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An asteroidal object of magnitude 22, discovered already on Oct. 20, 2014 by G. Bernstein and P. Bernardinelli with the 4.0m reflector of the Cerro Tololo Interamerican Observatory, displayed cometary activity in mid-June 2021. Comet C/2014 UN271 (Bernardellini-Bernstein) showed an 8" coma of total magnitude 19.5, asymmetric towards p.a. 40°. The comet will pass its extremely distant perihelion on Jan. 22, 2031 at the solar distance of 10.95 AU and could then reach magnitude 16-17 (CBET 4983/89).
At the opening of August 2025 the published observations can be plausibly represented by the parameters m0 ≈ 0.5 mag / n ≈ 3, still showing a large uncertainty and even hinting towards a larger activity parameter. It will certainly take at least additional 2 years until the uncertainty will be significantly reduced. If the comet continues to develop in this way, it can reach a maximum brightness of around 13.5m. In this case it would be brighter than 16.0m between mid-2023 and mid-2038. During this period it moves from Hydrus towards Centaurus (perihelion) and thereafter through the constellations Hydra, Corvus, Virgo, Coma Berenices and Canes Venatici. From mid-European locations meaningful observations are possible not before start of 2032.
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An asteroidal object of magntiude 19, which was already discovered on Apr. 21, 2021 by the ATLAS-Team in the constellation Canis Major showed faint cometary signatures during follow-up observations. Until October 2021 additional observations clearly confirmed the cometary nature. Comet C/2021 G2 (ATLAS) will pass perihelion on Sep. 9, 2024 at the solar distance of 4.98 AU, expected to reach magnitude 15.0 in spring 2024 and 2025 (CBET 4988/5057). It should be brighter than 16 mag between November 2023 and August 2025. During this period it moves through the constellations Hydra, Corvus, Virgo and Libra. From mid-European latitudes it will appear in December 2024 above the southeastern morning horizon, and will change into the evening sky in May 2025.
Based on 253 observations from 34 observers (up to the beginning of August 2025) the comet shows different developments pre- and post-perihelion. While the brightness pre-perihelion increased slightly above average, post-perihelion the heliocentric brightness has so far remained constant. However, it can be assumed that future observations will eventually show a decrease in heliocentric brightness. The appropriate brightness parameters are:
pre-perihelion : m0 = 2.7 mag / n = 4.5
post-perihelion: m0 = 10.5 mag / n = 0
Thus the comet reached its peak brightness of about 13.5 mag at the beginning of May 2025, after it had already become 13.8 mag bright at the end of April 2024. By the beginning of August 2025 the comet had fades to 14.5 mag.
Total Brightness and Coma Diameter (standard time scale)
Total Brightness and Coma Diameter (compressed time scale)
After the coma diameter increased from 0.6' (130,000 km) at the beginning of 2024 to 1.1' (210,000 km) in April, it decreased to 0.6' (175,000 km) by the end of August. After perihelion the apparent coma diameter increased from 0.8' to the maximum of 1.4' (May 2025), thereafter decreasing to 1.0' by the beginning of August. The absolute coma diameter increased from 200,000 km to the maximum of 250,000 km, which then remained constant until the beginning of August. The degree of condensation increased from DC 4-5 at the beginning of 2024 to DC 6 in May 2024. Until spring 2025 it had decreased to DC 3-4. A tail, pointing constantly in westerly directions, was observed throughout the entire apparition. It was 3' (4 mio. km) long in 2024 and showed a length of 9' (12 mio. km) in 2025.--------------------
An 18 mag asteroidal object, discovered by the ATLAS team on Mar. 7, 2022 in the constellation Antlia showed cometary morphology in the course of follow-up observations. Comet C/2022 E2 (ATLAS) showed a highly condensed 7" coma of total magnitude 18.0, but no tail. The comet will pass perihelion on Sep. 15, 2024 at the solar distance of 3.67 AU, expected to reach magnitude 13 (CBET 5109). It should be brighter than 16 mag between March 2021 and January 2026. During this interval it will move through the constellations Hydra, Cancer, Gemini, Lynx (perihelion), Camelopardalis, Cassiopeia, Lacerta and Pegasus. Thus it will be well-placed for mid-European locations during the most interesting months.
