P/Nanshan-Hahn = 2024 FG9
This object was noted as a possible comet by Alan Hale on account of its original orbit on April 16. Follow up by Sam
Deen suggested a possible coma and tail, but also refined the orbit to a short period one of around 6 years.
Maik Meyer notes that it has undergone a series of Jupiter encounters since 1999
which have progressively reduced the perihelion distance. Further observations
confirmed the presence of a coma, but it took the MPC until June 1 to revise the
designation. [MPEC 2024-L04, CBET 5401, 2024 June 1] The CBET gives more details of the confusion in MPC over this object.
The designation of 2024 FG9 was given on the basis of a set of observations by Mt Lemmon on March 21. However it had been
discovered at the Mt Nanshan station of Xinjiang Astronomical Observatory with a 1-m reflector on March 8.58 and 9 and properly
reported by them to the MPC. A linkage wasn't made until Robson Henrique dos Santos Hahn (Moeckmuehl, Germany) discovered an object
in images obtained remotely on April 10.87 and 12 with his 0.36-m f/2 Celestron 14 (+ Hyperstar) reflector located near Valdin, Ourenses, Spain.
He noted that it was interesting and it was then placed on the NEOCP, though not the PCCP. Sam Deen found ZTF observations from
2018 March, April and May. The comet passed 0.20 au from
Jupiter in 2021 April and will again pass 0.20 au from Jupiter in 2033 April. In the more distant future there are passes to 0.1 au.
Despite designating it as a comet, the MPC failed to number it at the next oportunity.
P/Lemmon = 2023 JN16
An asteroid was discovered at 19th magnitude by the Mt Lemmon Survey in images taken with the 1.5m
reflector on 2023 May 10.23. Sam Deen, Arndt Schnabel and K Ly made
follow-up observations and detected clear signs of cometary activity on 2023 June 16,
which was reported on the comets-ml at the time. It was at perihelion in 2020 July
at 2.3 au and has a period of 4.4 years in a low eccentricity orbit, which gives no particularly close planetary approaches.
It returns to perihelion in 2024 December. The brightness and lack of pre-discovery observations was
suggested by Peter VanWylen in 2024 February to indicate a possible main belt comet on the basis of his work on a machine learning algorithm.
The MPC finally got round to re-designating it as a comet in 2024 August, following further reports of its cometary nature
in 2024 June. There were pre-
discovery observations from 2018 March and 2023 April, although the object was
then stellar. There appears to have been an initiation of activity between 2023
April 27 and 29. [MPEC 2024-Q04, CBET 5430, 2024 August 16/17]. Despite designating it as a comet,
the MPC failed to number it at the next oportunity.
P/PANSTARRS = 2019 A8 = 2025 B3
A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m
Ritchey-Chretien on 2019 January 11.64. It was placed on the PCCP as P10LqGV. [CBET
4608, MPEC 2019-C20, 2019 February 4] The comet currently has a period of
around 5.9 years and was at perihelion at 1.9 au in 2018 August.
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.
P/Rankin = 2024 L4 = 2014 N4 = 2017 B6
David Rankin discovered a comet of 21st magnitude in images taken with the 1.5-m
reflector of the Mt Lemmon Survey on June 15.43. It was posted on the PCCP as
CAPN0N2. [MPEC 2024-N106, CBET 5409, 2024 July 9]. The comet was at perihelion at 0.7 au in 2024 April and has
a period of 3.33 years. Sam Deen on the comets-ml notes that it is a very unusual object. It has the smallest
aphelion distance on record, is in a stable orbit and is intrinsically faint. He suggests that it may be
a recent rotational disintegration, or impacted object as he could not find it in ZTF images from
early May, which would explain the reported condensed coma. Peter Jenniskens
notes that there is a possible associated meteor shower, the delta1 Canis
Minorids.
Sam Deen subsequently found pre-discovery images from PanSTARRS taken on 2014 July 4.58, with other images from
NEOWISE on January 31 and the CFHT on July 18. The comet was designated 2014 N4 for the return.
He then found images from Suburu taken on 2017 January 21.23, 23 and 26,
and 2016 December 23 and the comet was designated 2017 B6 for this return. He also found images taken by the CFHT on 2004 August 19,
but for some reason it was not given a designation at this return. [MPEC
2025-D238, 2025 February 28]. Further details are given in a CBET, including
that the comet passed 0.011 au from Venus in 1997 July and 0.079 au from Venus
in 2020 December. [CBET 5520, 2025 March 11]. The next close approach to Venus
is not until 2060.
