SB11

The Desert Fireball Network is a fireball observing network which stretches across the southern part of the Australian continent. To date, it has over 50 cameras, covering an area of approximately 2.5m km2. Its purpose is to observe and triangulate fireballs, calculate trajectories for incoming meteorites. The camera network has been operational in digital form since 2012, and to date as captured approximately 1.5PTB of data, primarily all sky images. We present an overview of the DFN results to date, detailing the dataset of approximately 1500 orbits, and over 30 possible candidate meteorite falls, and describe the most recent results. In particular, the team have recently recovered two candidate meteorites; one from the Nullarbor and one from the Simpson Desert in South Australia. The comparison the stories of these recoveries illustrate the typical issues of searching meteorite searching, and of verifying the meteorite’s provenance, and possible origin of the rocks is interesting to compare.

How to cite: Towner, M., Sansom, E., Cupak, M., Devillepoix, H., Anderson, S., Shober, P., Howie, R., Hartig, B., and Bland, P.: The Australian Desert Fireball Network: overview and recent results, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-167, https://doi.org/10.5194/epsc2021-167, 2021.

• Introduction

In Spain, the Spanish Meteor Network (SPMN) has been operating for 25 years, recording meteoric events and re-entries over the Iberian Peninsula, Morocco, and the insular territory [1]. This is a pro-am project involving a scientific team specialized in areas such as astronomy, geology, geophysics, and chemistry.

Obtaining the trajectory of meteoroids impacting the atmosphere is crucial both for the recovery of possible meteorites and for studying their origin in the Solar System. Some of these objects can be dynamically associated with their parent bodies, being part of meteoroid streams [2]. Herein lies the importance of monitoring the sky constantly and completely from multiple monitoring stations. The SPMN network has 34 stations equipped with all-sky cameras or wide-angle lenses, and we recently upgraded the software to reduce the ever-increasing amount of data. Here we present our automated Python (called 3D-FireTOC) pipeline for meteor detection from digital systems, astrometric measurements, photometry, atmospheric trajectory reconstruction and heliocentric orbit computation, all in all quantifying the error measurements in each step [3].

• Analytical procedures of the 3D-FireTOC software

A key step to achieve proper reduction is the development of automated astrometry to ensure the measurement of meteors appearing in the field of view of video-detection systems. To do this, we use computer vision techniques to obtain the pixel coordinates corresponding to the moving meteor in each frame. Each image is processed and compared with a reference image (without detection) allowing us to extract the pixels that have been activated by the meteor. In this way, the centroid of the detected pixel area corresponds to the position in the image of the meteoroid (see Figure 1).

Due to the changing nature of this type of recordings as well as possible light reflections and obstacles in the field of view, we have implemented three methods to avoid false positives: 1) discriminating by the size of the detected area excluding excessively small and large contours, 2) predicting the next position of the meteor with a Kalman filter, and 3) post-processing the detected points and applying clustering algorithms to check if the trajectory is consistent with a more or less straight line. Figure 2 shows an example of false positive avoidance.

To transform the pixels into real coordinates is necessary to identify stars in the image to obtain their position in the sky for the date of the event. To do this, we use corner detection algorithms since the stars appear randomly distributed in the sky and far from each other. Again, we use clustering algorithms but this time selecting the points identified as noise, as can be seen in Figure 2.

Once the stars have been identified, thanks to JPL's Horizons ephemerides, we can model the deformation produced by the lens by finding the correspondence between pixel and real position. In particular, we apply a polynomial variant [4] of the method proposed by [5] for all-sky camera astrometry. 

Fig.1

Fig. 2

The result we obtain from each observation is an apparent trajectory projected on the celestial sphere. Naturally, two or more observations sufficiently far apart are required to triangulate the real position of the meteoroid. Because these fragments reach the Earth at very high velocities, air resistance practically does not bend their trajectories so that they can approximate a straight line. This allows the plane intersection method to be applied to reconstruct the atmospheric flight [6]. Finally, the trajectory is projected backwards to obtain the radiant, i.e. the position of origin in the sky. From the atmospheric flight, the α-β criterion can be applied approximating the chances that the event produced meteorites [7,8].

• Recent example: SPM010521 event

On May 1, 2021, a bolide flew over Aragón reaching a magnitude of -11. It was recorded by 6 stations of the SPMN network (Table 1 and Figure 3). The luminous phase started at 107 km altitude and ended at 43 km. The flight angle with respect to the horizontal was 24º degrees. With a geocentric velocity of 30 km/s, its orbital parameters indicate a possible association with a IAU working list of meteor showers called Southern May Ophiuchids. Unfortunately, it was not a meteorite-dropper event as reveals the α-β criterion result: α=315.4, β=1.2, an estimated initial mass of 0.1 kg and an estimated final mass less than one gram. Figure 4 shows the 3D representation and scale of the reconstructed atmospheric trajectory, as well as the calculated heliocentric orbit.

Fig. 3

Fig. 4

• Conclusions

With the implementation of this new software, the SPMN increases its capacity to rapidly generate new knowledge about the origin of large meteoroids, and their capacity to generate hazard. Multi-station analyses also provide valuable information about their bulk physical properties and, from their heliocentric orbits, the dynamic association with comets, asteroids, or even planetary bodies can be inferred [3]. In addition, the automation of the meteor detection and the entire analysis process allows immediate preparation of meteorite search campaigns. Our software developments will be soon applied to increase our close cooperation with FRIPON [9].