The comet shows a very steady brightness development, as demonstrated by 397 observations from 51 observers (until the start of August 2025). This can be represented well with the parameters
m0 = 6.7 mag / n = 2.6.
This results in a first maximum of 13.3 mag in mid-February 2024 and a peak brightness of 12.8 mag at the end of November 2024. However, the comet seems to have experienced a short-lived increase of activity in January 2025, resulting in an increase of the brightness up to 12.9 mag. At the opening of July 2025 the comet had faded to 14.5 mag.
Total Brightness and Coma Diameter (standard time scale)
Total Brightness and Coma Diameter (compressed time scale)
The coma diameter measured 0.4' for many months, but starting in October 2023 it increased noticeably, reaching 1.3' at the beginning of February 2024. After decreasing, due to a temporary increase in the distance to Earth, it again increased, reaching 1.4' at maximum in November 2024. At the end of June 2025 it measured 0.5'. The absolute coma diameter measured 100,000 km during the first months. Thereafter it constantly measured 175,000 km until the start of 2025. It then shrunk to 125,000 km until June 2025. In 2024 the coma showed a constant degree of condensation of DC 4-5. At the start of 2025 DC 3 was reported. Since the start of the apparition a tail can be detected, which reached a length of 8' (6 mio. km) in winter 2024/25. Most of the apparition the tail was oriented towards East to Southeast. In winter 2024/25 it turned from Southeast towards ENE.--------------------
On July 4, 2022 the PANSTARRS team discovered a comet of magnitude 20 in the constellation Sagittarius. Comet C/2022 N2 (PANSTARRS) showed a condensed 2" coma and a 3" tail in p.a. 260°. It will pass perihelion at the solar distance of 3.84 AU on Aug. 3, 2025, expected to peak at magnitude 14.5 in October/November 2025 (CBET 5148). At discovery it was still at a distance of 9.5 AU from the Sun! Between April 2025 and February 2026 it should be brighter than 16 mag. During this period it moves from central Pisces northeastward to the region near the border of the constellations Aries/Taurus. Thus the observing conditions are optimal for mid-European locations during the time the comet is brightest.
Based on 115 observations by 24 observers (until the start of August 2025), the comet shows a steady brightness development, which can be well represented with the parameters
m0=5.5 mag / n=4.
It thus reached an inferior maximum of 15.0 mag in October/November 2024 and should reach the actual maximum of 13.8 mag at the beginning of November 2025. At the beginning of August 2025 it was of magnitude 14.3.
Total Brightness and Coma Diameter
The coma diameter reached 0.8' (130,000 km) in 2024 and measured 0.7' (120,000 km) at the beginning of August 2025. Overall, the coma is quite diffuse (early August: DC 2-3). CCD observations show a tail up to 4' (2 mio. km) long, oriented towards WSW.--------------------
Comet C/2022 QE78 (ATLAS), which will pass perihelion at the solar distance of 5.48 AU on Sep. 10, 2025, became brighter than originally expected, as 111 observations (mostly via CCD) from 19 observers (until the start of August 2025) indicate. Between September 2024 and end of January 2025 the comet brightened from 16.0 mag to a first maximum of 15.3 mag (originally a peak brightness of about 16.5 mag was expected). The brightness development can be described in a plausible manner with the parameters
m0=0.5 mag / n=6.
Thus the comet should reach the main maximum of 15.0 mag in mid-January 2026. The medium-condensed (DC 5) coma reached a diameter of 0.6' (140,000 km) in winter 2024/25. CCD observers could detect a short tail.
Total Brightness and Coma Diameter
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On Feb. 1, 2023 the ATLAS team discovered a 19th magnitude asteroidal object near the border of the constellations Centaurus/Vela, which showed cometary morphology in follow-up observations. Comet C/2023 C2 (ATLAS) exhibited a 9" coma of total magnitude 19.0 with a central condensation. The comet will pass perihelion at the solar distance of 2.37 AU on Nov. 16, 2024 and should reach a maximum brightness of 13.5-14.0 mag in August 2024 (CBET 5240). It should be brighter than 16 mag between March 2024 and July 2025. During this period it moves through the constellations Apus, Triangulum Australis, Norma (maximum brightness), Scorpius, Sagittarius (perihelion), Capricornus, Aquarius, Pegasus, Andromeda and Cassiopeia. From central European locations the comet can be sighted just above the southwestern evening horizon between November 2024 (14.0 mag) and January 2025 (14.5 mag) during the first period. It then reappears over the eastern morning horizon in March 2025 (15.0 mag), slowly gaining altitude during the following months, thereby steadily fading.
