BAA Comet Section : Comets discovered in 2023
Updated 2024 March 28
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 magnitude parameters [ updated 2023 January 3] of comets that are currently visible
should give a reasonable prediction for
the current brightness. The evidence shows that VEM magnitudes do
not require a correction for aperture. Visual observations however do, and
are therefore now corrected to a standard aperture of 30cm.
The correction is about 0.033 per centimetre. Visual observers using
smaller apertures may find a comet to be brighter than indicated by the
equation. 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 comets in 2023 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.
1808 R1 (Pons)
During research for their book on unconfirmed comets, Maik Meyer and Gary Kronk discovered manuscript letters from
Pons to B A von Lindenau at the Seeborg Observatory from 1808 September. These had sufficient information for them to be able to
derive positions and then for Syuichi Nakano to compute an orbit for a previously undocumented comet. This was at perihelion
at 1.1 au in 1808 September and was around 8th magnitude when observed. [CBET 5258, 2023 May 16]
1951 G1 (Groeneveld)
Ingrid Groeneveld of Yerkes Observatory discovered a 15th magnitude comet in 1954 January on a minor planet survey
plate taken with a 0.25m astrograph at the McDonald Observatory, Texas on 1951 April 2.17. In 2018 Maik Meyer
remeasured the original plate, finding that the original measurements had been for equinox 1900 and not as reported in
IAUC 1437 for equinox 1950.
In 2023 Maik Meyer, Gary Kronk and W H Osborn found the comet on
additional plates which had all been taken by H Rubingh and had been digitised. The MPEC says that these were taken for
the comet, but as they pre-date the discovery this is clearly an error. The comet was found on plates taken between
1951 March 31 and April 7. This allowed an orbit to be computed and the designation changed from X/ to C/. The
published orbit is however unbelievably accurate for such a short arc. The comet was at perihelion at 3.6 au in 1951 November.
[MPEC 2023-F18, CBET 5234, 2023 March 16]
1951 G2 = 1952 C1 (Groeneveld-Palomar)
Ingrid Groeneveld of Yerkes Observatory discovered a 16th magnitude comet in 1954 January on a minor planet survey
plate taken with a 0.25m astrograph at the McDonald Observatory, Texas on 1951 April 9.22. In 2018 Maik Meyer and Gary Kronk
remeasured the original plate, finding that the original measurements had been for equinox 1900 and not as reported in
IAUC 1437 for equinox 1950 and also that the sign of the declination was wrong.
Ronald Weinberger found a comet on a Palomar Sky Survey plate taken on on 1952 February 1.42 during a systematic search of the
plates. This was announced on IAUC 3246 [1978 July 18] as X/1952 C1. The plate was remeasured by Reiner Kracht in 2012.
In 2022 Maik Meyer investigated whether some X/ comets could be linked and found that this was possible for these two objects.
He and Gary Kronk then found the comet on
additional plates which had been taken on
1950 June 12, July 5, July 16 and 1951 April 7.
The designation for both objects was changed from X/ to C/.
The comet was at perihelion at 3.6 au in 1950 July.
[MPEC 2023-J76, CBET 5253 quickly replaced by 5254, 2023 May 10]
1971 M1 (Edwards)
Leonard R Edwards discovered a 9th magnitude comet on plates taken with the 0.5 m Baker-Nunn camera at the Mount John Observatory,
Lake Tekapo, New Zealand on 1971 June 19.59.
This was reported on an IAUC a year later, and no further observations were made. In 2023 Maik Meyer and Gary Kronk found the comet on
additional plates taken between 1971 June 20 and July 25 from South Africa which
had been digitised. This allowed an orbit to be computed and a designation
given. The
published orbit is again unbelievably accurate for such a short arc and an ephemeris is given for 2023 with the comet at 32nd magnitude.
The comet was at perihelion at 2.9 au in 1971 December.
[MPEC 2023-F148, CBET 5239, 2023 March 27]
2008 VA110 [A/Lemmon]
A possible cometary candidate of 21st magnitude was discovered on 2023 October 10.3 in images taken with the 1.5-m
reflector of the Mt Lemmon Survey. It was placed on the PCCP as C9MH8A2. It was fairly quickly linked to an object
discovered by Mt Lemmon on 2008 November 2.40.
[MPEC 2023-T234, 2023 October 14]. No cometary activity has been reported and it is classified by JPL as a
Centaur. It is at perihelion at 3.3 au in 2024 April and is in a retrograde orbit with a period
of 14.7 years.
2010 VH95 (P/Catalina)
The Catalina Sky Survey discovered a 19th magnitude asteroid with the 0.68m
Schmidt on 2010 November 7.49. Prediscovery observations were found from 1997 December and 1998 January (Air Force Maui Optical Station)
and 2010 October (Spacewatch). In 2023 Peter Veres of the MPC reported cometary features in images taken with the 0.5 m Schmidt at Rio Hurtado, Chile on
March 14, with archival images showing cometary activity back to January 16.The comet passed 0.10 au from Jupiter in 1937
January, 0.90 au from Jupiter in 2008 August and 0.24 au from Jupiter in 2020
February. It will also pass 0.37 au from Jupiter in 2032 April. [MPEC 2023-F167,
CBET 5240, 2023 March 27]. It has a period of 5.8 years and the most recent
perihelion was at 1.4 au in February. The Jupiter encounters are currently
pumping up the eccentricity and reducing the perihelion distance.
2014 OL465 (P/PanSTARRS)
Observations of a 22nd magnitude asteroidal object discovered by PanSTARRS 2014 July 25.43
were published on a MPS in 2022 March. There were also pre-discovery PanSTARRS observations
from 2012 March, published in 2023 February. Follow-up observations from ATLAS showed the
object to be brighter than expected and further observations in April and May showed a
coma and tail. It was therefore redesignated as a comet. It was at perihelion at 3.4 au
in 2023 February and has a period of 10.1 years.
[MPEC 2023-K66, CBET 5262, 2023 May 20]
2015 XG422 (P/PanSTARRS)
PanSTARRS 1 discovered a 22nd magnitude asteroid in images taken with the 1.8m Ritchey-Chretien on 2015 December 13.63.
The MPC and CBET give slightly different stories about the discovery of cometary activity by K Ly in 2023 August.
The MPEC notes that Ly found that it showed cometary activity in archical images taken with the Subaru 8.2m telescope
at Maunakea on 2016 March 3 (though this may be a typo for March 7). The CBET suggests that Ly found cometary activity
in images taken with with the "SkyMapper" 1.35-m f/4.8 reflector at Siding Spring on March 5. Ly and PanSTARRS then found
further images showing cometary activity between March and August. There were pre-discovery PanSTARRS images from 2010
September and October.
[MPEC 2023-P35, CBET 5284, 2023 August 7/8]
The comet has a period of 9 years and is next at perihelion at 3.0 au in 2025 January. It can make close approaches
to Jupiter, passing 0.3 au from the planet in 2010 November.
