BAA Comet Section : Periodic Comets 400 - 499

Updated 2024 June1


  • 400P/PanSTARRS
  • 401P/McNaught
  • 402P/LINEAR
  • 403P/Catalina
  • 404P/Bressi
  • 405P/Lemmon
  • 406P/Gibbs
  • 407P/PanSTARRS-Fuls
  • 408P/Novichonok-Gerke
  • 409P/LONEOS-Hill
  • 410P/NEAT-LINEAR
  • 411P/Christensen
  • 412P/WISE
  • 413P/Larson
  • 414P/STEREO
  • 415P/Tenagra
  • 416P/Scotti
  • 417P/NEOWISE
  • 418P/LINEAR
  • 419P/PanSTARRS
  • 420P/Hill
  • 421P/McNaught
  • 422P/Christensen
  • 423P/Lemmon
  • 424P/La Sagra
  • 425P/Kowalski
  • 426P/PanSTARRS
  • 427P/ATLAS
  • 428P/Gibbs
  • 429P/LINEAR-Hill
  • 430P/Scotti
  • 431P/Scotti
  • 432P/PanSTARRS
  • 433P/NEAT
  • 434P/Tenagra
  • 435P/PanSTARRS
  • 436P/Garradd
  • 437P/PanSTARRS
  • 438P/Christensen
  • 439P/LINEAR
  • 440P/Kobayashi
  • 441P/PanSTARRS
  • 442P/McNaught
  • 443P/PanSTARRS-Christensen
  • 444P/WISE-PanSTARRS
  • 445P/Lemmon-PanSTARRS
  • 446P/McNaught
  • 447P/Sheppard-Tholen
  • 448P/PanSTARRS
  • 449P/Hartley-Leonard
  • 450P/LONEOS
  • 451P/Christensen
  • 452P/Sheppard-Jewitt
  • 453P/WISE-Lemmon
  • 454P/PanSTARRS
  • 455P/PanSTARRS
  • 456P/PanSTARRS
  • 457P/Lemmon-PanSTARRS
  • 458P/Jahn
  • 459P/Catalina
  • 460P/PanSTARRS
  • 461P/WISE-Lemmon
  • 462P/LONEOS-PanSTARRS
  • 463P/NEOWISE-SWAN
  • 464P/PanSTARRS
  • 465P/Hill
  • 466P/PanSTARRS
  • 467P/LINEAR-Grauer
  • 468P/Siding Spring
  • 469P/PanSTARRS
  • 470P/PanSTARRS
  • 471P/LINEAR-Fazekas
  • 472P/NEAT-LINEAR
  • 473P/NEAT
  • 474P/Hogan
  • 475P/Spacewatch-LINEAR
  • 476P/PanSTARRS
  • 477P/PanSTARRS
  • 478P/ATLAS
  • 479P/Elenin
  • 480P/PanSTARRS
  • 481P/Lemmon-PanSTARRS
  • 482P/PanSTARRS
  • 483P/PanSTARRS
  • 484P/Spacewatch
  • 485P/Sheppard-Tholen
  • P/Leonard
  • P/Hahn
  • Comets 1 - 99
  • Comets 100 - 199
  • Comets 200 - 299
  • Comets 300 - 399
  • Comets 400 - 499
  • Not numbered objects
  • 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.

    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.


    400P/PanSTARRS = 2013 PA104 = 2020 R1
    PanSTARRS 1 discovered a 20th magnitude comet in images taken with the 1.8m Ritchey-Chretien on September 9.50. It was placed on the NEOCP with an unknown designation. Richard Weryk of the PanSTARRS team found pre-discovery images from 2013 August, 2014, 2015, 2016 and earlier in 2020. The MPC then gave it an asteroidal designation of 2013 PA104 and deleted it from the NEOCP but did not place it on the list of previous designations. In the meantime the Mt Lemmon Survey reported the detection of a comet on September 10.38 and this was placed on the PCCP as C35DT72. When follow-up observations were made it became obvious that the two objects were the same, but apart from admitting the goof, the MPC has not given further explanation of what went wrong. [CBET 4845, MPEC 2020-R101, 2020 September 13] The comet is at perihelion at 2.1 au in 2021 February and has a period of 6.7 years. 

    This should have been numbered 405 if given in sequential order.


    401P/McNaught = 2006 H1 = 2020 R3
    Rob McNaught discovered another comet, during the course of the Siding Spring Survey, on 2006 April 29.79. The object was 18th magnitude and was at perihelion in early May at 2.4 au. It is in a short period orbit, with period of 14 years.

    Erwin Schwab recovered the comet in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain. on 2020 September 11.09. The indicated delta-T correction to the prediction, by Gareth Williams, on MPC 58118 is -0.15 days. [CBET 4847, MPEC 2020-R159, 2020 September 14]

    This should have been numbered 406 if given in sequential order.


    402P/LINEAR = 2002 T5 = 2020 Q3
    An apparently asteroidal object of mag 18.4 reported by LINEAR on 2002 October 5.39, posted on the NEO Confirmation Page due to unusual motion, has been found to be cometary in appearance. D. T. Durig and J. A. K. Blackwood, University of the South, Sewanee, TN, report that CCD images taken with a 0.30-m reflector on 2002 October 18.4 UT show the object to be diffuse with a hint of a tail 12"-15" long in p.a. 330 deg and a soft coma of diameter 5"-8". Images taken by G. Hug, Eskridge, KS, also with a 0.30-m reflector at about the same time, show a nearly stellar coma with extension about 10"-15" long in p.a. about 280 deg. [IAUC 7998, 2002 October 22]

    The comet is a distant object and reached perihelion at the end of June 2003. The period is 18.5 years and the perihelion distance 3.93 au. Observers contributing to the preliminary orbit included BAA Member Peter Birtwhistle.

    Erwin Schwab recovered the comet in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain. on 2020 August 18.11. The comet was some 5' from the expected position. [CBET 4835, 2020 August 19] It was finally given a designation for the return in MPEC 2020-S155 [2020 September 23].

    This should have been numbered 403 if given in sequential order.


    403P/Catalina = 2007 VQ11 = 2020 T1
    A slightly diffuse object found by Andrea Boattini on Catalina images taken on 2008 February 1.1, was confirmed by J Young at Table Mountain Observatory and then linked by Tim Spahr with an object found by Catalina on 2007 November 3.42. This had been designated following linkage with observations made from Purple Mountain Observatory on November 6. The comet has a period of around 13 years and was near perihelion.

    The Mt Lemmon Survey discovered a comet on 2020 October 15.45, which was placed on the PCCP as C3HU5C2. Hirohisa Sato subsequently realised that this was a return of 2007 VQ11 and it was withdrawn from the PCCP.  CBET 4869 and MPEC 2020-U169 were issued on October 22.  The comet was some 22' from the expected position, corresponding to a delta T of around -1.9 days.


    404P/Bressi = 2011 U2 = 2020 M6
    Terry H Bressi discovered a 19th magnitude comet in Spacewatch images taken with the 0.9-m f/3 reflector at Kitt Peak on 2011 October 24.21. The comet reached perihelion at 4.8 au in May 2012 and has a period of around 13 years.

    Syuichi Nakano found images of the comet in PanSTARRS 1 data taken with the 1.8m Ritchey-Chretien on 2020 June 17.55 and on July 17 and 20. The comet was close to the expected position. The comet passed 0.97 au from Jupiter in 2020 February in an encounter that reduced the perihelion distance from 4.8 to 4.1 au and the period from 12.7 to 10.3 years. [CBET 4831, 2020 August 16] It was finally given a designation for the return in MPEC 2020-U182 [2020 October 23]. It was numbered 404 in CBET 4898 [2020 December 18], though it should have been 400.


    405P/Lemmon = 2013 TL117 = 2020 U1
    An unusual asteroid, classified as an Amor, was discovered during the Mt Lemmon survey with the 1.5m telescope on 2013 October 4.25 and was also designated as 2013 UT2. [MPEC 2013-U68, 2013 October 28, 24-day orbit]. Further observations showed cometary characteristics, and the object was given a cometary designation on MPEC 2013-X59 [2013 December 12]. The object has a period of around 6.8 years and perihelion at 1.1 au in 2014 February. The Tisserand parameter of the orbit with respect to Jupiter is 2.64 and the object can approach within 0.5 au of the planet and to 0.2 au from the Earth, which it did in 1980.

    An object briefly appeared on the PCCP as P218YG3 before being transferred to the "Previous NEOCP Objects" page having been identified as a return of comet 2013 TL117, though it was given on the page as 2013 TL17. The PCCP recovery was by by PanSTARRS 2 on 2020 October 25.6. Shortly afterwards further details were given in MPEC 2020-U231 and CBET 4874 [2020 October 25/26]. These reveal the continuing tensions between the MPC and CBET. Erwin Schwab had recovered the comet on October 17.13 with the Calar Alto 0.8m Schmidt (not Calar Alto-Schmidt as given in the MPEC). Additional independent recoveries were made at the Dominion Astrophysical Observatory on October 22 and by T. Ikemura and Hirohisa Sato on October 23/24.


