Asteroid 2024 BX1 was the eighth asteroid that was discovered shortly before colliding with the Earth. The associated bolide was recorded by dedicated instruments of the European Fireball Network and ...the AllSky7 network on 2024 January 21 at 0:32:38–44 UT. We report a comprehensive analysis of this instrumentally observed meteorite fall, which occurred as predicted west of Berlin, Germany. The atmospheric trajectory was quite steep, with an average slope to the Earth’s surface of 75°.6. The entry speed was 15.20 km s −1 . The heliocentric orbit calculated from the bolide data agrees very well with the asteroid data. However, the bolide was fainter than expected for a reportedly meter-sized asteroid. The absolute magnitude reached −14.4, and the entry mass was estimated to be 140 kg. The recorded bolide spectrum was low in iron, based on which, the meteorite was expected to be rich in enstatite. The recovered meteorites, called Ribbeck, were classified as aubrites. The high albedo of enstatite (E-type) asteroids can explain the size discrepancy. The asteroid was likely smaller than 0.5 meter and should rather be called a meteoroid. During the atmospheric entry, the meteoroid severely fragmented into much smaller pieces already at a height of 55 km under an aerodynamic pressure of 0.12 MPa. The primary fragments then broke up again, most frequently at heights 39−29 km (0.9–2.2 MPa). Numerous small meteorites and up to four stones larger than 100 g were expected to land. Within a few days of publication of the location of the strewn field, dozens of meteorites were found in the area we had predicted.
Context.
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Herculid meteor outburst or even storm was predicted to occur by several models around 5 UT on 31 May 2022 as a consequence of the break-up of comet 73P/Schwassmann-Wachmann 3 in 1995. ...The multi-instrument and multi-station experiment was carried out within the Czech Republic to cover possible earlier activity of the shower between 21 and 1 UT on 30/31 May.
Aims.
We report meteor shower activity that occurred before the main peak and provide a comparison with the dynamical simulations of the stream evolution. The physical properties of the meteoroids are also studied.
Methods.
Multi-station observations using video and photographic cameras were used to calculate the atmospheric trajectories and heliocentric orbits of the meteors. Their arrival times were used to determine the shower activity profile. The physical properties of the meteoroids were evaluated using various criteria based on meteor heights. The evolution of the spectra of three meteors were studied as well.
Results.
This annual but poor meteor shower was active for the whole night many hours before the predicted peak. A comparison with dynamical models shows that a mix of older material ejected after 1900 and fresh particles originating from the 1995 comet fragmentation event was observed. The radiant positions of both groups of meteors were identified and were found to agree well with the simulated radiants. Meteoroids with masses between 10 mg and 10 kg were recorded. The mass distribution index was slightly higher than 2. The study of the physical properties shows that the
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Herculid meteoroids belong to the most fragile particles observed ever, especially among higher masses of meteoroids. The exceptionally bright bolide observed during the dawn represents a challenge for the dynamical simulations as it is necessary to explain how a half-metre body was transferred to the vicinity of the Earth at the same time as millimetre-sized particles.
We introduce a new method for the determination of the atmospheric velocity of bright meteors (fireballs). The method uses high-time-resolution light curves of fireballs and photographic or digital ...records of the fireballs where dynamics data are not available, i.e. a rotating shutter was not used. Simultaneous identification of flares or other unambiguous events is needed on both the light curve and the photographic or digital record. These events, flares for instance, serve as time-marks and substitute the artificial rotating shutter time-marks. We studied the method on nine selected fireballs that fulfill the above conditions, occupy a wide interval of possible initial velocities (from 14.5 to 50 km s-1), and are of a different orbital origin (cometary and asteroidal). The method provides correct velocities with scatter of a few km s-1 around the average value that corresponds to the rotating shutter velocity.