The next close approach is in 2093, when the comet gets to within 0.21 au of
Jupiter.
2023 A1 (Leonard)
Gregory Leonard discovered a comet of 19th magnitude in images taken with the 1.5-m
reflector of the Mt Lemmon Survey on 2023 January 9.54.
It was placed on the PCCP as C8T3Z82.
[MPEC 2023-B66, CBET 5204, 2023 January 22]. The comet is at perihelion at 1.8 au in 2023 March.
2023 A2 (SWAN)
On January 26 Vladimir Bezugly reported on the comets-ml a possible faint comet
in SWAN images that he'd discovered on January 15 in images dating back to
January 6. A team of amateurs then went into action, confirming the comet and
eventually tracking it down in STEREO H1 images, which gave better astrometry.
Ground based imagers including Michael Mattiazo were able to locate it and only
then was it posted on the PCCP, which gave a preliminary designation of SWAN23A
and a discovery date of February 1.9. The comet was at perihelion at 0.9 au in January and was around
13th magnitude. It was formally confirmed on February 23 with the issue of
MPEC 2023-D49 and CBET 5226. The comet will fade, but might be observable in a dark sky
from southern hemisphere locations towards the end of the first week of March.
If the comet had returned to perihelion in early June it would have made a close
pass to the Earth later in the month, passing less than 0.05 au from us and
perhaps reaching naked eye visibility. The orbit MOID from Earth is 0.037
au. There is therefore the possibility
of a meteor shower from the comet in late June.
2023 A3 (Tsuchinshan-ATLAS)
The ATLAS (Asteroid Terrestrial-impact Last Alert System) team discovered an
18th magnitude asteroidal object in images taken with the 0.5 m Schmidt at
Sutherland, South Africa on February 22.08. It was posted on the PCCP as A10SVYR
and follow up observations suggested that it was a comet. These enabled
pre-discovery observations by ZTF on December 22 to be found. The comet was
linked to "isolated tracklet file" observations from Purple Mountain Observatory
on January 9.90, which had been posted on the NEOCP as one of X80918 or X80988,
but with no follow up had been assumed lost on January 30, when the object was
removed. [MPEC 2023-D77, CBET 5228, 2023 February 28/29]. The comet is at
perihelion at 0.4 au in 2024 September. It briefly appeared on the PCCP again in
2023 July as A10VOWR.
The comet could become a visual telescopic object in 2024 February and will still be a telescopic
object for UK observers when lost in the summer twilight in June. If SOHO is still operational
it will pass through the C3 field as a bright object between about October 6 and 12. It
quickly emerges into the evening sky, when it could be an easily visible object with a tail. It
could remain a binocular object into December and a telescopic object into 2025. The MPC and CBAT
magnitude parameters make different assumptions and we should wait for more VEM observations
before making excitable predictions. The comet could turn out to be a
small one and disintegrate at perihelion.
2023 B1 (P/PanSTARRS)
PanSTARRS 2 discovered an 18th magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
January 21.48. It was placed on the PCCP as P21D3Eu. There were prediscovery images with ATLAS-HKO
on January 13 and Xingming Observatory #3, Nanshan on January 19. Alan Fitzsimmons suggests that it may
be a Centaur asteroid that is undergoing an outburst.
[MPEC 2023-B118, CBET 5209, 2023 January 25/26] The comet is at perihelion at 6.1 au in 2023 June and has a period
of around 20 years. It may have passed around 1 au from Jupiter in 1930
October.
2023 B2 (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 Sutherland, South Africa on January 21.97. It was posted on the PCCP as A10Scue.
There were pre-discovery PanSTARRS 1 images from 2022 November 16.
[MPEC 2023-C44, CBET 5217, 2023 February 7]. The comet is at perihelion at 1.7 au in 2023 March.
2023 B3 (P/PanSTARRS)
PanSTARRS 2 discovered an 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
January 23.43. It was placed on the PCCP as P21Ddk2.
[MPEC 2023-D10, CBET 5222, 2023 February 17] The comet was at perihelion at 4.0 au in 2020 August and has a period
of around 10 years. It passed around 0.12 au from Jupiter in 2005 April. The failure to discover it when
nearer to perihelion and the lack of any archival observations suggests that it may be in outburst.
2023 C1 (P/Jahn)
In mid March German amateur astronomer Jost Jahn discovered a comet in images he had taken with the 0.6m ROTAT
telescope of the Universitaet Tuebingen located at the Observatoire de Haute Provence on February 14.94. This
was reported to the MPC and posted on the PCCP as Lienen. The MPC then quickly found isolated tracklets from 2021
October and 2023 February. With a better orbit, additional images were soon found extending the arc back to 2016. A
PanSTARRS image on 2016 February 10.56 was used to give the designation 2016 C3.
The CBAT also asked Sam Deen to check and he found DECam images back to 2013 November.
[MPEC 2023-F123, CBET 5236, 5237, 2023 March 24] The comet was at perihelion at 2.6 au in 2022 October and has a period
of 7.6 years.
2023 C2 (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 1.25. It was posted on the PCCP as A10SuBN.
[MPEC 2023-F141, CBET 5238, 2023 March 26/27]. The comet is at perihelion at 2.4
au in 2024 November. The comet could reach 13th magnitude around the time
of perihelion, when it is at high southern declination.
2023 DP5 [A/Lemmon]
A possible cometary candidate of 21st magnitude was discovered on 2023 February 19.24 in images taken with the 1.5-m
reflector of the Mt Lemmon Survey. It was placed on the PCCP as C8Y7YG2. There were pre-discovery Mt Lemmon images
from 2022 December 23 and PanSTARRS images from January 21.
[MPEC 2023-L28, 2023 June 7]. No cometary activity has been reported and it is classified by JPL as a
Trans-Neptunian Object. It is at perihelion at 4.8 au in 2023 September and is in a retrograde orbit with a period
of 900 years.
2023 E1 (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 Sutherland, South Africa on March 1.00. It was initially posted on the NEOCP as A10TcmV,
but tranferred to the PCCP with a discovery date of 2022 December 25.5 when Peter Veres of the Minor Planet Centre linked it to
an isolated tracklet from February 26 by ATLAS (Chile). He was then able to link it to additional tracklets from Mt Lemmon (February 4),
PanSTARRS (January 22) and finally Kitt Peak-Bok (December 25) and show that the orbit was highly eccentric. Follow-up astrometry then
showed cometry features.
[MPEC 2023-E59, CBET 5233, 2023 March 12]. The comet was at perihelion at 1.0 au in 2023 July and has a period of 85 years. It
will pass 0.4 au from the Earth in 2023 August, but is intrinsically faint.
It has however brightened rapidly and seems to have an
assymetric light curve that makes it brighter post perihelion. It was a very
easy object for me at 8.3 in 20x80B from a dark sky site on August 6, but difficult at 8.7 in
the same binoculars from an urban site on August 9.
