Two meteor shower outbursts with potential connection to comet 73P/Schwassmann-Wachmann

By Denis Vida, Damir Šegon and Paul Roggemans

Abstract: Two new meteor showers with a Jupiter Family Comet type orbit (2.00 < TJ < 3.00) were detected during 2025 May 30–June 3 by the Global Meteor Network. Meteors belonging to these new showers were observed from two radiants at R.A. = 197°, Decl.= +52° and R.A. = 203°, Decl.= +7°, both likely dynamical related to comet 73P/Schwassmann-Wachmann fragments. The new meteor showers have been listed in the Working List of Meteor Showers under the temporary name-designation: M2025-L1 and M2025-L2.

Introduction

The first outburst occurred during 2025 May 30–June 1. Thirty-three meteors were recorded using the Global Meteor Network low-light video cameras. The shower was detected by stations in 14 countries; Belgium, the Czech Republic, Germany, France, Croatia, Hungary, Italy, South Korea, The Netherlands, New Zealand, Russia, Slovenia, the United Kingdom, and the United States. The shower had a median geocentric radiant with coordinates R.A. = 196.4°, Decl. = +51.0° (equinox J2000.0), within a circle with a standard deviation of ±1.8°. The geocentric velocity was 12.1 ± 0.1 km/s (Figure 1).

The second outburst began roughly simultaneously with the first one but lasted longer, until June 3. Forty-one meteors were recorded using the Global Meteor Network low-light video cameras. The shower was detected by stations in 16 countries; Australia, Belgium, Brazil, Canada, Germany, Greece, Croatia, Hungary, Italy, South Korea, The Netherlands, New Zealand, Slovenia, South Africa, the United Kingdom, and the United States. The radiants of the second outburst were significantly offset from the first, by around 44 degrees in equatorial coordinates. The second shower had a median geocentric radiant with coordinates R.A. = 203.0°, Decl. = +7.6° (equinox J2000.0), within a circle with a standard deviation of ±0.9°. The geocentric velocity was 11.7 ± 0.1 km/s (Figure 2).

Figure 1 – Heat map with 62286 radiants obtained by the Global Meteor network in May 2025 in Sun-centered geocentric ecliptic coordinates. The radiant of the first outburst is marked with a red arrow (M2025-L1).

Figure 2 – Heat map with 51531 radiants obtained by the Global Meteor network in June 2025 in Sun-centered geocentric ecliptic coordinates. The radiant of the second outburst is marked with a red arrow (M2025-L2).

The first analysis

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 this method, 33 orbits were identified with the first outburst and 41 with the second outburst.

Figure 3 – Dispersion on the radiant position for the first outburst (M2025-L1).

Figure 4 – Dispersion on the radiant position for the second outburst (M2025-L2).

The radiant drift in R.A. was +1.68° on the sky per degree of solar longitude and –0.44° in Decl., both referenced to solar longitude 69.5° for the first outburst (Figure 5).

The radiant drift in R.A. was –0.07° on the sky per degree of solar longitude and +0.46° in Decl., both referenced to solar longitude 71.5° for the second outburst (Figure 6).

Figure 5 – The radiant drift for the first outburst.

Figure 6 – The radiant drift for the second outburst.

For the first outburst, the geocentric, Sun-centered ecliptic longitude (λ–λ_ʘ) was 96.87°, and the geocentric ecliptic latitude was +52.23° (Figure 9). The activity period spanned solar longitudes 68°–73°, with a clear peak at 69.5° with a zenith hourly rate (ZHR) of about 0.2 meteors/hr. This peak of activity matches the tau Herculid meteor shower, although the radiant location is over 10 degrees away from the 2022 tau Herculid outburst.

For the second outburst, the geocentric, Sun-centered ecliptic longitude (λ–λ_ʘ) was 126.99°, and the geocentric ecliptic latitude was +15.9.°. The activity period spanned solar longitudes 68°–73°, with a broad peak around 71.5°.

Both outbursts were reported to the IAU-MDC working list of meteor showers and added as M2025-L1 for the first outburst and M2025-L2 for the second outburst.