As an example of application, we present the results obtained on SPMN010521, a recent fireball recorded and analyzed by the SPMN, which did not produce meteorites and seems to be dynamically associated with an unestablished meteor shower.

Acknowledgements

This research has been funded by the research project PGC2018-⁠097374-⁠B-⁠I00, (MCI-⁠AEI-⁠FEDER, UE). Funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme for the project “Quantum Chemistry on Interstellar Grains” (QUANTUMGRAIN, grant agreement No. 865657) is acknowledged. 

References

• [1] Trigo-Rodríguez J.M. et al. (2006) Astronomy & Geophysics 47, 6.26
• [2] Hughes, D. W.(1990) MNRAS 245, 198-203.
• [3] Peña-Asensio, E., Trigo-Rodríguez, J. M., Gritsevich, M., & Rimola, A. (2021) MNRAS 504(4), 4829-4840.
• [4] Bannister, S. M., Boucheron, L. E., & Voelz, D. G. (2013) ASP125(931), 1108.
• [5] Borovička, J. (1992) AICAS, 79.
• [6] Ceplecha, Z. (1987) BAIC, 38, 222-234.
• [7] Gritsevich M., 2009, Advances in Space Research, 44, 323.
• [8] Sansom E. K., et al., 2019, The Astrophysical Journal, 885, 115.
• [9] Colas, F. et al. (2020) Astronomy & Astrophysics 644, id.A53, 23 pp.

How to cite: Peña-Asensio, E., Trigo-Rodríguez, J. M., Gritsevich, M., Rimola, A., Izquierdo, J., Zamorana, J., Chioare-Díaz, M., Iglesias-Marzoa, R., Milian Biel, J., Ibañez, V., Robles, A. J., Pastor, S., de los Reyes, J. A., Guasch, C., Aznar Carbó, M., and Lasala, A.: New SPMN network software for fireball detection and analysis: the SPMN010521 bolide event, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-738, https://doi.org/10.5194/epsc2021-738, 2021.

On February 28, 2020 at 09:30:32 UTC, a daytime superbolide was observed over southeastern Slovenia and neighbouring countries¹. In the following days, three meteorite pieces (469, 203, and 48 grams)² were recovered nearby the Slovenian city of Novo Mesto by local people. The meteorite was classified as an L5 ordinary chondrite, more or less brecciated and shocked.

In this work we reconstruct the trajectory using the available video data which consist of two static security cameras and four dash cameras mounted on cars in motion (Figure 1). We use a new radial distortion method developed by Vida et al. (2021) to accurately model the lens distortion of individual cameras and we determine the position of the vehicles to a precision of several centimetres on every video frame.

Figure 1. Map of observer locations and the fireball trajectory (red line).

The preliminary trajectory was computed using the lines of sight method and the trajectory uncertainties were computed using the Monte Carlo method (Vida et al., 2020) by adding 3σ noise to the original measurements. The fireball was first observed at a height of 68.7 km and it reached an end height of 17.1 km. The fireball had an entry angle of 47.812° ± 0.096° and an initial velocity of 22.098 ± 0.012 km/s (computed using measurements above 45 km, i.e. before any noticeable deceleration was visible). Figure 2 shows that the average per-station trajectory spatial fit errors were around 100 m (200 m maximum). More observations will be included in a future analysis.

Figure 2. Spatial trajectory fit residuals. The Tkon and Senj stations were fixed security cameras, but only Tkon was calibrated on stars.

The fireball had the following geocentric radiant (J2000):

The computed orbit is:

A parent body search returned a match for a few objects, depending on the used D criterion. The Potentially Hazardous Asteroid 2005 OX had the Southworth & Hawkins (1963) D_SH criterion value of 0.078, while the Drummond (1981) criterion had close matched for asteroids 2008 DK5 (D_D = 0.043), 2004 DF2 (D_D = 0.050), and also 2005 OX (D_D = 0.058). Possible connection to these objects may be a topic of future work, although these correlations might be spurious as the orbital parameter space is dense in that region.

The fireball was bright enough to be picked up by the US government sensors³ which measured a total radiated energy of 11.5×10¹⁰ J. Assuming a typical L chondrite bulk density of 3620 kg/m³, we estimate that the meteoroid had an initial mass of 470 kg, corresponding to a diameter of about 0.63 m. We use the energy estimate to scale the observed light curve using the luminous efficiency of Borovička et al. (2020) – it compares well to an empirically derived light curve using a light source of known magnitude (reflection of the Sun from a chromium sphere at various distances). The fireball had one major fragmentation event at the height of 35 km which was picked up by the seismographs in the vicinity.

A total of 18 fragments were tracked on the videos after the main fragmentation. The dynamic mass analysis shows that the final mass of the largest fragment was on the order of 10 kg. This rather large fragment has not been found yet – it is possibly buried into the soft ground and ploughed over. The fireball experienced fragmentations at dynamic pressures of 2.5, 3.5, and 10 Mpa, as shown in Figure 3. The peak dynamic pressure is the highest ever measured, after the the Benešov fall (Borovička et al., 1998).