2023 F1 (PanSTARRS)
PanSTARRS 1 discovered a 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
March 27.60. It was placed on the PCCP as P11Ebg3. There were prediscovery images with PanSTARRS 2
on March 18.
[MPEC 2023-H184, CBET 5247, 2023 April 26] The comet is at perihelion at 1.7 au in 2023 June.
2023 F2 (SOHO)
Hanjie Tan discovered a Meyer group comet in SOHO C3 images on March 21. Karl Battams and Hanjie Tan measured positions from
March 21.00 to 21.61 from which Bill Gray computed a parabolic orbit. Despite the very short arc, the MPC decided to produce
a hyperbolic orbit, something not justified by the data. The comet was at perihelion at 0.034 au when observed.
[MPEC 2023-K46, 2023 May 18].CBET 5261 [2023 May 19] also recommends
disgregarding the MPC orbit.
2023 F3 (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 March 28.35. [The MPEC says it was discovered
on March 3, but this is likely a typo.] Cometary activity was reported
by Hirohisa Sato and other astrometrists. It was posted on the PCCP as A10UeAm.
[MPEC 2023-O43, CBET 5268, 2023 July 20/21]. The comet is at perihelion at 5.2
au in 2025 February and is in a retrograde orbit.
2023 G1 (P/NEOWISE-SWAN)
On April 16 Rob Matson discovered an object in SWAN images taken between April 5 and 15. Michael Mattiazzo confirmed it with a ground
based observation on April 18. Follow up by the amateur community fairly quickly established a link with 2018 HT3, an Apollo asteroid
discovered by NEOWISE on 2018 April 22.96. PanSTARRS observations from 2012 September, October and 2013
June were subsequently found. The
object was recovered in 2022 November by Spacewatch II. Sam Deen noted that it might be visible in SWAN imagery from 1997 August,
2002 September, 2007 October, 2012 December and 2018 January. It was also visible in STEREO images from 2012 November.
The comet is past perihelion but
approaching Earth. It is estimated at around 13th magnitude and
won't get any brighter but the elongation will improve. It is at high southern
declination. This object probably won't receive the above designation as the MPC use a different logic to that used by Brian Marsden
who devised the system.
2023 H1 (PanSTARRS)
PanSTARRS 2 discovered a 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
April 17.35. It was placed on the PCCP as P21EEX6.
[MPEC 2023-J101, CBET 5256, 2023 May 12] The comet is at perihelion at 4.5 au in 2024 November.
2023 H2 (Lemmon)
A possible NEO candidate of 21st magnitude was discovered on 2023 April 23.28 in images taken with the 1.5-m
reflector of the Mt Lemmon Survey. It was placed on the PCCP as C95VDX2. Subsequently other astrometrists reported
that it had cometary features. There were pre-discovery PanSTARRS images from March 26 and April 18.
[MPEC 2023-K122, CBET 5264, 2023 May 24]. The comet is at perihelion at 0.9 au in 2023 October. After
perihelion it passed 0.2 au from the Earth when it reached 6th magnitude. JJ Gonzalez observing on September 18
estimated it at mag 9.3 in his 20cm SCT, significantly brighter than expected,
although with a large diffuse coma. Sam Deen suggests that the comet is a better
possible progenitor for the Lambda Ursae Majorids than 1975 T2.
2023 H3 (PanSTARRS)
PanSTARRS 2 discovered a 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
April 28.40. It was placed on the PCCP as P21EXHF.
There were pre-discovery PanSTARRS observations from March 16, 31, April 15 and
21. [MPEC 2023-K195, CBET 5267, 2023 May 30] The comet is at perihelion at 5.2 au in 2024 February and
has a period of around 50 years. If the orbit is correct Syuichi Nakano notes
that the comet would have passed 0.005 au from Uranus in 1938 November, before
which the comet had perihelion at 6.2 au in 1924 October and a period of 66
years.
2023 H4 (A/PanSTARRS)
PanSTARRS 2 discovered a 22nd magnitude object in images taken with the 1.8 m Ritchey-Chretien on
April 23.58. It was placed on the PCCP as P21EOEN and on the previous NEOCP page is now listed as a comet.
[MPEC 2023-L26, CBET 52xx, 2023 June 7] No cometary activity has been detected to date. The object is in a
near parabolic orbit with perihelion at 2.1 au in 2023 August.
The MPC listing of orbits currently [2023 June 18] gives an implausibly large
value for the K magnitude parameter.
2023 H5 (Lemmon)
A possible NEO candidate of 20th magnitude was discovered on 2023 April 19.18 in images taken with the 1.5-m
reflector of the Mt Lemmon Survey. It was placed on the PCCP as C94R802, before the
three comets subsequently designated as 2023 H2 to H4.
Martin Tichy reported that it had cometary features in follow-up images taken on April 21. There were pre-discovery PanSTARRS images from
2022 December 1, 2023 January 20, March 27 and Mt Lemmon images from January 28.
[MPEC 2023-M44, CBET 5272, 2023 June 19, CBET 5274, 2023 July 1]. The comet is at perihelion at 4.3 au in 2025 June.
The second CBET attempts to explain the nomenclature.
2023 H6 (467P/LINEAR-Grauer)
Marco Micheli and Charles Schambeau recovered comet 2010 TO20 in images taken on April 20.39 and May 25 with the Gemini
South 8.1m reflector. It was 23rd magnitude and had been at perihelion at 5.5 au in 2022 December. Sam Dean had previously found ZTF images from 2009 July.
[MPEC 2023-O88, CBET 5283, 2023 July 27] The comet passed 0.24 au from Saturn in 1960 August,
0.35 au from Jupiter on 2003 August 26, and 0.075 au from Jupiter on 2009 October 22.
It currently has a period of 14.1 years.
2023 JW18 [A/PanSTARRS]
PanSTARRS 1 discovered a 22nd magnitude object in images taken with the 1.8 m Ritchey-Chretien on
May 1.60. It was placed on the PCCP as P11EZlW. There were pre-discovery observations from March 27.
[MPEC 2023-L27, 2023 June 7] No cometary activity has been detected to date and JPL classify it as
a Centaur. The object is in a
115 year retrograde orbit with perihelion at 4.5 au in 2023 October.
2023 K1 (ATLAS)
The ATLAS (Asteroid Terrestrial-impact Last Alert System) team discovered an 18th magnitude comet
in images taken with the 0.5 m Schmidt at Rio Hurtado, Chile on May 27.09. It was posted on the PCCP as A10VCQK.
[MPEC 2023-L19, CBET 5268, 2023 June 5/6]. The comet is at perihelion at 2.0
au in 2023 September and is in a retrograde orbit. The MPC orbit gives a period of around
250 years, however it is only a six day arc and the 1-sigma uncertainty is
+/-250 years. Clearly a near parabolic orbit is just as likely and this is what
the CBET gives.