This comet showed a very continuous brightness development, based on 76 observations from 20 observers (until the start of August 2025). The estimates can be rather well represented by the brightness parameters
m0 = 9.8 mag / n = 2.0.
It reached peak magnitude of 13.5 in August 2024. Until December 2024 it had faded to 14.0 mag, until start of July 2025 to 15.0 mag.
Total Brightness and Coma Diameter
The coma diameter increased from 0.4' (50,000 km) at the start of the apparition to 0.8' (75,000 km) at the end of August 2024. The degree of condensation was constant at about DC 4. In summer 2025 the comet showed a well-condensed (DC 5) coma of 0.7' (100,000 km) diameter. CCD-observers detected a tail of up to 1' (700,000 km) length, which was oriented towards West until the beginning of July 2024, thereafter towards Southeast.--------------------
Comet C/2023 Q1 (PANSTARRS), which passed perihelion on Dec. 1, 2024 in the solar distance of 2.58 AU, became brighter than expected (originally a maximum brightness of 16.0 mag in December 2024 was predicted). Based on 65 observations (mainly per CCD) from 16 observers the brightness development can be represented quite well with the parameters
m0 = 11.9 mag / n = 2.5.
Thus the comet reached a maximum brightness of 14.9 mag in December 2024. The medium-condensed coma reached a maximum diameter of 0.7' (55,000 km). The observers recognized a very short, westward pointing tail.
Total Brightness and Coma Diameter
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The PANSTARRS team discovered another comet on Sep. 7, 2023 near the border of the constellations Pisces/Andromeda. Comet C/2023 R1 (PANSTARRS) showed a 1.5" coma of total magnitude 19.5. It will not pass its mid-distance perihelion at the solar distance of 3.57 AU until Apr. 14, 2026 (then expected to be of magnitude 15) and should peak at 14 mag in June 2026 (CBET 5293). It should be brighter than 16 mag between July 2025 and October 2026, when it will move through the constellations Pegasus, Vulpecula, Sagitta, Aquila (perihelion), Scutum, Serpens Cauda, Ophiuchus, (maximum brightness), Serpens Caput and Libra. From Central European locations it can be followed until September 2026 - with the exception of the period from mid-December 2025 to the end of January 2026.
The comet reached a brightness of 15.5 mag and a coma diameter of 0.6' (100,000 km) at the beginning of August 2025. Based on only 28 observations from 15 observers (until start of August 2025) the brightness parameters can be roughly determined as
m0 = 6.5 mag / n = 4.
This means that the comet should reach a maximum brightness of around 14.0 mag in mid-June 2026.
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Comet P/2023 S1 (PANSTARRS) (P=7.54a) became 1.5 mag brighter than expected. Originally a maximum brightness of 16.5 mag had been predicted.
The brightness development can be represented reasonably well with a classic log r - formula (albeit with extremely high parameter values), but much better with a time-dependent |t-T|-formula. Therefore, both formulas are noted in the diagram. The total of 73 observations (mainly by CCD) from 16 observers yield the following brightness parameters:
log r - formula: m0 = -12.5m / n = 25
|t-T| - formula: pre-perihelion : m0 = 13.4m / nt = 0.009
post-perihelion: m0 = 13.4m / nt = 0.018
The maximum brightness of 14.6 mag was reached at the end of February 2025.