Footnotes:

How to cite: Vida, D., Šegon, D., Šegon, M., Atanackov, J., Ambrožič, B., McFadden, L., Ferrière, L., Kac, J., Kladnik, G., Živčić, M., Merlak, A., Skokić, I., Pavletić, L., Vinčić, G., Ćiković, I., Perkó, Z., Ilari, M., Malarić, M., and Macuka, I.: Novo Mesto meteorite fall – trajectory, orbit, and fragmentation analysis from optical observations, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-139, https://doi.org/10.5194/epsc2021-139, 2021.

Meteors and fireballs, often as part of meteor showers, are commonly observed in the atmosphere of Earth. The same phenomena is expected to take place in other planets (Christou, 2005). Observations are rare, as no suitable instruments have been launched in interplanetary missions, however, these observations can push forward our understanding of interplanetary dust (Christou et al., 2019). In recent years, a number of impacts on Jupiter have been reported based on ground based amateur observations (Hueso et al., 2018) and Juno observations (Giles et al., 2021). On Mars, the Panoramic Camera on Mars Exploration Rover Spirit tried to observe meteors, with no conclusive detections (Domokos et al., 2007), however a meteor was possibly imaged by a navigation camera (Selsis et al., 2005).

The Visual Monitoring Camera (VMC) onboard Mars Express is a wide field camera initially designed as an engineering camera (Ormston et al., 2011). VMC was recently upgraded to a science instrument, and in recent years different works have shown the scientific capabilities of this camera (e.g. Sánchez-Lavega 2018; Hernández-Bernal et al., 2021a;2021b). 

As part of the VMC science program, we performed a few campaigns to try to find meteors or fireballs. To maximize probabilities, we programmed observations coincident with theoretically predicted meteor showers on Mars. While the sensibility of the VMC sensor is low, which reduces the probability to find meteors, its field of view is very wide compared to other instruments, which enhances the probabilities. So far, we have not captured any clear meteor or fireball.

Methodology

We planned our campaigns based on predictions published by Christou (2010). Hardware limitations require all other instruments to be switched off when VMC is observing, this is an important limitation to this work, as only a few observations could be performed, and VMC observations cannot be very long. VMC accepts exposures of up to ~90 s, however observations longer than ~30 s are highly affected by the thermal noise of the sensor, additionally there is a gap of around 48 s between VMC images. As a result, less than 40% of the time VMC is switched on can be effectively used for monitoring.

Exposures of a few seconds by VMC are usually noisy, and they require processing to extract the presence of dim objects, such as stars, planets (e.g. https://twitter.com/esaoperations/status/1247096203550101504), or in this case, meteors. In the case of meteors, we expect them to appear as dim lines in only one image, then the best way to extract the noise from an image is by making a synthetic dark from images obtained close in time. Considering the sensibility of VMC as revealed by observations of stars, we expect it to be able to capture only very bright meteors, around absolute magnitudes of -6 to -10. Figure 1 shows an example of the simulations performed to analyze observability.

Figure 1.

Results

We performed two campaigns to try to find meteors or fireballs, table 1 summarizes these campaigns.

Table 1. Meteor shower details from Table 2 in Christou (2010).

Once processed, images did not show any significant trace potentially related to a meteor burning in the atmosphere. The total effective observation time was 46 minutes, part of this time elapsed out of the expected area for the meteor shower.

Figure 2. Scheme of an observation. The area expected for the meteor shower is green shaded. Dark shaded area is the night.

Conclusions

We did not achieve positive results. The main reason is probably the low sensibility of the VMC sensor. While VMC is a low quality engineering camera designed in the 90s, modern commercial cameras can achieve very high sensibilities. The technical planning of these campaigns shows that VMC-like cameras could be a tool suitable to monitor meteor activity on Mars and other planets from space in the future, as already pointed by Christou et al. (2012). The wide field of view of VMC, when exploited from a moderate distance to the planet, provides full-disk images covering wide areas, and thus potentially enabling the large-scale monitoring of meteor activity. 

References

Christou, A. A., "Predicting Martian and Venusian meteor shower activity." Modern Meteor Science An Interdisciplinary View. Springer, Dordrecht, 2005. 425-431.

Christou, A. A., "Annual meteor showers at Venus and Mars: lessons from the Earth." Monthly Notices of the Royal Astronomical Society 402 (2010): 2759-2770.

Christou, A. A., et al. "Orbital observations of meteors in the Martian atmosphere using the SPOSH camera." Planetary and Space Science 60 (2012): 229-235.

Christou, A. A., et al. "Extra-terrestrial meteors." (2020). Chapter 5 in “Meteoroids: Sources of Meteors on Earth and Beyond”, Cambridge University Press (2019)

Domokos, Andrea, et al. "Measurement of the meteoroid flux at Mars." Icarus 191 (2007): 141-150.

Hernández‐Bernal, J., et al. "An extremely elongated cloud over Arsia Mons volcano on Mars: I. Life cycle." Journal of Geophysical Research: Planets 126 (2021a): e2020JE006517.

Hernández‐Bernal, J., et al. "A Long‐Term Study of Mars Mesospheric Clouds Seen at Twilight Based on Mars Express VMC Images." Geophysical Research Letters 48 (2021b): e2020GL092188.

