BAA Comet Section : Comets discovered in 2025
Updated 2025 March 4
2025 A1 [A/Lemmon]
An object of 21st magnitude was discovered on January 2.28 in images taken with
the 1.5-m reflector of the Mt Lemmon Survey. It was placed on the PCCP as CCMJ452.
There were pre-discovery images from Mt Lemmon (2024 October 28, November 14),
PanSTARRS (November 2, 27) and Kitt Peak-Bok (December 20).
[MPEC 2025-A108, 2025 January 6]. No cometary activity has been detected to date.
The object is at perihelion at 5.4 au in 2027 March.
2025 A2 (P/PANSTARRS)
PanSTARRS 1 discovered a 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
January 7.42. It was placed on the PCCP as P125uch. There were pre-discovery images from DECam on
2024 November 27, 28 and 30, Mt Lemmon on December 1 and 27 and PanSTARRS on December 23, 27, 31 and
2025 January 2.
[MPEC 2025-A162, CBET 5494, 2025 January 11] The comet was at perihelion at 3.4 au in 2024 October and has
a period of around 11 years. The comet passed 0.3 au from Jupiter in 2022
October.
2025 A3 (Tsuchinshan)
Zhijian Xu reported the discovery of a comet in survey images taken on January 5.82
using the 1.04-m f/1.8 Schmidt telescope at the
Xuyi Observatory of Purple Mountain Observatory (Tsuchinshan) in the course of
the "China Near Earth Object Survey Telescope" (CNEOST) search program. The
object was initially submitted as an asteroidal target by the CNEOST automated
system but was then found to show cometary feature. Zhijian then contacted the
Kottomia Observatory in Egypt for confirmatory observations. The comet was posted on
the PCCP as X85042 and PanSTARRS found pre-discovery observations from December 25, 28, 29
and January 4. [MPEC 2025-A178, CBET 5495, 2025 January 15]. The comet is at perihelion at 5.6 au
in 2026 January and has a period of about 33 years.
2025 A4 (PANSTARRS)
PanSTARRS 2 discovered a 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
January 3.63. It was placed on the PCCP as P2225WF. There were pre-discovery images from Mt Lemmon on December 21.
[MPEC 2025-B11, CBET 5496, 2025 January 18] The comet was near perihelion at 3.8 au and has
a period of around 35 years, with an uncertainty of about a year.
2025 A5 (P/Catalina)
PanSTARRS 1 accidentally recovered 2019 Y3 on 2025 January 7.22 at 19th magnitude. It was briefly posted on the PCCP as
P125u6N, then removed without people noticing. Further reports also made it to the PCCP as A11hRte (January 20),
A11hVVH (January 21) and C44DR81 (February 3). Michael Jaeger also made an independent recovery on January 29.8
that was reported to the CBET. [MPEC 2025-C161, CBET 5504, 2025 February 11/12] The recovery indicates a correction of
Delta(T) = +1.37 days to previous predictions. The comet reaches perihelion at 0.9 au in March. The comet will pass
0.34 au from the earth on 2025 March 18 and 0.33 au from Jupiter on 2033 July 4. The comet passed
0.072 au from Venus in 1958 and 0.11 au from Jupiter in 1926. It is an intrinsically faint object that is only
predicted to reach 16th magnitude during the approach, which is favourable for northern hemisphere observers.
2025 A6 (Lemmon)
An object of 22nd magnitude was discovered on January 3.34 in images taken with
the 1.5-m reflector of the Mt Lemmon Survey. It was placed on the PCCP as CCNG6P2.
There were pre-discovery images from PanSTARRS on November 12, 28, December 2, 6, 22, 23, 30.
[MPEC 2025-D55, CBET 5508, 2025 February 21/22].
The comet is at perihelion at 0.5 au in 2025 November and has a period of over 1000 years.
The comet could reach 10th magnitude in late
October, or possibly brighter if the initial magnitudes correspond to a nuclear magnitude.
During October it rapidly switches from a morning object at the start of the month, to an early evening
one at the end.
