Meteor astronomy

The radiant and orbit of the Quadrantid meteoroid stream are studied on the basis of the updated version of the IAU MDC photographic meteor catalogue. The mean orbit, the shape, size and ephemeris of the radiant are derived. The radiant area of the central part of the stream is more concentrated and is of the size 4 • ×2 • . The origin of the stream is discussed and orbital evolution over 5000 years of five filaments found in the stream is compared with asteroid 2003 EH1, the recently proposed parent of the stream . Two of the filaments follow the orbital evolution of 2003 EH1.

The present work is based on an analysis of 64 650 precisely-determined meteor orbits collected in the Japanese meteor shower catalogue from video observations by SonotaCo [5]. The shower meteor data have been analysed with the aim of determining the orbits' distribution in major meteor streams with heliocentric velocities close to the parabolic limit, in which the errors in the velocity determination correspond to large differences in 1/a. As the value of semimajor axis a is very sensitive to the value of the heliocentric velocity vH, especially near the parabolic limit, any error in the determination of vH can push the orbit over the parabolic limit and create a group of meteoroids apparently moving in hyperbolic orbits.

In this paper, we present an analysis of Polish Fireball Network (PFN) observations of enhanced activity of the Southern Taurid meteor shower in 2005 and 2015. In 2005, between October 20 and November 10, seven stations of the PFN determined 107 accurate orbits, with 37 of them belonging to the Southern Taurid shower. In the same period of 2015, 25 stations of the PFN recorded 719 accurate orbits with 215 orbits of the Southern Taurids. Both maxima were rich in fireballs, which accounted for 17 per cent of all observed Taurids. The whole sample of Taurid fireballs is uniform in the sense of starting and terminal heights of the trajectory. However, a clear decreasing trend in geocentric velocity with increasing solar longitude was observed. The orbital parameters of observed Southern Taurids were compared to orbital elements of near-Earth objects (NEOs) from the NEODyS-2 data base. Using the Drummond criterion D with a threshold as low as 0.06, we found over 100 fireballs strikingly similar to the orbit of asteroid 2015 TX24. Several dozens of Southern Taurids have orbits similar to three other asteroids: 2005 TF50, 2005 UR and 2010 TU149. All mentioned NEOs have orbital periods very close to the 7 : 2 resonance with Jupiter's orbit. This confirms the theory of a resonant meteoroid swarm within the Taurid complex, which predicts that, in specific years, the Earth is hit by a greater number of meteoroids capable of producing fireballs.

We carried out a high-sensitivity TV observation of the Leonid meteor shower at the Nobeyama Radio Observatory, from 15h20m UT through 20h24m UT on 1998 November 17. We detected 58 Leonid meteors, along with 99 sporadic meteors. The peak of the activity, as expected around 20h UT, was not clearly observed. The average influx rate of meteoroids was 1.4x 10-5 km-2 s _1 (mag < +8) during our observation.

In November 1997 a shower of bright Leonid mete- ors was observed from Spain. The visual and photographic mea- surements of the Zenital Hourly Rates (ZHRs) and the respective spatial number densities together with the meteor distribution characteristics indicate the existence of a broad component rich in large grains prior to the perihelion passage of P/Tempel-Tuttle comet. This dust component may be responsible for similar out- bursts in previous appearances. However, the Lunar conditions impeded in 1997 obtaining conclusive evidence of the presence of a component of small meteoroids from more recent ejecta, really responsible for past meteor storms. After comparing 1997 peak data with 1965 data, a very close pattern is detected that supports the presence of future storms.

We calculate the position of dust trails from comet 8P/Tuttle, in an effort to explain unusual Ursid meteor shower outbursts that were seen when the comet was near aphelion. Comet 8P/Tuttle is a Halley-type comet in a 13.6-year orbit, passing just outside of Earth's orbit. We find that the meteoroids tend to be trapped in the 12:14 mean motion resonance with Jupiter, while the comet librates in a slightly shorter period orbit around the 13:15 resonance. It takes 6 centuries to decrease the perihelion of the meteoroid orbits enough to intersect Earth's orbit, during which time the meteoroids and comet separate in mean anomaly by 6 years, thus explaining the 6-year lag between the comet's return and Ursid outbursts. The resonances also prevent dispersion along the comet orbit and limit viewing to only one year in each return. We identified past dust trail encounters with dust trails from 1392 (Dec. 1945) and 1378 (Dec. 1986) and predicted another outburst on 2000 December 22 at around 7:29 and 8:35 UT, respectively, from dust trails dating to the 1405 and 1392 returns. This event was observed from California using video and photographic techniques. At the same time, five Global-MS-Net stations in Finland, Japan, and Belgium counted meteors using forward meteor scatter. The outburst peaked at 8:06 ± 07 UT, December 22, at zenith hourly rate ∼90 per hour, and the Ursid rates were above half peak intensity during 4.2 h. We find that most Ursid orbits do scatter around the anticipated positions, confirming the link with comet 8P/Tuttle and the epoch of ejection. The 1405 and 1392 dust trails appear to have contributed similar amounts to the activity profile. Some orbits provide a hint of much older debris being present as well. This work is the strongest evidence yet for the relevance of mean motion resonances in Halley-type comet dust trail evolution.