2023 KF3 (471P/LINEAR-Fazekas)
Jacqueline Fazekas reported in June that she had noted cometary activity in an object
discovered with the 1.5-m reflector of the Mt Lemmon Survey on 2023 May 24.44.
The activity was confirmed by several
other observers and reported on the comets-ml on September 6. It was linked to
an object discovered by LINEAR on 2010 December 31.29 and designated as 2010 YK3 and there was a Spacewatch image from
1996 June. The MPC later confirmed the cometary nature [MPEC 2023-R42,
2023 September 8]. The comet is
at perihelion in December at 2.1 au and has a period of 13.6 years. It has a Jupiter MOID of 0.3 au, with an approach
to 0.9 au in 1995 May and one to 0.6 au in 2039 February.
2023 L1 (P/Hill)
Facility astronomers recovered 2008 L2 in images taken with the ESA TBT 0.56-m f/2.52 astrograph at the ESO La Silla
Observatory, Chile on June 1.39, with additional images on June 2 and 8. The comet was 19th magnitude and near perihelion.
[MPEC 2023-L67, CBET 5270, 2023 June 12/13]
The TBT (Test Bed Telescope) is a collaboration between the European Space Agency and the European Southern Observatory
to design an autonomous network of telescopes for survey of transients and moving objects. First light was in 2021, and
there is a northern component at the Cebreros Satellite Tracking Station in Spain.
2023 M1 (P/PanSTARRS)
PanSTARRS 1 discovered a 20th magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
June 16.41. It was placed on the PCCP as P11G8vW. There were prediscovery PanSTARRS images
on April 24, 30, May 12, 15 and from Mt Lemmon on May 24. The May 12 and 24 observations were in the MPC
isolated tracklet file, which would in some previous cases give Mt Lemmon co-discovery status.
[MPEC 2023-M65, CBET 5273, 2023 June 20] The comet is at perihelion at 2.8 au in 2023 December and has a period
of around 18 years.
2023 M2 (P/PanSTARRS)
PanSTARRS 1 discovered a 20th magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
June 22.57. It was placed on the PCCP as P11GzhE.
[MPEC 2023-N15, CBET 5276, 2023 July 6] The comet is at perihelion at 3.5 au in 2023 July and has a period
of around 13 years.
2023 M3 (P/PanSTARRS)
A possible new comet of 19th magnitude was discovered on June 26.42 in images taken with the 1.5-m
reflector of the Mt Lemmon Survey. It was placed on the PCCP as C9DRXC2. Following some confirmatory observations
and astrometry, M Suzuki identified it as a return of 2015 T3 some 0.2 degrees from its predicted position, requiring
a correction of Delta(T) = +0.58 day to previously published elements.
[MPEC 2023-N18, CBET 5277, 2023 July 7]. The comet was at perihelion at 2.2 au in 2023 May
and has a period of 8.12 years. The comet passed 0.63 au
from Jupiter on 2003 August 24 and will pass 0.28 au from Jupiter on 2025 December 24
in an encounter that will slightly increase the perihelion distance.
2023 M4 (P/ATLAS)
The ATLAS (Asteroid Terrestrial-impact Last Alert System) team discovered a 17th magnitude object
in images taken with the 0.5 m Schmidt at Sutherland, South Africa on June 21.06. It was posted on the PCCP as A10VJYv.
PanSTARRS noted cometary activity in pre-discovery images taken on June 18. As the orbit improved further pre-discovery
images from Cerro Tololo-DECam (2021 March 17 - 2021 June), PanSTARRS (2021 April - 2023 June) and Catalina Sky Survey
(2023 June) were found.
[MPEC 2023-O51, CBET 5281, 2023 July 22]. The comet was at perihelion at 3.9 au in 2022 April and has a period of 12.7 years.
The comet is much brighter than might be expected given the time from perihelion, so it may be in outburst.
2023 NY6 [A/PanSTARRS]
PanSTARRS 2 discovered a 22nd magnitude object in images taken with the 1.8 m Ritchey-Chretien on
July 12.28. It was placed on the PCCP as P21GTRq.
[MPEC 2023-P40, 2023 August 8] No cometary activity has been detected and JPL classify it as
a Centaur. The object is in a
15 year retrograde orbit with perihelion at 2.6 au in 2023 August. The orbit has a Jupiter MOID of 0.26 au
and it passed 0.9 au from the planet in 2022 April.
2023 NC7 [A/PanSTARRS]
PanSTARRS 2 discovered a 22nd magnitude object in images taken with the 1.8 m Ritchey-Chretien on
July 7.30. It was placed on the PCCP as P21GNQK.
[MPEC 2023-P64, 2023 August 13] No cometary activity has been detected and JPL classify it as
a Centaur. The object is in a
23 year retrograde orbit with perihelion at 3.3 au in 2024 March.
2023 O1 (468P/Siding Spring)
Martin Masek recovered 2004 V3 in images
taken on July 19.37 with a 0.3m reflector at the Pierre Auger Observatory, Malargue and then found it in images from July 18.
The comet was over 0.5 degrees from the predicted position, requiring a correction of Delta(T) = -3.20 days to the predicted
time of perihelion. The comet is fainter than expected, so the light curve may be assymetric.
[MPEC 2023-O89, CBET 5282, 2023 July 27]. The comet is at perihelion at 3.9 au in 2023 November and has a period of 19.0 years.
It passed 0.27 au from Saturn in 1980 March and 1.03 au from Jupiter in 1986 September.
2023 O2 (470P/PanSTARRS)
John Maikner recovered 2014 W1 with the 0.3m telescope at the Comet Hunter Observatory 2 at New Ringgold on August 2.24, with a
confirming image on August 11. Werner Hasubick also imaged it from his Buchloe Observatory on August 14. The MPC have
however decided that the recovery observation was made by PanSTARRS on July 30.54.
This was found by the MPC in the "isolated tracklet file" and reported as an unidentified object,
though it is not clear when this report was made. PanSTARRS then found further
images from June 22, 29, July 29 and August 22. The previously published orbit
required a correction of Delta(T) = -0.14 day.
[MPEC 2023-Q142, CBET 5288, 2023 August 26]
2023 P1 (Nishimura)
A 10th magnitude object, discovered on August 12.78 by Hideo Nishimura, Kakegawa, Japan, was posted on the PCCP as HN00003.
He made the discovery using a 200-mm f/3 lens mounted on a Canon EOS 6D, then found the comet in pre-discovery
images taken on August 11.77. Following posting on the PCCP it was
subsequently detected (and previously suspected) in SWAN imagery by Vladimir Bezugly and others, and then imaged by Sam
Dean and Andrew Pearce. The initial orbits computed by the MPC appeared unrealistic and clearly reflected their
priority in dealing with NEO asteroids, but with further observations the orbit stabilised.