2025 A7 [A/Lemmon]
An object of 20th magnitude was discovered on January 6.49 in images taken with
the 1.5-m reflector of the Mt Lemmon Survey. It was placed on the PCCP as CCPHVR2.
There were pre-discovery images from PanSTARRS on 2024 December 2.
[MPEC 2025-D151, 2025 February 24]. No cometary activity has been detected to date.
The object is at perihelion at 2.9 au in 2025 March.
2025 B1 (PANSTARRS)
PanSTARRS 2 discovered a 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
January 20.24. It was placed on the PCCP as P225G7o. There were pre-discovery images from Mt Lemmon on December 24 and January 3.
[MPEC 2025-B77, CBET 5497, 2025 January 23] The comet is at perihelion at 3.5 au in 2025 June.
2025 B2 (Borisov)
Gennady Borisov discovered a 20th magnitude comet in images taken with the MARGO 0.5-m f/1.9
reflector at Nauchnij, Crimea on January 20.78. It was placed on the PCCP as
gb00784 and quickly confirmed by other astrometrists. There was a pre-discovery image by PanSTARRS on January 8.29.
[MPEC 2025-C153, CBET 5501, 2025 February 9/10] The comet is at perihelion at 8.2 au in 2026 September.
The discovery is eligible for the Edgar Wilson Award.
2025 B3 (P/PANSTARRS)
2019 A8 was accidentally recovered in images taken images taken with
the 1.5-m reflector of the Mt Lemmon Survey on January 24.39 at 21st magnitude. Michael Jaeger et al also made an
independent recovery on February 22. [MPEC 2025-D234, CBET 5516, 2025 February 27/28] The relatively short arc, combined
with a close approach to Jupiter gave rise to a Delta(T) of +49.2 days for the time of perihelion compared to previous
predictions. The comet made close approaches of 0.3 au to Jupiter in 2009 November and 2021 November. It now has a period
of 6.3 years and is at perihelion at 2.1 au in 2025 March.
2025 C1 (P/ATLAS)
The ATLAS (Asteroid Terrestrial-impact Last Alert System) team discovered an 18th magnitude object
in images taken with the 0.5 m Schmidt at Haleakala on February 2.63. It was posted on the NEOCP as A11izBV. Alan Hale
suggested that it showed some cometary nature on the comets-ml and this was soon confirmed. It was then transferred to
the PCCP until the orbit was published. [MPEC 2025-C158, CBET 5502, 2025 February 10]. It seems likely that the comet
was discovered in outburst as it brightened by a magnitude 24 hours after discovery
and there were no prediscovery observations. The comet was near perihelion at 2.7 au
and has a period of around 8.5 years, though this is uncertain by about 17 days.
The orbit has a Jupiter MOID of 0.25 au.
2025 D1 (Groeller)
Hannes Groeller discovered a comet of 20th magnitude on February 20.33 in images taken with
the 2.25-m Bok reflector at Kitt Peak. It was placed on the PCCP as C11KVH5.
Sam Deen soon found pre-discovery images from Kitt Peak (2018 June 6, 7, 9, 18, 2019 February 9, 12), CFHT (2022 February 2)
and Suburu (2022 May 30) all showing cometary features.
[MPEC 2025-D83, CBET 5509, 2025 February 22/24].
The comet is at perihelion at 14.1 au in 2028 May. Sam Deen noted on the comets-ml that this is a record perihelion
distance, which was previously held at 11.4 au by 2003 A2 (Gleason). He also said:
Perihelion distance aside, the 2018 images I've found of it establish it as a member of the very exclusive club of comets active beyond 20
au as well (2010 U3, 2014 UN271, 2017 K2, and 2019 E3). I have no idea how far out it was truly active because the 2018 images (taken by the 2.5-m Bok telescope) are the earliest publicly available archival images of its location. PANSTARRS may be able to push this date a bit further back, but regardless activity at 21.3
au from the Sun is very impressive indeed.