    406P/Gibbs = 2007 R2 = 2020 R8
    Alex R Gibbs discovered an 18th magnitude comet on 2007 September 10.41 in images taken during the Catalina Sky Survey with the 0.68m Schmidt. The cometary nature was confirmed following posting on the NEOCP. The comet had a period of 6.4 years and was just past perihelion at 1.5 au.

    Comet 2007 R2 was recovered during observations with the Korea Microlensing Telescope Network-SSO 1.6m reflector on 2020 September 11.64, when it was around 22nd magnitude. PanSTARRS 2 recorded it two days later and the Korean group made further observations on September 15. All these observations were published in MPEC 2020-S188 as observations of 2007 R2, though none of the observers realised that it was a recovery. [2020 September 25] Syuichi Nakano of the CBAT later noticed the observations and drew attention to the recovery. T. Ikemura and Hirohisa Sato made follow-up observations on October 10 and 12, with PanSTARRS 1 observing it on October 20. The comet was missed at the 2014 return and passed 0.74 au from Jupiter in 2016 March.  The encounter increased the perihelion distance to 1.6 au and the period to 6.8 years. The comet was at perihelion in September. [CBET 4884, MPEC 2020-U269, 2020 October 30/31]. The CBET yet again hints at the tensions between the CBAT and MPC.


    407P/PanSTARRS-Fuls = 2013 J4 = 2019 Y2
    Pan-STARRS discovered a 21st magnitude comet on 2013 May 5.26. It reached perihelion at 2.3 au in 2013 July and was thought to have a period of around 16 years.  [MPEC 2013-J51, 2013 May 13]. There were only observations over a seven day arc.

    D Carson Fuls discovered a comet of 19th magnitude in Mt Lemmon Survey images taken with the 1.5m reflector on 2019 December 21.53. It was placed on the PCCP as C1N4PQ2 and confirmed by other observers including Michael Jaeger and Eric Bryssinck. [CBET 4709, MPEC 2020-A91, 2020 January 7/8]. The comet was at perihelion at 2.1 au in 2020 January and has a period of around 6 years.

    Sam Deen has shown that the two comets are identical. The comet passed 0.34 au from Jupiter in 2010 in an encounter that significantly changed the orbit. [CBET 4792, 2020 June 8]. 

    The comet should have been numbered 397, but the MPC have ignored the convention of numbering in order of orbit determination and returns.  An MPEC announcing the identity was finally published on 2020 November 11 [MPEC 2020-V67].


    408P/Novichonok-Gerke = 2011 R3 = 2020 M7
    MPEC 2011-R34 announced the discovery by Artyom Novichonok of a comet with the 0.4-m f/8 Ritchey-Chretien at Ka-Dar Observatory, TAU Station, Nizhny Arkhyz on images taken on 2011 September 7.02 by Vladimir Gerke. The comet has a period of 11 years with perihelion at 3.6 au in 2012 April.

    Only the name Novichonok was originally given to the comet, however the discoverer was clear that it was a team effort with Gerke, and the name was later amended.

    Denis Denisenko noted

    As usual, there's a whole story behind the new discovery. This comet was caught just 63 (!!!) pixels from the edge of 1330x890 CCD image in 3x3 binning mode in the first night. Upon posting at NEO Confirmation Page most people (including myself) originally thought it to be identical to 111P (whose predicted position was less than 5' away, yet the magnitude was almost identical to the new object). But the direction of motion of the Comet Novichonok was totally different from Comet Helin-Roman-Crockett, and the new object was about twice slower.

    Congratulations to Artyom with the first Russian periodic comet since the breakup of USSR! If you remember, two Comets Elenin were discovered on the telescope installed in USA. This time the observation was made in southern Russia, in the Republic of Karachay-Cherkessia in northern Caucasus, not far away from the 6-meter BTA telescope.

    Syuichi Nakano found images of 2011 R3 in PanSTARRS 1 data taken with the 1.8m Ritchey-Chretien on 2020 June 20.49 and July 18.36. The comet was close to the expected position. The comet was put into its present orbit during a series of encounters with Jupiter: 0.87 au in 1992 October, 0.11 au in 1993 August and 0.45 au in 2005 April. Prior to these encounters the comet was in a more distant orbit with perihelion at 5.2 au and a period of 19.4 years. [CBET 4833, 2020 August 17] It was finally given a designation for the return in 2020 November [MPEC 2020-V78, 2020 November 12].


    409P/LONEOS-Hill = 2005 XA54 = 2020 V1
    On 2006 January 6.41 BAA Member Rik Hill found an obvious comet in Catalina Sky Survey images. Tim Spahr identified this with an asteroid discovered by LONEOS on 2005 December 4.38 and observed on two nights. The comet had a period of 15.2 years and reached perihelion in early March at 1.8 au. It is an intrinsically faint object.

    According to the MPEC the comet was recovered on 2020 November 3.49 by the Zwicky Transient Facility with the 1.2m Oschin Schmidt and by the Mt Lemmon Survey with the 1.5m reflector on November 16.51. The indicated delta-T correction to the prediction by G. V. Williams on MPC 75706 is -1.08 days and it was some 30' from the expected position.   The CBET gives priority to the Mt Lemon Survey for reporting a new comet and then drawing attention to the likely identity with 2005 XA54.  [CBET 4885, MPEC 2020-W25, 2020 November 17]  The comet has perihelion at 1.8 au in 2021 January and a period of 14.9 years.


    410P/NEAT-LINEAR = 2003 WR168 = 2005 CR16 = 2020 W2
    David Rankin discovered a comet of 20th magnitude, which was in the same field as 2020 W1, in images taken with the 1.5m reflector on November 16.35 during the Mt Lemmon Survey. It was placed on the PCCP as C3XUF62. The MPC and CBET then give slightly different accounts as to how it was linked to an apparently asteroidal object found by NEAT on 2003 November 19.36 (2003 WR168) and LINEAR on 2005 February 19.36 (2005 CR16). These had previously been linked by Tim Spahr in 2008. Carl Hergenrother then re-examined images taken on 2005 March 8 with the Catalina Station 1.54m reflector finding a possible coma, and Sam Deen found images from the CFHT taken on 2005 April 11 which showed a faint tail. Given the clear nature of the independent discovery it isn't obvious why the comet wasn't named NEAT-LINEAR-Rankin. [CBET 4894, MPEC 2020-X10, 2020 December 4]. The comet has a period of 17 years and is at perihelion at 3.2 au in 2021 June. The MPC don't currently give it a name, so perhaps the addition of Rankin is under consideration.
    411P/Christensen = 2007 B1 = 2020 W3
    Eric Christensen discovered a 19th magnitude comet during the Catalina Sky Survey on 2007 January 17.27. Following posting on the NEOCP it was confirmed by several observers including Giovanni Sostero. It has an elliptical orbit with period of 14 years and was near perihelion at 2.4 au at discovery.

    Erwin Schwab recovered comet 2007 B1 as a stellar object in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain, on November 17.13. The comet was some 20' from the predicted position, requiring a Delta(T) of -0.89 day. [CBET 4903, MPEC 2021-A66, 2021 January 7/9]


    412P/WISE = 2010 B2 = 2020 Y1
    A comet was discovered in images from the the Wide-field Infrared Survey Explorer (WISE) satellite on 2010 January 22.64. The object showed a hazy coma and tail in all the infra-red images. It was confirmed by ground-based observations from Mauna Kea and Kitt Peak. The comet has a period of 5.5 years and was at perihelion at 1.6 au in 2009 December.

    Brian Marsden noted on MPEC 2010-F69 [2010 March 23] that further [astrometric] observations of this comet were desirable.

    The comet is one of those suspected to have undergone nuclear splitting according to the list of Marcos & Marcos [Dynamically correlated minor bodies in the outer solar system, MNRAS, 474, 838, 2018 February]. They note that it appears to be related to the multiple fragments of 332P/Ikeya-Murakami.

    Quanzhi Ye recovered comet 2010 B2 in images taken with the 4.3 m Lowell Discovery Telescope on December 19.46. The recovery confirms the identification made by Sam Deen of a single observation made by the DECam on the Cerro Tololo 4 m reflector in 2015 June. [CBET 4904, MPEC 2021-A76, 2021 January 8/9] The comet passed 0.075 au from Mars on 1999 February 18. It passed 0.44 au from Jupiter on 1962 November 12 and 0.72 au on 1974 October 11. The comet will pass 0.51 au from Jupiter on 2045 September 12


    413P/Larson = 2014 E1 = 2020 W4
    Steve Larson discovered a 17th magnitude comet during the Catalina Sky Survey with the 0.68m Schmidt on 2014 March 10.45. Prediscovery images from 2014 January were found in CSS data. [MPEC 2014-E78, 2014 March 12] The comet was at perihelion at 2.1 au in 2014 May and has a period of around 7.1 years. 

