By Paul Roggemans, Denis Vida, Damir Šegon, James M. Scott, Jeff Wood
Abstract: An activity source identified as the xi2-Lupids was detected between the 27h of January and the 7th of February 2024–2026. It has a radiant at R.A. = 244.9° and Decl.= –35.2°, and a geocentric velocity of 64.9 km/s. The shower is the twin of the July Pegasids (JPE#175) with C/1979 Y1 (Bradfield) and the great Comet of 1771 (C/1771 A1) as parent body. This case study confirms the existence of this annual meteor shower that fulfils the criteria in order to be nominated for established status by the IAU-MDC.
1 Introduction
A weak activity source was spotted on the GMN radiant density maps in late January and early February 2026. The radiant was identified as the xi2-Lupids (XLU#1100). This shower was noticed by Jenniskens (2023) in CAMS data recorded in 2020–2021. A first solution was reported to the IAU Meteor Data Center (MDC) Working List of Meteor Showers, based upon 28 meteors recorded by CAMS.
GMN has collected sufficient data to confirm and improve characterization of this weak minor shower. The results are presented and discussed in this case study.
Figure 1 – Radiant density map with 46139 radiants obtained by the Global Meteor Network during January, 2026. The position of the xi2-Lupids in Sun-centered geocentric ecliptic coordinates is marked with a yellow arrow.
Figure 2 – The weak footprint of the xi2-Lupids during three consecutive nights.
2 Shower classification based on radiants
The GMN shower association criteria assume that meteors within 1° in solar longitude, within 3.5° in radiant in this case, 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). Using these meteor shower selection criteria, 133 orbits have been identified as xi2-Lupids recorded in 2024–2026 by 205 GMN cameras installed in Australia, Brazil, Bulgaria, Greece, Mexico, New Zealand, Russia, United States and South Africa. The final results have been listed in Table 2.
Figure 3 – Dispersion median offset on the radiant position.
Figure 4 – The radiant distribution during the solar-longitude interval 307.5° – 317.0° in equatorial coordinates.
Figure 5 – The radiant drift.
Figure 6 – The radiant distribution during the solar-longitude interval 307.5° – 317.0° in Sun centered geocentric ecliptic coordinates.
3 Shower classification based on orbits
A complete independent meteoroid stream search has been applied to orbit data obtained between Solar Longitude 291.0° and 318.0° during the years 2019 to 2026. 168670 orbits were available within this time interval and a final mean orbit has been computed by the method of Jopek et al. (2006) for the thresholds according to the Rayleigh fit in Figure 7, DSH < 0.15 and DD < 0.06 and DJ < 0.15 (Southworth and Hawkins, 1963; Drummond, 1981; Jopek, 1993. The results and mean orbit based upon 122 meteors for 2022–2026 are listed in Table 2. The method has been described in detail in a separate publication (Roggemans et al., 2026a).
Figure 7 – Rayleigh fit on the Drummond criterion for xi2-Lupids, 2026 data.
Figure 8 – The radiant distribution during the solar-longitude interval 304° – 318° in equatorial coordinates, color-coded for different threshold values of the combined similarity criteria.
Figure 9 – The radiant distribution during the solar-longitude interval 304° – 318° in Sun-centered geocentric ecliptic coordinates, color-coded for different threshold values of the combined similarity criteria.
During 2024–2026 and within the activity period for Solar Longitude 307°–318°, both methods recorded 134 candidate xi2-Lupids. Of these, 86 (64%) were identified in common, 47 (35%) were detected by the radiant method but failed to fit the orbit similarity thresholds, and one (1%) was detected by the orbit method but ignored by the radiant method. In this case, the radiant method turns out to be more tolerant than the orbit method. Figure 8 shows an elongated radiant, stretched due to the radiant drift caused by the Earth on its orbit around the Sun. In Sun-centered ecliptic coordinates the radiant appears as a compact cluster (Figure 9) but surrounded by a concentration of non-shower radiants that failed to fit the D-criteria thresholds but which fulfill the radiant position and velocity filter of the radiant method.
The ratio shower/non-shower results in an activity profile with a broad plateau activity without any clear peak (Figure 10). The relative activity in the past three years covered by the radiant method was slightly stronger than the activity detected by the orbit method during 2021–2026. Jenniskens (2023) gives as activity period Solar Longitude 291°–318°, but no trace of activity was detected by GMN before λʘ = 301°. The orbit method detected XLU-orbits one week earlier than the radiant method and the profile suggests that the activity may last until past λʘ = 318°, which was the end of the studied time interval.