This comet is correspondingly dynamically new as well - the incoming barycentric aphelion is 56,600 +/- 4200
au using the observations I have. Unfortunately despite its very unusual (if not entirely unique) nature among comets, its high perihelion distance means it's not going to be getting very bright: considering its very slow magnitude slope from 2018-2025 I sincerely doubt it will get brighter than magnitude 20 as it passes perihelion in 2028. Of course, it will stay bright enough for targeted observations for many decades, so plenty of time to figure out more about this strange object.
2025 D2 (P/PANSTARRS)
PanSTARRS 2 discovered a 22nd magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
February 22.33. It was placed on the PCCP as P226VEQ. There were pre-discovery images from Mt Lemmon on
February 4, 19.
[MPEC 2025-D149, CBET 5510, 2025 February 24] The comet is at perihelion at 7.2 au in 2028 January and has
a period of somewhere around 30 years.
2025 D3 (P/PANSTARRS)
PanSTARRS 2 discovered a 22nd magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
February 22.43. It was placed on the PCCP as P2265Dx. There were pre-discovery images from PanSTARRS on
2024 December 30, 2025 January 6, February 6 and 7.
[MPEC 2025-D211, CBET 5513, 2025 February 26/27] The comet was at perihelion at 3.0 au in 2024 July and has
a period of around 8 years.
2025 D4 (P/ATLAS)
The ATLAS (Asteroid Terrestrial-impact Last Alert System) team discovered a 19th magnitude object
in images taken with the 0.5 m Schmidt at Rio Hurtado, Chile on February 24.31. It was posted on the NEOCP as A11jANL.
Pre-discovery images were quickly found from PanSTARRS (2023 December 10, 14, 18, 23, 2024 January 5, February 6,
March 29, April 27, May 8, 22, 26, 2025 January 6) and ATLAS from the day before discovery.
[MPEC 2025-D235, CBET 5514, 2025 February 27/28]. The comet was near perihelion at 3.3 au and has a period of
around 27 years.
2025 E1 (PANSTARRS)
PanSTARRS 1 discovered a 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
March 2.43. It was placed on the PCCP as P127ExT. There were pre-discovery images from PanSTARRS on January 3, 4, 25.
[MPEC 2025-E58, CBET 5518, 2025 March 3/4] The comet is at perihelion at 4.0 au in 2026 September.
When observing a comet please try to forget how bright you think the comet
should be, what it was when you last viewed it, what other observers think
it is or what the ephemeris says it should be.
The equations for the light curves of comets that are currently visible
use only the raw observations and should give a reasonable prediction for
the current brightness. If the comet has not yet been observed or has
gone from view a correction for aperture is included, so that telescopic
observers should expect the comet to be fainter than given by the equation.
The correction is about 0.033 per centimetre. Values for the r parameter
given in square brackets [ ] are assumed. The form of the light curve is
either the standard m = H0 + 5 log d + K0 log r or the linear brightening
m = H0 + 5 log d + L0 abs(t - T + D0) where T is the date of perihelion,
t the present and D0 an offset, if L0 is +ve the comet brightens towards
perihelion and if D0 is +ve the comet is brightest prior to perihelion.
Observations of new comets in 2025 are given in ICQ format.
Full details of recently discovered objects will not appear until they are
available on the CBAT web pages. The actual accuracy of preliminary orbits is often
(nearly always) much worse than the published
accuracy implies. In part this is because
each orbital solution is treated as a mathematical construct and does not take account of observational
error. JPL does publish the errors,
whereas the MPECs do not.
Ephemerides of current comets are available on the CBAT
ephemeris page and positions of newly discovered comets are on the
NEO confirmation page.
More information on LINEAR. A list of comets
discovered by selected search programs.
The Northumberland refractor
is the telescope that was used in the search for Neptune.
It now has a 0.30-m f20 doublet lens which gives a stellar limiting magnitude of around
15 at the zenith on good nights.
The Thorrowgood refractor was
built in 1864 and has a 0.20-m f14 doublet lens.
Published by Jonathan Shanklin. Jon Shanklin - jds@ast.cam.ac.uk