    Erwin Schwab recovered the comet as a stellar object in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain, on 2020 November 25.17. [CBET 4910, MPEC 2021-A147, 2021 January 11/12]


    414P/STEREO = 2016 J3 = 2021 A3
    Scott Ferguson reported a comet in STEREO H1 images from 2016 May 14 to Karl Battams on May 26. Man-To Hui measured the images and Battams sent the astrometry to the MPC who computed an orbit. Battams noted that strong forward scattering may have contributed to the comet's brightness, which reached around 8th magnitude. [CBET 4281, MPEC 2016-K41, 2016 May 31]. The comet was at perihelion on 2016 May 21 at 0.47 au and has a period of 7.7 years according to the MPC elements. The orbital elements are also extremely uncertain, and JPL give error bars of 1.0 au in the perihelion distance and 59 years in the period!

    An object was discovered by the Zwicky Transient Factory on January 5.1 and posted on the PCCP as ZTF01on. It was summarily removed on January 8 and noted to be P/2016 J3. The previous evening Maik Meyer had discovered the identity, computed a linked orbit and informed the MPC and CBAT.  Maik's linked orbit shows that the period is 4.67 years, with perihelion at 0.53 au on January 25.  Despite this it was not designated 2021 A1.  Michael Jaeger has imaged it, finding it to be around 14th magnitude.

    Sam Dean notes:

    It's caught in a Kozai resonance with Jupiter that it's currently on the higher-e, lower-i leg of. I think that'll peak around 2400-2500 before cycling back. Like plenty of Earth-crossing Kozai oscillating objects, its orbit also crosses Earth sometimes, creating a potential for meteor showers. It last crossed Earth's orbit within 0.1 au in the 1300s, coming as close as 0.07 au - and it will next do so in the 2200s/2300s, coming less than 0.01 au around 2300, where it should create a fairly regular and impressive meteor shower considering that it would be even more active than it is now.
    Sam also suggests that the absolute magnitude is very faint, around 23 and that it brightens rapidly, perhaps at 20 log r.

    Rather belatedly the CBAT issued CBET 4911 on January 11, with a revision coming 15 minutes later.  This gives a similar account to that given above and notes that the comet will pass Jupiter at 0.9 au in 2031 December.  It also hints that either the comet shows strong non-gravitational forces or that the 2016 positions are somewhat out. The MPC finally issued MPEC 2021-A157 on January 12. This does not give elements for 2016, although the published elements for 2021 and 2025 do use observations from 2016, so it may just be an oversight.

    J J Gonzalez made a visual observation of the comet on 2021 January 16.78 from his mountain observing site, estimating it at 9.7 in his 20 cm SCT.


    415P/Tenagra = 2013 EW90 = 2020 Y4
    Michael Schwartz and Paulo Holvorcem discovered an asteroid like object of 19th magnitude on 2013 March 3.19 at the Tenagra II Observatory in Arizona. Later observations then showed cometary features. [MPEC 2013-J52, 2013 May 13]  Perihelion was at 3.3 au in 2012 October. It has a period of 8.3 years. 

    The comet was acccidently recovered in astrometry taken by PanSTARRS on 2020 December 25.57. It was independently deliberately recovered by Erwin Schwab as a stellar object in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain, on 2021 January 13.01. The comet will pass 0.5 au from Jupiter in 2033 December in an encounter that will increase the perihelion distance to 3.8 au. [CBET 4918, MPEC 2021-B17, 2021 January 16/17]


    416P/Scotti = 2013 A2 = 2021 A8
    Jim Scotti discovered a 20th magnitude comet in Spacewatch images taken with the 0.9-m f/3 reflector at Kitt Peak on 2013 January 6.29.  The preliminary orbit was based on a two day arc, yet gave values to five significant figures. [MPEC 2013-A45, 2013 January 8]  It has a period of 8.0 years and was at perihelion at 2.2 au in February.  It approaches within 0.6 au of Jupiter, but these encounters have made only minor changes to the orbit.

    Erwin Schwab recovered the comet as a nearly stellar object in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain, on 2021 January 14.01. [CBET 4919, MPEC 2021-B21, 2021 January 17]


    417P/NEOWISE = 2015 J3 = 2021 B1
    A 19th magnitude object found by the NEOWISE satellite on 2015 May 15.06 was found to show cometary features by ground based astrometrists after the object was posted on the PCCP. [CBET 4102, MPEC 2015-K55, 2015 May 23] The comet was at perihelion at 1.5 au in 2015 March and has a period of 6.1 years.

    Erwin Schwab recovered the comet as a nearly stellar object in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain, on 2021 January 17.23. The comet passed 0.48 au from Jupiter in 1952 August and will pass 0.43 au from the planet in 2024 September in an encounter that will increase the perihelion distance from 1.49 to 1.57 au. [CBET 4920, MPEC 2021-B118, 2021 January 22/23]


    418P/LINEAR = 2010 A5 = 2020 Y5
    An apparently asteroidal object of 20th magnitude discovered by LINEAR with the 1.0-m reflector on 2010 January 14.45 was found to show a cometary appearance by other astrometrists, including Rolando Ligustri, Ernesto Guido and Giovanni Sostero. The comet has a period of 11.5 years, with perihelion at 1.7 au in April.

    An object recorded at 22nd magnitude in astrometry taken by PanSTARRS 2 on December 23.49 was subsequently identified as as a return of 2010 A5 by the MPC. It was also detected by PanSTARRS 1 and Mt Lemmon later in 2021 January. [CBET 4928, MPEC 2021-B140, 2021 January 29]


    419P/PanSTARRS = 2015 F1 = 2021 A11
    A 19th magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 2015 March 21.58. [CBET 4082, MPEC 2015-F119, 2015 March 26] The comet was at perihelion at 2.5 au in 2015 March and has a period of 6.6 years.

    Erwin Schwab recovered comet 2015 F1 as an apparently stellar object in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain, on 2021 January 13.06. Additional observations were made on February 10, 13 and 14. The comet was some 4' from the predicted position, implying a delta T of -0.2 days. The comet passed 0.46 au from Jupiter in 1975 December in an encounter that substantially reduced the perihelion distance. The comet is significantly fainter at this return than it was at the discovery return. [CBET 4933, MPEC 2021-D104, 2021 February 16/25].  In what seems to be competition between the CBET and MPC the MPEC was issued nine days after the CBET.


    420P/Hill = 2009 Q1 = 2021 E1
    Rik Hill discovered an 18th magnitude comet on 2009 August 27.40, during the Catalina Sky Survey with the 0.68m Schmidt. The comet was at perihelion at 2.8 au in 2009 July and had a period of 13 years. This was the 100th comet found by the Catalina and Mt Lemmon team.

    In 2009 October Rob Matson found images of the comet on three Heleakala-NEAT images from 1996, which in turn allowed him to find it in two more nights from 1998. It was very bright in the 1996 images showing obvious coma, but barely detectable in 1998.

    Erwin Schwab recovered the comet as a stellar object in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain, on 2021 March 11.13. The recovery was confirmed by Diana Abreu using the 1.0m reflector at the ESA Optical Ground Station, Tenerife on March 14. The comet was some 9' from the expected position and does not reach perihelion until 2022 May. When Syuichi Nakano computed a linked orbit the observations showed that non-gravitiational parameters were required. When these were included it was found that the 1996 observations reported by Rob Matson were of the comet, though his 1998 measurements did not fit so well. [CBET 4943, MPEC 2021-F07, 2021 March 16/17]


    421P/McNaught = 2009 U4 = 2020 H10
    Rob McNaught discovered a 17th magnitude comet on images taken during the Siding Spring Survey with the 0.5-m Uppsala Schmidt on 2009 October 23.49. Following this he was able to locate prediscovery observations from October 22 and then October 11. The comet was at perihelion at 1.6 au in early September and has a period of around 11 years.

    Brian Marsden noted on MPEC 2009-Y57 [2009 December 29] that further [astrometric] observations of this comet were desirable.

    In 2021 May the MPC linked isolated tracklets from PanSTARRS and Mt Lemmon made in 2020 April and May to 2009 U4 (P/McNaught). [CBET 4971, MPEC 2021-K101, 2021 May 31]  The comet was at perihelion at 1.6 au in 2021 January, about 6 days earlier than predicted, and has a period of 11.4 years.


    422P/Christensen = 2006 S4 = 2021 L1
    Eric Christensen discovered another 17th magnitude comet on 2006 September 22.37 during the course of the Catalina Sky Survey with the 0.68-m Schmidt telescope. It was at perihelion at 3.1 au in early 2006 June. It has a period of 16 years.