Seventy-five orbits of Leonid meteors obtained during the 1998 outburst are presented. Thirtyeight are precise enough to recognize significant dispersion in orbital elements. Results from the nights of 1998 November 16/17 and 17/18 differ, in agreement with the dominant presence of different dust components. The shower rate profile of 1998 November 16/17 was dominated by a broad component, rich in bright meteors. The radiant distribution is compact. The semimajor axis is confined to values close to that of the parent comet, whereas the distribution of inclination has a central condensation in a narrow range. On the other hand, 1998 November 17/18 was dominated by dust responsible for a more narrow secondary peak in the flux curve. The declination of the radiant and the inclination of the orbit are more widely dispersed. The argument of perihelion, inclination, and the perihelion distance are displaced. These data substantiate the hypothesis that trapping in orbital resonances is important for the dynamical evolution of the broad component.

359 precisely reduced meteor orbits are presented that are the result of the Dutch Meteor Society's Photographic Meteor Survey in the period 1981 until 1993. Orbits include those of major and minor showers, doubling the number of known precise orbits of some meteor streams. From the spread in solutions of all possible sets of two photographic stations, we derive the measurement uncertainties from which we are able to calculate the intrinsic scatter in the Perseid meteor stream. The new Geminid orbits are compared to those obtained in similar surveys in the 1950's. This first measurement of the rate of change of Geminid orbits over time agrees well with model predictions.

Context. The existence of meteor clusters has long since been a subject of speculation and so far only seven events have been reported, among which two involve less than five meteors, and three were seen during the Leonid storms. Aims. The 1995 outburst of Comet 73P/Schwassmann-Wachmann was predicted to result in a meteor shower in May 2022. We detected the shower, proved this to be the result of this outburst, and detected another meteor cluster during the same observation mission. Methods. The τ-Herculids meteor shower outburst on 31 May 2022 was continuously monitored for 4 h during an airborne campaign. The video data were analyzed using a recently developed computer-vision processing chain for meteor real-time detection. Results. We report and characterize the detection of a meteor cluster involving 38 fragments, detected at 06:48 UT for a total duration of 11.3 s. The derived cumulative size frequency distribution index is relatively shallow: s = 3.1. Our open-source computer-...

The possibility of observing enhanced meteoric activity, at Earth, from dust associated with C/1995 01 Hale-Bopp is investigated. We consider the nodal distribution of dust ejected from the comet during post-discovery nuclear outbursts, and we consider the hypothetical nodal distribution of meteoroids ejected from the comet during an assumed previous perihelion passage. In each case we find no reason to believe that the Earth will sample any significant numbers of C/1995 01 derived meteoroids.

Photographic meteor observations of the Perseid meteoroid stream compiled from the IAU Meteor Data Center catalogue are analyzed from the viewpoint of possible long-term variation of meteor heights with the solar-cycle activity, which was previously reported from radio observations. The observed beginning and end-point heights of the Perseids, normalized for the geocentric velocity and the absolute photographic magnitude, do not show a variation consistent with the solar-cycle activity. This result is valid for the mass range of larger meteoroids observed by photographic techniques, and must be still verified also for the range of smaller meteoroids observed by TV and radio methods.

The Lunar Dust Experiment (LDEX) onboard the Lunar Atmosphere and Dust Environment Explorer mission orbited the Moon from 2013 October to 2014 April and detected impact ejecta generated by the continual bombardment of meteoroids to the lunar surface. While the Moon transited the Geminid meteoroid stream, LDEX observed a large enhancement in the lunar impact ejecta cloud, particularly above the portion of lunar surface normal to the Geminids radiant. Here, we present the LDEX measurements during the Geminids, using the surface density of impact ejecta at the Moon as a proxy for meteoroid activity. We find two peaks during the Geminids, a smaller peak at solar longitude λ = 261. • 3 ± 0. • 12 followed by a larger peak at λ = 262. • 2 ± 0. • 12, with a surface density ratio of 2.6 between the two. Both peaks coincide with radar observations of shallower mass indices than most of the Geminids, suggesting an enhancement of larger particles during the two peaks. The total duration of the 2013 Geminid meteoroid shower at the Moon measured by LDEX is λ = 1. • 7 for activity >10 per cent of the peak value, corresponding to a width of 1.9 × 10 6 km normal to the Geminids velocity vector. The timing of the main observed peak matches ground-based visual observations of meteors with magnitude of −1 to −3 and suggests LDEX is detecting ejecta from primary impactors with radii ∼2 mm to 2 cm during this time.