Figure 7 – The radiant distribution during the solar-longitude interval 68° – 73° in equatorial coordinates for the first outburst.

Figure 8 – The radiant distribution during the solar-longitude interval 68° – 73° in equatorial coordinates for the second outburst.

Figure 9 – The radiant distribution during the solar-longitude interval 68° – 73° in Sun centered geocentric ecliptic coordinates for the first outburst.

Figure 10 – The radiant distribution during the solar-longitude interval 68° – 73° in Sun centered geocentric ecliptic coordinates for the second outburst.

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 different criteria thresholds. 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 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. We consider five different threshold levels of similarity:

Low: D_SH < 0.25 & D_D < 0.105 & D_H < 0.25;
Medium low: D_SH < 0.2 & D_D < 0.08 & D_H < 0.2;
Medium high: D_SH < 0.15 & D_D < 0.06 & D_H < 0.15;
High: D_SH < 0.1 & D_D < 0.04 & D_H < 0.1.
Very high: D_SH < 0.05 & D_D < 0.02 & D_H < 0.05.

For the first outburst the procedure converged after a few iterations at a mean orbit for all orbits that fitted the high threshold class. The radiant points for the lower threshold classes appear very scattered but with a clear concentration of radiants (Figure 11). The second outburst took many more iteration steps and converged at an optimal mean orbit for the very high threshold class for which the radiants show a very distinct concentration (Figure 12).

Figure 11 – The radiant distribution during the solar-longitude interval 68° – 73° in equatorial coordinates for the first outburst, color coded for different thresholds of the DD orbit similarity criteria.

Figure 12 – The radiant distribution during the solar-longitude interval 68° – 73° in equatorial coordinates for the second outburst, color coded for different thresholds of the DD orbit similarity criteria.

Looking at the plot with the radiants in Sun-centered geocentric ecliptic coordinates for the first outburst (Figure 13), the radiant drift has been compensated but the radiant of the first outburst still appears rather diffuse compared to the concentration at the bottom right in the plot which is the radiant for the second outburst. Figure 14 shows the radiants in Sun-centered geocentric ecliptic coordinates centered on the second outburst.

Figure 13 – The radiant distribution in Sun-centered geocentric ecliptic coordinates for the first outburst, color coded for different thresholds of the DD orbit similarity criteria.

Figure 14 – The radiant distribution in Sun-centered geocentric ecliptic coordinates for the second outburst, color coded for different thresholds of the DD orbit similarity criteria.

The concentration of similar orbits becomes even more obvious in the diagram of the inclination i against the longitude of perihelion Π. The concentration is more distinc in this diagram than in the radiant plots, for the orbits of the first outburst in Figure 15 and the second outburst in Figure 16. Orbits that fit the more tolerant discrimination thresholds are most likely sporadics that fullfil these criteria by chance but some orbits may be more dispersed shower members. Similarity criteria do not provide any certainty in these specific cases.

Figure 15 – Diagram of inclination i against the longitude of perihelion Π for the first outburst, color coded for different thresholds of the DD orbit similarity criteria.

Figure 16 – Diagram of inclination i against the longitude of perihelion Π for the second outburst, color coded for different thresholds of the DD orbit similarity criteria.

When all data were collected the GMN shower association criterion identified 52 orbits for the first outburst, eight of which fail in the discrimination threshold with D_SH < 0.1 & D_D < 0.04 & D_H < 0.1. 46 orbits were identified for the second outburst according to the GMN shower association criterion for which only two fail to fit the above thresholds of the similarity criteria.

The method based on D-criteria identified 56 orbits for the first outburst that fulfil the discrimination threshold with D_SH < 0.1 & D_D < 0.04 & D_H < 0.1 of which 12 were not detected by the GMN shower association criterion. For the second outburst this method identified 47 orbits of which only three were not detected by the GMN shower association criterion.