    Cristovao Jacques recovered the comet at the SONEAR observatory on 2021 June 5.32. Taras Prystavski independently recovered the comet on 2021 June 15.75 using the 0.5 m iTelescope at Siding Spring, some 9' from the ephemeris position. The recovery was reported on the comets-ml on June 15/16, with Jacques noting that he had sent the observations to the MPC 10 days previously. The MPC is a bit behind with processing comet observations and did not announce the recovery until June 17 [MPEC 2021-M34, CBET 4979]


    423P/Lemmon = 2008 CL94 = 2021 A12
    An asteroid discovered during the course of the Mt Lemmon survey on 2008 February 8 was shown to be cometary. It has a 15.3 year period and was at perihelion at 5.4 au in 2006 July.

    The comet was recovered in astrometry taken with the Gemini North 8.1 m telescope at Mauna Kea on January 9.27 and January 15. The comet passed 0.7 au from Jupiter in 1921 and 0.9 au from the planet in 1986.  These encounters modified the elements, but kept the perihelion distance between 5.2 and 5.6 au. [MPEC 2021-M89 CBET 4992, 2021 June 26]. The MPEC does not say why there was such a long gap between the observations and announcement.


    424P/La Sagra = 2012 S2 = 2021 L5
    The observing team at OAM Observatory, La Sagra (S. Sanchez, J. Nomen, M. Hurtado, J. A. Jaume, W. K. Y. Yeung, P. Rios, F. Serra and T. Valls) using the 0. 45-m f/2. 8 reflector discovered an 18th magnitude comet on 2012 September 23.07. It was at perihelion at 1.4 au in mid August and has a period of 9.3 years.

    Images of the comet were found in incidental PanSTARRS 1 asrometry taken with the 1.8m Ritchey-Chretien on 2021 June 6.53. It was independently found later in images from ATLAS at Mauna Loa. [CBET 49xx, MPEC 2021-N47, 2021 July 8] The comet is at perihelion at 1.4 au in 2021 October and has a period of 9.3 years.


    425P/Kowalski = 2005 W3 = 2021 O2
    Richard Kowalski discovered a 19th magnitude comet in the course of the Catalina Sky Survey on 2005 November 25.32. The comet is a periodic one, with a period of 16.2 years, and it was at perihelion at 3.0 au in late August 2005.

    PanSTARRS 1 discovered a 20th magnitude comet in images taken with the 1.8m Ritchey-Chretien on July 20.60. It was identified as a return of 2005 W3 by the MPC. There were prediscovery PanSTARRS observations from 2020 September, October, November and December.  The comet was some 13' from the predicted position, corresponding to a delta T of around -1.0 days. [CBET 4506, MPEC 2021-O66, 2021 July 30] At this return the comet is at perihelion at 2.9 au in 2021 September and has a period of 15.9 years. It made a distant encounter (1.1 au) with Saturn in 2014 July.


    426P/PanSTARRS = 2019 A7 = 2021 K4
    A 20th magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 2019 January 8.38.  There were prediscovery observations from PanSTARRS 1 in 2018 October and November. It was placed on the PCCP as P10LcVo.  [CBET 4605, MPEC 2019-B66, 2019 January 23]  The comet has a period of 5.7 years and was at perihelion at 2.7 au in 2018 January.

    Marco Micheli recovered 2019 A7 in images taken by other observers with the 8.1m Gemini South telescope on May 17.17. He found confirmatory images of the comet in data from the Canada-France-Hawaii at Mauna Kea taken on June 13. [MPEC 2021-P78, CBET 5010, 2021 August 8] It reaches perihelion in 2023 September.


    427P/ATLAS = 2017 S5 = 2021 L6
    An 18th magnitude comet was discovered in images taken with the 0.5m Schmidt at Haleakala on 2017 September 27.48 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. It had been posted on the PCCP as A104e5G. There were prediscovery ATLAS observations back to September 11. [CBET 4434, MPEC 2017-S213, 2017 September 29]. The comet was at perihelion at 2.2 au in 2017 July and has a period of 5.6 years.

    Marco Micheli recovered 2017 S5 in images taken by other observers with the 8.1m Gemini South telescope on June 9.07. [MPEC 2021-P79, CBET 5011, 2021 August 8]. It reaches perihelion in 2023 March.


    428P/Gibbs = 2014 W12 = 2021 Q1
    Alex Gibbs discovered an 18th magnitude comet during the Mt Lemmon Survey with the 1.5m reflector on 2014 November 30.07. [CBET 4032, MPEC 2014-X33, 2014 December 5] It was at perihelion at 1.7 au in 2014 November and has a period of 6.5 years. 

    Erwin Schwab recovered comet 2014 W12 as a 20th magnitude object in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain, on 2021 August 16.13.  It was a long way from the predicted position, with a delta T of -37.6 days,  putting the comet at perihelion in 2021 May rather than June.  Hirohisa Sato then reported the comet in images taken on August 7, with Syuichi Nakano then able to find images from the Catalina Sky Survey from 2008 November.  There have been no close encounters with any major planets.  [MPEC 2021-Q47, CBET 5025, 2021 August 22/23]


    429P/LINEAR-Hill = 2008 QP20 = 2021 M1
    Rik Hill discovered an 18th magnitude comet on CCD images taken with the 0.68-m Catalina Schmidt telescope on 2008 September 23.63, which was confirmed as cometary by many observers following posting on the NEOCP. K Smalley of the MPC then identified the comet with an asteroidal object found by LINEAR on 2008 August 25.40. The comet was at perihelion at 1.7 au in early November 2008 and has a period of 6.5 years.

    In 2020 Sam Deen found images of the comet in DECam data taken with the 4.0m reflector at Cerro Tololo on 2016 January 15.26 and 2016 March 1.14. These were identified by Syuichi Nakano as being a return of 2008 QP20. The comet was close to the expected position. [CBET 4832, 2020 August 17] It was not given a designation for the return, nor was it numbered at the time, though it should have been 410P.

    PanSTARRS found a 23rd magnitude image of 2008 QP20 in data taken with the PanSTARRS 1 1.8m Ritchey-Chretien on June 18.59, with additional images from July and August. Despite having been identified at the 2015 return it was given a year identifier. The CBET suggests that it should have been designated as 2016 [A]10 at that return. [MPEC 2021-Q68, 2021 August 28, CBET 5040, 2021 September 18] The comet is at perihelion at 1.8 au in 2022 January and now has a period of 6.7 years following a distant encounter with Jupiter in 2017 July.


    430P/Scotti = 2011 A2 = 2021 Q2
    Jim Scotti discovered a 20th magnitude comet in Spacewatch images taken with the 0.9-m f/3 reflector at Kitt Peak on 2011 January 11.46.

    Gareth Williams noted on MPEC 2011-A65 [2011 January 14] that it was probable that this was a short-period comet and that further [astrometric] observations of the comet were desirable.

    Further observations confirmed the short period orbit, and Hirohisa Sato gave a period of around 5.5 years with perihelion at 1.6 au in 2010 December.

    The comet was recovered on 2021 August 20.50 in images taken by the Zwicky Transient Factory with the 1.2m Oschin Schmidt. It was also present in images taken on August 23, 24 and 25. The comet is at perihelion at 1.6 au in December and has a period of 5.5 years. It was some 17' from the predicted position, corresponding to a delta T of +0.79 days.  The comet passed 0.41 au from Jupiter in 1986.  [MPEC 2021-Q69, CBET 5026, 2021 August 28/31]


    431P/Scotti = 2015 Q1 = 2021 P5
    Jim Scotti discovered a 19th magnitude comet in images taken with the 0.9-m Spacewatch telescope at Kitt Peak on 2015 August 18.46. [CBET 4138, MPEC 2015-Q25, 2015 August 19]. The comet was at perihelion at 1.8 au in September and has a period of around 6 years [MPEC 2015-S97, 2015 September 28].  By contrast JPL gave a nearly parabolic orbit until late September, but did publish error bars.

    Francois Kugel recovered 2015 Q1 in images taken on August 2.96 at his observatory "Chante-Perdrix" (Dauban, France) with his 0.4-m f/2.8 reflector. This was confirmed in follow up observations on August 7 and 16 and by other amateurs Jean-Francois Soulier and John J Maikner. [MPEC 2021-Q75, 2021 August 29, CBET 5038, 2021 September 17] Rob Matson then found prediscovery observations made with the 1.2-m Palomar Schmidt in 2002, but no designation has yet been assigned for that return. The comet passed 0.6 au from Jupiter in 2005 December in an encounter that reduced the perihelion distance, whilst it passed 1.5 au in 2017 December, which increased the perihelion distance. The comet is next at perihelion at 1.8 au in 2022 February and has a period of 6.5 years.


    432P/[PanSTARRS] = 2021 N4 = 2016 U2
    PanSTARRS 1 discovered a 22nd magnitude comet in images taken with the 1.8m Ritchey-Chretien on 2021 August 9.57 It was placed on the PCCP as P11iUGx. It was then linked to an object in incidental astrometry taken by PanSTARRS on 2021 July 8.53. [MPEC 2021-Q01, CBET 5019, 2021 August 16]. The comet was near perihelion at 2.3 au and has a period of 5.3 years. It has not yet been officially named, as the preliminary orbit is similar to that of a main belt asteroid.