Giles et al. “Detection of a bolide in Jupiter’s atmosphere with Juno UVS”. Geophysical Research Letters, 48 (2021).

Hueso, Ricardo, et al. "Small impacts on the giant planet Jupiter." Astronomy & Astrophysics 617 (2018): A68.

Ormston, T., et al. "An ordinary camera in an extraordinary location: Outreach with the Mars Webcam." Acta Astronautica 69.7-8 (2011): 703-713.

Sánchez-Lavega, A., et al. "Limb clouds and dust on Mars from images obtained by the Visual Monitoring Camera (VMC) onboard Mars Express." Icarus 299 (2018): 194-205.

Selsis, Franck, et al. "A martian meteor and its parent comet." Nature 435.7042 (2005): 581-581.

How to cite: Hernández-Bernal, J., Sánchez-Lavega, A., Del Río-Gaztelurrutia, T., Hueso, R., Cardesín-Moinelo, A., Marín-Yaseli de la Parra, J., Merrit, D., Wood, S., Martin, P., and Titov, D.: Looking for Meteors and Fireballs in the atmosphere of Mars from the Visual Monitoring Camera (VMC) on Mars Express, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-515, https://doi.org/10.5194/epsc2021-515, 2021.

During its first six months of operations onboard the Zvezda module of the International Space Station, the Mini-EUSO wide-field telescope detected more than two thousand meteors in approximately 40 hours of data taking. Mini-EUSO observes the Earth’s atmosphere in the UV range (290 – 430 nm) with a field of view of about 44° x 44° through a nadir-facing, UV-transparent window with a focal surface of 48 x 48 pixels and a resolution of about 6.3 km on ground. While temporal resolution and triggering are at the timescales of 2.5 μs to potentially record UHECR showers and TLEs, Mini-EUSO performs a continuous monitoring of the UV emission at a 40.96 ms timescale, where meteors are recorded. We developed an analysis pipeline able to offline detect, track and characterize meteor events and subsequently compute their physical parameters, such as tangential speed, magnitude, duration and trajectory azimuth. In this contribution, we present the implemented reduction methods and the results of the analysis of the sample, providing comparisons with existing databases of meteors observed in the optical band.

How to cite: Barghini, D., Battisti, M., Belov, A., Bertaina, M. E., Bertone, S., Bisconti, F., Capel, F., Casolino, M., Cellino, A., Ebisuzaki, T., Gardiol, D., Klimov, P., Marcelli, L., Miyamoto, H., Picozza, P., Piotrowski, L. W., Prévot, G., Reali, E., Sakaki, N., and Takizawa, Y. and the Mini-EUSO collaboration: Analysis of meteors observed in the UV by the Mini-EUSO telescope onboard the International Space Station, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-243, https://doi.org/10.5194/epsc2021-243, 2021.

PRISMA is the Italian fireball network dedicated to the observation of bright meteors. It is active since 2016 and formed a collaboration involving more than 60 institutes, being coordinated by INAF, the Italian National Institute for Astrophysics. PRISMA is also a member of the European network FRIPON. To date, the network counts more than 60 all-sky detectors and has observed more than 2000 bright meteor, four of them being meteorite-dropping fireballs with a predicted strewn-field over the Italian territory. On 04/01/2020, two meteorite pieces were recovered near Cavezzo (MO) in the predicted area just three days after the fall. This was the first recovery of this type in Italy. However, due to the morphology of the two fragments, other meteorites pieces are yet to be found. More recently, on 15/03/2021, a similar event was observed in the skies of southern Italy, near Isernia. Searches for the meteorite are still ongoing, involving the local people and volunteers. In addition, two more meteorite-dropping fireballs were observed, in 2017 and 2018, for which a reliable strewn-field is available. We will report on the current status of the network operations.

How to cite: Barghini, D., Carbognani, A., Di Carlo, M., Di Martino, M., Gardiol, D., Pratesi, G., Riva, W., Stirpe, G. M., and Volpicelli, C. A. and the PRISMA team: PRISMA: an Italian network for the recovery of freshly fallen meteorites, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-201, https://doi.org/10.5194/epsc2021-201, 2021.

The Romanian all-sky network Meteorites Orbits Reconstruction by Optical Imaging (MOROI) was deployed in 2017 [3] and it is fully compatible with the FRIPON one [2]. In 2020 we started to integrate the MOROI database into the FRIPON one. Figure 1 presents the statistics of the weekly multiple events (detected by two or more cameras) for 2017-2019. Figure 2 presents the preliminary statistics of number of meteors vs. duration of luminous phenomenon for 2017-2020. Nowadays the MOROI network consists of 16 all-sky cameras (to be extended to 24).

In [1] is presented a mathematical model for the dark-flight trajectory of a meteoroid based on the influence of the wind, the properties of the atmosphere, the Coriolis force and the centrifugal force. This model uses the ellipsoid shape of the Earth instead of the classical spherical one and a stochastic analysis of meteoroids inside a range of velocities using a Gaussian distribution.

In this paper we present some of the detections from the MOROI network. We present their luminous trajectory and we apply the dark-flight model from [1] in order to obtain their strewn field.