Figure 10 – The percentage of xi2-Lupids relative to the total number of meteors, for the radiant method (2024–2026) and the orbit classification method 2023–2026.
Table 1 – Number of xi2-Lupid orbits detected by GMN per year.
| Year | Orbit method | Radiant method |
| 2021 | 1 | – |
| 2022 | 3 | – |
| 2023 | 16 | – |
| 2024 | 31 | 44 |
| 2025 | 42 | 55 |
| 2026 | 29 | 34 |
4 Orbit and parent body
The diagram of the inclination i versus the Longitude of Perihelion Π shows a concentration in i, stretched in Π (Figure 11). The eccentricity e versus the Longitude of Perihelion Π appears scattered (Figure 12). The spread in Longitude of Perihelion is caused by a steep increase in Longitude of Perihelion during the activity period (Figure 16). The perihelion distance q increases (Figure 17), eccentricity e decreases (Figure 18) and inclination i remains stable (Figure 19) during the activity period. The cluster of XLU orbits is best visible in the diagram perihelion distance versus inclination (Figure 14).
Figure 11 – Inclination i versus the Longitude of Perihelion Π color-coded for different classes of D-criteria thresholds, for λʘ between 304° and 318°. Spor. = sporadics.
Figure 12 – Eccentricity e versus the Longitude of Perihelion Π color-coded for different classes of D-criteria thresholds, for λʘ between 304° and 318°. Spor. = sporadics.
Figure 13 – Eccentricity e versus the inclination i color-coded for different classes of D-criteria thresholds, for λʘ between 304° and 318°. Spor. = sporadics.
Figure 14 – Perihelion distance q versus the inclination i color-coded for different classes of D-criteria thresholds, for λʘ between 304° and 318°. Spor. = sporadics.
Figure 15 – Perihelion distance q versus the eccentricity e color-coded for different classes of D-criteria thresholds, for λʘ between 304° and 318°. Spor. = sporadics.
Figure 16 – The evolution of the Longitude of Perihelion Π in function of the Solar Longitude λʘ based upon the radiant method (2024–2026) and upon the orbit method (2021–2026).
Figure 17 – The evolution of the perihelion distance q in function of the Solar Longitude λʘ based upon the radiant method (2024–2026) and upon the orbit method (2021–2026).
Figure 18 – The evolution of the eccentricity e in function of the Solar Longitude λʘ based upon the radiant method (2024–2026) and upon the orbit method (2021–2026).
Figure 19 – The evolution of the inclination i in function of the Solar Longitude λʘ based upon the radiant method (2024–2026) and upon the orbit method (2021–2026).
The Tisserand value relative to Jupiter with TJ = –0.25 is typical for a long-period cometary orbit (Figure 20). The meteoroid stream crosses the ecliptic and Earth’s orbit on a retrograde orbit (i > 90°) at its ascending node (Figure 21).
Table 2 – Comparing solutions obtained by the radiant method for 2024–2026, the orbit method 2021–2026 for DD < 0.06 and DD < 0.05, compared to the solution by Jenniskens (2023).
| Radiant 2024–26 | Orbit
DD < 0.06 |
Orbit
DD < 0.05 |
Jenniskens (2023) | |
| λʘ (°) | 311.5 | 311.5 | 312.6 | 307 |
| λʘb (°) | 301.0 | 301.1 | 304.0 | 291 |
| λʘe (°) | 318.0 | 318.0 | 318.0 | 318 |
| αg (°) | 244.9 | 243.2 | 244.3 | 238.0 |
| δg (°) | –35.2 | –34.8 | –35.1 | –34.0 |
| Δαg (°) | +0.98 | +0.98 | +1.00 | +0.90 |
| Δδg (°) | –0.17 | –0.17 | –0.14 | –0.26 |
| vg (km/s) | 64.9 | 65.1 | 65.2 | 65.4 |
| Hb (km) | 110.8 | 111.0 | 111.0 | 112.5 |
| He (km) | 98.6 | 99.0 | 98.8 | 98.0 |
| Hp (km) | 103.9 | 104.0 | 104.0 | 101.8 |
| MagAp | –0.7 | –0.6 | –0.6 | +1.3 |
| λg (°) | 249.1 | 247.8 | 248.6 | 243.2 |
| λg – λʘ (°) | 296.1 | 296.0 | 296.0 | 296.6 |
| βg (°) | –13.6 | –13.6 | –13.7 | –13.5 |
| a (A.U.) | 10.2 | 11.4 | 12.3 | 28.8 |
| q (A.U.) | 0.522 | 0.524 | 0.528 | 0.522 |
| e | 0.949 | 0.954 | 0.957 | 0.982 |
| i (°) | 149.9 | 150.1 | 150.0 | 150.2 |
| ω (°) | 272.2 | 272.6 | 273.0 | 272.7 |
| Ω (°) | 132.8 | 131.2 | 132.1 | 126.6 |
| Π (°) | 45.0 | 43.8 | 45.1 | 37.6 |
| Tj | –0.25 | –0.31 | –0.35 | –0.57 |
| N | 133 | 122 | 88 | 106 |
Figure 20 – Comparing the radiant determined xi2-Lupids solution (yellow) with the orbit determined solution (blue). (Plotted with the Orbit visualization app provided by Pető Zsolt).