    As the orbit improved it became possible to search for earlier observations and PanSTARRS found images of the comet in data taken on 2016 October 25.47 and November 15. It was designated 2016 U2 for this return, though the MPEC does not give elements for that epoch. The CBET confirms the comet name as PanSTARRS. [MPEC 2021-Q96, 2021 August 31, CBET 5041, 2021 September 19]


    433P/NEAT= (248370) = 2005 QN173
    This object was classed as a main-belt asteroid and was discovered by the NEAT survey at Palomar on 2005 August 29. Nicolas Erasmus noted that it had a tail in ATLAS images taken on 2021 July 7.6 and was brighter than expected. It had no tail in images taken on June 27.6. However a tail was present in ZTF images taken on June 11.4, but not in images taken on 2020 July 9.  Imaging by Gianluca Masi on 2021 August 29 showed that the tail was still present.  Further imaging by Fabrizio Montanucci on 2021 September 29 showed little sign of any activity.

    A paper by Hsieh et al characterises the object as a Main Belt Comet, with activity driven by sublimation around perihelion. They note that archival observations also show activity at the last perihelion in 2016 and estimate a nuclear radius of around 1.6 km. They suggest that it might be a fast rotator.


    434P/Tenagra = 2012 TK8 = 2021 S2
    A 20th magnitude asteroidal object discovered at the Tanagra Observatory on 2012 October 6.32 by Michael Schwartz and Paulo Holvorcem was subsequently shown to be a comet. It reached perihelion at 3.1 AU in 2013 May and had a period of 8.6 years.

    Erwin Schwab recovered comet 2012 TK8 as a 20th magnitude object in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain, on 2021 September 30.16. The comet was some 6' from the predicted position, indicating a Delta(T) of -0.38 day. [MPEC 2021-T44, CBET 5048, 2021 October 4] The comet was at perihelion at 3.0 au in 2021 October and now has a period of 8.4 years.


    435P/PanSTARRS = 2015 K6 = 2021 T3
    PanSTARRS 1 discovered a 20th magnitude comet in images taken with the 1.8m Ritchey-Chretien on October 2.40. It was placed on the PCCP as P11lWkH and pre-discovery PanSTARRS observations were quickly found, first PanSTARRS 1 and 2 observations from 2020 April and May, then PanSTARRS 1 observations from the previous return between 2015 and 2017 for which it was given the designation 2015 K6. [The MPC seem to have developed a convention whereby a comet can be designated at one previous pre-discovery apparition and that it is the first reported one.] Sam Deen then found DECam images from 2015 February and Sloan Digital Sky Survey images from 2002 January. [MPEC 2021-T184, CBET 5056, 2021 October 9] The comet was at perihelion at 2.1 au in 2021 July.
    436P/Garradd = 2007 R4 = 2021 U2
    Gordon Garradd discovered an 18th magnitude comet on images taken for the Siding Spring Survey with the 0.5-m Uppsala Schmidt on 2007 September 14.61. The cometary nature was confirmed following posting on the NEOCP. The comet has a period of around 14 years and was near perihelion at 1.9 au.

    Taras Prystavski recovered 2007 R4 in images taken with the 0.51m iTelescope at Siding Spring on October 24.43. Confirmation came from John Drummond who had imaged the comet on September 5.47. The MPEC gives additional positions from John taken on August 15.61 but does not mention the September observations. The CBET does include these observations, along with additional ones by Filipp Romanov on August 13.61.  The comet was some 7' east of the ephemeris position, corresponding to a delta-T of -0.2 days. [MPEC 2021-U108, CBET 5061, 2021 October 27]


    437P/PanSTARRS = 2011 UE215 = 2021 V3
    PanSTARRS 1 discovered a 21st magnitude comet in images taken with the 1.8m Ritchey-Chretien on November 1.50. It was placed on the PCCP as P11o2nD and pre-discovery observations by PanSTARRS 1 & 2 in October were quickly found. The MPC then linked it to isolated tracklets from Mt Lemmon in 2012, Tenagra in 2012 and 2013 .  The comet was then linked to asteroid 2011 UE215, discovered by the Mt Lemmon survey on 2011 October 24.26. [MPEC 2021-V173, CBET 5069, 2021 November 9] The comet is at perihelion at 3.4 au in 2022 August and has a period of 9.7 years.  The comet passed 0.4 au from Jupiter in 2007 December, prior to which it was in a longer period orbit with perihelion at 4.0 au.
    438P/Christensen = 2005 T2 = 2012 V5 = 2020 OV62
    Eric Christensen discovered a 20th magnitude comet in the course of the Mt Lemon survey on 2005 October 7.21. It is in a periodic orbit of 7.5 years and perihelion was at 2.21 au in mid April 2005.

    Alessandro Odasso identified an object given the minor planet designation of 2020 OV62, found by the Mt Lemmon Survey on 2020 July 31.42, as being a return of 2005 T2. The MPC then found detections by PanSTARRS on 2012 November 5.21 at which return it was given the designation 2012 V5. Sam Deen then found additional PanSTARRS detections from 2012 August, in images taken with the CFH telescope at Mauna Kea in 2013 October and with DECam in 2019 June. The 2012 positions were over a degree from that expected from published predictions. [MPEC 2021-W47, CBET 5073, 2021 November 24/26] The comet will pass 0.40 au from Jupiter in 2037 November, although the 2012 Jupiter MOID was 0.45 au.


    439P/LINEAR = 2008 WZ96 = 2021 W1
    An 18th magnitude apparently asteroidal object was discovered by LINEAR on 2008 November 30.06 and designated 2008 WZ96. It was refound by LINEAR on 2008 December 28.07 and a linked orbit calculated by the MPC. Subsequently it was found to show cometary characteristics by other astrometrists. The comet was at perihelion in late 2009 January at 1.65 au, and Brian Marsden notes that it passed 0.36 au from Jupiter in 2006 April.

    Erwin Schwab recovered the comet as a 20th magnitude object in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain, on 2021 November 30.03. The position was close to that previously predicted, although it was missed at the 2015 return. The MPC then found an isolated tracklet from PanSTARRS 1 from August 8. [MPEC 2021-X81, CBET 5078, 2021 December 3] The comet passed 0.81 au from Jupiter in 2017 October in an encounter that has increased the perihelion distance to 1.85 au. The next close Jupiter encounter is in 2077, when the comet passes within 0.3 au.


    440P/Kobayashi = 1997 B1 = 2021 W2
    This object was initially reported to the IAU by S Nakano as an asteroid discovered by Takao Kobayashi on 1997 January 31, but subsequent observations showed that it was in a cometary orbit and further observations by W Offutt showed it to have a coma and tail. The nuclear magnitude of the comet was around 17, but visual observations may put it brighter. This is the first amateur CCD discovery of a comet and is also the faintest amateur discovery and shows that the field is not lost to the professional search teams.

    The Purple Mountain Observatory discovered a potential 20th magnitude NEO at their XuYi station with their 1.04m Schmidt on 2022 January 11.67. The MPC identified this as a return of 1997 B1 and then found isolated tracklets from 2021 November 29 taken with the Bok 2.25m reflector at Kitt Peak. PanSTARRS then found the comet in images taken earlier in November. This sequence suggests that the comet should have been designated 2022 A2 as this was the discovery. The comet was some 0.5 degrees from the prediction based on observations in 1997. [MPEC 2022 A164, CBET 5091, 2022 January 11/12] The comet is at perihelion at 2.0 au in March and has a period of 25 years. The comet was close to 67P/ in the sky and Nick James subsequently discovered that he had imaged it on January 9, as did Peter Carson.


    441P/PanSTARRS = 2017 R1 = 2022 B2
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 2017 September 14.41. There were also pre-discovery images from July 30, August 1, 3, 17 and Mt Lemmon from September 2.  It had been posted on the PCCP as P10D5ss.   [CBET 4430, MPEC 2017-S97, 2017 September 22] The comet was at perihelion at 3.3 au in 2017 April and has a period of about 8 years. JPL classify it as an Encke-type Comet and it has a Jupiter MOID of 0.41 au.

    The MPC identified a 21st magnitude object found in incidental astrometry from Mt Lemmon on January 25.51 and PanSTARRS 2 on February 10.50 as being a return of 2017 R1. [CBET 5100, MPEC 2022-D03, 2022 February 16] The comet is at perihelion at 3.3 au in 2025 September and has a period of 8.4 years.


    442P/McNaught = 2000 W6? = 2011 Q3 = 2022 G1
    Rob McNaught discovered a 19th magnitude comet on CCD images taken with the 0.5-m Uppsala Schmidt telescope at Siding Spring on 2011 August 29.74. The comet reached perihelion at 2.4 au in August and has a period of 11 years.

    The comet is one of those suspected to have undergone nuclear splitting according to the list of Marcos & Marcos [Dynamically correlated minor bodies in the outer solar system, MNRAS, 474, 838, 2018 February]. They link it to 208P/McMillan.