                                                                 Figure 1: Number of weekly events for 2017-2019

                                                                Figure 2: Distribution of duration of meteors for 2017-2020

Acknowledgements:

This work was supported by a grant of the Romanian Ministry of Education and Research, CNCS-UEFISCDI, project number PN-III-P1-1.1-PD-2019-0784, within PNCDI III.

References:

[1] Boaca I., Nedelcu A., Birlan M., Boaca T., Anghel S. Mathematical model for the dark-flight trajectory of a meteoroid, submitted to Romanian Astronomical Journal.

[2] Colas F., Zanda B., Bouley S., Jeanne S., Malgoyre A., Birlan M., Blanpain C., Gattacceca J., Jorda L., Lecubin J., et al. (385 more) FRIPON: a worldwide network to track incoming meteoroids. Astronomy &. Astrophys. 644, A53. doi:10.1051/0004-6361/202038649. 2020.

[3] Nedelcu D.A., Birlan M., Turcu V., Boaca I., Badescu O., Gornea A., Sonka A.B., Blagoi O., Danescu C., Paraschiv P. Meteorites Orbits Reconstruction by Optical Imaging (MOROI) Network. Romanian Astronomical Journal 28(1), 57 – 65. 2018.

How to cite: Boaca, I. L., Nedelcu, A., Birlan, M., Boaca, T., and Anghel, S.: Trajectory and dark-flight estimation for meteoroids detected by the MOROI network, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-307, https://doi.org/10.5194/epsc2021-307, 2021.

How to cite: Nissinen, M., Gritsevich, M., Oksanen, A., and Suomela, J.: Dust Trail Observations of Comet 17P/Holmes and Predictions for 2021-2022, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-86, https://doi.org/10.5194/epsc2021-86, 2021.

Understanding the tension between the dynamical and physical characteristics of solar system debris has been a goal of astronomers and planetary scientists for a long time. This study considered a large (>1400) dataset of orbits gathered from six years of fireball observations observed by the Desert Fireball Network. We focused on the meteoroids we detected originating from short-period comet orbits (2 < T_J < 3). We examined how durable they were as they went through the atmosphere and their orbital evolution over the previous ten thousand years. Our results show that almost all of the meteoroids we see in this size range are sourced from the main belt, not the Jupiter-family comet population. The fact that we do not see these objects shows that genetically cometary material in the centimeter size range does not last long in the inner solar system. Even when meteor shower debris is taken into account, the majority of material at centimeter to meter-scales on comet-like orbits is from the main belt.

We worked with inclusive criteria to be considered cometary in origin. To be classified as cometary, a meteoroid must be at least a Type II according to the PE criterion and have a >50% probability of originating from an unstable orbit over the previous 10 kyrs. Of the 50 sporadic comet-like fireballs observed by the DFN since 2014, only 2 fulfilled this criterion (figure below). Using a Markov Chain Monte Carlo to draw samples from the posterior distribution, we found that sporadic JFC-like meteoroids in NEO space is 94.2% ± 3.2% from the main belt when considering an uninformed prior. This demonstrates that cometary debris has physical lifetimes in near-Earth space less than the decoherence lifetimes for a stream (<1000 years). Material from the main belt becomes the dominant source of debris in this size range as it diffuses out via some combination of orbital resonances, Kozai resonances, nongravitational forces, and close encounters with terrestrial planets (Bottke et al. 2002; Fernández et al. 2014; Hsieh & Haghighipour 2016; Shober et al. 2020a, 2020b). 

How to cite: Shober, P., Sansom, E., Bland, P., Devillepoix, H., Towner, M., Cupak, M., Howie, R., Hartig, B., and Anderson, S.: Main-belt debris on comet-like orbits, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-320, https://doi.org/10.5194/epsc2021-320, 2021.

We present the results of modeling the meteoroids streams of two long-period comets, C/1992 W1 (Ohshita) and C/1853 G1 (Schweizer). The streams of both comets create at least two meteor showers in the Earth’s atmosphere.

1. Introduction

The relationships of minor meteor showers to comets with large aphelion distances have not been revealed as often as those associated to short-period comets. It especially concerns those cases when showers are caused by parts of the stream in which meteoroids move on orbits altered with regard to the orbit of their parent body.

After being ejected from the comet, meteoroids are influenced by gravitational perturbations of planets and non-gravitational forces. This is why meteoroid streams often form filamentary structures. If more than a single filament passes through the Earth’s orbit, we observe several meteor showers associated with the same parent body. Their radiants often exhibit a symmetry in respect to the Earth’s apex (e.g. Fig. 1).

2. The χ-Andromedids and January α-Ursae Majorids

We modelled and studied the dynamical evolution of a meteoroid stream assumed to originate from the long-period comet C/1992 W1 (Ohshita) [1]. The theoretical stream approached the Earth’s orbit in six various filaments corresponding to six different meteor showers. We identified two of them in the IAU MDC Shower database [2] as the χ-Andromedids (#580) and, possibly, the January α-Ursae Majorids (#606), and found their real counterparts in the meteor databases [3, 4, 5], see Fig. 1. The other predicted showers have not been found among real meteors. 

Figure 1. The radiant positions of the modelled meteors associated to C/1992 W1 (black dots) and of their real counterparts (colored symbols – different video databases), shown in the Earth-apex-centered ecliptical coordinates.