Total Brightness and Coma Diameter
The moderately condensed coma reached a maximum diameter of 0.8' at the beginning of February, which corresponds to 60,000 km. A tail pointing to the WNW could be detected. In April 2025 the comet became fainter than 16 mag.--------------------
On May 6, 2024 the ATLAS team discovered a comet near the border of the constellations Sagittarius/Corona Australis. Comet C/2024 J3 (ATLAS) showed a highly condensed 9" coma of total magnitude 17.5 and a 12" tail in p.a. 220°. This comet will not pass perihelion at the solar distance of 3.86 AU until Nov. 24, 2026, expected to reach magnitude 13.0 (CBET 5398). It should be brighter than 16 mag between April 2025 and May 2028. During this period it will pass through the constellations Sagittarius, Scutum, Aquila, Delphinus, Vulpecula, Cygnus, Lyra (perihelion), Cygnus, Cepheus, Cassiopeia, Camelopardalis and Auriga. From Central European locations it should be observable from April to November 2025 (first in the morning sky, at the end in the evening sky), and then continuously from February 2026 to May 2028. The Earth will cross the comet's orbital plane every Jan. 7 and July 8.
Since May 2025 the comet is under scrutinity and has increased its brightness from 16.0 mag to 15.3 mag by the beginning of August. Based on 30 observations from 9 observers (up to the beginning of August 2025) the brightness parameters can be very roughly determined as
m0 ≈ 4.5 mag / n ≈ 4.
It should thus peak at 13.2 mag in mid-August 2026. The coma diameter measures currently 0.4' (85,000 km).
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On June 29, 2024 the ATLAS team discovered an asteroidal object of magnitude 18 in the constellation Caelum, which showed a cometary morphology during follow-up observations. Comet C/2024 M1 (ATLAS) exhibited a highly condensed 8" coma and a 6" tail in p.a. 240°. On images taken by the 4m reflector of the Cerro Tololo Observatory on May 10, 2022 it appeared stellar. The comet will pass perihelion at the solar distance of 1.70 AU on Nov. 20, 2024, expected to reach magnitude 13.5-14.0 (CBET 5419). It should be brighter than 16 mag between mid-September 2024 and mid-February 2025. During this period it will move through the constellations Canis Major, Monoceros, Orion (perihelion), Taurus, Perseus and Andromeda. From Central European locations it will initially be a morning object at low altitudes, but starting in November it will become an all-night object, reaching ever greater altitudes. Finally, it will get fainter than 16 mag in the evening sky at high altitudes. The Earth will cross the comet's orbital plane on Dec. 8.
The comet remained a little fainter than expected, as shown by 79 CCD observations from 20 observers. The brightness development can be represented reasonably well with the parameters
m0 = 11.8 mag / n = 6,
yielding a peak brightness of 14.5 mag at the beginning of December 2024. Although the comet came quite close to Earth the coma diameter did not exceed 0.4', which corresponds to an absolute diameter of just 13,000 km! The coma was extremely condensed (DC 8-9). A tail was not observed. At the beginning of 2025 it faded below 16.0 mag.
Total Brightness and Coma Diameter
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An asteroidal object of 19th magnitude, discovered by the ATLAS project on Oct. 2, 2024 near the border of the constellations Phoenix/Eridanus, revealed its cometary nature during follow-up observations. Comet C/2024 T5 (ATLAS) showed a stellar central condensation surrounded by an extremely diffuse 11" coma of total brightness 18.5 mag. The comet will not pass perihelion at the solar distance of 3.85 AU until May 7, 2027. It could reach 14.0 mag at the turn of the years 2026/27 (CBET 5472). Between May 2026 and May 2028 the comet should be brighter than 16 mag. During this period it will move through the constellations Eridanus, Lepus, Orion, Taurus (perihelion), Gemini, Cancer, Lynx and Ursa Major. For Central European locations it will appear in the morning sky in September 2026 and disappear from the evening sky in April 2027. The second apparition begins in August 2027. Thereafter the comet can be easily tracked until it fades below 16 mag.
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On May 23, 2025 the PANSTARRS project discovered a comet near the border of the constellations Cygnus/Draco. Comet C/2025 K3 (PANSTARRS) showed a strongly condensed coma measuring only 1" with total magnitude 21.0 and a 2" tail in p.a. 170°. The comet will not pass perihelion at the solar distance of 3.46 AU until Dec. 14, 2028. It should reach 15.5 mag in spring 2028 and peak at 14.0 mag in February 2029 (CBET 5564). It should be brighter than 16 mag between February 2028 and August 2029. During this period it will move through the constellations Bootes, Canes Venatici, Ursa Major, Leo, Virgo, Crater (perihelion), Hydra (maximum brightness) and Pyxis. From Central European locations it can initially be observed at high altitudes throughout the night, but will disappear above the western evening horizon in July. At the end of October 2028 it reappears in the morning sky at significantly lower altitudes and can then be followed at low altitudes until the end of April 2029.