    Hirohisa Sato recovered 2011 Q3 at 20th magnitude in images taken with the 0.51-m f/6.8 iTelescope astrograph at Siding Spring on 2022 April 5.79, with confirming images taken with the same telescope five days later. [MPEC 2022-H01, CBET 5115, 2022 April 16/19].  The comet is at perihelion at 2.3 au in August.  Following the recovery Syuichi Nakano was able to link isolated observations made on 2000 November 28.21 by Spacewatch to the comet.  He notes that the comet passed 0.75 au from Jupiter in 1990 and 0.53 au in 2002, in encounters that made changes mostly to the angular elements.


    443P/PanSTARRS-Christensen = 2005 N11 = 2015 PO210 = 2022 E1
    Eric Christensen discovered a comet of 21st magnitude in images taken with the 1.5-m reflector of the Mt Lemmon Survey on 2022 March 2.45. It was placed on the PCCP as C72DD5T2. [MPEC 2022-E167, CBET 5107, 2022 March 10/11]. The comet is at perihelion at 3.0 au in 2022 October and has a period of around 8 years. The orbit was uncertain. As more observations accumulated Syuichi Nakano was able to improve the orbit and link isolated observations made in 2005 and 2006 by Mt Lemmon and 2006 by Spacewatch to the comet. He then asked Richard Weyrk to check PanSTARRS observations for the comet. Weyrk pointed out that observations of 2015 PO210 appeared to be of the comet , and that there were also isolated observations by PanSTARRS 1 and Mt Lemmon in 2014. The comet was therefore renamed from P/Christensen to P/PanSTARRS-Christensen. The comet passed 0.5 au from Jupiter in 1978. [MPEC 2022-H49, CBET 5117, 2022 April 25]
    444P/WISE-PanSTARRS = 2010 LK36 = 2016 MD = 2016 PM1 = 2022 C4
    The Wide-field Infrared Survey Explorer (WISE) spacecraft discovered an apparently asteroidal object on 2010 June 9.12, and it was given the designation 2010 LK36. It was then found with the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE; a rename of WISE) on 2016 June 16.86, but not identified with the two-day 2010 arc at that time and was given the new minor-planet designation 2016 MD. Finally PanSTARRS 1 discovered an asteroid in images taken with the 1.8-m Ritchey-Chretien on 2016 August 16.58, which was designated 2016 PM1 and linked to the previously discovered objects. Earlier observations were subsequently found in Sloan Digital Sky Survey images obtained at Apache Point on 2003 April 26.26. The ATLAS (Asteroid Terrestrial-impact Last Alert System) team noted cometary features in images taken with the 0.5 m Schmidt at Mauna Loa on 2022 June 8.35, however it had been observed by PanSTARRS on 2022 February 7.54, so it was given the designation 2022 C4. [CBET 5137, MPEC 2022-M81, 2022 June 27]. The comet passed 0.13 au from Jupiter in 2013 July. The logic for the naming of the comet is not entirely clear.
    445P/Lemmon-PanSTARRS = 1998 W9 = 2006 S14 = 2014 R5 = 2022 L5
    A 19th magnitude comet was suspected in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on September 19.47. Tim Spahr linked the suspect with an apparently asteroidal object found during the Mt Lemmon Survey on September 14.39. Other CCD astrometrists then commented on the suspects cometary characteristics. [CBET 3987, MPEC 2014-S81, 2014 September 24] The comet was at perihelion at 2.4 au in 2014 June and has a period of around 8 years. 

    It appeared on the PCCP as 2F61M11 on 2022 June 7.65, so was presumably recovered, though confirmation had to wait a month. Following the recovery additional tracklets from 1998 and 2006 were identified. The comet is at perihelion at 2.4 au in 2022 August and has a period of 8.2 years. [MPEC 2022-N51, CBET 5149, 2022 July 8]


    446P/McNaught = 2012 O3 = 2022 G2
    Rob McNaught discovered an 18th magnitude comet on CCD images taken with the 0.5-m Uppsala Schmidt telescope at Siding Spring on 2012 July 23.69. The comet was near perihelion at 1.6 au and has a period of 9.7 years.

    PanSTARRS 2 discovered a new object on June 28.58, which the MPEC automatically identified as a return of 2012 O3. Hirohisa Sato was then able to find the comet in images taken with the 0.51-m f/6.8 iTelescope astrograph at Siding Spring on April 10.80. PanSTARRS checked their images and confirmed that they did show cometary activity. [MPEC 2022-N81, CBET 5150, 2022 July 12].  The comet was at perihelion at 1.6 au in May. It is not clear why the MPEC did not designate the comet as 2022 M2 (or M1) as would be expected from the discovery date.

    The comet orbit has a Jupiter MOID of 0.65 au and the comet approached to 0.74 au in 1933 June.


    447P/Sheppard-Tholen = 2021 R9 = 2008 T14
    In 2022 July Scott Sheppard and David Tholen discovered a 22nd magnitude comet in images taken with the "Hyper Suprime-Cam" CCD on the 8.2-m f/2.2 Subaru reflector at Mauna Kea on 2021 September 5.62. After the discovery PanSTARRS was asked to search archival imagery and found images of the comet from 2021 June to 2022 January. It was placed on the PCCP as g293400. After the astrometry was published Syuichi Nakano found isolated tracklets from 2008 October from Mt Lemmon and Sam Deen found an image from 2007 June taken with the CFH 3.6-m reflector. [MPEC 2022-O19, CBET 5152, 2022 July 22] The comet was at perihelion at 4.6 au in 2022 August and currently has a period of 13.4 years. It passed 0.45 au from Jupiter in 1931 January and will pass a similar distance in 2037 March, though the encounters do not make drastic changes to the orbit.
    448P/PanSTARRS = 2008 T13 = 2015 X1 = 2022 Q1
    A 20th magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 2015 December 1.30. There were pre-discovery PanSTARRS images from August and September, and Catalina images from October. [CBET 4212, MPEC 2015-X58, 2015 December 5] The comet was at perihelion at 2.1 au in 2015 October and has a period of around 7 years.

    Erwin Schwab recovered comet 2015 X1 at 21st magnitude and essentially stellar, in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain, on 2022 August 23.09. Additional confirming observations were made on August 24. Following recovery, Syuichi Nakano was able to link MPC ITF positions from 2008 October 1.38 and 2008 December 31 taken by the Catalina Sky Survey to the comet. [MPEC 2022-Q153, CBET 5164, 2022 August 28]. The comet is at perihelion at 2.1 au in September and has a period of 6.9 years. The comet passed 0.6 au from Jupiter in 2005 January; the orbit has a Jupiter MOID of 0.54 au.


    449P/Hartley-Leonard = 1987 A2 = 2013 Y3 = 2020 S6
    Gregory Leonard discovered a comet of 21st magnitude in images taken with the 1.5m reflector on September 29.40 during the Mt Lemmon Survey. It was placed on the PCCP as C3D5RV2. There were pre-discovery images for August 28 and September 18 from Mt Lemmon and for September 22 from PanSTARRS 2.  [CBET 4868, MPEC 2020-U151, 2020 October 21]. The comet is at perihelion at 1.9 au in 2020 November and has a period of 6.8 years. The comet passed about 0.076 au (range 0.07 to 0.23 according to JPL) from Jupiter in 1983 July.

    In 2022 October Maik Meyer linked the comet to a comet discovered by Malcolm Hartley on a plate taken on 1987 January 5.73 with the 1.22m Southern Schmidt at Siding Spring. The comet was not found on the plate until March, so there were no follow up observations, and with only one plate the direction of motion was ambiguous so it was given an X/ designtion. Sam Dean was then able to find observations of the comet made with the 3.58m Canada-France-Hawaii telescope on 2013 December 29.30 and 2014 January 3. [MPEC 2022-T74, CBET 5173, 2022 October 5] Logically the comet should now be designated Hartley-Leonard.


    450P/LONEOS = 2004 A1 = 2022 Q3
    Brian Skiff discovered a faint comet on LONEOS images taken by himself on 2004 January 13.27. Although the object appeared stellar, he requested additional images from other observers because of the motion of the object. These showed a slight coma. The comet reached perihelion in late August 2004. It is a distant periodic comet with period of 22.2 years and perihelion at 5.46 au.

