomographic method of the analysis of the interferometric data of meteor radar gives us the possibility of measuring coordinates and velocities of very weak meteor showers with a 2 × 2 square degree resolution on the celestial sphere. The minimal rate of the meteors in each microstream is five meteors per day. At such sensitivity, basic distinctions between irregularities of the sporadic background and meteor streams vanish. More than 1000 of the detected microshowers per month are associated with a combination of (a) the large known meteor showers, (b) the weaker known meteor showers and (c) till now unknown associations of microshowers. All microshowers regardless of association have the identical velocities, limited areas of radiation and near simultaneity of their acting dates. The results are compiled as maps of radiant distribution and average velocities of microstreams for different months. From these it is possible to see how the microshower activity for various discrete sites on the celestial sphere correlate with the behavior of the well-known meteor streams and thus to infer the orbital properties of the different microstream configurations.     

Observations of the 2001 Leonid meteor shower using VHF meteor radar

Every year the Earth crosses or passes near one of the dust trails left by Comet 55P/Tempel-Tuttle in its pass through the Solar System every 33.2 years. This produces a meteor shower Commonly called the Leonid. The 2001 Leonid meteor shower is one of the strongest in recent years. We present observations made by the 50 MHz all-sky meteor radar located at the Platteville Atmospheric Observatory in Colorado (40° N, 105° W). The spatial and temporal distributions of the meteor activity detected by the radar during the 2001 Leonid shower differs from the observed sporadic activity detected by VHF radars. Estimation of the radiant flux of the meteor shower of the shower by a well-known methodology is presented, and the intensity of the phenomena is discussed.