On Monday 12 June 1989 a detonating fireball was widely observed from the East Coast-Bay of Plenty region of New Zealand, and subsequently a number of small meteoritic specimens were recovered near Opotiki. These were submitted to the Geological Survey of New Zealand in Wellington where they were identified as fragments of a carbonaceous chondrite. However, no detailed account of this meteorite was written up and published either at that time or subsequently. This belated report summarises what we know about the Opotiki Bolide, and is based on contemporary newspaper reports, and fieldwork conducted in the impact area at the time by the two authors of this paper and by the Scottish-Australian astronomer, Robert McNaught.

J.M. Trigo-Rodríguez, J.M. Madiedo, J. Vaubaillon, M. Gritsevich, L.G. Morillas, E. Blanch, P. Pujols, F. Colas and P. Dupuoy. Institute of Space Sciences (IEEC-CSIC), Barcelona, Spain mmoreno@ice.csic.es; trigo@ice.csic.es 2 Finnish Geospatial Research Institute, Masala, Finland. Facultad de Ciencias Experimentales, Universidad de Huelva, Huelva, Spain. Departamento de Física Atómica, Facultad de Física, Universidad de Sevilla, Molecular y Nuclear, Sevilla, Spain. Institut de mécanique céleste et de calcul des éphémérides Observatoire de Paris PSL, Paris, France. Department of Physics, University of Helsinki, Helsinki, Finland. Institute of Physics and Technology, Ural Federal University, Ekaterinburg, Russia. IES Cañada de las Fuentes, Jaén, Spain. Observatori de l’Ebre (OE, CSIC – Univ. Ramon Llull), Tarragona, Spain. 10 Agrupació Astronómica d’Osona (AAO), Vic, Spain. 11 Dax Observatoire, Dax, France.

The Ursid meteor shower is an annual shower that usually shows little activity. However, its Zenith hourly rate sometimes increases, usually either when its parent comet, 8P/Tuttle, is close to its perihelion or its aphelion. Outbursts when the comet is away from perihelion are not common and outbursts when the comet is close to aphelion are extremely rare. The most likely explanation offered to date is based on the orbital mean motion resonances. The study of the aphelion outburst of 2000 December provided a means of testing that hypothesis. A new aphelion outburst was predicted for 2014 December. The SPanish Meteor Network, in collaboration with the French Fireball Recovery and InterPlanetary Observation Network, set up a campaign to monitor this outburst and eventually retrieve orbital data that expand and confirm previous preliminary results and predictions. Despite unfavourable weather conditions over the south of Europe over the relevant time period, precise trajectories from multistation meteor data recorded over Spain were obtained, as well as orbital and radiant information for four Ursid meteors. The membership of these four meteors to the expected dust trails that were to provoke the outburst is discussed, and we characterize the origin of the outburst in the dust trail produced by the comet in the year AD 1392.

By analyzing high-accuracy Leonid orbits obtained from multiple-station meteor observations during the 1998 outburst and 1999 storm, we have detected the presence of meteoroids with peculiar orbits. These meteoroids are characterized by having a geocentric radiant nearly identical to the members of the storm that appeared with them but showing different orbital elements owing to their lower geocentric velocities. The changes in some orbital elements are significant and allow us to interpret the cause of such differences. Mainly, the semimajor axis and the eccentricity of these anomalous orbits are lower than expected for members of the dust trail or members coming from the background component linked to the annual stream. From these characteristics it is likely that these peculiar meteoroids suffered some perturbations on very short timescales. We have investigated several causes, including planetary perturbations, collisions, and radiative effects in order to explain the observed orbital changes. We conclude that these orbital changes can be explained by the loss of orbital energy close to the ecliptic plane. Such an effect can only be explained clearly by collisions of the original meteoroids with dust particles associated with the zodiacal dust cloud. We have applied this hypothesis in order to constrain some physical properties of 55P/ Tempel-Tuttle cometary meteoroids.