Figure 21 – Comparing the radiant determined xi2-Lupids solution (yellow) with the orbit determined solution (blue), close-up at the inner Solar System. (Plotted with the Orbit visualization app provided by Pető Zsolt).
Table 3– Top ten matches of a search for possible parent bodies with DD < 0.3, based upon the mean orbit derived from the radiant classification method.
| Name | DD |
| C/1771 A1 (Great comet) | 0.073 |
| C/1979 Y1 (Bradfield) | 0.106 |
| C/1590 E1 | 0.122 |
| C/1992 J2 (Bradfield) | 0.123 |
| C/1995 Q1 (Bradfield) | 0.198 |
| C/2015 G2 (MASTER) | 0.212 |
| C/1976 E1 (Bradfield) | 0.227 |
| C/1896 C1 (Perrine-Lamp) | 0.257 |
| C/1822 K1 (Pons) | 0.263 |
| C/1864 R1 (Donati) | 0.278 |
Table 4 – The orbital elements of the xi2-Lupids, the two possible parent bodies, C/1771 A1, C/1979 Y1 and the twin shower July Pegasids (Jenniskens, 2023) with the D-criteria relative to XLU.
| XLU #1100N | C/1771 A1 | C/1979 Y1 | JPE #175 (CAMS) | |
| q | 0.522 | 0.528 | 0.545 | 0.559 |
| e | 0.949 | 1.000 | 0.988 | 0.968 |
| i | 149.9 | 148.56 | 148.6 | 149.2 |
| ω | 272.2 | 260.4 | 257.6 | 265.4 |
| Ω | 132.8 | 111.9 | 103.2 | 113.1 |
| Π | 45.0 | 12.3 | 0.8 | 18.5 |
| DD | 0.073 | 0.106 | 0.085 | |
| DSH | 0.21 | 0.33 | 0.25 |
The solutions found with the radiant and orbit method (Table 2) are in agreement and confirm the orbit obtained by CAMS (Jenniskens, 2023). Figure 21 reveals that the ascending node is also close to the Earth orbit. Such a situation makes it very likely that the Earth encounters the same dust twice as a twin shower.
The twin of the xi2-Lupids is likely to be the July Pegasids (JPE#175), an established shower that displays a much stronger activity than the xi2-Lupids. Holman and Jenniskens (2013) have shown that the July Pegasids are related to the Great Comet of 1771 (C/1771 A1) as well as the comet C/1979 Y1 Bradfield identified earlier by Ueda (2012). Both may be the same comet or remnants of a larger body that broke up at the formation of the related meteoroid streams. Hajduková and Neslušan (2017), modelled the dust trails produced by comet C/1979 Y1 (Bradfield) and linked this to the observed July Pegasids. The xi2-Lupids are very likely related to the filament F2 in this model, but the shower was unknown at the time of the publication of the model in 2017.
Although the thresholds for the Drumond criterion with DD = 0.085 looks like a favorable degree of similarity, the Southworth and Hawkins criterion is less convincing with DSH = 0.25. The XLU-orbit and the JPE-orbit differ significantly in node and longitude of perihelion. The low activity level without a clear peak activity and the scatter on the Kepler elements indicate that the Earth crosses the outliers of the meteoroid stream at the ascending node. The xi2-Lupids are a barely detectable footprint of this dust while Earth encounters the denser part of the stream at the descending node which is responsible for the much better activity levels of the July Pegasids. Table 4 lists the Kepler elements and the DD and DSH criteria thresholds relative to the XLU-orbit.