Through an international collaboration between Imperial College London, the Ondřejov Observatory in the Czech Republic and the Western Australian Museum, the installation of the Australian Desert ...Fireball Network in the Nullarbor Region of Western Australia was completed in 2007. Currently, the Network, which is the first to be established in the southern hemisphere, comprises four all-sky autonomous observatories providing precise triangulation of fireball records to constrain pre-atmospheric orbits and fall positions of meteorites over an area of approximately 200 000 km
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. To date, the Network has led to the successful recovery of two observed meteorite falls. The first recovery was three fragments (174, 150 and 14.9 g) of the same meteorite fall recorded on 20 July 2007 at 19 h 13 m 53.2 s±0.1 s UT that were found within 100 m of the predicted fall line. Named Bunburra Rockhole, the meteorite is a basaltic achondrite with an oxygen isotopic composition (Δ
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O = −0.112 ‰) distinguishing it from basaltic meteorites belonging to the Howardite-Eucrite-Diogenite clan thought to be derived from asteroid 4Vesta, and therefore must have come from another differentiated asteroid in the terrestrial planet region. Bunburra Rockhole was delivered to Earth from an Aten-like orbit that was almost entirely contained within the Earth's orbit. The second recovered fall was detected by the Network on 13 April 2010 and led to the recovery of a 24.54 g meteorite fragment that is yet to be fully described. To date, the Network has recorded ∼550 fireballs. Records from which precise orbits and trajectories can be determined number ∼150. In addition to the two recovered falls twelve fireballs are considered to have resulted in meteorite falls. Of these, four are probable falls (10's-100 g), and five are certain falls (>100 g). Having proved the potential of the Network, ultimately a large dataset of meteorites with orbits will provide the spatial context for the interpretation of meteorite composition that is currently lacking in planetary science.
Meteoroids impacting the Earth on a daily basis are fragments of asteroids and comets. By studying fireballs produced during their disintegration in the atmosphere, we can gain information about ...their source regions and the properties of their parent bodies. In this work, data on 824 fireballs presented in an accompanying paper and catalog are used. We propose a new empirical parameter for the classification of the physical properties of meteoroids, based on the maximum dynamic pressure suffered by the meteoroid in the atmosphere. We then compare the physical and orbital properties of meteoroids. We find that aphelion distance is a better indicator of asteroidal origin than the Tisserand parameter. Meteoroids with aphelia lower than 4.9 AU are mostly asteroidal, with the exception of the Taurids and
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Capricornids associated with the comets 2P/Encke and 169P/NEAT, respectively. We found another population of strong meteoroids of probably asteroidal origin on orbits with either high eccentricities or high inclinations, and aphelia up to χ 7 AU. Among the meteoroid streams, the Geminids and
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Virginids are the strongest, and Leonids and α Capricornids the weakest. We found fine orbital structures within the Geminid and Perseid streams. Four minor meteoroid streams from the working list of the International Astronomical Union were confirmed. No meteoroid with perihelion distance lower than 0.07 AU was detected. Spectra are available for some of the fireballs, and they enabled us to identify several iron meteoroids and meteoroids deficient in sodium. Recognition and frequency of fireballs leading to meteorite falls is also discussed.
Context . A meteor outburst consisting of at least 22 meteors above the Baltic sea and southern Scandinavia that occurred on 30 October 2022 was recorded using multiple cameras. A bright fireball was ...followed by fainter meteors over a 10 second period. All the meteors were travelling on parallel trajectories. Aims . The goal of this study is to determine the atmospheric trajectories and photometric masses of meteors and to use these data to determine the specifics of the progenitor meteoroid break-up and cluster formation. Methods . Double and triple-station observations using video cameras were used for the calculation of the atmospheric trajectories and photometric masses of the meteors. Their relative positions and mass distribution were then used to determine the time and cause of the meteoroid fragmentation. Results . The relative position of the cluster particles in the atmosphere and the distribution of their masses best correspond to the separation of the smaller fragments from the mass-dominant fragment 10.6 ± 1.7 days before the collision with Earth, assuming a meteoroid bulk density of 1000 kg m −3 . The ejection velocities are in the range 0.16–0.61 ms −1 . The directions of the ejection velocities are bounded by a cone with an apex angle of 43°. The axis of this cone has ecliptic coordinates of l = 154° and b = 26° and is 66° away from the direction to the Sun. Thermal stresses appear to be the most likely cause of such meteor cluster formation.