Jupiter and Saturn produce important gravitational impulses on meteoroids released by comet 109P/Swift-Tuttle. The meteoroids from this comet once released follow retrograde orbits that during their periodic approaches to these planets (within 1.6 and 0.9 A.U., respectively) are impulsed gaining orbital energy. This perturbation effect is translated into a net inward shift in the node of the perturbed meteoroids. Such geometry with Jupiter occurred in 2004 over a meteoroid trail ejected by this comet during the 1862 A.D. return of the comet to perihelion. In order to study the predicted outburst produced by onerevolution meteoroids, the Spanish Photographic Meteor Network (SPMN) performed an extensive

We report here the observation of the first peak belonging to the 2002 Leonid meteor storm made during the night of November 18-19, 2002. This feature, produced by a 7-revolution dust trail, was observed from several photographic stations of the Spanish Photographic Meteor Network (SPMN) and one video station operated from the Instituto de Astrofísica de Andalucía (IAA) in an intensive campaign from the ground working in collaboration with the 2002 Leonid MAC mission. We used photography, slow-scan Charge Coupled Devices (CCD) and video CCD-imaging techniques to deduce the meteoroid flux density profiles in different ranges of masses. Additionally, we present multi-station work, developed during the storm, that allows us to deduce the orbital elements of ten meteoroids associated with this dust trail. We have found a clear similarity between their orbits and the one belonging to a theoretical orbit for particles ejected from 55P/Tempel-Tuttle in 1767.

William Stewart (WS) Alex Pratt (ARP) and Len Entwisle (LE) employed the same equipment and methods as described on the NEMETODE website 1 and in their paper on the 2012 Perseids. 2 In early 2013 January WS commissioned a third camera and realigned his two original cameras to achieve better overlap with ARP. In the Republic of Ireland Mike Foylan (MF, Co. Meath) operated two Watec 902DMS cameras with 8mm f/0.8 lenses, and Michael O’Connell (MC, Co. Kildare) ran his Watec 902H and 12mm f/0.8 lens. LE’s meteor camera was active on the nights of August 10/11 and 12/13, recording to VHS tape. ARP post-processed LE’s tape via UFO Capture.

The outburst of the Lyrid meteor shower in 1803 was remarkable for being rich in bright ®reballs and the generation of electrophonic sounds. The implications implicit to the detection of electrophonic sounds are studied in this paper. We present estimates for the minimum-sized Lyrid meteoroid capable of generating electrophonic sounds, and compare these lower limits with the largest meteoroid that might reasonably be ejected from a cometary nucleus through coupling with the sublimation gas out¯ow. A difference of a factor of order 30 is found between the two limiting sizes. A minimum diameter of order 1 m is required for a Lyrid meteoroid to satisfy the conditions necessary for generating electrophonic sounds. The mechanisms responsible for the placement of large, metre-sized meteoroids into the Lyrid stream are not well de®ned, but they possibly relate to surface ageing effects of the parent comet, Comet C/1861 G1 Thatcher, and to a history of nuclear fragmentation.

We present the ®rst measurements of the radiant and orbit of meteoroids that are part of the unusual Perseid activity called the`Perseid Filament'. This ®lament was encountered by Earth in the years before and after the return of the comet to perihelion in December of 1992. Between 1989 and 1996, there were brief meteor outbursts of near-constant duration with a symmetric activity pro®le. In 1993, however, rates increased more gradually to the peak. That gradual increase is identi®ed here as a separate dust component, which we call the`Nodal Blanket'. We ®nd that the Nodal Blanket has a very small radiant dispersion. On the other hand, the Perseid Filament has a radiant that is signi®cantly dispersed and systematically displaced by 0.38. This dispersion implies that unusually high ejection velocities or planetary perturbations must have had time to disperse the stream. In both cases, one would expect a rapid dispersion of matter along the comet orbit. In order to explain the concentration of dust near the comet position, we propose a novel scenario involving long-term accumulation in combination with protection of the region near the comet against close encounters with Jupiter due to librations of the comet orbit around the 1:11 mean-motion resonance.

Seventy-five orbits of Leonid meteors obtained during the 1998 outburst are presented. Thirtyeight are precise enough to recognize significant dispersion in orbital elements. Results from the nights of 1998 November 16/17 and 17/18 differ, in agreement with the dominant presence of different dust components. The shower rate profile of 1998 November 16/17 was dominated by a broad component, rich in bright meteors. The radiant distribution is compact. The semimajor axis is confined to values close to that of the parent comet, whereas the distribution of inclination has a central condensation in a narrow range. On the other hand, 1998 November 17/18 was dominated by dust responsible for a more narrow secondary peak in the flux curve. The declination of the radiant and the inclination of the orbit are more widely dispersed. The argument of perihelion, inclination, and the perihelion distance are displaced. These data substantiate the hypothesis that trapping in orbital resonances is important for the dynamical evolution of the broad component.