5 Conclusion
This GMN meteoroid orbit data case study confirms the existence of the xi2-Lupids. The activity period starts at λʘ = 301°, ten days later than previously assumed. The activity last longer than λʘ = 318°, previously assumed as the end of the activity. The solution has been checked by using two independent shower identification methods as a two-factor authentication for the validation of the analysis. The xi2-Lupids appear to be the twin shower of the July Pegasids, encountered at the descending node of the meteoroid stream. This shower has been associated with C/1771 A1 (Great comet) and C/1979 Y1 (Bradfield) which may be remnants of a larger object that created the meteoroid stream during a major break up. Further adjusted modelling may reveal the past evolution of this dust stream. Our independent solution has been reported to the IAU-MDC, and the shower now fulfils the criteria for being upgraded to be nominated for established status.
Acknowledgments
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 927 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 2025 annual report (Roggemans et al., 2026b). The following 459 cameras contributed to paired meteors used in this study:
AU0002, AU0003, AU0004, AU0006, AU0007, AU0009, AU000A, AU000B, AU000C, AU000D, AU000E, AU000F, AU000G, AU000J, AU000R, AU000U, AU000V, AU000W, AU000X, AU000Y, AU0010, AU0011, AU001A, AU001B, AU001C, AU001E, AU001F, AU001G, AU001K, AU001L, AU001N, AU001P, AU001Q, AU001R, AU001S, AU001U, AU001W, AU001X, AU001Y, AU001Z, AU0028, AU0029, AU002A, AU002B, AU002C, AU002E, AU002F, AU0030, AU0031, AU0036, AU0038, AU003C, AU003E, AU003F, AU003H, AU003J, AU0040, AU0042, AU0047, AU0048, BG000K, BR000F, BR000G, BR0015, BR001M, BR001T, BR001U, CA002K, CA002U, CA0035, GR0008, HR0025, HR002G, KR000D, KR000J, KR000P, KR000S, KR0010, KR001B, KR001C, KR002K, KR002S, KR003M, KR003T, MX000D, NZ0001, NZ0002, NZ0003, NZ0004, NZ0007, NZ0009, NZ000A, NZ000B, NZ000D, NZ000F, NZ000H, NZ000K, NZ000M, NZ000N, NZ000Q, NZ000R, NZ000S, NZ000T, NZ000U, NZ000V, NZ000Y, NZ000Z, NZ0011, NZ0012, NZ0014, NZ0015, NZ0016, NZ0017, NZ0018, NZ001A, NZ001C, NZ001E, NZ001G, NZ001L, NZ001N, NZ001Q, NZ001R, NZ001S, NZ001V, NZ001Y, NZ001Z, NZ0020, NZ0022, NZ0023, NZ0024, NZ0026, NZ0027, NZ0028, NZ0029, NZ002B, NZ002D, NZ002E, NZ002F, NZ002G, NZ002H, NZ002K, NZ002L, NZ002N, NZ002P, NZ002R, NZ002S, NZ002T, NZ002U, NZ002W, NZ002X, NZ002Y, NZ002Z, NZ0030, NZ0032, NZ0033, NZ0034, NZ0035, NZ0036, NZ0037, NZ0038, NZ0039, NZ003A, NZ003B, NZ003C, NZ003E, NZ003F, NZ003H, NZ003K, NZ003L, NZ003M, NZ003R, NZ003S, NZ003T, NZ003U, NZ003V, NZ003W, NZ003X, NZ003Y, NZ003Z, NZ0040, NZ0041, NZ0045, NZ0046, NZ0049, NZ004A, NZ004B, NZ004C, NZ004D, NZ004H, NZ004J, NZ004N, NZ004R, NZ004U, NZ004V, NZ004W, NZ004Y, NZ004Z, NZ0051, NZ0059, NZ005F, NZ005G, NZ005K, NZ005N, NZ005R, NZ0063, NZ0065, NZ006C, RU0003, RU000M, RU0019, US0002, US0003, US0004, US0005, US0009, US000A, US000C, US000D, US000E, US000G, US000H, US000J, US000K, US000L, US000M, US000N, US000R, US001R, US0021, US0030, US004C, US004P, US005A, US005B, US0066, USL003, USL004, USL007, USL008, USL009, USL00A, USL00B, USL00C, USL00F, USL00H, USL00K, USL00L, USL00M, USL014, USL016, USL018, USL01C, USL01D, ZA0001, ZA0006, ZA0007, ZA0008, ZA000C and ZA000F.
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