P/COIAS = 2016 P5
H. Fukuyama discovered a comet in images acquired with the Subaru 8.2-m telescope at Mauna Kea in 2016 during
the Japanese citizen-science "Small Solar System Bodies Search Project" (COIAS).
The object was first reported to the Minor Planet Center in observations made on 2016 August 1.49
(which did not show cometary appearance), but Fukuyama noticed
cometary activity on Subaru images obtained on 2016 July 3 and 7. This was
reported to the MPC by Fukuyama on 2025 March 16 and the object placed on the PCCP as H431154. Sam Deen then
found the object in Isaac Newton Telescope images from 2004 June 23, a single Subaru image from 2012 July 22.26,
a single r-band image taken with the 2.65-m VLT Survey Telescope at Paranal,
Chile, on 2013 July 28.04 and images with the 4-m reflector (+ DECam) at Cerro Tololo on
2023 April 17.32 and 2023 April 23.29. The orbit is low eccentricity with perihelion at 4.4 au in 2023 May and a period
of 10.2 years. The comet passed 0.9 au from Jupiter in 1988 September and will do so again in 2054 May.
[MPEC 2025-F40, CBET 5529, 2025 March 21]
Sam Deen commented on the comets-ml that the magnitude was quite variable, but
none of the images were clear enough to detect any cometary activity. The observations gave a deterministic orbital
solution going back to around 1800 and forwards to around 2200, and a very chaotic and very quasi-hilda-esque orbital
evolution all the while. It spent between 1796 and 1979 (nearly two centuries) with a perihelion further than Jupiter's
semimajor axis in a 29P-type gateway comet orbit, and the solution confirms that in 2054 it will become a more 'classical' quasi-hilda.
He also noted that there were suggestions of non-gravitational effects, confirming the cometary nature.
[P/WISE] = 2010 LH155 = [2024 Y2]
Y. Ramanjooloo found a comet in PanSTARRS imagery on 2024 December 31.60. It was posted on the PCCP as P124Qvg. PanSTARRS then
found pre-discovery images from 2024 November. This was then linked to an object that was observed at Cerro Paranal
in 2018 May and also observed by PanSTARRS. This was then further linked to an object observed by
the WISE spacecraft on 2010 June 14.71 and followed it until June 15.83. The CBET notes that it should have received provisional
designations at both the 2018 and 2024 returns.
The comet has a period of 7.2 years with perihelion
at 2.2 au. The comet passed 0.80 au from Jupiter on 1998 February 19 and 0.96 au on 2023 March 20 .
[MPEC 2025-H69, CBET 5540, 2025 April 22/24]
[P/Palomar] = 2009 KF37
There are a few inconsistencies in the MPEC announcing this object. It gives the discovery observation by the PTF as being on 2009
May 27.20. Cometary activity was first detected in images from 2009 May 25 (which are given in the CBET),
but this was not reported until 2012 October 16. Pre-discovery LONEOS observations from 2001 were then found. The comet is next
at perihelion at 2.8 au in 2026 January and has a period of 8.3 years. [MPEC 2025-H87, CBET 5543, 2025 April 23/26].
The comet passed 0.95 au from Jupiter in 2012 January.
[P/WISE-LINEAR] = 2010 KG43 = 2010 PT8
The WISE spacecraft observed an object on 2010 May 20.54 and followed it until May 21.66. Other observatories followed it during 2010, though
only one reported cometary activity and then in 2012. It was independently found by LINEAR on 2010 August 3.41 and designated as 2010 PT8.
In 2023 Sam Deen found further indications of cometary activity at 2010 return,
which encouraged other observers to check at the next return in 2023. The comet has a period of 13.2 years with perihelion
at 2.9 au in 2023 August. [MPEC 2025-H90, CBET 5545, 2025 April 22/26]
P/NEAT= 2003 QX29 = 2025 H1
A 20th magnitude comet was discovered by NEAT on 2003 August 23.28, although some CCD
observers estimate it a little brighter. The comet was nearly a year past perihelion
and faded. The perihelion distance was 4.2 au and the period around 23 years.
Maik Meyer subsequently found prediscovery observations from Palomar/NEAT made
in June 2002, which gave
a period of 22.73 years and perihelion at 4.24 au according to calculations
by Muraoka.
An apparently asteroidal object reported by NEAT (Palomar
discovery observation originally posted on the NEO
Confirmation Page, then assigned the designation 2003 QX_29 on MPEC
2003-Q33; observations on MPS 93475-93476) has been found to have
cometary appearance on CCD images taken by I. Griffin and S. G.
