Meteor Observations Research Articles

Investigation of solar cycle dependence of the tides in the low latitude MLT using meteor radar observations

Solar cycle dependence of the dominant tides, i.e. diurnal and semidiurnal components in the mesosphere and lower thermosphere (MLT) is investigated from a Southern hemispheric low-latitude station, Cachoeira Paulista (22.7oS, 45oW) using long-term meteor wind observations (1999–2018). Although the long-term variations of the tides in aggregate do not show any significant relationship with the solar activity, the individual seasonal profiles reveal appreciable correlation in equinoxes with maximum in fall and no evident correlation in summer. The diurnal tide seasonal profiles show negative correlation with the solar activity and the semidiurnal tide exhibits both negative and positive correlations that vary with altitude within the MLT. The zonal diurnal tide shows positive correlation with the solar flux in the upper MLT in solar minima. However, the meridional semidiurnal tide reveals negative correlation in solar minima condition. No evident relationship between the tides and solar flux is found in solar maxima condition. Since the present study points out resemblance as well as dissimilarity with a handful of previous investigations, further long-term and coordinated studies are being sought to obtain critical understanding of the persistent enigmatic features.

The possibility of using all-sky meteor radar to observe ionospheric E-region field-aligned irregularities

All-sky meteor radars are primarily used for meteor observations. This paper reports the first observations of ionospheric E-region field-aligned irregularities (FAIs) from a conventional all-sky meteor radar located at Wuhan (31°N, 114°E) for the period of March–June 2018. E-region FAI echoes evident in range-time intensity (RTI) maps show quasiperiodic striations with positive and negative slopes, which are consistent with multiple FAI structures moving across the wide beam of the meteor radar. A statistical analysis shows that out of a total of 111 d, there are 73 d with E-region FAI echoes detected by the meteor radar. The FAI events correspond well with the presence of sporadic-E layers which provide the necessary plasma density gradient for the development of gradient drift instability producing FAIs. The results demonstrate the capability of conventional meteor radars to make simultaneous routine observations of meteors and ionospheric E-region FAIs through incorporating RTI and spectral analysis into the online realtime data processing. Meteor radar observations could potentially address the limitations of ionospheric radars, which cannot provide simultaneous measurements of neutral winds and irregularity structures, and thereby contribute to better understanding of the dynamical processes producing E-region irregularities.

Development of meteor astronomy at the Odessa University during the period of Ukraine's independence

The article using the methods of bibliographic and source study analysis and systems approach highlights the state and main trends in the development of meteor astronomy in Odessa during the time of independent Ukraine. At the beginning of the 21st century, continuous meteor patrol was restored at the Odessa Astronomical Observatory, which was intensively conducted at the Observatory during Soviet times. It was based on the use of the television and telescopic method, which was used in the CIS for the first time. The advantages of using the television telescopic method in comparison with the photographic and radar methods for solving the fundamental problems of meteor astronomy are noted. The text gives valuable information on the features of continuous meteor patrols at the observation station Kryzhanovka and the work of the expeditionary automatic meteor patrol on Snake Island (Odessa region, Ukraine). The methods of conducting telescopic television observations and processing observational material developed by Odessa researchers are considered. The main directions of meteoric studies conducted in the Odessa Astronomical Observatory using television meteor patrol materials were determined. Studying the physics of meteoric phenomena, obtaining exact coordinates of individual meteor radiant, spectral observations of meteors, studying double and multiple meteors, studying the structure and density of meteoric dust particles, solving interaction problems meteor showers with the Earth’s atmosphere, statistics of meteor phenomena in the Earth’s atmosphere are the main directions of meteoric studies of Odessa Astronomical Observatory. The scientific potential of Yu. M. Gorbanev in the field of meteor astronomy of, the leader of the meteoric group, O. V. Holubaieva, the head of the meteor's television patrol at the Kryzhanovka observation station in 2003-2011, as well as participation in the meteor research S. H. Kimakovskyi, I. I. Kimakovskyi, S. V. Podlesniak, I. A. Stognieieva, L. A. Saresta, A. F. Prinzykov, V. A. Shestopalov, etc are noted. Conclusions are drawn about the importance of conducting meteoric research for the development of fundamental and applied science.