3. The γ-Aquilids and 52 Herculids

Our model of a theoretical stream of the comet C/1853 G1 (Schweizer) showed that two meteor showers may originate from this comet [6]. One of them corresponds to the γ-Aquilids (#531) and the other, though not certainly, to the 52 Herculids (#605). Both showers were found among real meteors in the databases. Possible consequences of the uncertainty of the cometary orbit were estimated by constructing models based on a set of cloned orbits (Fig. 2).

Figure 2. The positions of the radiants in the models derived from the cloned orbits (black) and from the nominal orbit (red) of the C/1853 G1, shown in the Earth-apex-centered ecliptical coordinates.  

Acknowledgements

This work was supported by the Slovak Grant Agency for Science (VEGA), grant No. 2/0037/18, and by the Slovak Research and Development Agency under the contract No. APVV-16-0148.

References

[1] Hajduková, M. and Neslušan, L., Icarus 351, 113960, 2020

[2] Jopek, T.J., Kaňuchová, Z., Planetary and Space Science, 143, 3, 2017

[3] Jenniskens, P., Nenon Q., Gural, P. S., Albers, J., Haberman, B., Johnson, B., Morales, R., Grigsby, B. J., Samuels, D., Johannink, C., Icarus, 266,3 84-409, 2016

[4] Kornoš, L., Koukal, J., Piffl, R., Tóth, J., Proceedings of the International Meteor Organization Conference, eds. M. Gyssens, P. Roggemnas, P. Zoladek, Poznan, Poland, 23-25, 2013

[5] SonotaCo, WGN, the Journal of the International Meteor Organization, 44, 42-45, 2016

[6] Neslušan, L., and Hajduková, M., Monthly Notices of the Royal Astronomical Society, 498, 1013-1022, 2020

How to cite: Hajdukova, M. and Neslušan, L.: Unknown sibling showers of comets C/1992 W1 (Ohshita) and C/1853 G1 (Schweizer), Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-214, https://doi.org/10.5194/epsc2021-214, 2021.

Some processes in the physics of small solar system bodies depend on the detailed shape of the body. One of them is the YORP effect, which affects the rotation of asteroids and can lead to rotational bursting. The YORP effect can be modelled because the shape of asteroids can be determined from spacecraft images, radar observations, or inversions of asteroid light curves. A similar effect, caused by the reflection of solar radiation from an irregularly shaped body, affects the rotation of meteoroids. However, this effect is very difficult to model because we are not able to determine the shapes of meteoroids.

In this presentation we show our approach to obtain shapes suitable for characterizing meteoroids. For meteoroids of asteroidal origin, we simulated their formation during a collision in the main belt by fragmentation a sample of an ordinary meteorite using explosive charge technique and performed the digitization of fragments. To describe the cometary meteoroids, we used the shapes of interplanetary dust particles determined by X-ray microtomography. Finally, we show a comparison of the ability of the two types of shapes (asteroidal vs. cometary) to be spun up by the solar radiation.

How to cite: Čapek, D., Kohout, T., Pachman, J., Macke, R., and Koten, P.: Digital 3D shapes suitable for the description of meteoroids, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-306, https://doi.org/10.5194/epsc2021-306, 2021.

Although numerous observers reported that meteors appear in pairs or groups, recent papers based on instrumental observations did not confirm such results. At least, among older meteor showers such grouping was not confirmed. On the other hand, among younger streams, such behaviour is still possible.

In our recent paper dedicated to the search of pairs among Geminid meteors, we found that we have no evidence for the physically connected pairs despite the fact that a number of potential candidates have been detected. Monte Carlo statistical test showed that all the cases can be results of coincidental approaches of the particles in a similar space and time.

Therefore, we prepared a model of orbital fragmentation of meteoroids in the vicinity of the Earth, which follows trajectories of fragmented particles ejected with different velocities in different directions under  the solar radiation pressure. The collisions with interplanetary particles as the possible source of the pairs are taken into account for the major meteor showers during whole year. 

The paper will provide constraints on the time of ejection, ejection velocities and ejection angles, which will allow the pairs or groups to be detected in the Earth atmosphere by the video or photographic cameras.

How to cite: Koten, P. and Čapek, D.: On the detectability of the meteor pairs created by fragmentation in near-Earth space, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-482, https://doi.org/10.5194/epsc2021-482, 2021.

• Introduction

The constant influx of new material from space to Earth provides an opportunity to delve into the processes that took place in the formation of the Solar System [1]. Some fragments of asteroids or comets have been wandering through space remaining practically unaltered, ending their journey upon impact with our atmosphere producing the spectacular luminous phenomenon known as a meteor or fireballs [2,3]. These almost meter-sized fragments, also called meteoroids, may be dynamically associated with the decay of comets or asteroid impacts [4]. In addition, their study provides us with valuable information about one of the major potential cosmic sources of near-term danger [5].

In order to achieve this goal, 25 years ago the Spanish Meteor and Fireball Network (SPMN) began monitoring the sky by recording and analyzing large fireballs [6]. Today, the network has 34 stations distributed throughout the Iberian Peninsula, and now also in the Canary Islands. This expansion of stations has resulted in the first detection of a fireball over these islands and analyzed entirely by a national team. Thanks to the new 3D-FireTOC software [7], we have been able to reconstruct the atmospheric trajectory and heliocentric orbit of the bolide SPMN30032021 from CCD video recordings.