    B. A. Skiff, Lowell Observatory, reports the discovery of a comet found on CCD images taken by himself on 2004 January 13.27 in the course of the LONEOS program with the 0.59-m Schmidt telescope. The LONEOS images showed stellar appearance, but the motion led Skiff to request that a pair of 5-min R-band CCD exposures be taken of the object by H. R. Miller at the Perkins 1.8-m reflector, and these images show a 3" well- condensed coma and a 12" tail in p.a. 290 deg. To get additional observations, the object's ephemeris was then posted on the NEO Confirmation Page, which resulted in CCD images taken by J. Young (Table Mountain, CA, 0.6-m reflector) on Jan. 13.5 UT that show a 4" coma with a very faint 10" tail in p.a. 262 deg. [IAUC 8267, 2004 January 13]

    The comet was finally named in 2004 November: The IAU Committee on Small Bodies Nomenclature has decided to name three comets as follows: C/1996 R3 (Lagerkvist), P/2003 A1 (LINEAR), P/2004 A1 (LONEOS). [IAUC 8430, 2004 November 6]

    Charles Schambeau recovered comet 2004 A1 at 25th magnitude in images taken with the 8.1 m Gemini North telescope at Maunakea on 2022 August 21.52. Additional confirming observations were made on August 23. [MPEC 2022-T106, CBET 5178, 2022 October 8]. The comet is at perihelion at 5.5 au in 2027 January and has a period of 22.5 years. The elements by Syuuchi Nakano show that the comet passed 0.031 au from Saturn on 1992 July 30 in an encounter that reduced the perihelion distance from 9.8 au and the period from 43 years. The previous perihelion had been in 1951 October. The comet will approach Jupiter to 0.5 au in 2026 July, with a further small reduction in perihelion distance and period.


    451P/Christensen = 2006 WY182 = 2007 A2 = 2022 S2
    Eric Christensen discovered a 19th magnitude comet during the Mount Lemmon Survey on 2007 January 10.41. Following the IAUC announcement it was linked to asteroid 2006 WY182. It has an elliptical orbit with period of 16 years and was near perihelion at 2.8 au.

    Erwin Schwab recovered comet 2007 A2 at 21st magnitude and essentially stellar, in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain, on 2022 September 27.17. Additional confirming observations were made on October 1. [MPEC 2022-T107, CBET 5177, 2022 October 8]. The comet is at perihelion at 2.8 au in November and has a period of 15.9 years.


    452P/Sheppard-Jewitt = 2003 CC22 = 2022 B5
    An asteroid, of 22nd magnitude, was discovered by a team including Scott Sheppard and David Jewitt using the 3.6-m Canada-France- Hawaii and 2.2-m University of Hawaii telescopes on Mauna Kea on 2003 February 8.34. It is in a 21 year orbit, with perihelion at 4.20 au and an eccentricity of 0.44. It was at perihelion in September and faded. [MPEC 2002-G16, 2003 April 3, 1-month orbit] The orbit is unusual, crossing that of Jupiter and Saturn, both of which it can approach to within 1 au.

    In October 2022 Michael Kelley reported that 2003 CC22 showed a tail in ZTF images taken on September 27. Sam Dean then noted that images since at least 2018 showed considerable variation in brightness.

    Despite this report, the MPC decided to designate it as 2022 B5 based on images taken at Santa Maria de Montmagastrell on 2022 January 28.80. The MPEC also reports that archival ZTF images show cometary activity back to 2022 February. They do not report any of the 2018 observations mentioned by Sam Deen. [MPEC 2022-V36, CBET 5186, 2022 November 2]  The comet passed 0.12 au from Saturn in 1938 January and 0.50 au from Jupiter in 1947 June, with more distant passes from Saturn in 1997 September and Jupiter in 2002 September.

    Images by several amateurs in 2023 February showed a somewhat elongated and weak central condensation and a tail.


    453P/WISE-Lemmon = 2010 BN109 = 2022 V1
    An apparently asteroidal object of 19th magnitude was found by the Mt Lemmon Survey in images taken with the 1.5-m reflector on 2022 November 1.33 It was placed on the PCCP as C8AXVA2 after cometary characteristics were noted by Hirohisa Sato and confirmed by other astrometrists. There were pre-discovery Mt Lemmon images from 2022 October 7. Subsequently Nakano was able to link the comet with an asteroid discovered by WISE on 2010 January 28.89 and designated as 2010 BN109. [MPEC 2022-W148, CBET 5193, 2022 November 23]. The comet is at perihelion at 2.3 au in 2023 March and has a period of 12.7 years.
    454P/PanSTARRS = 2022 U5 = 2013 W3
    PanSTARRS 2 discovered a 21st magnitude asteroid in images taken with the 1.8 m Ritchey-Chretien on September 24.50. Follow up observations with the CFHT showed cometary features and it was placed on the PCCP as P21AXhm. PanSTARRS then found prediscovery PanSTARRS 1 observations showing it as apparently asteroidal made between 2013 November 25 and 2014 January 6 (with a nominal discovery date of 2013 November 27.58), and PanSTARRS observations from 2021 August to 2022 September. There were also DECam observations from 2021 September and from the Mt Lemmon Survey on 2022 October 20.44. [MPEC 2022-W234, CBET 5197, 2022 November 28] The comet was at perihelion at 2.7 au in 2022 July and has a period of 8.6 years.
    455P/PanSTARRS = 2017 S9 = 2022 R7 = 2011 Q5
    A 22nd magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 2017 September 30.59.  There were pre-discovery PanSTARRS images from September 19. It had been posted on the PCCP as P10E2ep.  [CBET 4448, MPEC 2017-U237, 2017 October 28] The comet was at perihelion at 2.2 au in 2017 July. It has a period of 5.6 years and JPL classify it as a Encke-family comet.

    Comet 2017 S9 was recovered at 22nd magnitude in PanSTARRS images taken with the 1.8 m Ritchey-Chretien on 2022 September 2.37. There were earlier PanSTARRS 2 images from August 6. Once recovered, even earlier PanSTARRS images from 2011 August (earliest on August 21.56) and September were found. The prediction based on the 2017 observations required a correction of Delta(T) = -0.69 day. [MPEC 2022-Y14, CBET 5200, 2022 December 17] The comet is at perihelion at 2.2 au in 2023 February and has a period of 5.6 years.


    456P/PanSTARRS = 2021 L4 = 2012 Q3
    PanSTARRS 1 discovered a 21st magnitude comet in images taken with the 1.8m Ritchey-Chretien on 2021 June 14.27. It was placed on the PCCP as P11h3rz. There were prediscovery Spacewatch and PanSTARRS observations from earlier in the month. [CBET 4986, MPEC 2021-M77, 2021 June 23] The comet was at perihelion at 2.8 au in 2019 September and has a period of 5.6 years. Given the long time since perihelion it might be in outburst. 

    Sam Deen and K Ly later identified images of the comet in archival data from the Canada-France-Hawaii 3.6m telescope on Mauna Kea taken on 2012 August 18, 28, September 12 and 14. It was completely asteroidal and was given the designation 2012 Q3. [CBET 5210, MPEC 2023-B135, 2023 January 27]


    457P/Lemmon-PanSTARRS = 2020 O1 = 2016 N7
    PanSTARRS 1 discovered a 21st magnitude comet in images taken with the 1.8m Ritchey-Chretien on July 20.44, with pre-discovery images from May, June and earlier in July. Independent observations of an asteroid on July 19.41 were reported from Mt Lemmon. It was placed on the PCCP as P112Sqo. [CBET 4820, MPEC 2020-P07, 2020 August 2] The comet was at perihelion at 2.3 au in 2020 May and has a period of around 4.3 years.

    In 2023 March K Ly reported finding the comet in images taken with the 8.2m Subaru telescope in 2016 July and August. [MPEC 2023-F99, F100, 2023 March 22]


    458P/Jahn = 2023 C1 = 2016 C3
    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.
    459P/Catalina = 2010 VH95
    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.
    460P/PanSTARRS = 2016 BA14 = 2020 U6
    A 19th magnitude asteroid discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 2016 January 22.34, was subsequently shown to have a faint tail. Pre-discovery PanSTARRS images were then found from 2015 December. Denis Denisenko suggests that the orbit is very similar to that of 252P/LINEAR. [CBET 4257, MPEC 2016-C192, 2016 February 15] The comet was at perihelion at 1.0 au in 2016 March and passed 0.024 au from the Earth on March 22. This was nearly optimum for a close approach as the MOID is 0.017 au; the Jupiter MOID is 0.094 au. It has a period of 5.3 years. It will make another close approach to the Earth in 2048, but there are no very close approaches to Jupiter over the century centred on the present, although it will pass 0.67 au from the planet in 2034 January and 0.76 au in 2046 July. Although intrinsically very faint, the comet reached 13th magnitude at closest approach, when it was moving rapidly across northern skies.

    In 2023 Richard Weryk reported the recovery of 2016 BA14 in images taken in 2020 October (recovery image October 17.52), November, December, and 2021 January from Pan-STARRS 1. [MPEC 2023-G14, CBET 5243, 2023 April 2] The MPEC has a helpful ephemeris to allow you to find the 31st magnitude comet.