A catalog of 824 fireballs (bright meteors), observed by a dedicated network of all-sky digital photographic cameras in central Europe in the years 2017–2018 is presented. The status of the European ...Fireball Network, established in 1963, is described. The cameras collect digital images of meteors brighter than an absolute magnitude of about −2 and radiometric light curves with a high temporal resolution of those brighter than a magnitude ≈−4. All meteoroids larger than 5 g, corresponding to sizes of about 2 cm, are detected regardless of their entry velocity. High-velocity meteoroids are detected down to masses of about 0.1 g. The largest observed meteoroid in the reported period 2017–2018 had a mass of about 100 kg and a size of about 40 cm. The methods of data analysis are explained and all catalog entries are described in detail. The provided data include the fireball date and time, atmospheric trajectory and velocity, the radiant in various coordinate systems, heliocentric orbital elements, maximum brightness, radiated energy, initial and terminal masses, maximum encountered dynamic pressure, physical classification, and possible shower membership. Basic information on the fireball spectrum is available for some bright fireballs (apparent magnitude <−7). A simple statistical evaluation of the whole sample is provided. The scientific analysis is presented in an accompanying paper.
Context. A bright fireball was observed above the Czech Republic on September 9, 2016, at 23:06:59 UT. Moreover, the video cameras at two different stations recorded eight fainter meteors flying on ...parallel atmospheric trajectories within less than 2 s. All the meteors belong to the September epsilon Perseid meteor shower. The measured proximity of all meteors during a very low activity meteor shower suggests that a cluster of meteors was observed. Aims. The goal of the paper is first to determine whether this event was a random occurrence or a real meteor cluster and second, if it was a cluster, to determine the epoch and at what distance from the Earth the separation of the particles occurred. Methods. The atmospheric trajectories of the observed meteors, masses, and relative distances of individual particles were determined using a double-station observation. According to the distances and masses of the particles, the most probable distance and time of fragmentation is determined. Results. The observed group of meteors is interpreted as the result of the orbital fragmentation of a bigger meteoroid. The fragmentation happened no earlier than 2 or 3 days before the encounter with the Earth at a distance smaller than ~0.08 AU from the Earth.
The Chelyabinsk superbolide of February 15, 2013, was caused by the atmospheric entry of a ~19 m asteroid with a kinetic energy of 500 kT TNT just south of the city of Chelyabinsk, Russia. It was a ...rare event; impacts of similar energy occur on the Earth only a few times per century. Impacts of this energy near such a large urban area are expected only a few times per 10 000 years. A number of video records obtained by casual eyewitnesses, dashboard cameras in cars, security, and traffic cameras were made publicly available by their authors on the Internet. These represent a rich repository for future scientific studies of this unique event. To aid researchers in the archival study of this airburst, we provide and document a catalog of 960 videos showing various aspects of the event. Among the video records are 400 distinct videos showing the bolide itself and 108 videos showing the illumination caused by the bolide. Other videos show the dust trail left in the atmosphere, the arrival of the blast wave on the ground, or the damage caused by the blast wave. As these video recordings have high scientific, historical, and archival value for future studies of this airburst, a systematic documentation and description of records is desirable. Many have already been used for scientific analyses. We give the exact locations where 715 videos were taken as well as details of the visible/audible phenomena in each video recording. An online version of the published catalog has been developed and will be regularly updated to provide a long–term database for investigators.
In 1999, 2001, 2002, and 2006 favourable returns of Leonids occurred and were observable, at least partly, from Central Europe. We present results on 54 photographically recorded multi-station Leonid ...fireballs and their probable identification from five individual dust trails or the Leonid Filament. Atmospheric behaviour was studied on the basis of beginning and terminal heights, dynamic pressures, PE coefficients, and light curves. The apparent non-dependence of beginning heights on initial photometric mass suggests the existence of a height $h_{\lim} = 111 \pm 5$ km, which is the height where all Leonids reach an absolute magnitude of about -2m. Three different shapes of the light curves were recognized and a recently implemented photometric method was used for the determination of the brightness of the Leonids. The precise heliocentric orbits and geocentric radiants for 34 Leonids with known times of meteor passage are also presented.
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