359 precisely reduced meteor orbits are presented that are the result of the Dutch Meteor Society's Photographic Meteor Survey in the period 1981 until 1993. Orbits include those of major and minor showers, doubling the number of known precise orbits of some meteor streams. From the spread in solutions of all possible sets of two photographic stations, we derive the measurement uncertainties from which we are able to calculate the intrinsic scatter in the Perseid meteor stream. The new Geminid orbits are compared to those obtained in similar surveys in the 1950's. This first measurement of the rate of change of Geminid orbits over time agrees well with model predictions.

Ah&a&. The discovery of enhanced Leonid activity in 1994 led to the mounting of a multi-station photographic campaign on two continents during the Leonids of 1995. The goal was to determine orbits and trajectories of outburst Leonids. The outburst did recur as predicted, resuhing in 23 precisely reduced Leonid orbits and 30 Leonid trajectories. Individual velocities and radiant positions, as well as the average orbit are presented. It is found that the distribution of Leonid radiants contains a dense cluster of seven radiant positions. This clustering is tentatively associated with the visually observed outburst component. These seven meteors provide the first orbital elements of outburst Leonids-and put strong constraints models of the origin and evolution stream.

Seventy-five orbits of Leonid meteors obtained during the 1998 outburst are presented. Thirtyeight are precise enough to recognize significant dispersion in orbital elements. Results from the nights of 1998 November 16/17 and 17/18 differ, in agreement with the dominant presence of different dust components. The shower rate profile of 1998 November 16/17 was dominated by a broad component, rich in bright meteors. The radiant distribution is compact. The semimajor axis is confined to values close to that of the parent comet, whereas the distribution of inclination has a central condensation in a narrow range. On the other hand, 1998 November 17/18 was dominated by dust responsible for a more narrow secondary peak in the flux curve. The declination of the radiant and the inclination of the orbit are more widely dispersed. The argument of perihelion, inclination, and the perihelion distance are displaced. These data substantiate the hypothesis that trapping in orbital resonances is important for the dynamical evolution of the broad component.

IRAS has detected dust trails in the orbit of short-period comets but has been unable to detect such trails in the orbit of long-period comets. We now present observations from the study of a meteor outburst that identify the event as being due to just that. Ten orbits of meteoroids were measured during a brief but intense outburst of the a Monocerotid shower that conÐrm the theory that a trail of dust is brought occasionally in collision with the Earth by planetary perturbations. Observations of this event by multiple meteor observing techniques provide the Ðrst direct measurement of the size distribution of dust in a comet dust trail, the dust density in the trail of a long-period comet, and a cross section of such a trail in the path of Earth. The implication for detecting potential Earth-threatening long-period comets by their meteoric signature is discussed.

We calculate the position of dust trails from comet 8P/Tuttle, in an effort to explain unusual Ursid meteor shower outbursts that were seen when the comet was near aphelion. Comet 8P/Tuttle is a Halley-type comet in a 13.6-year orbit, passing just outside of Earth's orbit. We find that the meteoroids tend to be trapped in the 12:14 mean motion resonance with Jupiter, while the comet librates in a slightly shorter period orbit around the 13:15 resonance. It takes 6 centuries to decrease the perihelion of the meteoroid orbits enough to intersect Earth's orbit, during which time the meteoroids and comet separate in mean anomaly by 6 years, thus explaining the 6-year lag between the comet's return and Ursid outbursts. The resonances also prevent dispersion along the comet orbit and limit viewing to only one year in each return. We identified past dust trail encounters with dust trails from 1392 (Dec. 1945) and 1378 (Dec. 1986) and predicted another outburst on 2000 December 22 at around 7:29 and 8:35 UT, respectively, from dust trails dating to the 1405 and 1392 returns. This event was observed from California using video and photographic techniques. At the same time, five Global-MS-Net stations in Finland, Japan, and Belgium counted meteors using forward meteor scatter. The outburst peaked at 8:06 ± 07 UT, December 22, at zenith hourly rate ∼90 per hour, and the Ursid rates were above half peak intensity during 4.2 h. We find that most Ursid orbits do scatter around the anticipated positions, confirming the link with comet 8P/Tuttle and the epoch of ejection. The 1405 and 1392 dust trails appear to have contributed similar amounts to the activity profile. Some orbits provide a hint of much older debris being present as well. This work is the strongest evidence yet for the relevance of mean motion resonances in Halley-type comet dust trail evolution.