Astrometric calibration for all-sky cameras revisited

Context. Several fireball networks deploy all-sky cameras for the observation of bright meteors and bolides. Because the field is heavily distorted, a dedicated astrometric reduction is needed. A precise computation of the astrometric solution is essential to determine reliable orbital elements of the parent body and to recover possible fragments on ground.Aims. The purpose of this article is to assess the astrometric performances of this type of instruments, which is characterized by a wide field of view and small apertures. The currently available parametric models show a high level of complexity and generally suffer from parameter crosstalk and local minimum confinement if the initial estimates are not precisely provided. We address these issues here and propose a solution by adopting a new explicit parametrisation.Methods. The mismatch between the optical axis and the local zenith direction requires a geometric description that includes two centres of symmetry that lie very close to each other on the focal plane, causing an unreliable estimate of the related parameters. The introduction of new physical coordinates overcomes these issues, allowing a direct and independent estimation. We assessed the performances of different centroiding algorithms in the experimental conditions of an undersampled point spread function of reference stars and saturated bolides on video records. We implemented the algorithm for an automatic identification of bright sources on calibration frames and subsequent correlation with catalogue positions using astrometric projections of increasing complexity.Results. The algorithm and the new parametrisation of the astrometric solution are tested against real data from the PRISMA Italian fireball network and ensure good convergence properties for all cameras we tested so far. By processing astrometric data with a few months’ statistics, we can achieve a random projection indeterminacy of the order of 10 arcsec, which is negligible with respect to single measurement errors on the bolide position.

A Decade of Sporadic Meteoroid Mass Distribution Indices in the Southern Hemisphere Derived from SAAMER’s Meteor Observations

Abstract We present determinations of the meteoroid differential mass index, s, using over a decade of meteor observations from the Southern Argentina Agile MEteor Radar (SAAMER). For this, we employ an autonomous statistical technique to determine this parameter from the measured radar echo amplitudes. Unlike previous studies, we examine the role of the system noise in the determination of this parameter and found that if not taken into account appropriately, the results can yield significant over estimations of the mass index. In general we found that a value of s = 2.0 represents SAAMER’s results in general agreement with recent studies performed in the northern hemisphere. We explore both the index interannual and seasonal variability and, unlike previous studies, we found them to be constant, except during the presence of the Southern δ Aquariids meteor shower which is so strong that it dominates the meteor counts when present. Our study suggests that using the maximum echo amplitude for these studies is not ideal as it can be biased by many factors which make the inaccuracies larger than the precision estimated by the fitting routine. A method that results in a more direct estimate of the electron line density would be required which takes into account range, gain pattern, system noise, etc.

OBSERVACIÓN DE METEOROS DE DOS ESTACIONES CON MINI-MEGATORTORA Y FAVOR UN SISTEMA DE MONITOREO EN CAMPO AMPLIO

Here we present the results of our four years long observations of meteors with Mini-MegaTORTORA wide-field monitoring system with sub-second temporal resolution. Over this period, we detected and catalogued more than 175000 faint meteors with magnitudes down to 8-10 mag and angular velocities up to 40 deg/s. Recently, we started double-station observations using Mini-MegaTORTORA together with reconstructed FAVOR camera on 3.8 km baseline. This setup allows to observe tens of faint meteors per night. We present the preliminary results of such observations.

Meteor trail drift research based on baseline observations

We analyze the results of a rare long-lived quasisymmetric ellipsoidal-annular meteor trail recorded on November 18, 2017 by two optical all-sky cameras, spaced at a distance of 150 km. The analysis is based on astrometric processing results with the use of baseline measurement methods. We determine spatial-kinematic characteristics of the meteor trail, and find features of its evolution. The ignition and extinction heights of the meteor were in the range 75–120 km. The estimate of the meteor brightness gives the absolute magnitude value of about –7.3m. It is shown that the distribution of all parts of the long-lived meteor trail occurs in the same plane at a height of ~90 km at a speed of ~320 m/s and, apparently, cannot be a consequence of an air mass movement. The total time of the meteor trail observation was more than 30 min. We offer possible explanations for the results obtained in the context of upper atmosphere processes.

Исследование дрейфа метеорного следа по данным базисных наблюдений

We analyze the results of a rare long-lived quasisymmetric ellipsoidal-annular meteor trail recorded on November 18, 2017 by two optical all-sky cameras, spaced at a distance of 150 km. The analysis is based on astrometric processing results with the use of baseline measurement methods. We determine spatial-kinematic characteristics of the meteor trail, and find features of its evolution. The ignition and extinction heights of the meteor were in the range 75–120 km. The estimate of the meteor brightness gives the absolute magnitude value of about –7.3m. It is shown that the distribution of all parts of the long-lived meteor trail occurs in the same plane at a height of ~90 km at a speed of ~320 m/s and, apparently, cannot be a consequence of an air mass movement. The total time of the meteor trail observation was more than 30 min. We offer possible explanations for the results obtained in the context of upper atmosphere processes.