The orbits of both outbursts

The discovery of the two outbursts was announced as soon as the data for these nights were processed (Vida et al., 2025). The data has also been added to the IAU MDC Working List of Meteor Showers as M2025-L1 and M2025-L2. Meanwhile more meteors were associated with both orbits and identified as M25L1 and M25L2 in the GMN meteor orbit dataset. The mean orbits for the different datasets and methods are in very good agreement apart from the difference in radiant drift for the first outburst which is due to the rather scattered radiant and short time span to derive the radiant drift. The different solutions are listed in Table 1 for the first outburst and in Table 2 for the second outburst. The column MDC lists the initial values as included in the IAU MDC Working List of Meteor Showers, M25-L1 and M25-L2 are the parameters for all orbits with this identification in the GMN orbit dataset. The columns D_D < 0.04 and D_D < 0.02 are the solutions obtained with the shower identification method based on D-criteria for these D-criteria thresholds. The different datasets and both different methods result in almost identical orbital parameters.

Table 1 – Comparing the orbits for the first outburst, derived by the two methods, MDC lists the orbital parameters as initially derived and reported to the IAU-MDC, M25-L1 with all data processed, D_D < 0.04 and D_D < 0.02 are the mean orbits according to the method described in Section 3.

	MDC	M25-L1	D_D < 0.04	D_D < 0.02
λ_ʘ (°)	69.5	69.6	69.7	69.5
λ_ʘb (°)	68.0	68.4	68.4	68.4
λ_ʘe (°)	73.0	73.0	73.0	73.0
α_g (°)	197.0	196.6	196.6	196.6
δ_g (°)	+51.5	+51.6	+51.6	+51.2
Δα_g (°)	+1.68	+1.82	+1.43	–
Δδ_g (°)	–0.44	–0.31	+0.33	–
v_g (km/s)	12.1	12.0	12.0	12.0
λ_g (°)	166.37	165.88	165.9	166.5
λ_g–λ_ʘ (°)	96.87	95.91	96.1	96.8
β_g (°)	+52.23	+51.69	+51.7	+51.7
a (A.U.)	2.83	2.80	2.80	2.81
q (A.U.)	1.013	1.013	1.013	1.013
e	0.642	0.638	0.639	0.640
i (°)	14.6	14.5	14.5	14.5
ω (°)	182.4	182.2	182.4	182.4
Ω (°)	69.8	70.0	70.0	69.6
Π (°)	252.2	252.1	252.3	252.0
T_j	2.93	2.95	2.95	2.94
N	33	52	56	20

Figure 17 – The mean orbits for both outbursts, blue is for L2025-L1 and red for L2025-2. (Plotted with the Orbit visualization app provided by Pető Zsolt).

Table 2 – Comparing the orbits for the second outburst, derived by the two methods, MDC lists the orbital parameters as initially derived and reported to the IAU-MDC, M25-L2 with all data processed, D_D < 0.04 and D_D < 0.02 are the mean orbits according to the method described in Section 3.

	MDC	M25-L2	D_D < 0.04	D_D < 0.02
λ_ʘ (°)	71.5	71.0	71.0	71.2
λ_ʘb (°)	68.0	68.8	68.8	68.8
λ_ʘe (°)	73.0	72.9	72.9	72.9
α_g (°)	203.1	203.1	203.2	203.2
δ_g (°)	+7.5	+7.3	+7.3	+7.3
Δα_g (°)	–0.07	–0.06	+0.02	+0.09
Δδ_g (°)	+0.46	+0.45	+0.23	+0.46
v_g (km/s)	11.7	11.8	11.8	11.8
λ_g (°)	198.49	198.46	198.5	198.6
λ_g–λ_ʘ (°)	126.99	127.32	127.5	127.4
β_g (°)	+15.93	+15.81	+15.9	+15.9
a (A.U.)	3.921	4.03	3.96	3.96
q (A.U.)	0.980	0.979	0.979	0.979
e	0.750	0.757	0.753	0.753
i (°)	4.8	4.8	4.8	4.8
ω (°)	202.9	202.9	202.8	202.9
Ω (°)	71.1	71.0	71.1	71.1
Π (°)	274.0	273.9	273.9	274.0
T_j	2.47	2.44	2.46	2.46
N	41	46	47	38

Figure 18 – The mean orbits for both outbursts, blue is for L2025-L1 and red for L2025-2, close-up in the inner Solar System. (Plotted with the Orbit visualization app provided by Pető Zsolt).