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The structure of the Taurid meteor complex based on photographic orbits available in the IAU Meteor database is studied. We have searched for potential sub-streams or filaments to be associated with the complex utilizing the Southworth-Hawkins D-criterion. Applying a strict limiting value for D=0.10, fifteen sub-streams or filaments, consisting of more than three members, could be separated out from the general complex. To confirm their mutual consistence as filaments, rather than fortuitous clumping at the present time, the orbital evolution over 5000 years of each member is studied. Utilizing the D-criterion we also searched for NEOs that might be associated with the streams and filaments of the complex and investigated the orbital evolution of potential members. Possible associations between 7 Taurid filaments and 9 NEOs were found. The most probable are for S Psc(b) -- 2003QC10, N Tau(a) -- 2004TG10, o Ori -- 2003UL3 and N Tau(b) -- 2002XM35. Some of the potential parent objects...

Since 2007 the Japanese video network provided significant amount of meteor data observed by multi station video meteor network located in Japan. The network detects meteors mostly up to +2 magnitude and is probably the most accurate and largest freely accessible video meteor database up-to-date. In this paper we present our analysis on the qualitative aspects of the meteor orbits derived from the multi station video observation and the separation of the shower meteors from the sporadic background.

December Monocerotids and November Orionids are weak but established annual meteor showers active throughout November and December. Analysis of a high quality orbits subset of the SonotaCo video meteor data base shows that the distribution of orbital elements, geocentric velocity and also the orbital evolution of the meteors and potential parent body may imply a common origin for these meteors coming from the parent comet C/1917 F1 Mellish. This is also confirmed by the physical properties and activity of these shower meteors. An assumed release of meteoroids at the perihelion of the comet in the past and the sky-plane radiant distribution reveal that the December Monocerotid stream might be younger than the November Orionids. A meteoroid transversal component of ejection velocity at the perihelion must be larger than 100 m s −1. A few authors have also associated December Canis Minorids with the comet C/1917 F1 Mellish. However, we did not find any connection.

Based on the catalogs of comets capable of nucleus splitting and comets with abnormal tail 30 short-Jupiter-family comets were identified, which are capable of producing meteoroid swarms that do not intersect the Earth's orbit, but are of interest for drafting of space missions and studying the distribution of meteoroid streams.

The article gives an overview of the most important problems of modern meteoric astronomy and briefly describes ways and methods of their solutions. Particular attention is paid to the construction and arrangement of meteoric video cameras intended for registration of the meteoric phenomena as the main method of obtaining reliable and objective observational data on the basis of which the solution of the described tasks is possible.

During routine low-light level video observations with CAMS (Cameras for All-sky Meteor Surveillance) made in the month of July 2011, we detected the July Gamma Draconids (GDR), a meteor stream discovered by P. Babadzhanov in 1963, and observed by the SonotaCo Network in 2007-2008. The stream is included in the IAU Working List of Meteor Showers as shower #184, awaiting verification. We detected this shower beginning on July 24, through its peak on July 28, and to the shower's end on August 1. Our mean orbital elements are q = 0.978 ± 0.001 AU, 1/a = 0.022 ± 0.005 AU −1 , i = 40. • 24 ± 0. • 20, ω = 202. • 31 ± 0. • 22, and Ω = 124. • 66 ± 0. • 37 (N = 25). The GDR meteors move in an intermediate long-period comet orbit with orbital period between 270 and 600 years. The parent body remains undiscovered.

The asteroid 2003 EH1, proposed as the parent body of the Quadrantid meteor shower, is thought to be the remnant of a past cometary object, tentatively identified with the historical comets C/1490 Y1 and C/1385 U1. In this work, we use recovery astrometry to extend the observed arc of 2003 EH1 from 10 months to about 5 years, enough to exclude the proposed direct relationship of the asteroid with both of the comets.

A method to separate stream and sporadic activity of forward scatter meteor counts is applied to two widely different station set-ups: one had a long baseline and uses scatter from a high power TV video carrier, whilst the other had a much shorter baseline and records echoes from a low powered beacon. The method was applied to the 2005 Geminids

There was a special attention for Perseid meteor shower observations in view of the predictions of an intense activity on 11 th August 2004 caused by a filament of dust drifting across the Earth's orbit. Results of a systematic study of Perseid meteor shower observations, carried out during 12-15 August 2004 using Indian MST radar are presented. Based on over 27 hours of observing time, we detected 2260 meteor echoes occurring between 80 km and 120 km with a mean height of 103 km. For our observations, the peak activity of the shower occured on 12/13 August, corresponding to solar longitude λ o = 140.565 ± 0.16 with an average rate of 250 meteor echoes per hour. The SNR distribution of the echoes observed during the shower indicates that the smaller size meteoroids are more compared to larger size meteoroids in the perseid meteor stream. The three distinct peaks observed in the shower activity is presented and discussed.