The orbit has an MOID of 0.06 au, so there might be the possibility of an
associated meteor shower. This was confirmed when CBET 5290 was issued on August
29. Following release of a new orbit, PanSTARRS were able to find images from
January 19, 24 and 25, with Sam Dean finding a ZTF image from March 10. The latest orbit shows that the comet has a period of
437 years and
is associated with the sigma Hydrid meteors. The shower peaks around November
30. The comet has just crossed the Earth's orbit,but the
Earth is still 1.4 au from the intersection point, so significantly enhanced
activity is unlikely. To date there is no linkage with any historical comet.
I was able to observe it from central
Cambridge on August 30, when it was 7.1 in 20x80B, though it was a difficult
object. I made some further observations from near Chester on September 4 and 5,
when it was around 5th magnitude.
The comet has passed perihelion and is at a poor solar elongation. Despite the small elongation JJ Gonzalez
was able to observe it on September 18, when it was mag 2.5. Nick James also imaged it from La Palma the same day. It
remains fairly close to the Sun after perihelion and is unlikely to be
observable again until it has faded past 10th magnitude. Amazingly Willian Souza was able to observe the comet on September 23.9,
when it was 4.5 in binoculars. It transited through the STEREO field between
September 17 and October 3 and Nick James created a movie from the images.
Nick James imaged the comet on 2023 December 17, just after the orbital plane
crossing, with his image showing a broad fan of material in the plane.
2023 Q1 (PanSTARRS)
Peter Veres of the MPC linked five "isolated tracklet" observations made between August 20 and September 20
to obtain a parabolic orbit. He then asked PanSTARRS to check their images, with the team finding that the
object did show cometary features on August 20.55, when it was 22nd magnitude. The object was posted on the
PCCP as C9JMD92, suggesting that the original linkage was with Mt Lemmon images taken on September 6.38.
There were pre-discovery PanSTARRS images from July 25, 26 and 29.
[MPEC 2023-T08, CBET 5300, 2023 October 3] The comet is at perihelion at 2.6 au in 2024 December.
2023 Q2 (PanSTARRS)
PanSTARRS 2 discovered a 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
August 23.25. It was placed on the PCCP as P21IhFT. There were pre-discovery PanSTARRS images from July 6.
[MPEC 2023-U285, CBET 5307, 2023 October 30] The comet is at perihelion at 3.2 au in 2024 June.
2023 QE7 [A/PanSTARRS]
PanSTARRS 1 discovered a 22nd magnitude object in images taken with the 1.8 m Ritchey-Chretien on
August 20.56. It was placed on the PCCP as P11I4ri.
[MPEC 2023-Q155, 2023 August 28] No cometary activity has been detected and JPL classify it as
a TNO. The object is in a 700 year retrograde orbit with perihelion at 3.1 au in 2023 October.
2023 R1 (PanSTARRS)
PanSTARRS 2 discovered a 20th magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
September 7.57. It was placed on the PCCP as P21IGyX. There were pre-discovery PanSTARRS images from July and August.
[MPEC 2023-R197, CBET 5293, 2023 September 14/15] The comet is at perihelion at 3.6 au in 2026 April.
2023 R2 (PanSTARRS)
PanSTARRS 2 discovered a 21st magnitude object in images taken with the 1.8 m Ritchey-Chretien on
September 10.59. It was placed on the PCCP as P21J4LW and found to be cometary in follow up images.
[MPEC 2023-T07, CBET 5301, 2023 October 3] The comet is at perihelion at 0.9 au in 2024 August.
Although it may reach 11th magnitude, it is badly placed near perihelion and unlikely to be observed
visually.
2023 R3 (A/PanSTARRS)
PanSTARRS 2 discovered a 22nd magnitude object in images taken with the 1.8 m Ritchey-Chretien on
September 15.43. It was placed on the PCCP as P21JDKb but so far no cometary activity has been detected.
[MPEC 2023-T161, 2023 October 11] The object is at perihelion at 1.4 au in 2023 December and is in
a near parabolic orbit. It may show cometary activity when closer to perihelion.
2023 RN3 (ATLAS)
The ATLAS (Asteroid Terrestrial-impact Last Alert System) team discovered a 17th magnitude asteroid
in images taken with the 0.5 m Schmidt at Haleakala on September 4.56. On November 11, images from the 0.5 m
Schmidt at Sutherland showed the object to have a coma and this was confirmed by other astrometrists.
[MPEC 2023-X85, CBET 5321, 2023 December 6]. The comet was at perihelion at 5.2 au in 2023 January and has a period of
around 32 years.
2023 RC49 [A/PanSTARRS]
PanSTARRS 1 discovered a 21st magnitude object in images taken with the 1.8 m Ritchey-Chretien on
September 11.28. It was placed on the PCCP as P11J7Hk.
[MPEC 2023-S227, 2023 September 26] No cometary activity has been detected and JPL classify it as
a Centaur. The object is in a 23 year near perpendicular retrograde orbit with perihelion at 4.7 au
in 2024 September, though it is only determined over a 5-day arc.
The orbit has a Jupiter MOID of 0.3 au.
2023 RL75 (P/NEAT-LINEAR)
This object was discovered at 21st magnitude by Erwin Schwab with the Calar Alto-Schmidt on September 9.09. JPL classified it as
a Centaur. The object is in a 21 year orbit with perihelion at 3.4 au
in 2024 July.
The orbit has a Jupiter MOID of 0.7 au and a Saturn MOID of 0.3 au.
Alessandro Odasso pointed out on October 24 via the comet-ml that the orbit for this object was close to that of
2002 T6 (P/NEAT-LINEAR). The MPC confirmed this on October 30 with the issue of MPEC 2023-U279. Neither this
nor CBET 5306 credits Alessandro, although the CBET alludes to the posting leading to further observations.
Given that an orbit was published before the identification was known the comet
should become P/NEAT-LINEAR-Schwab.
2023 S1 (P/PanSTARRS)
PanSTARRS 2 discovered a 20th magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
September 20.60. It was placed on the PCCP as P21Kaye. There were pre-discovery PanSTARRS and Mt Lemmon
images from earlier in the month. There were also three
observations made by T. Maroti with a 0.28-m f/2.2 reflector between September 19.99 and 20.02 at
Csokako, Hungary, in the MPC's "isolated tracklet file". This may be the reason why the comet has
not been formally named.
[MPEC 2023-S264, CBET 5296, 2023 September 29/30] The comet is at perihelion at 2.6 au in 2025 February
and has a period of 7.5 years. The preliminary orbit suggests that the comet passed only 0.0017au from
Jupiter around 2021 June 8. Prior to this encounter the comet was in a more distant orbit with
perihelion at 5.0 au and a period of 26 years.
It briefly appeared on the PCCP again on October 10 as P11LgS9.