Figure 17 shows both orbits relative to the planets. M2025-L1 has its aphelion (4.6 AU) within the orbit of Jupiter and M2025-L2 has its aphelion (7 AU) between the orbits of Jupiter and Saturn. Figure 18 shows a close-up in the inner solar system with both dust trails catching up with the Earth from the rear, meaning that the radiants are located at the evening sky with meteors that hit the Earth with a very slow geocentric velocity.

Parent body search

The Tisserand’s parameter T_j identifies the orbits of both outbursts as of a Jupiter Family Comet type, hence a comet is the most likely candidate as parent body.

A search for a parent body using the Drummond D-criterion returned several matches on minor planets with D_D < 0.07, but only one comet: 73P/Schwassmann-Wachmann (D_D = 0.06), the parent body of the tau Herculids, suggests a tentative dynamical relationship for the first outburst (Table 3).

Table 3 – Top ten search results for possible parent bodies for the first outburst M2025-L1with D_D < 0.07.

Name	D_D
2014 JL25	0.039
2010 JN71	0.053
2014 ER49	0.055
2021 GR7	0.056
2018 JZ1	0.059
2019 KZ3	0.061
2006 HQ30	0.062
73P/Schwassmann-Wachmann 3-S	0.062
2025 KH2	0.062
2007 KE4	0.065

For the second outburst the top-ten closest objects during a parent-body search using the Drummond D-criterion were all fragments of comet 73P, all with D_D < 0.062; the best matching fragment was component Y, with D_D = 0.054 (Table 4).

Table 4 – Top ten search results for possible parent bodies for the second outburst M2025-L2 with D_D = 0.062.

Name	D_D
73P/Schwassmann-Wachmann 3-Y	0.054
73P/Schwassmann-Wachmann 3-BW	0.056
73P/Schwassmann-Wachmann 3-AP	0.059
73P/Schwassmann-Wachmann 3-AS	0.059
73P/Schwassmann-Wachmann 3-BC	0.06
73P/Schwassmann-Wachmann 3-AL	0.06
73P/Schwassmann-Wachmann 3-BV	0.06
73P/Schwassmann-Wachmann 3-Q	0.06
73P/Schwassmann-Wachmann 3-BS	0.06
73P/Schwassmann-Wachmann 3-W	0.06

The Canadian Meteor Orbit Radar (CMOR) did not detect any members of either outburst, suggesting that the events were dominated by larger particles, in contrast to the 2022 tau Herculid outburst, which was rich in smaller meteoroids and well observed by CMOR (Egal et al., 2023). The two temporally adjacent but dynamically distinct 2025 outbursts indicate the presence of separate dust filaments from comet 73P intersecting the Earth’s orbit within a few days of each other (M2025-L1 represented best by 73P fragment S). Although similar in timing to the 2022 tau Herculid outburst, both 2025 radiants are spatially offset, implying distinct release epochs or differing trail evolution.

Notably, the 2022 tau Herculid radiant at R.A. = 209.17°, Decl. = +28.21°, lies almost equidistant between the 2025 outburst radiants (about 20° from each one), further supporting the interpretation of multiple discrete filaments originating from comet 73P. The complicating factor in dynamical modelling of the meteoroid complex is the high uncertainty of the comet’s orbit prior to 1930. Further modelling work is required to investigate whether the observed showers are caused by older trails, ejecta from the fragments after the break-up (observed for some of them shortly after 1995), or by material released in 1995 but with different ejection velocities.

Conclusion

Two meteor outbursts detected and covered by the Global Meteor Network during 2025 May 30–June 3 have been analyzed by two different methods and were reported to the IAU MDC as two possible new meteor showers. The orbits proved to be Jupiter Family comet type meteor orbits and a parent body search resulted in a most likely dynamical relationship with comet 73P/Schwassmann-Wachmann fragments related with the tau Herculids which displayed strong activity in 2022. No other optical or radar observations for these 2025 outbursts were know at the time this report was written.

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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