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On June 6, 2025 the ATLAS team discovered a comet near the border of the constellations Eridanus/Horologium. Comet C/2025 L1 (ATLAS) exhibited a highly condensed, 1.5" coma with total magnitude 18.0 and a faint, 3" tail in p.a. 300°. It will pass perihelion at the solar distance of 1.68 AU on Jan. 12, 2026 and should reach a peak brightness of 14.0 mag in March 2026 (CBET 5566). It should be brighter than 16 mag from October 2025 to May 2026. During this period it will pass through the constellations Centaurus, Lupus (perihelion), Scorpius, Libra, Serpens (maximum brightness), Bootes and Canes Venatici. From Central European locations it will appear in the morning sky at the beginning of February 2029, thereafter quickly gaining high altitudes.
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On June 22, 2025 the PANSTARRS team discovered a 19th magnitude comet in the constellation Capricornus. Comet C/2025 M2 (PANSTARRS) showed a strongly condensed coma measuring just 1.5". It will pass perihelion on Nov. 26, 2027 at a solar distance of 2.73 AU and could reach a maximum brightness of about 12.5 mag in March 2028 (CBET 5576). It would be brighter than 16 mag between January 2027 and February 2029, during which time it will pass through the constellations Sagittarius, Scorpius, Libra, Virgo (perihelion and maximum brightness), Leo and Cancer. From Central European locations it can be followed between March and August 2027, between December 2027 and May 2028 and finally between September 2028 and February 2029.
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On Oct. 11, 2024 comet 37P/Forbes (P=6.44a) will pass perihelion for another time, this time at the solar distance of 1.62 AU, expected to reach magnitude 13.5. Between June and December 2024 it should be brighter than 16 mag. During this period it will move through the constellations Corvus, Hydra, Libra, Scorpius, Sagittarius into Capricornus. Thus it will be uncomfortably placed in the evening sky for mid-European locations, never attaining an altitude of more than 10°.
Just 23 CCD observations from 8 observers can be used for a very preliminary analysis. These indicate a time-dependent development of the activity and can be best described by the parameters
m0 = 12.5 mag / nt = 0.02,
indicating that the comet peaked at 13.0 mag at the end of December 2024. The coma diameter measured 0.7' (60,000 km). The comet will now be unobservable until July 2025.
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Comet 47P/Ashbrook-Jackson (P=8.36a) will pass perihelion at the solar distance of 2.81 AU on Oct. 27, 2025, but should reach its maximum brightness of 14.5 mag as early as September. For mid-European locations the comet will appear in the morning sky at the beginning of July.
Just 15 CCD observations of the comet can be used for a very preliminary analysis at the beginning of August 2025. These indicate the brightness parameters
m0=7.5 mag / n=6.
Thus the comet could reach a maximum brightness of 15.5 mag in September 2025. The comet's diameter has so far been estimated around 0.4'. The comet should become fainter than 16.0 mag in November.
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Comet 49P/Arend-Rigaux (P=6.74a) can be observed in the evening sky with large instruments until the end of April 2025. Thereafter it is too near the Sun for reasonable observations. It moves from the constellation Cetus into Taurus. The comet passes perihelion at the solar distance of 1.43 AU on Apr. 10, 2025.
The comet became somewhat brighter than expected and reached a maximum brightness of 13.8 mag at the beginning of April 2025, after having been only about 18 mag in mid-December 2024. On the basis of only 17 CCD observations the brightness development can be represented reasonably well with the parametersTotal Brightness and Coma Diameter
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Comet 65P/Gunn (P=7.68a) will pass perihelion at a solar distance of 2.93 AU on June 16, 2025 and could then reach a maximum brightness of around 15.0-15.5 mag. It is positioned in the southern part of the constellation Sagittarius, so it will be a very difficult object for mid-European locations.
Less than 20 CCD observations can I use for a very preliminary analysis at the opening of August 2025. The brightness estimates can be represented reasonably well with the brightness parameters
m0=9.0 mag / n=4.