Construction of a meteor orbit calculation system for comprehensive meteor observation at Kochi University of Technology

The development of a Ham-band Radio meteor Observation (HRO) Interferometer (IF) at Kochi University of Technology began in 2003. Meteor orbit calculation system uses multi-site radio observation with global positioning system (GPS) timing combined with 5 channel (5 ch) interferometer. The HRO-IF utilizes forward-scattering of 53.750 MHz continuous radio waves transmitted from the Sabae station, realized in 2012. Since the last development, the observation data has been used to study the upper atmosphere from the meteor phenomenon. Here, we introduce the results of the 2015 Geminid meteor shower recorded by forward-scatter multi-site observations as a low-cost and low-power 24/7 continuous meteor observation system, as well as the concept of a comprehensive radio meteor orbit calculation system. As a result, 20 examples of Geminid meteor shower events with 3 levels of noise signal classification recorded in our observations. The predicted Geminid meteor shower speed is about 34 ± 8.86 km/s based on the average value of 12 meteor shower data group in the minimum noise signal category (class A).

Properties of meteors with double-peaked light curves

Twenty-one meteors showing double peaked light curves were analysed with observations collected with the Canadian Automated Meteor Observatory tracking system. Each event has orbital information, photometry, and at least one high-resolution observation. Two distinct light curve shapes were found: sudden double peaked curves, and smooth double peaked curves. The sudden peaked curves were produced by objects on asteroidal orbits and mostly showed noticeable fragmentation, while the smooth peaked curves were produced by cometary meteoroids and predominantly showed little to no visible fragmentation. An attempt to model these meteors as single bodies with two chemical components was unsuccessful, implying that fragmentation must be included in meteoroid ablation models.

On the variability of tides during a major stratospheric sudden warming in September 2002 at Southern hemispheric extra-tropical latitude

Investigation of the middle atmospheric tidal response to the September 2002 sudden stratospheric warming (SSW) is carried out from a Southern hemispheric extra-tropical location Cachoeira Paulista (22.7°S, 45°W) using meteor radar observations and reanalysis database. Significant diurnal and semidiurnal tidal amplitudes are found in the mesosphere and lower thermosphere (MLT) a few days prior to the warming onset consistent with the high latitude observations. In the troposphere and stratosphere (TS) the tidal amplitudes attain higher value during the main phase of the warming which decrease subsequently. The simultaneous enhancement of the tidal amplitudes in the TS and diminution in the MLT may imply strong dissipation of the upward propagating tides during the SSW at present location. An evident signature of the tide-planetary wave coupling due to nonlinear interactions is found. A preferential modulation of the tidal amplitudes by long/short period planetary waves are observed in the MLT/TS. The migrating diurnal tide (DW1) and nonmigrating semidiurnal tide (SW1) at 10 hPa pressure level show considerable variability during the warming episode.

ПРО МОЖЛИВІСТЬ ЗАСТОСУВАННЯ ТЕПЛОВІЗОРІВ ДЛЯ СПОСТЕРЕЖЕННЯ МЕТЕОРІВ ТА ІНШИХ АТМОСФЕРНИХ УТВОРЕНЬ У ДАЛЕКОМУ ІНФРАЧЕРВОНОМУ ДІАПАЗОНІ

The characteristics of the modern low-cost thermal vision cameras for possible observations of meteors and other atmospheric formations in long wave infrared spectrum range of 8-14 μm are investigated. An overview of meteor observations in non-traditional spectrum ranges: ultra-violet, near infrared, short wave, mid wave, and long wave infrared is done. A short description of the modern instruments for infrared observations is presented. By the example of a modern inexpensive model of thermal vision camera of the lower price segment there are presented results of test observations of clouds, possible atmospheric bolide tails and inversion t tracks of airplanes, meteors, and thunderstorm discharges. A short analysis of technical characteristics of the selected model, and corresponding software is given, the merits and demerits of the given type of observational instruments are analyzed as well. The conclusion for outlook of using in the future the thermal vision cameras in meteor astronomy and geophysics is done.