• Methodology

To correct for the large distortions produced by fisheye lenses, especially near the edges, we calibrated the cameras with the method proposed by [8], which is a polynomial variant of [9]. Once we obtained the apparent trajectories for each station, we applied the plane intersection method to obtain the atmospheric trajectory [10]. We solve the astrometric system combining the Simplex algorithm [11] and Powell's methods [12]. Finally, projecting this trajectory backwards and correcting for diurnal aberration and zenith attraction, we compute the radiant position and the heliocentric orbit.

For the error calculation we have applied Monte Carlo methods. Using the calibration uncertainties, we generate random variations with a normal distribution for each bolide coordinate. In this way, we used 1000 clones to obtain the average values and the standard deviation of each computed parameter.

• Case Study: Bolide SPMN30032021

On Mars 30, 2021, a bright bolide catalogued as SPMN30032021 event occurred over the Canary Islands (see Table 1). It was an event of considerable importance because it has been the first to be recorded and analyzed by two stations of the SPMN network over the archipelago. One of the cameras is located at sea level, in Playa Blanca, on the island of Lanzarote. The other camera is located at the Roque de los Muchachos observatory, in the GranTeCan facilities, which can be seen in Figure 1.

Fig. 1

The meteoroid began its luminous phase at an altitude of 77.9 ± 0.4 km with a velocity of 14.07 ± 0.15 km/s. It penetrated the atmosphere to a height of 35.3 ± 0.3 km, indicating that it likely did not produce meteorites. The point of maximum brightness reached a magnitude of -11 ± 1, it could have been seen with the naked eye from Morocco. The flight angle with respect to the horizontal was 40.45 ± 0.11 degrees. Due to its low geocentric velocity its atmospheric trajectory was greatly affected by gravitational attraction. Its orbital elements indicate that it originated from the inner asteroid belt. Figure 2 shows the 3D and scaled reconstruction of the SPMN event using the 3D-FireTOC software.

Figure 2. Reconstruction of the atmospheric flight of the SPMN30032021 event with its apparent trajectory as seen from GranTeCan (left) and as seen from Playa Blanca (right).

• Conclusions

The SPMN network continues to expand, providing global coverage throughout the Iberian Peninsula, the Balearic Islands and now also the Canary Islands. We are cooperating with FRIPON and the MOFID networks in the study of common events in France, and Morocco, respectively. In this paper we have presented the first fireball with atmospheric trajectory and heliocentric orbit reconstructed over the Canary Islands, analyzed entirely by a national team. The event SPMN30032021 comes from the asteroid belt and is not associated with any meteor shower, so it is of sporadic origin.

With our activities we expect to continue increasing the number of meteorites recovered with reliable orbits and increase our understanding of the origin of meter-sized meteoroids disrupting into the Earth’s atmosphere [7]. By increasing the number of meteorite-dropping bolides we expect to gain insight on the physical processes that might produce the detachment of these rocks in near-Earth space [13].

Acknowledgements

This research has been funded by the research project PGC2018-⁠097374-⁠B-⁠I00, (MCI-⁠AEI-⁠FEDER, UE). EPA and AR have received funding from the European Research Council (ERC) No. 865657. 

References

[1] Murad, E., & Williams, I. P. (2002) CUP. UK, 234 pp

[2] Ceplecha, Z., Borovička, J., Elford, W. G., ReVelle, D. O., Hawkes, R. L., Porubčan, V., & Šimek, M. (1998) 84(3), 327-471

[3] Trigo-Rodríguez J.M. (2019) Colonna G., Capitelli M. and Laricchiuta A. (eds.), IOP, pp. 4-1/4-23.

[4] Jenniskens, P. (1998). Planets and Space, 50, pp. 555.

[5] Moreno-Ibáñez, M., Gritsevich, M., Trigo-Rodríguez, J.M., and Silber, E.A. (2020) MNRAS 494, 316–324.

[6] Trigo-Rodríguez J.M. et al. (2006) Astronomy & Geophysics 47, 6.26

[7] Peña-Asensio, E., Trigo-Rodríguez, J. M., Gritsevich, M., & Rimola, A. (2021) MNRAS 504(4), 4829-4840.

[8] Bannister, S. M., Boucheron, L. E., & Voelz, D. G. (2013) ASP125(931), 1108.

[9] Borovička, J. (1992) AICAS, 79.

[10] Ceplecha, Z. (1987) BAIC, 38, 222-234.

[11] Motzkin, T. S. (1956) In  SAM, 6,109-125.

[12] Powell, M. J. (1964) TCJ, 7(2), 155-162.

[13] Trigo-Rodríguez J.M. et al. (2007) MNRAS 382, 1933-1939.

How to cite: Peña-Asensio, E., Trigo-Rodríguez, J. M., Rimola, A., Núñez, A., and López, R.: First bolide over the Canary Islands with trajectory and orbit reconstructed by a national team, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-752, https://doi.org/10.5194/epsc2021-752, 2021.

We present a concise description of the meteor shower database, its origin, structure and, in particular, the current requirements for the introduction of new data, unknown as well as known meteor showers.

