Video observations of meteors in the CEMeNt network in May and June 2025
In May and June, only one relatively strong meteor shower is active — the Eta Aquariids. The Eta Aquariids have a broad maximum at the beginning of May and, similar to the Orionids, are characterised by several secondary peaks. The activity of the sporadic background starts to grow after its minimum in March and April. For the rest of both months, only isolated weak showers are active, mostly originating from the antihelion source. The radiants of these weaker showers lie mainly in Sagittarius, Scorpius and Ophiuchus and therefore rise only low above the horizon during the night. Overall, the weather during May and June was less favourable; nevertheless, in May at least one meteor was recorded at some network station on 22 nights, and in June on 27 nights. Lower meteor counts are affected by the length of the night and changeable weather during individual nights.
The maximum of the Eta Aquariid meteor shower occurred in the morning of 4 May 2025. Cameras of the CEMeNt network recorded a total of 27 multi-station orbits of meteors from this stream. According to the visual activity plot of the IMO VMDB (International Meteor Organization Visual Meteor Database), the maximum corrected hourly rate of the Eta Aquariids this year reached 40.2 ± 8.6 meteors, with the maximum on 4 May 2025 at 08:00 UT. The activity of the Eta Aquariids was below average this year and the total number of visual observations at maximum is very low. A secondary maximum with a rate of 38.8 ± 5.9 meteors occurred on 7 May 2025 at 01:28 UT.
Fig. 1: Overall 2D projection of multi-station atmospheric tracks recorded in the CEMeNt network in May 2025. Authors: Jakub Koukal, Alexandra Mikušková
Fig. 2: Overall 2D projection of multi-station atmospheric tracks recorded in the CEMeNt network in June 2025. Authors: Jakub Koukal, Alexandra Mikušková
Fig. 3: Radiants of stream and sporadic multi-station meteors recorded in the CEMeNt network in May and June 2025. A sinusoidal projection with the equatorial coordinate system is used. Authors: Jakub Koukal, Alexandra Mikušková
In May 2025, cameras of the CEMeNt network recorded 5,421 single-station meteors, which combined into 1,083 multi-station orbits (Fig. 1, 3). As of today, observations from stations on the outer perimeter of the network — Rokycany (CZ), Plzeň (CZ), Karlovy Vary (CZ), Blahová (SK) and Zvolenská Slatina (SK) — are not included, as their processing is not yet finished.
In June 2025, cameras of the CEMeNt network recorded 7,408 single-station meteors, which combined into 1,516 multi-station orbits (Fig. 2, 3). As of today, observations from stations on the outer perimeter of the network — Rokycany (CZ), Plzeň (CZ), Karlovy Vary (CZ), Blahová (SK) and Zvolenská Slatina (SK) — are not included, as their processing is not yet finished.
Fig. 4: 3D projection of heliocentric multi-station orbits of meteors belonging to the Eta Aquariid stream (ETA) in the Solar System. A total of 27 multi-station orbits of ETA were recorded in May 2025. Authors: Jakub Koukal, Alexandra Mikušková
Fig. 5: 3D projection of heliocentric multi-station orbits of meteors belonging to the Eta Lyrid stream (ELY) in the Solar System. A total of 23 multi-station orbits of ELY were recorded in May 2025. Authors: Jakub Koukal, Alexandra Mikušková
Fig. 6: 3D projection of heliocentric multi-station orbits of meteors belonging to the June Rho Cygnids (JRC) in the Solar System. A total of 28 multi-station orbits of JRC were recorded in June 2025. Authors: Jakub Koukal, Alexandra Mikušková
Most multi-station orbits belong to the sporadic background (2,161 orbits), followed by the June Rho Cygnids (JRC, 28 orbits, Fig. 6), Eta Aquariids (ETA, 27 orbits, Fig. 4), Eta Lyrids (ELY, 23 orbits, Fig. 5), and then other weaker streams, including members of the antihelion source with radiants in Ophiuchus, Sagittarius and Scorpius. The numbers of single-station meteors (as well as multi-station orbits) are historically the highest within the CEMeNt network since its inception in 2009. Pairing efficiency in May and June 2025 decreased to 60.6% and 63.4%, respectively, which is related to variable weather at individual stations. The station/orbit ratio is stable: 3.03 stations per orbit in May 2025 and 3.09 in June 2025. In total this year so far (as of 30 June 2025) 47,032 single-station meteors have been recorded, combining into 10,059 multi-station orbits (Tab. 1).
Tab. 1: Overview of the numbers of recorded and paired meteors in 2025 at CEMeNt network stations. Authors: Jakub Koukal, Alexandra Mikušková
In June (21 June 2025), a new station was installed in Veselí nad Moravou (CZ), equipped with a CMOS camera with a Sony Starvis IMX 290 LQR sensor; this camera operates at FHD resolution of 1920 × 1080 px (2.1 MPx) at 30 fps. The Starlight high-aperture lens (f/0.95) with a fixed focal length (4 mm) provides a field of view of 89 (± 1) × 50° in this configuration. The field of view is aimed to the northeast and complements the stations in Valašské Meziříčí, Vsetín and Ždánice; the station operator is Ivo Míček. In connection with the launch of the Southern Spectroscopic Observatory in Chile, from May the data processing from CEMeNt network stations has been carried out by Alexandra Mikušková, a specialist at the Valašské Meziříčí Observatory.