Initial Results of Meteor Observations with Langfang MF Radar

中频雷达用来开展夜间100km高度以上的流星观测，获得流星随时间、高度、方位的分布情况及流星体速度、流星辐射点、流星余迹径向速度等参数，其探测数据可用于流星天文学、中层大气动力学等领域的研究.利用2017年11月16日12：00UT-22：00UT期间廊坊观测站（39.4°N，116.7°E）的中频雷达数据，首次开展了中国中纬度地区夜间流星观测实验，共检测到94个流星回波信号，集中分布在97～115km高度范围内，平均高度为106.5km，计算得到了流星回波的双极扩散系数、方位分布等相关参数，并与国外中频雷达流星探测结果进行了初步比较.

Physical properties of the meteoroids using simultaneous radar and optical observations

The calculation results of photographic and radar meteoroid mass of simultaneous radio - TV and radio-photographic observations of meteors in 1977–1980 in Hissar Astronomical Observatory of the Institute of Astrophysics, Academy of Sciences of Tajikistan. The analyses' results of the shape of light curves of meteors within the theory of evaporation and the theory of the quasi-continuous fragmentation are presented.The photographic meteoroid mass from the light curve were defined: a) by the value of maximum luminous intensity at a height hm and b) by the integration light curve. Based on analysis of the data of the photographic mass were obtained correction factor that takes into account the effect of fragmentation and other factors to determine the mass of meteoroids first method. Average value of the mass of meteoroids calculated from the light curve for meteors with magnitude M ≤ 1 is 19∗10−3g, and the average value of the mass found on magnitude of the luminous intensity at the height the maximum brightness consist 18.2∗10−3g, that is in satisfactory agreement between. Masses of the meteoroids was calculated also radio method by value of maximum linear electron density at the height of maximum ionization.In the framework of the classical theory and the theory quasi-continuous fragmentation, we analyzed the shape of the light curves of simultaneous radio - optical meteors. It is shown that the main mechanism of ablation approximately 60% of simultaneous radio - optical meteors is a quasi-continuous fragmentation. The bulk density and porosity of showers and sporadic meteoroids were determined. Found that the Geminids meteoroids and S.δ-Aquariids have the largest bulk densities (δ0=3.6g/cm3), and have not porosity (K = 0). A meteoroids of the showers Orionids and Leonids have the lowest bulk density (δ0≤0.6g/cm3), and the highest value of the porosity (60≤K≤80%). The mass fragments of shower and sporadic meteoroids lie in the range of 5∗10−8÷10−5g.

Progress of Radar Observations of Meteors in Kazan (Russia) over the Last Sixty Years

AbstractThis paper presents a brief survey on the history of radar observations of meteors in Kazan from 1950s to present days. Such achievements of Kazan researchers as development and further improvement of original measuring equipment and antenna systems, of observational data processing methods, their contribution to the theory of physics of meteor phenomena and theoretical interpretation of experimental data are highlighted. A particular progress in meteor astronomy has been achieved with a new discrete quasi-tomoghraphic method for faint meteor showers identification that uses goniometer data of meteor radio reflections detected on radar as input data. The current state and new horizons of meteor studies in Kazan are stated.

Meteor head and terminal flare echoes observed with the Gadanki MST radar

Meteor observations with Gadanki MST radar usually detect variety of meteor echoes that includes head echoes, specular and non-specular trail echoes. Sometimes, but not always head echoes are followed by a sudden increase in signal strength amounting to many decibels at terminal end point of the trail, known as terminal flare echoes - a feature mostly observed with optical and high power large aperture (HPLA) radar systems. In this study, we report some examples of terminal flare echoes observed with Gadanki MST radar. Because these echoes provide valuable insight into the role of diffusion and plasma instabilities in the formation and evolution of meteor trail. From the observations, it has been noticed that the head echoes at higher altitudes are generating non-specular trail echoes, whereas they disintegrate as terminal flares associated with meteoroid fragmentation in lower altitudes. Although meteoroid fragmentation is a common phenomenon, but terminal flaring is a rare feature observed with Gadanki radar. A small, but non-negligible fraction of meteor events (∼2.5% of all head echo events) showed flaring apparently produced by terminal destruction of a meteoroid fragmentation along with the insights into the fragmentation and terminal flaring process.