2023 S2 (ATLAS)
The ATLAS (Asteroid Terrestrial-impact Last Alert System) team discovered a 15th magnitude comet
in images taken with the 0.5 m Schmidt at Rio Hurtado, Chile on September 28.99. It was posted on the PCCP as A10X1pX.
[MPEC 2023-T05, CBET 5299, 2023 October 2]. The comet is near perihelion at 1.1 au and has a period of around 1000 years
according to the MPC, although the CBET give a parabolic orbit.
The comet may have a steep light curve as it was reasonably placed for some time before discovery.
The large diffuse coma points against an outburst. It is
around 12th magnitude to visual observers and is likely to remain near this brightness.
2023 S3 (Lemmon)
A possible NEO candidate of 20th magnitude was discovered on September 25.45 in images taken with the 1.5-m
reflector of the Mt Lemmon Survey. It was placed on the PCCP as C9KD7J2. Subsequently other astrometrists reported
that it had cometary features.
[MPEC 2023-V01, CBET 5310, 2023 November 1]. The comet is at perihelion at 0.8 au in 2024 January and is
in a retrograde orbit with a period of about 150 years. It is a bad return, with the comet on the far
side of the Sun at perihelion.
2023 S4 = 2023 X5 (474P/Hogan)
Joshua Hogan discovered a possible comet of 20th magnitude on December 15.25 in images taken with the 1.5-m
reflector of the Mt Lemmon Survey. It was placed on the PCCP as CA1HX32. The MPEC says that discovery was on December
14, but there are no observations on that date. Logically it should therefore have been designated as 2023 X5, however
there were Mt Lemmon observations on September 25.45, presumably in an ITF, so they chose to use that date for the
discovery designation. With a better orbit, archival observations back to 2005 June were found, with 2017 July
30.58 also being indicated as a discovery date, however there is no designation associated with it. The CBET suggests
that the MPC made a mistake, and that it should indeed have been designated 2023 X5. They also give a designation
of 2017 O4 using the PanSTARRS observations in 2017. This will create further problems as on 2024 January 28 the MPC
had given a designation of 2023 X5 to a recovery of 2001 Q6.
[MPEC 2024-B74, CBET 5341, 2024 January 20/29]. The comet was at perihelion at 2.5 au in 2023 July and has a period of 5.5 years.
It passed 0.08 au from Ceres in 2012 December.
2023 T1 (P/PanSTARRS)
PanSTARRS 2 discovered a 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
October 9.45. It was placed on the PCCP as P21L9BT. There were pre-discovery PanSTARRS images from
July 16 and Mt Lemmon images from September 15 and 25.
[MPEC 2023-U53, CBET 5302, 2023 October 17] The comet is at perihelion at 2.8 au in 2024 May
and has a period of 8.7 years. Although the orbit is preliminary, it suggests that the comet passed
0.054 au from Jupiter on 2007 October 29 and 0.15 au from the planet on 2019 May 16. Prior to these
encounters the comet had an orbit with a 29 year period and perihelion at 5.1 au.
2023 T2 (Borisov)
Gennady Borisov discovered a 19th magnitude comet in images taken with the MARGO 0.5-m f/1.9
reflector at Nauchnij, Crimea on October 14.69. It was placed on the PCCP as
gb00642 and quickly confirmed by other astrometrists.
[MPEC 2023-U162, CBET 5304, 2023 October 21] The comet is at perihelion at 2.0 au in 2023 December.
The discovery is eligible for the Edgar Wilson Award.
2023 T3 (Fuls)
David Carson Fuls discovered a comet of 19th magnitude in images taken with the 1.5-m
reflector of the Mt Lemmon Survey on 2023 October 15.47.
It was placed on the PCCP as C9Q3GV2.
[MPEC 2023-U290, CBET 5309, 2023 October 30]. The comet is at perihelion at 3.4 au in 2025 January.
2023 TX4 [A/PanSTARRS]
PanSTARRS 1 discovered a 21st magnitude object in images taken with the 1.8 m Ritchey-Chretien on
October 7.55. It was placed on the PCCP as P11KWdr.
[MPEC 2023-T142, 2023 October 10] No cometary activity has been detected and JPL classify it as
a Centaur. The object is in a 28 year retrograde orbit with perihelion at 1.4 au
in 2024 February, though it is only determined over a 14-day arc.
The orbit has an Earth MOID of 0.5 au and a Jupiter MOID of 0.5 au.
2023 TW36 [A/PanSTARRS]
PanSTARRS 1 discovered a 22nd magnitude object in images taken with the 1.8 m Ritchey-Chretien on
October 11.37. It was placed on the PCCP as P11LiYE. There were prediscovery PanSTARRS images
from August 22, September 11, 16, October 8 and Mt Lemmon from October 5
[MPEC 2023-U142, 2023 October 20] No cometary activity has been detected and JPL classify it as
a Centaur. The object is in a 78 year retrograde orbit with perihelion at 2.7 au
in 2024 February.
2023 TD38 [A/PanSTARRS]
PanSTARRS 1 discovered a 22nd magnitude object in images taken with the 1.8 m Ritchey-Chretien on
October 15.56. It was placed on the PCCP as P11LQTX.
[MPEC 2023-U188, 2023 October 21] No cometary activity has been detected and JPL classify it as
a TransNeptunian Object. The object is in a retrograde orbit of uncertain period with perihelion at 3.0 au
in 2024 February.
2023 U1 (Fuls)
David Carson Fuls discovered a comet of 19th magnitude in images taken with the 1.5-m
reflector of the Mt Lemmon Survey on 2023 October 16.48.
It was placed on the PCCP as C9QHK92.
[MPEC 2023-U290, CBET 5308, 2023 October 30]. The comet is at perihelion at 5.0 au in 2024 October.
2023 V1 (Lemmon)
A comet of 20th magnitude was discovered on November 2.23 in images taken with the 1.0-m reflector of the Mt Lemmon
station at the Steward Observatory and it was also found in images taken with
the 1.5-m reflector of the Mt Lemmon Survey on November 2.17, which were
reported second. It was placed on the PCCP as C9RR4L2. Subsequently pre-discovery images from
PanSTARRS (August 2, 23, September 21, 29, October 22, 27) and Mt Lemmon Survey (September 9, 21, October 4, 21) were found
in the isolated tracklets files or by direct searching of archive images.
[MPEC 2023-V23, CBET 5311, 2023 November 4]. The comet is at perihelion at 5.1 au in 2025 July.
2023 V2 (P/PanSTARRS)
PanSTARRS 2 discovered a 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
November 4.47. It was placed on the PCCP as P21NdOI. There were pre-discovery PanSTARRS images from
from September 9 and October 6, 15, 18 and 24.
[MPEC 2023-V108, CBET 5312, 2023 November 8] The comet is at perihelion at 3.1 au in 2024 February
and has a period of 20 years. The comet passed 0.003 au from Saturn on 2018
February 3.
