By Denis Vida, Damir Šegon and Paul Roggemans
Abstract: A new meteor shower on a retrograde Halley-type comet orbit (TJ = 0.10) has been detected during June 15–30, 2025 by the Global Meteor Network. Meteors belonging to the new shower were observed between 85° < λʘ < 99° from a radiant at R.A. = 319.4° and Decl.= +9° in the constellation of Equuleus, with a geocentric velocity of 56.9 km/s. The new meteor shower has been listed in the Working List of Meteor Showers under the temporary name-designation: M2025-O1.
Introduction
The GMN radiant map for June 2025 shows a weak concentration of related radiants in the constellation of Equuleus. 46 meteors of this meteor shower were observed by the Global Meteor Network low-light video cameras on 2025 June 16 – 30 (Figure 1). The shower was independently observed by cameras in 22 countries across the globe (Australia, Austria, Belgium, Brazil, Chile, Croatia, Czechia, France, Germany, Greece, Hungary, Italy, Luxembourg, Netherlands, New Zealand, Portugal, Slovenia, South Korea, Spain, Switzerland, United Kingdom, United States).
The shower had a median geocentric radiant with coordinates R.A. = 319.4°, Decl. = +9.2°, within a circle with a standard deviation of ±1.2° (equinox J2000.0) see Figure 2. The radiant drift in R.A. is +0.66° on the sky per degree of solar longitude and +0.21° in declination, both referenced to λʘ = 92.2° (Figures 3 and 4). The median Sun-centered ecliptic coordinates were λ – λʘ = 232.75°, β = 23.72° (Figure 5). The geocentric velocity was 56.9 ± 0.7 km/s.
All meteors appeared during the solar-longitude interval 85° – 99°, with most events around 23–24 June (λʘ = 92.2°).
Figure 1 – Heat map with 51531 radiants obtained by the Global Meteor network in June 2025. A weak concentration is visible in Sun-centered geocentric ecliptic coordinates which was identified as a new meteor shower with the temporary identification M2025-O1.
Figure 2 – Dispersion on the radiant position.
Figure 3 – The radiant drift.
Figure 4 – The radiant distribution during the solar-longitude interval 85° – 99° in equatorial coordinates.
Figure 5 – The radiant distribution during the solar-longitude interval 85° – 99° in Sun centered geocentric ecliptic coordinates.
First detection
The GMN shower association criterion assumes that meteors within 1° in solar longitude, within 3° in radiant, and within 10% in geocentric velocity of a shower reference location are members of that shower. Further details about the shower association are explained in Moorhead et al. (2020). This is a rather strict criterion since meteor showers often have a larger dispersion in radiant position, velocity and activity period. Using these meteor shower selection criteria, 46 orbits have been associated with the new shower in the GMN meteor orbit database and the mean orbit has been listed in Table 1. This possible new meteor shower was reported to the IAU MDC and added under the temporary identification 2025-O1.
Another search method
Another method has been applied to check this new meteor shower discovery. The starting point here can be any visually spotted concentration of radiant points or any other indication for the occurrence of similar orbits. The method has been described before (Roggemans et al., 2019). The main difference with the method applied in Section 2 is that three different discrimination criteria are combined in order to have only those orbits which fit the threshold for different criteria. The D-criteria that we use are these of Southworth and Hawkins (1963), Drummond (1981) and Jopek (1993) combined. Instead of using a cutoff value for the threshold of the D-criteria these values are considered in different classes with different thresholds of similarity. Depending on the dispersion and the type of orbits, the most appropriate threshold of similarity is selected to locate the best fitting mean orbit as the result of an iterative procedure.
This method resulted in a mean orbit with 45 related orbits that fit within the similarity threshold with DSH < 0.20, DD < 0.08 and DJ < 0.2, recorded 2025 June 16 – 30. The plot of the radiant positions in equatorial coordinates, color coded for different D-criteria thresholds, shows a stretched trail in Right Ascension from about 314° to 324° due to the radiant drift (Figure 6), see also Figure 3.
Looking at the Sun-centered geocentric ecliptic coordinates the radiant drift caused by of the Earth moving on its orbit around the Sun is compensated and a more compact radiant becomes visible (Figure 7). The blue dots with DSH < 0.25, DD < 0.105 and DJ < 0.25 as well as the green dots with DSH < 0.20, DD < 0.08 and DJ < 0.2 display a large dispersion and may include sporadics. To reduce the risk of contamination with sporadic orbits, in the second method only orbits with DSH < 0.15, DD < 0.06 and DJ < 0.15 are considered. Figures 8 and 9 show that these radiants appear on top of an evenly distributed sporadic radiant background. The diagram with the inclination against the longitude of perihelion (Figure 10) shows quite a lot dispersion on the longitude of perihelion Π.
Figure 6 – The radiant distribution during the solar-longitude interval 85° – 99° in equatorial coordinates, color coded for different values of the DD orbit similarity criterion.
Figure 7 – The radiant distribution during the solar-longitude interval 85° – 99° in Sun-centered geocentric ecliptic coordinates, color coded for different values of the DD orbit similarity criterion.
Figure 8 – The sporadic radiants during the solar-longitude interval 85° – 99° in Sun-centered geocentric ecliptic coordinates, with M2025-O1 radiants marked in grey for DD < 0.06.