RADIANTS AND ORBITAL DISTRIBUTION OF TV FAINT SPORADIC METEORS

Double station meteor observation using TV CCD unintensified techniques was started in 2013 in Nikolaev astronomical observatory (RI NAO). During observational campaign in 2013-2016 catalog containing 1055 meteoroid orbits has been obtained. Registered meteoroid photometric masses (Kruchinenko, 2012) are between 10 -7 and 10 - 2 kg. Distribution of radiants, velocities and elements of heliocentric orbits with accent on meteoroids with low masses are analyzed in the work. Comparison with data from meteoroid orbit catalogs SonotaCo, EDMOND and NFC networks is also given. Two kinds of databases/catalogs are distinguished: “narrow field” and “wide field” depending on which type of camera system were used in observations. For analysis of the different catalogs only sporadic meteors were selected. Comparison of sporadic meteoroid radiants and orbital elements for different databases has shown that “narrow field” observations have next typical characteristics: 1) more relative number of low-mass meteoroids (about 30%) than large databases obtained by wide-angle observations; 2) significant increasing of number of low-velocity ( V g 4.6 predominantly; 3) low-mass meteoroids in “wide-field” databases caused Apex contribution only, notable part of this objects from “narrow-field” data has radiants close to Antihelion source.

Observations of meteors in the Earth’s atmosphere: Reducing data from dedicated double-station wide-angle cameras

Meteoroids entering the Earth’s atmosphere can be observed as meteors, thereby providing useful information on their formation and hence on their parent bodies. We developed a data reduction software package for double station meteor data from the SPOSH camera, which includes event detection, image geometric and radiometric calibration, radiant and speed estimates, trajectory and orbit determination, and meteor light curve recovery. The software package is designed to fully utilise the high photometric quality of SPOSH images. This will facilitate the detection of meteor streams and studies of their trajectories. We have run simulations to assess the performance of the software by estimating the radiants, speeds, and magnitudes of synthetic meteors and comparing them with the a priori values. The estimated uncertainties in radiant location had a zero mean with a median deviation between 0.03∘ and 0.11∘ for the right ascension and 0.02∘ and 0.07∘ for the declination. The estimated uncertainties for the speeds had a median deviation between 0.40 and 0.45 km s−1. The brightness of synthetic meteors was estimated to within +0.01 m. We have applied the software package to 177 real meteors acquired by the SPOSH camera. The median propagated uncertainties in geocentric right ascension and declination were found to be of 0.64∘ and 0.29∘, while the median propagated error in geocentric speed was 1.21 km s−1.

Luminosity function of faint sporadic meteors measured with a wide-field CMOS mosaic camera Tomo-e PM

Imaging observations of faint meteors were carried out on April 11 and 14, 2016 with a wide-field CMOS mosaic camera, Tomo-e PM, mounted on the 105-cm Schmidt telescope at Kiso Observatory, the University of Tokyo. Tomo-e PM, which is a prototype model of Tomo-e Gozen, can monitor a sky of ∼1.98deg2 at 2 Hz. The numbers of detected meteors are 1514 and 706 on April 11 and 14, respectively. The detected meteors are attributed to sporadic meteors. Their absolute magnitudes range from +4 to +10mag in the V-band, corresponding to about 8.3×10−2 to 3.3×10−4g in mass. The present magnitude distributions we obtained are well explained by a single power-law luminosity function with a slope parameter r=3.1±0.4 and a meteor rate log10N0=−5.5±0.5. The results demonstrate a high performance of telescopic observations with a wide-field video camera to constrain the luminosity function of faint meteors. The performance of Tomo-e Gozenis about two times higher than that of Tomo-e PM. A survey with Tomo-e Gozenwill provide a more robust measurement of the luminosity function.

In Search of Recent Disruption of (3200) Phaethon: Model Implication and Hubble Space Telescope Search

Abstract Near-Earth asteroid (3200) Phaethon is notable for its association with a strong annual meteor shower, the Geminids, indicative of one or more episodes of mass ejection in the past. The mechanism of Phaethon’s past activity is not yet understood. Here, we present a Hubble Space Telescope (HST) search of meter-sized fragments in the vicinity of Phaethon, carried out during Phaethon’s historic approach to Earth in mid-December of 2017. Numerical simulations conducted to guide HST’s pointing also show that the dynamical evolution of Phaethon-originated particles is quick, as ejected materials take no longer than ∼250 years to spread to the entire orbit of Phaethon. Our search was completed down to a 4 m class limit (assuming Phaethon-like albedo) and was expected to detect 0.035% of particles ejected by Phaethon in the past several decades. The negative result of our search capped the total mass loss of Phaethon over the past few dozen orbits to be 1012 kg at the 3σ level, taking the best estimates of size power-law from meteor observations and spacecraft data. Our result also implies a millimeter-sized dust flux of within 0.1 au of Phaethon, suggesting that any Phaethon-bound mission is unlikely to encounter dense dust clouds.