Huerta (Cerro Tololo 0.9-m reflector, Aug. 31.1 UT; visible coma of
red mag 18.0-19.4 with FHWM = 2".3-2".6 in raw 300-s images, while
stacked 10-exposure image shows a fan-shaped tail at least 17" long
in p.a. 58 deg) and by J. Young (Table Mountain 0.6-m reflector,
Sept. 1.2; 3" coma, slightly elongated in p.a. 260 deg, with a 16"
curved tail starting in p.a. 243 deg; possible slight brightening
in the tail at a point 4"-5" from the coma edge). J. Ticha
subsequently reports that Klet images from Aug. 23.9 show the
object to be slightly diffuse, while on Aug. 24.9 it exhibited a 8"
coma. Astrometry, orbital elements (T = 2002 Oct. 17.3 TT, Peri. =
37.1 deg, Node = 264.9 deg, i = 11.4 deg, equinox 2000.0, e = 0.445,
q = 4.311 AU, P = 21.6 yr), and an ephemeris appear on MPEC 2003-R14.
[IAUC 8192, 2003 September 2]
Sam Deen found a probable recovery of 2003 QX29 in DECam images from 2024 September 1.
It was accidently recovered in images taken with the 1.5-m reflector of the Mt Lemmon Survey on April 23.45 at 20th
magnitude and posted on the PCCP as CD876E2. Pre-recovery images
from PanSTARRS on 2024 July 1 were then found. The previously published orbit required a correction of Delta(T) = -2.25 days.
The comet is at perihelion at 4.2 au in 2025 August and has a period of 22.6 years. [MPEC 2025-H183, CBET 5547, 2025 April 28]
1743 X1
Maik Meyer and Gary Kronk have derived a new orbit
for 1743 X1 and linked it to 1402 D1 and possibly earlier comets. They predict it will return around 2097. Tail simulation broadly agrees with the
main linkage, but raises some queries as to previous apparitions. Certainty will only come when the comet is recovered.
P/Lemmon = 2007 SA24
David Rankin discovered a 20th magnitude comet in images taken with the
1.5-m reflector of the Mt Lemmon Survey on .2023 October 10.38. It was quickly
identified with an object of 21st magnitude discovered on 2007 September 25.28 in images
also taken with
the 1.5-m reflector of the Mt Lemmon Survey. It was observed until 2008 February by several observatories.
It seems to have been forgotten about by the MPC and the 2023 recovery was not
given a designation. [MPEC 2025-H103, CBET 5548, 2025 April 24/29]. The comet
was at perihelion at 2.7 au in 2022 December and has a period of 15.5 years.
P/PANSTARRS = 2017 FL36
Peter VanWylen suggested that 2017 FL36 might be a comet on the comets-ml. This was confirmed with the issue of MPEC 2025-H86 on 2025 April 23.
The comet was discovered by PanSTARRS on 2017 March 18.39 with observers reporting cometary features from 2017 March in 2024 February and May.
The comet is at perihelion at 2.8 au in 2025 August and has a period of 5.0 years. [MPEC 2025-H86, CBET 5551, 2025 April 23/ May 1]
P/PANSTARRS = 2011 F2 = 2018 L1 = 2025 F3
A 20th magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m
Ritchey-Chretien on 2018 June 3.28. It was placed on the PCCP as P10HyFo. [CBET
4521, MPEC 2018-L36, 2018 June 8] The comet has a period of around 7.0 years and was at perihelion at 1.9 au in 2018 November.
According to the MPC, PanSTARRS recovered 2018 L1 in images taken on 2025 March 31.43 at 21st magnitude, with confirming images from other observatories.
The CBET on the other hand assigns the credit to Taras Prystavski using the
iTelescope at Rio Hurtado on April 9.34, when the comet was 6.5' from the
expected position. The March 31 observations were actually in the ITF and should
not have been used to give the recovery designation. Following recovery PanSTARRS images of the comet taken on 2011 March 26.48
were found, with additional images from the Catalina Sky Survey.
[MPEC 2025-J73, CBET 5554, 2025 May 8/10] The comet is at perihelion at 1.9 au in 2025 November and has a period of 7.0 years.
It will pass 0.5 au from Jupiter in 2048.
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 order given here is provisional and based on the logical sequence of
linked orbits. The final numbering scheme does not seem to follow this
logical pattern.
Published by Jonathan Shanklin. Jon Shanklin - jds@ast.cam.ac.uk