2023 V3 (PanSTARRS)
PanSTARRS 1 discovered a 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
November 3.46. It was placed on the PCCP as P11N8Vj. There were pre-discovery PanSTARRS images from
from September 25 and October 7, 11, 15 and 30.
[MPEC 2023-V109, CBET 5313, 2023 November 8] The comet was at perihelion at 4.5 au in 2023 August
and has a period of 50 years.
2023 V4 (Camarasa-Duszanowicz)
Jordi Camarasa (Sabadell, Barcelona, Spain) and Grzegorz Duszanowicz (Akersberga, Sweden) discovered a
somewhat-diffuse comet in CMOS-camera images taken on November 5.06 using two 0.28-m f/1.9
Schmidt-Cassegrain (Celestron C11) telescopes located at Duszanowicz's
"Moonbase South Observatory" at the Hakos "Astro Farm" in Namibia. This was confirmed by follow up
images by themselves and other astrometrists.
[MPEC 2023-V192, CBET 5315, 2023 November 11]. The comet is at perihelion at 1.1 au in 2024 May.
It is then at a poor solar elongation and is likely to be too faint for visual observation when
it becomes better placed in July.
2023 V5 (Leonard)
Gregory Leonard discovered a comet of 17th magnitude in images taken with the 0.68m Schmidt
of the Catalina Sky Survey on 2023 November 6.14.
It was placed on the PCCP as C40DFE1.
[MPEC 2023-V193, CBET 5316, 2023 November 11]. The comet is at perihelion at 0.8 au in 2023 December.
It had approached to 0.2 au from the Earth on November 4. It will fade as it recedes from the Earth,
although still approaching the Sun.
Reinder Bouma pointed out in a message sent to the comet-ml on November 6, that the orbital elements
appeared very similar to those of the Liller group of comets, which are named after 1988 A1 and also
include 1996 Q1, 2015 F3 and 2019 Y1.
2023 V6 (P/PanSTARRS)
PanSTARRS 1 discovered a 21st magnitude comet in images taken with the 1.8 m
Ritchey-Chretien on November 8.56. It was placed on the PCCP as P11NzCq. There
were pre-discovery PanSTARRS images from from October 16, 22, 25 and November 4.
[MPEC 2023-V262, CBET 5312, 2023 November 15] The comet was at perihelion at 4.4
au in 2022 December and has a period of around 12 years, but uncertain by nearly
two months. The comet may have passed 0.3 au from
Jupiter on 2020 December.
2023 V7 (475P/Spacewatch-LINEAR)
Marco Micheli reported the recovery of 2004 DO29 (P/Spacewatch-LINEAR) in images
taken on November 11.24 with the 1.0-m reflector of the ESA Optical Ground
Station, Tenerife. Francisco Ocana reported an independent recovery in images
taken November 13.22 with the Calar Alto 0.8-m Schmidt.[MPEC 2024-B93, 2024 January 22]
The CBET gives a different take on affairs, suggesting that their first
indication of the recovery was from Richard Weyrk discovering a new comet in
PanSTARRS images from November 25.63, which he linked to 2004 DO29. He then
found pre-discovery images from November 11.6. As most of these
observations had been kept confidential, Michal Jager made another independent
recovery on 2024 January 17.14 The correction to the perihelion time compared to
the previous orbit was Delta(T) = -1.50 days. [CBET 5335, 2024 January 23] The comet is at
perihelion at 4.1 au in 2024 June and has a period of 19.8 years.
2023 V8 (477P/PanSTARRS)
T Oribe recovered 2018 P3 in images taken with the 1.03-m reflector at the Saji Observatory
on November 15.39. It was 21st magnitude. The CBET draws attention to observations made in 2013
at Mauna Kea (Published in 2022) and by PanSTARRS (published in 2023), which should have been given
a 2013 designation. [MPEC 2024-B135, CBET 5336, 2024 January 26]
THe comet was at perihelion at 1.8 au in 2023 December and has a period of 5.2 years.
2023 W1 (473P/NEAT)
Comet 2001 Q6 was recovered at Skygems Chile, Rio Hurtado on 2023 November 29 by
Hidetaka Sato. The delta-T correction was -2.7 days compared to the published
orbit. The comet passed 0.7 au from Jupiter in 1957 November. It is at
perihelion at 1.4 au in 2024 February and has a period of 22 years. On December
9 the MPC posted it on the PCCP as CA06E32 without realising that it had already
been recovered. It is a poor return, but if it again brightens rapidly it could
reach 13th magnitude. It took the MPC another four days to issue MPEC 2023-X258,
with CBET 5325 following.
2023 W2 (476P/PanSTARRS)
John Maikner recovered 2015 HG16 with the 0.3-m telescope at the Comet Hunter Observatory 2 at New Ringgold on November 17.15, with
confirming images two days later. The MPEC states that the recovery images were on November 19 and 20, but the published positions
are on November 17 and 19, once again suggesting the proof reading is not a strong point. The previously published orbit
required a correction of Delta(T) = 0.5 day. The CBET remarks that the November 17 observations have large residuals and may not be
real. They give a recovery date of November 19.15 and also noted that the MPC had found additional ITF observations from December 7, 8 and 16.
They also note that supposed observations of the comet made by ATLAS in 2018 July and published by the MPC are almost certainly not of this comet.
[MPEC 2024-B134, CBET 5337, 2024 January 26] The comet is at perihelion at 3.1 au in 2024 October and has a period of 10.5 years. It passed
0.066 au from Jupiter in 2006 November, prior to which it had a period of 22 years with perihelion at 4.9 au.
2023 WM26 (P/Elenin)
In something of a repeat performance the MPC published an orbit for a 22nd magnitude asteroid discovered by PanSTARRS on
2023 November 18.46, with further pre-discovery PanSTARRS images from October 17, 24 and November 12. [MPEC 2023-Y72,
2023 December 21]. Three hours later Maik Meyer put a message on the comets-ml noting that this was actually a
return of 2011 NO1. It is not clear whether this will result in a new designation of Elenin-PanSTARRS, or even Elenin-Meyer.
The MPC eventually acknowledged the identity in MPEC 2024-B143 [2024 January 28] wrongly atributing Hirohisa Sato as the first
to point out the identity. The CBET acknowledge Maik Meyer as being the first to suggest the identity. The previously
published elements require a correction of Delta(T) = -0.25 day. [CBET 5339 (wrong elements, 5340, 2024 January 28] The
comet is at perihelion in 2024 May at 1.2 au and has a period of 13.3 years. It could reach 14th magnitude around the time
of perihelion.
2023 X1 (Leonard)
Gregory Leonard discovered a comet of 17th magnitude in images taken with the 1.5-m
reflector of the Mt Lemmon Survey on 2023 December 4.44.
It was placed on the PCCP as C42KPG1. The MPC wrongly designated it as C/Lemmon due to a "production error", and corrected this some
three hours later. The CBET suggests that the comet was three magnitudes brighter than indicated by the discovery magnitude, though
it would then be surprising for it not to have been discovered by some amateur surveys.