Mathematical modelling has shown that activity of the Geminid meteor shower should rise with time, and that was confirmed by analysis of visual observations 1985-2016. We do not expect any outburst activity of the Geminid shower in 2017, even though the asteroid (3200) Phaethon has a close approach to Earth in December of 2017. A small probability to observe dust ejected at perihelia 2009-2016 still exists.

We investigate numerically the dynamical evolution of simulated meteoroid stream of the Quadrantids ejected from the parent body of the asteroid (196256) 2003 EH1. The main goal of this work is to identify mean motion and secular resonances and to study the mutual influence of resonance relations and close encounters with the major planets. Since the dynamics of this asteroid is predictable only on short time intervals, and not only close and/or multiple close encounters with major planets, but also the presence of at least one unstable resonance can lead to chaotic motion of test particles, we studied their resonant dynamics. The dynamical evolution of the test particles expects possible scenario for resonant motion. We conjecture that the reasons of chaos are the overlap of stable secular resonances and unstable mean motions resonances and close and/or multiple close encounters with the major planets. The estimate of the stability of orbits in which the particles in simulations mo...

The activity of the Perseid stream in the range of photographic meteors is reviewed. An attention is paid to the activity of the stream close to the parent-comet return in 1991 to 1994, characteristics of the so-called new maximum and two different dust components − blanket in the present node of the comet and a ribbon-like structure, named as Nodal Blanket (Jenniskens et al., 1998) and Perseid Filament (Lindblad and Porubčan, 1994), respectively. A fine structure of the Perseid stream and its filaments is studied using the method of indices-the procedure based only on mathematical statistics. In the study the new completed 2003 version of the IAU Meteor Data Center catalogue of precise photographic orbits (Lindblad et al., 2005) is employed. 560 (64%) of 875 Perseids taken into account were sorted out to 17 filaments found. The selected filaments are not distributed in the space accidentally, but they form higher structures consisting of 1 individual filament, 3 branches of the stream containing 9 filaments together and a central part of the stream. In the central part of Perseids, 3 branches and 1 individual filament were identified. The structures are dived into a cloud of 315 dispersed orbits. Positions of 17 filaments are compared with strong mean-motion resonances with Jupiter and Saturn. The existence of gaps in the distribution of the semimajor axes of the Perseids is confirmed using the considerably more numerous material.

Aims. In our overall work, we attempt to predict some new meteor showers associated with as many as possible known periodic comets and to find the generic relationship of some already known showers with these comets. In this paper, we focus our attention on the meteor-shower complex of the long-period comet C/1917 F1 (Mellish), which is the known parent body of the December Monocerotids. Some other showers have also been suggested to be associated with this comet. We map its whole complex here. Methods. For five perihelion passages of the parent comet in the past, we model associated theoretical streams, with each consisting of 10 000 test particles and follow their dynamical evolution until the present. Subsequently, we analyze the orbital characteristics of the parts of found streams that approach the Earth's orbit. Results. We confirm the generic relationship between the studied parent comet and December Monocerotids. The comet is probably also the parent body of the April ρ-Cygnids. The evolution of meteoroids to the orbits of April ρ-Cygnids is very long at about 20 millennia. If we follow even a longer evolutionary period, which is up to 50 millennia, then two diffuse showers with the radiant situated symmetrically to both the December Monocerotids and April ρ-Cygnids showers with respect to the apex of the Earth's motion occur. Our simulation does not confirm any relationship between C/1917 F1 and the November Orionids, although this shower was found in all three databases of observed orbits.

A fine structure of the Perseid stream in the range of photographic magnitudes is studied using the method of indices. A new completed 2003 version of the IAU Meteor Data Center Catalogue of 4581 photographic orbits is used. The method of indices is used to acquire a basic data set for the Perseids. Subsequently, the method is applied on the chosen Perseids to study their structure. Sixty four percent of chosen Perseids taken into account are attached to one of the 17 determined filaments of orbits. The filaments are not distributed in the space accidentally, but they form a higher structure consisting of at least four well-defined and distinguished ''branches''.