Figure 9 – The M2025-O1 radiants for DD < 0.06 during the solar-longitude interval 85° – 99° in Sun-centered geocentric ecliptic coordinates, with the sporadic radiants marked in grey.
Figure 10 – The diagram of the inclination i against the longitude of perihelion Π for different classes of D criterion threshold.
Orbit and parent body
Figure 11 visualizes the two orbits plotted in the solar system. Figure 12 is a close up in the inner solar system with the intersection of the meteoroid stream orbit and the Earth orbit. The M2025-O1 orbit encounters the Earth at its descending node. The Tisserand’s parameter Tj identifies the orbit as of a Halley-type comet in this case with a retrograde orbit. A parent-body search top 10 includes candidates with a Southworth and Hawkings D criterion value lower than 0.4 but none of which can be associated with any certainty (Table 2). It would be up to meteoroid stream modelers to reconstruct the dynamic orbit evolution to see if there could be any connection.
Figure 11 – Comparing the mean orbit based on the shower identification according to the two methods, blue is for M2025-O1 and red for the alternative shower search method with DD < 0.06 in Table 1. (Plotted with the Orbit visualization app provided by Pető Zsolt).
Figure 12 – Comparing the mean orbit based on the shower identification according to two methods, blue is for M2025-O1 and red for the other shower search method with DD < 0.06 in Table 1, close-up at the inner Solar System. (Plotted with the Orbit visualization app provided by Pető Zsolt).
Table 1 – Comparing the new meteor shower, derived by two different methods, M2025-O1 lists the orbital parameters as initially derived and DD < 0.06 lists the result obtained with the method described in Section 3.
| M2025-O1 | DD < 0.06 | |
| λʘ (°) | 92.2 | 92.2 |
| λʘb (°) | 85.0 | 87.5 |
| λʘe (°) | 99.0 | 98.7 |
| αg (°) | 319.4 | 318.7 |
| δg (°) | 9.2 | 8.6 |
| Δαg (°) | 0.66 | 0.64 |
| Δδg (°) | 0.21 | 0.33 |
| vg (km/s) | 56.9 | 57.2 |
| λg (°) | 324.95 | 324.35 |
| λg – λʘ (°) | 232.75 | 232.37 |
| βg (°) | +23.72 | +23.55 |
| a (A.U.) | 10.1 | 11.3 |
| q (A.U.) | 0.400 | 0.394 |
| e | 0.960 | 0.965 |
| i (°) | 118.4 | 118.3 |
| ω (°) | 283.5 | 284.2 |
| Ω (°) | 91.4 | 91.7 |
| Π (°) | 14.9 | 15.9 |
| Tj | 0.15 | 0.10 |
| N | 46 | 33 |
Table 2 – Top ten search results for possible parent bodies with DSH < 0.4.
| Name | DSH |
| C/2025 K1 (ATLAS) | 0.27 |
| C/1793 S2 (Messier) | 0.30 |
| C/1979 Y1 (Bradfield) | 0.34 |
| C/1771 A1 (Great comet) | 0.35 |
| C/1992 W1 (Ohshita) | 0.35 |
| C/1969 T1 (Tago-Sato-Kosaka) | 0.35 |
| C/2005 K2 (LINEAR) | 0.39 |
| C/2005 K2-A (LINEAR) | 0.39 |
| C/1780 U1 (Montaigne-Olbers) | 0.40 |
| C/1951 P1 (Wilson-Harrington) | 0.40 |
This possible new meteor shower is very likely an old trail of dust, dispersed with a rather large spread in the longitude of perihelion Π and with a barely detectable weak activity. The final mean orbits obtained via the two independent meteor shower search methods are in very good agreement. The first meteor shower search includes seven orbits that failed to fit the DD < 0.08 criteria in the second method, while the second method includes six orbits that were ignored by the first search method. The differences between both methods occurred mainly at the beginning of the detected activity period and concern outliers that could be sporadic contamination. In total 39 orbits were in common by both methods. All 33 orbits that fit the DD < 0.06 criteria in the second method were found by the first search method too.
Activity in past years
A search in older GMN orbit data revealed 16 orbits that fit the DD < 0.06 criterion during the interval 85° < λʘ < 99°, one in 2021, two in 2022, three in 2023 and ten similar orbits in 2024. Among the 529076 orbits of SonotaCo only three similar orbits were found. Another three similar orbits were found in EDMOND data from 2015 and 2016. CAMS orbit data has not been searched. The weak activity of this meteor shower requires a high-capacity camera network to resolve the presence of these orbits within the sporadic background.
Conclusion
The discovery of a new meteor shower with a radiant in the constellation of Equuleus based on forty-six meteors during 2025 June 15–30 has been confirmed by using two independent meteor shower search methods. The resulting mean orbits for both search methods are in good agreement. All meteors appeared during the solar-longitude interval 85° – 99°, with most events around 23–24 June (λʘ = 92.2°). There is almost no trace of this meteor shower in past years meteor orbit datasets.
Acknowledgment
This report is based on the data of the Global Meteor Network (Vida et al., 2020a; 2020b; 2021) which is released under the CC BY 4.0 license. We thank all 825 participants in the Global Meteor Network project for their contribution and perseverance. A list with the names of the volunteers who contribute to GMN has been published in the 2024 annual report (Roggemans et al., 2025).
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