[MPEC 2023-X222, X224, X225, CBET 5322, 2023 December 11/12]. The comet was at perihelion at 1.0 au in 2023 October.
2023 X2 (Lemmon)
A object of 20th magnitude was discovered on December 4.35 in images taken with the 1.5-m reflector of the Mt Lemmon Survey.
It was placed on the NEOCP as C9YKH92 as a potential NEO. Earlier, PanSTARRS had discovered a comet in images taken on
December 4.31, but this was not reported until after the Mt Lemmon observations were posted. There were pre-discovery
images from PanSTARRS (August 18, September 20, October 7, 12, 17, November 16) and Mt Lemmon Survey (November 4).
The MPC wrongly designated it as 2023 T4 (Lemmon) due to a "production error", and corrected this some
three hours later. Given the circumstances it is surprising that it wasn't designated Lemmon-PANSTARRS.
[MPEC 2023-X223, X224, X226, CBET 5323, 2023 December 12]. The comet is at perihelion at 5.1 au in 2025 December.
2023 X3 (P/PanSTARRS)
PanSTARRS 2 discovered a 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on
December 7.35. It was placed on the PCCP as P21P3ce. There were pre-discovery PanSTARRS images from
from October 22, 26 and December 4 and Kitt Peak-Bok images from November 11.
[MPEC 2023-X269, CBET 5326, 2023 December 13] The comet is at perihelion at 3.0 au in 2024 April
and has a period of 8.8 years. It passed 0.3 au from Jupiter in 2021 July.
2023 X4 (Hogan)
Joshua Hogan discovered a comet of 20th magnitude in images taken with the 1.5-m
reflector of the Mt Lemmon Survey on 2023 December 13.33. It was placed on the PCCP as CA0N8C2.
[MPEC 2023-X272, X224, X225, CBET 5327, 2023 December 14]. The comet was at perihelion at 3.7 au in 2024 May
and has a period of about 31 years.
2023 S4 = 2023 X5B (474P/Hogan)
Joshua Hogan discovered a possible comet of 20th magnitude on December 15.25 in images taken with the 1.5-m
reflector of the Mt Lemmon Survey. It was placed on the PCCP as CA1HX32. The MPEC says that discovery was on December
14, but there are no observations on that date. Logically it should therefore have been designated as 2023 X5, however
there were Mt Lemmon observations on September 25.45, presumably in an ITF, so they chose to use that date for the
discovery designation. With a better orbit, archival observations back to 2005 June were found, with 2017 July
30.58 also being indicated as a discovery date, however there is no designation associated with it. The CBET suggests
that the MPC made a mistake, and that it should indeed have been designated 2023 X5. They also give a designation
of 2017 O4 using the PanSTARRS observations in 2017.
[MPEC 2024-B74, CBET 5341, 2024 January 20/29]. The comet was at perihelion at 2.5 au in 2023 July and has a period of 5.5 years.
It passed 0.08 au from Ceres in 2012 December.
2023 X5A (473P/NEAT)
The MPC reported that
John Maikner recovered 2001 Q6 with the 0.3-m telescope at the Comet Hunter Observatory 2 at New Ringgold on December 12.95, with
other observers later providing confirming images, without realising that the
comet had already been recovered as 2023 W1. The MPC gave a designation of 2023 X5, ignoring the confusion created with
designations of 2023 S4 = 2023 X5. Until this is resolved I am using X5A for this comet and X5B for
P/Hogan.
[MPEC 2024-B144, 2024 January 28]
On January 29 MPEC 2023-B144 was retracted by the MPC, with the statement that
the designation 2023 X5 would be omitted. It is unclear whether 2023 S4 retains the 2023 X5
designation.
2023 X6 (P/PanSTARRS)
2014 A3 was recovered in incidental PanSTARRS astrometry on December 9.53 and on January 7 and 20. The MPEC and CBET give no clues as
to the process of identification. The previously published elements require a correction of Delta(T) = -0.02 day.
[MPEC 2024-B170, CBET 5342, 2024 January 31] The comet was at perihelion at 3.5 au in 2023 April
and has a period of 9.9 years. It passed 0.071 au from Jupiter in 1971 May and 0.6 au in 2006 September, and 0.7 au
from Saturn in 1942 December. Prior to 1971 the perihelion distance was 5.2 au and the period 18.2 years.
2023 X7 (PanSTARRS)
PanSTARRS 2 discovered a 21st magnitude object in images taken with the 1.8 m Ritchey-Chretien on
December 10.39. It was placed on the PCCP as P21PloW and shown to be cometary by Hirohisa Sato and
other astrometrists.
[MPEC 2024-D102, CBET 5355, 2024 February 22] The comet is at perihelion at 4.8 au in 2025 May.
2023 Y1 (P/Gibbs)
Alex Gibbs discovered a comet of 20th magnitude in images taken with the 1.5-m
reflector of the Mt Lemmon Survey on 2023 December 17.50.
It was placed on the PCCP as CA31MC2. There were pre-discovery PanSTARRS images from November 24.
[MPEC 2023-Y60, CBET 5328, 2023 December 19/20]. The comet was at perihelion at 2.1 au in 2023 November
and has a period of around 7 years.
2023 Y2 (P/Gibbs)
Alex Gibbs discovered a comet of around 20th magnitude in images taken with the 1.5-m
reflector of the Mt Lemmon Survey on 2023 December 17.47.
It was placed on the PCCP as CA315N2. There were pre-discovery PanSTARRS images from December 13 and
ITF positions from 2022 October 23 (PanSTARRS) and December 20 (Mt Lemmon).
[MPEC 2024-A148, CBET 5329, 2024 January 13]. The comet was at perihelion at 2.3 au in 2023 August
and has a period of 7.2 years. It passed 0.030 au from Jupiter in 1973 January
and 0.15 au in 2020 February. The residuals from the 2022 observations are
rather large, so non-gravitational forces may be significant making the timing
of Jupiter encounters less certain.
2023 Y3 (478P/ATLAS)
The ATLAS (Asteroid Terrestrial-impact Last Alert System) team discovered a 19th magnitude comet
in images taken with the 0.5 m Schmidt at Sutherland, South Africa on December 18.98. It was posted on the PCCP as A10ZtNK.
There were pre-discovery positions from ATLAS Chile from December 13 in an ITF. Richard Weyrk then linked the comet to the previously
discovered asteroid 2017 BQ100. This object was discovered by PanSTARRS on 2017 January 28.49.
[MPEC 2024-B139, CBET 5338, 2024 January 27]. The comet is at perihelion at 2.4 au in 2024 May and has a period of 7.0 years.
Ephemerides of current comets are available on the CBAT
ephemeris page and positions of newly discovered comets are on the
NEO confirmation page.
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 very 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