The paper deals with a search for chosen photographic meteoroid streams compiled from the IAU Meteor Data Center Lund catalogue from which less than 2% of the orbits had to be removed due to internal inconsistency among the orbitM parameters. Additional 35 orbits were removed due to extremely high hyperbolic velocities. The fina] set consists of 3411 orbits. Members of the Quadrantids, Lyrids, Perseids and Geminids were searched for, firstly, by a stream-search procedure utilizing the Southworth-tIawkins D-criterion. This choice, as a rule, represents the most abundaxtt filament of the stream. Secondly, rate distribution histograms of D were divided into region of shower meteors and region of sporadic background meteors. The searched database with a relatively low abundance of sporadic meteors in the analyzed periods simplified this choice, and followingly, fitting the obtained vMues by means of power and exponential functions, the limiting Ds for particular showers were derived. The derived Ds appears as the optimum value, as for higher D, the number of sporadic meteors included in the stream sample increases more rapidly than the number of additional shower meteors, and for sma]ler D, the nnmber of shower meteors decreases quicker than the number of omitted sporadic meteors. The following counts of shower meteors N and limiting Ds were found: Quadrantids (39, 0.22), Lyrids (11, 0.15), Perseids (595, 0.53) and Geminids (224, 0.32). Efficiency of the procedure was tested comparing the number of sporadic meteors in the region of radiant area and the neighbourlng regions of the same size.

A procedure of selection of meteoroids from major streams is suggested and applied to the IAU Lund photographic database modified by a check for internal consistency among orbital elements (3411 orbits). Limits for choice of stream members were defined by break points on the plots of the cumulative number N c vs. the Southworth-Hawkins D discriminant. For the break points were considered the points from which the dependence Nc rs. D changes to a quasi-linear one, and with the increasing D, N c changes only moderately. Except for the Tanrids which desire a separate ana.lysis, the N c vs. D diagrams are presented for the foUowing major meteoroid streams: Quadrantids, Lyrids, r/Aquarids, c~ Capricornids, N and S ~ Aquarids, Perseids, Orionids, Leonids and Geminids. The mean orbits, velocities and radiartts of the streams are derived and compared with the osculating orbits of their patent bodies. The limiting DB was found to be a function of the number of the stream members NcB. Omitting the exceptionally concentrated Geminids, the relation is in the form DB -~ 0.058 * In(NcB) -0.04.

The intense activity of cratering on the Moon and in the inner regions of the solar system was accomplished during the first 10^9 years [1]. Occasionally, some impact events occur even nowadays. In Section 1, we treat, from a historical point of view, the Earth-based observation of lunar impacts. In Section 2, we consider the visibility conditions of such events evaluating the luminosity of the background upon which an impact shines. In Section~3, the luminosity of an impact is discussed. The occurrence of lunar impact events outside of meteor shower periods is calculated using the hourly rate of the sporadic meteors and their population index. The evidence of a larger rate of impacts of meteoroids in the past under these hypotheses is presentend in the last section.

We analyse the outburst experienced by the September-Perseid meteor shower on 2013 September 9. As a result of our monitoring, the atmospheric trajectory of 60 multistation events observed over Spain was obtained and accurate orbital data were derived from them. On the basis of these orbits, we have tried to determine the likely parent body of this meteoroid stream by employing orbital dissimilarity criteria. In addition, the emission spectra produced by two events belonging to this meteor shower were also recorded. The analysis of these spectra has provided information about the chemical nature of their progenitor meteoroids. We also present an estimation of the tensile strength for these particles.

Mega-tsunami have affected much of the coastline of Australia over the past millennium. Such catastrophic waves have left an imprint consisting predominently of bedrock sculpturing of the rocky coastline and deposition of marine sediments to elevations reaching 130 m above sea level. One of the largest of these events occurred in eastern Australia in the fifteenth century. This event may be related to the Mahuika impact crater found at 48.3 S, 166.4 E on the continental shelf 250 km south of New Zealand. A comet at least 500 m in diameter formed the crater. Maori and Aboriginal legends allude to significant cosmogenic events in the region, while Aboriginal legends about tsunami are common along the eastern Australian coast. Evidence for legends that could describe the impact of a cosmogenic tsunami also exists in NW Australia. Here geological evidence of a single mega-tsunami as recent as in the seventeenth century covers 1500 km of coastline. We term this event Wandjina after the a...

Mega-tsunami have affected much of the coastline of Australia over the past millennium. Such catastrophic waves have left an imprint consisting predominently of bedrock sculpturing of the rocky coastline and deposition of marine sediments to elevations reaching 130 mabove sea level. One of the largest of these events occurred in eastern Australia in the fifteenth century. This event may be related to the Mahuika impact crater found at 48.38 S, 166.48 E on the continental shelf 250 km south of New Zealand. A comet at least 500 m in diameter formed the crater. Maori and Aboriginal legends allude to significant cosmogenic events in the region, while Aboriginal legends about tsunami are common along the eastern Australian coast. Evidence for legends that could describe the impact of a cosmogenic tsunami also exists in NW Australia. Here geological evidence of a single megatsunami as recent as in the seventeenth century covers 1500 km of coastline. We term this event Wandjina after the artwork related to the legends. More attention should be given to oral traditions in searching globally for other sites of significant mega-tsunami.