Thus the comet reached a maximum brightness of about 15.0 mag in July 2025, and should become fainter than 16.0 mag already in October. The coma diameter measured about 0.5'.
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Comet 217P/LINEAR (P=7.83a) passed perihelion at the solar distance of 1.23 AU on May 24, 2025, but was quite close to the Sun for a long time.
It is therefore no wonder that just a dozen CCD observations were available for a very preliminary analysis at the beginning of August 2025. These can be displayed reasonably well with the brightness parameters
m0=10.0 mag / n=5.
The comet peaked at 12.5 mag at the end of June 2025, the coma diameter at about 1'. Starting in mid-August 2025 the comet can be seen in the morning sky from mid-European locations, but should already become fainter than 16.0 mag in November. During this period it moves from the southwestern part of the constellation Gemini to the eastern part of the constellation Cancer.
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Comet 240P/NEAT (P=7.59a) will pass perihelion at the solar distance of 2.12 AU on Dec. 19, 2025 and will be in opposition to the Sun at this time, near the border of the constellations Taurus and Aries.
At the beginning of August 2025 only a dozen CCD observations can be used for a very preliminary analysis. Currently the comet is of magnitude 14.5, showing a coma diameter of 0.7'. For the brightness estimates only an interval of plausible values for the brightness parameters can currently be specified, ranging from
m0=5.0 mag / n=8 to m0=9.0 mag / n=4.
This means that the comet should peak at 12.0 mag (12.5 mag) in December 2025. From mid-August to mid-November the comet is situated near the border of the constellations Eridanus and Taurus, thus initially an object in the morning sky, and later throughout the night. Its brightness should increase from 14.0 mag (14.5 mag) to about 12.0 mag (12.5 mag).
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Comet 333P/LINEAR (P=8.67a) will pass perihelion in the solar distance of 1.11 AU on Nov. 29, 2024. It is predicted to reach magnitude 10.5, because it will approach Earth on Dec. 9 to within 0.54 AU. The comet should become observable in mid-October 2024 in the morning sky as an object of magnitude 14. Until the end of year it will move through the constellations Sextans, Leo, Ursa Major, Canes Venatici (perihelion), Ursa Major, Draco (perihelion) into Cygnus. Earth will cross the orbital plane on Jan. 16, 2025.
The comet showed a rapid increase and decrease in activity, as 81 observations by 33 observers indicate. The brightness development can be represented reasonably well with the parameters
m0 = 11.0 mag / n = 12.
The comet peaked at 11.1 mag at the time of perigee. At the beginning of November 2024 it was only of magnitude 14.0 and by the end of January 2025 it had already faded to 16.0 mag. The apparent coma diameter measured 1.5' at the beginning of November 2024, increasing to 3.0' by the time of perigee. By mid-January 2025 it had shrunk to less than 0.5'. The absolute coma diameter shrank throughout the apparition, from 90,000 km to 20,000 km. In parallel the degree of condensation decreased from DC 4 to DC 2. A tail up to 4' (300,000 km) length was observed throughout the apparition. It changed its orientation from West over North to Northeast.
Total Brightness and Coma Diameter
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Comet 487P/Siding Spring (P=8.67a), which passed perihelion on Oct. 20, 2024 at the solar distance of 1.81 AU, was followed by CCD observers. On the basis of only 39 observations from 14 observers the brightness development can only be roughly represented with the parameters
m0 = 11.5 mag / n = 6.
This results in a peak brightness of 15.0 mag in mid-November 2024, when it was closest to Earth at 0.88 AU. At the end of December it had faded below 16 mag. The moderately condensed (DC 4) coma constantly measured 0.4' (16,000 km). A tail with a maximum length of 2' (200,000 km) was directed towards WSW at the beginning and towards SSW at the end of the apparition.
Total Brightness and Coma Diameter
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Comet 496P/Hill (P=15.07a) = P/2010 A3 (Hill), which passed perihelion at a solar distance of 1.62 AU on March 10, 2025, reached a maximum brightness of about 15.0-15.5 mag at the end of March 2025. At the beginning of May it became fainter than 16 mag. The diameter of the moderately condensed coma reached about 1.5' (200,000 km).
Andreas Kammerer