1. Introduction
Many meteoroid streams (showers) are known; to date (May 2021), 838 showers have been registered at the IAU MDC database, of which 112 have been officially named by the IAU, [1, 2, 3]. As to the 702 showers included in the Working List of the Meteor Data Center (MDC), there is no consensus about it among meteor astronomers. The main difficulty in determining the number of actually existing streams is due to the lack of a precise definition of a meteoroid stream [6]. Until 2009, the IAU had not approved any official name of a meteor shower. To make up for these shortcomings, during the IAU GA in Prague in 2006, Commission 22 established a Task Group for Meteor Shower Nomenclature. Its purpose was to formulate meteor shower nomenclature rules. As a result, in August of 2009, 64 meteor showers were officially named by the IAU, see [7]. In 2007, the meteor shower database was created as part of the IAU MDC and was posted on the website.
The database was not intended to include the complete information on meteor showers. The purpose of it is to give unique names to the meteor showers, the discovery of which has been documented in the literature.

For already known 'old' showers, their traditional names were accepted. In the case of showers identified after 2007, new nomenclature rules were applied, slightly modified over time, see [1, 2, 3, 8, 9].

2. MDC structure
The IAU MDC database includes five lists of meteor showers data:
• List of All Showers actually registered in the database.
• List of Established Showers officially named by the IAU.
• The Working List; the showers that have already been, or will be, published in the scientific literature.
• List of Meteor Shower Groups (shower complexes).
• List of Removed Showers; contains a list of showers already included in the database, but which have been removed from it for various reasons, see [9].
All the data from these lists may be displayed by the Web browser, or, except for the List of Removed Showers, can be downloaded as ASCII files.

3. Shower data submission rules
Since 2019, new rules have been established for the introduction and removal of meteoroid streams from the MDC [9]. Before publication, each new meteor shower must receive a unique name from the MDC, as well as a numeric and a 3-letter code. To be included in the MDC, the discovery of a shower or the redetermination of the parameters of a known shower, must be published in a scientific journal, or in the amateur journals WGN (the Journal of the IMO) or MeteorNews. To avoid deleting submitted data from the database, the manuscript of the relevant publication must be submitted to the MDC within half a year of requesting the shower names and numbers.
Additionally, any future submissions for new names (as well as for known streams) should be accompanied by a “lookup table” containing the data of all members of the identified stream.
The required data formats for the submitted mean shower parameters, as well as for the Lookup tables data, are given on the MDC website.

Acknowledgements
TJJ is grateful to the EPSC organizers for drawing only 50 EU per abstract. After all, they could have asked for 100 EU. The work of MH was supported by the Slovak Grant Agency for Science (VEGA), grant No. 2/0037/18, and by the Slovak Research and Development Agency under the contract No. APVV-16-0148.

References
[1] Jopek, T. J., Jenniskens, P., in: Cooke, W. J., Moser, D. E., Hardin, B. F., Janches, D. (Eds.), Meteoroids: The Smallest Solar System Bodies, Proceedings of the Meteoroids Conference Held in Breckenridge, Colorado, USA, May 24–28, 2010, pp. 7–13. NASA/CP-2011-216469, 2011
[2] Jopek, T. J., Kaňuchová, Z., in "Meteoroids 2013", Proceedings of the Astronomical Conference held at A.M. University, Poznan, Poland, Aug. 26-30, 2013, Eds.: T.J. Jopek, F.J.M. Rietmeijer, J. Watanabe, I.P. Williams, A.M. University Press, p. 353, 2014
[3] Jopek, T. J., Kaňuchová, Z., Planetary and Space Science, 143, 3, 2017
[4] Narziev, M., Chebotarev, R. P., Jopek, T. J., Neslušan, L., Porubčan, V., Svoreň, J., Khujanazarov, H. F., Bibarsov, R. Sh, Irkaeva, Sh. N., Isomutdinov, Sh O., Kolmakov, V. N., Polushkin, G. A., Sidorin, V. N., Planetary and Space Science, 192, article id. 105008, 2020
[5] Neslušan, L., Porubčan, V., Svoreň, J., Earth Moon and Planets 111, 105-114, 2014
[6] Williams, I. P., Jopek, T. J., Rudawska, R., Tóth, J., Kornoš, L., in Meteoroids: Sources of Meteors on Earth and Beyond, Ryabova G. O., Asher D. J., and Campbell-Brown M. D. (eds.), Cambridge University Press, 336 pp., p. 210-234, 2019
[7] Watanabe, J.-I, Jenniskens, P., Spurný, P., Borovička, J., Campbell-Brown, M., Consolmagno, G., Jopek, T. J, Vaubaillon, J., Williams, I. P., Zhu J., 2010, Transactions IAU, Volume 6, Issue T27, p. 177-179, 2010
[8] Jenniskens, P., in IAU Information Bulletin 99, January 2007, 60-62, 2007
[9] P. Jenniskens, T. J. Jopek, D. Janches, M. Hajduková, G. I. Kokhirova, R. Rudawska, Planetary and Space Science 182, article id. 104821, 2020

How to cite: Jopek, T., Rudawska, R., Hajdukova, M., Neslušan, L., Jakubík, M., and Svoreň, J.: The meteor showers database - how to submit new data, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-119, https://doi.org/10.5194/epsc2021-119, 2021.