A rare event — the meteor cluster CM20250613_233904 — was recorded by CEMeNt cameras on 13 June 2025 from 23:39:04.5 ± 0.1 s UT to 23:39:05.5 ± 0.1 s UT. It consisted of three fragments formed by the breakup of the parent body before entering Earth’s atmosphere. Within the CEMeNt (Central European MetEor NeTwork) the cluster was captured directly by six wide-angle cameras (Fig. 7, 8). Recordings of the individual cluster members are available from Valašské Meziříčí NE and SE (CZ, Valašské Meziříčí Observatory), Ždánice E (CZ, Ždánice Observatory), Vsetín E (CZ, Vsetín Observatory), Pardubice SE (CZ, Pardubice Observatory) and Partizánske NE (SK, Observatory Partizánske).
Fig. 7: Composite image of the members of cluster CM20250613_233904, taken by the Ždánice E camera. Author: Ždánice Observatory
Fig. 8: Composite image of the members of cluster CM20250613_233904, taken by the Vsetín E camera. Author: Vsetín Observatory
A meteor cluster is a group of meteors that appear within a very short time interval (typically < 10 s), with the same or similar radiant, and have very similar orbits. A cluster can form by fragmentation of a larger particle just before atmospheric entry or in the upper atmosphere (an atmospheric cluster), or it can be an orbital cluster where fragments follow similar orbits and enter the atmosphere simultaneously due to a higher particle density in a meteor filament. The minimum number of meteors that can be considered a cluster is not strictly defined; it depends on context (observations, statistical analysis, physical interpretation).
Fig. 9: 3D projection of the heliocentric multi-station orbits of all members of cluster CM20250613_233904. Author: Jakub Koukal
The first criterion assessed was the probability of random occurrence. Using a Monte Carlo simulation, we calculated the probability that under the given conditions (meteor occurrence rate, camera field of view, total observation time, the ratio of meteors of the June Epsilon Cygnids stream within the time range considered to sporadic meteors) three meteor events with a time separation ≤ 1.03 seconds could occur within a random distribution of a total of 39 meteors during 388 minutes of observing time, with all belonging to the June Epsilon Cygnids (JEC). The number of simulation runs was set to 10,000 and the resulting probability of the defined event was 1.93 × 10⁻⁵. The second criterion assessed was the similarity of the heliocentric orbits of the meteors; the Southworth–Hawkins (DSH) orbital similarity criterion was used. The value of the Southworth–Hawkins criterion between individual cluster members was at most 0.034. These values confirm a very close relationship between all fragments.
The positions of all cluster members were converted to Cartesian coordinates in the ECEF (Earth-Centered, Earth-Fixed) system and the ejection velocities of the individual fragments (6.46; 4.44 and 2.31 m/s) relative to the parent body were then calculated. The estimated age of the cluster (i.e., the time of the original body’s breakup), taking into account acceleration due to solar radiation pressure, comes out to 5.56 h before atmospheric entry. Based on the calculations, the analysed cluster formed by natural fragmentation due to rapid rotation and centrifugal force, without the involvement of collisional or aerodynamic effects. This mechanism is compatible with the physical parameters, dynamics, and energy distribution of all fragments. The total estimated mass of the original meteoroid is 0.243 g, while the estimated sum of the masses of all three observed fragments is 0.178 g.
At the Valašské Meziříčí Observatory, three spectrographs are currently installed with monochrome CMOS cameras PointGrey Grasshopper3 GS3-U3-32S4M-C (2048 × 1536 px); the actual resolution of a recorded meteor spectrum (first order) averages 0.48 nm/px. These spectrographs are oriented SE, SW and NE; in the NW direction, a spectrograph with a monochrome CMOS camera QHY-III 178M (3072 × 2048 px) is installed, with an average spectral resolution of 0.35 nm/px (first order). In test operation, a spectrograph in the W direction is installed, consisting of a monochrome CMOS camera Flir BFS-U3-200S6M-C (5472 × 3648 px), with an average spectral resolution of 0.19 nm/px (first order). In May and June, 9 spectra from 6 individual fireballs were recorded by the spectrographs at the Valašské Meziříčí Observatory (Fig. 12–14).
Fig. 10: Composite image of the spectrum of fireball CM20250603_230025 MCY from spectrograph VM SPNW (resolution 0.36 nm/px). Author: Valašské Meziříčí Observatory
Fig. 11: Composite image of the spectrum of fireball CM20250603_230025 MCY from spectrograph VM SPW (resolution 0.19 nm/px). Author: Valašské Meziříčí Observatory
Acknowledgements
Thanks go to the companies DEZA, a.s., and CS CABOT, s.r.o., which contributed to the acquisition of equipment for the FHD stations located at the Valašské Meziříčí Observatory and within the CEMeNt network. Thanks also to all partner observatories (Ždánice, Vsetín, Rokycany, Plzeň, Karlovy Vary, Partizánske, Kysucké Nové Mesto) and to private station owners (Milan Čermák, Richard Kačerek, Jakub Kapuš, Tibor Csorgei, Vladimír Bahýl) for supporting the activities and growth of the network. Further thanks go to all involved institutions for supporting the network’s activities and growth. The RPOS project (Development of a Cross-Border Observation Network) was co-financed by the Small Project Fund of the Interreg V-A Slovakia–Czech Republic 2014–2020 programme, call code 5/FMP/11b, reg. no. CZ/FMP/11b/05/058. The projects KOSOAP (Cooperating Network in the Field of Astronomical Professional-Observational Programmes) and RPKS (Development of a Cross-Border Cooperating Network for Professional Work and Education) were implemented by the Valašské Meziříčí Observatory (CZ) and Kysucké Nové Mesto (SK) in cooperation with the SMPH (Society for Interplanetary Matter). The projects were co-financed by the Microprojects Fund of the Cross-Border Cooperation Operational Programme Slovakia–Czech Republic 2007–2013. The project for the purchase and operation of high-resolution spectroscopic cameras is partially funded by the Programme for Regional Cooperation of the Czech Academy of Sciences, reg. no. R200402101.