    461P/WISE-Lemmon = 2010 OE101 = 2021 LJ31
    This unusual asteroid was discovered in images from the the Wide-field Infrared Survey Explorer (WISE) satellite on 2010 July 25.02. It was thought to have a period of around 6.6 years and perihelion at 1.4 au. [MPEC 2010-P11, 2010 August 3, 9-day orbit]. It can pass within 0.1 au of Jupiter. The orbit has a Tisserand criterion value of 2.71 with respect to Jupiter.  At the time it seems that Hirohisa Sato reported cometary activity, but this was ignored until 2023. On 2021 June 6.48 the Mt Lemmon Survey discovered an asteroid, which was observed until 2021 August 27. This was noted by Kaspar Wierzchos as showing cometary activity, which was confirmed by other observers. After the object had been designated the two objects were linked. The MPC issued MPEC 2023-H227 on 2023 April 28, designating the asteroid as P/WISE. The available information suggests that it should be P/WISE-Lemmon. The linked orbit gives perihelion at 1.3 au in 2021 October and a period of 5.6 years. CBET 5250 came out on April 29.  The linked orbit has a Jupiter MOID of 0.6 au and an Earth MOID of 0.35 au, which occurred in 2021 October. The most recent moderately close approach to Jupiter was 0.7 au in 1957 October.
    462P/LONEOS-PanSTARRS = 2000 OZ21 = 2022 M1
    PanSTARRS 2 discovered a 21st magnitude comet in images taken with the 1.8 m Ritchey-Chretien on 2022 June 29.57. It was placed on the PCCP as P21v4t0. PanSTARRS then identified asteroidal images of the comet in MPC "isolated tracklet files" from May 31 (Mt Lemmon) and June 15 (DECam). [MPEC 2022-N46, CBET 5146, 2022 July 8] The comet was at perihelion at 2.1 au in 2022 August and has a period of around 11 years. It passed 0.5 au from Jupiter in 2013 October. The Jupiter MOID is 0.46 au.

    Following the discovery, Syuichi Nakano was  able to link an asteroid discovered by LONEOS on  2000 July 29.36 and designated 2000 OZ21, but only observed over a five day arc, with the comet.  [CBET 5166, 2022 September 3]. It should have been numbered 449, but seemed to have been overlooked; it was eventually numbered in 2023 July.


    463P/NEOWISE-SWAN = 2018 HT3 = (2023 G1)
    A 19th magnitude object was discovered from the NEOWISE satellite on 2018 April 22.96. The object was at perihelion at 0.5 au in 2018 April and seemed to be a typical NEO.

    On 2023 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 was past perihelion but approaching Earth. It was estimated at around 13th magnitude and won't get any brighter but the elongation will improve. It is at high southern declination. This object has not received the 2023 G1 designation as the MPC use a different logic to that used by Brian Marsden who devised the system. In 2023 October Rob Matson checked the SWAN images from 2018 January 16-20 and found the comet, though it was hard to locate being very faint.


    464P/PanSTARRS = 2014 OL465
    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]
    465P/Hill = 2008 L2 = 2023 L1
    Rik Hill discovered an 18th magnitude comet on CCD images taken with the 0.68-m Catalina Schmidt telescope on 2008 June 12.44. Hirohisa Sato suggested a short period orbit, which was confirmed by subsequent orbits, which give the period as 15 years, with perihelion at 2.3 au in mid August 2008.

    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.


    466P/PanSTARRS = 2015 T3 = 2023 M3
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 2015 October 13.41. [CBET 4152, MPEC 2015-U02, 2015 October 16] The comet was at perihelion at 2.1 au in 2015 December and has a period of around 9 years.

    The comet is one of those suspected to have undergone nuclear splitting according to the list of Marcos & Marcos [Dynamically correlated minor bodies in the outer solar system, MNRAS, 474, 838, 2018 February]. They link it to 10P/Tempel.

    A possible new comet of 19th magnitude was discovered on 2023 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.


    467P/LINEAR-Grauer = 2010 TO20 = 2023 H6
    A 19th magnitude asteroidal object discovered by LINEAR on 2010 October 1.31 was found to be cometary by Al Grauer on images taken during the Mt Lemmon survey on 2011 October 19.34. The comet has a period of 13 years with perihelion at 5.1 au in 2008 August. Gareth Williams noted on MPEC 2011-U41 [2011 October 21]
    The osculation epoch for the orbit is the current standard epoch, rather than the 40-day epoch closest to perihelion, which is normal for comets. Like the recent case of P/2011 P1 (McNaught), P/2010 TO20 (LINEAR-Grauer) has made a recent close approach to Jupiter (0.077 au on 2009 November 2). For current epochs, the perihelion date lies in 2008. For epochs in 2008, the perihelion date lies in 2012-2013.

    Marco Micheli and Charles Schambeau recovered comet 2010 TO20 in images taken on 2023 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.


    468P/Siding Spring = 2004 V3 = 2023 O1
    Rob McNaught discovered another comet, of 19th magnitude, during the Siding Spring Survey on 2004 November 3.40. It was in a periodic orbit of 19 years and was at perihelion at 3.9 au in mid November 2004.

    R. H. McNaught, Siding Spring Observatory, reports the discovery of an object on 2004 November 3.40 on images taken by G. J. Garradd with the 0.5-m Uppsala Schmidt telescope in the course of the Siding Spring Survey; McNaught later (November 5 and 6) found the object to be slightly diffuse on CCD images taken with the Siding Spring 1.0-m f/8 reflector. [IAUC 8429, 2004 November 6]

    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.


    469P/PanSTARRS = 2015 XG422
    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 archival 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 December. It can make close approaches to Jupiter, passing 0.3 au from the planet in 2010 November. The next close approach is in 2093.
    470P/PanSTARRS = 2014 W1 = 2023 O2
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 2014 November 17.35. [CBET 4018, MPEC 2014-W54, 2014 November 21] The comet was at perihelion at 2.7 au in 2014 August and has a period of 9.5 years. 

    John Maikner recovered 2014 W1 with the 0.3m telescope at the Comet Hunter Observatory 2 at New Ringgold on 2023 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]


    471P/LINEAR-Fazekas = 2010 YK3 = 2023 KF3
    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. The official name is still under consideration.
    472P/NEAT-LINEAR = 2002 T6 = 2023 RL75
    An object reported as asteroidal independently by the NEAT (2002 October 4.50, mag 20.1) and LINEAR surveys (2002 October 7.26, mag 19.4), and later placed on the NEOCP, was found to be cometary in appearance. P. Birtwhistle, Great Shefford, U.K., reports that CCD images taken with a 0.3-m reflector on 2002 October 27.9 UT show two faint, thin, straight tails in p.a. 107 deg (36" long) and 310 deg (39" long) and a nuclear condensation with diameter about 8". T. B. Spahr reports that 5-min exposures taken with the Mt. Hopkins 1.2-m reflector on 2002 October 29.2 show a small coma of diameter about 6" and an extremely faint tail about 10" long in p.a. 330 deg. [IAUC 8002, 2002 October 29]

    Although some time from perihelion, it is a distant object in a periodic orbit and will initially fade. The period is around 21.2 years and the perihelion distance 3.4 au. Observers contributing to the preliminary orbit include BAA Members Peter Birtwhistle and Stephen Laurie.

    An asteroid was discovered at 21st magnitude by Erwin Schwab with the Calar Alto-Schmidt on 2023 September 9.09. JPL classified it as a Centaur. The object was 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 have become P/NEAT-LINEAR-Schwab, but this approach was not followed.


    473P/NEAT = 2001 Q6 = 2023 W1 = 2023 X5A
    S. H. Pravdo, E. F. Helin, and K. J. Lawrence, Jet Propulsion Laboratory, report the discovery of another comet, of 18th mag on CCD images taken with the 1.2-m Schmidt telescope at Palomar in the course of the NEAT program; their discovery image on 2001 August 28.41 shows a central nebulosity of diameter about 3" and a tail about 10" long toward the west-southwest. Other reported physical descriptions from CCD images include: August 28.98 UT, diffuse (M. Tichy, Klet, 0.57-m reflector); 29.05, diffuse object (m_1 = 16.4) with a bright nucleus, m_2 = 17.9 (L. Sarounova and M. Wolf, Ondrejov, 0.65-m reflector); 29.38, coma diameter about 10" (K. Smalley, Louisburg, KS, 0.75-m reflector); 29.44, well-condensed coma, broad tail 15" long in p.a. 240 deg (D. Balam, Dominion Astrophysical Observatory, 1.82-m Plaskett telescope); 29.47, fuzzy with a hint of a bulge to the southwest (P. J. Shelus, McDonald Observatory, 0.76-m reflector).

    Additional astrometry and preliminary parabolic orbital elements (from 25 observations, August 28-29) appear on MPEC 2001-Q70. [IAUC 7698, 2001 August 29] The comet could reach 14th mag at high northern declination in October. This is NEAT's 15th comet and 13th this year.

    Additional astrometry orbital elements, published on MPEC 2001-S06, indicate this comet (cf. IAUC 7698) to be of short period, with a period of 23 years. [IAUC 7722, 2001 September 21]

    Visual m_1 estimates: September 22.00 UT, 14.0 (K. Sarneczky, Agasvr, Hungary, 0.44-m reflector); October 8.81, 11.8 (R. J. Bouma, Groningen, The Netherlands, 0.31-m reflector); 13.64, 11.9 (K. Yoshimoto, Yamaguchi, Japan, 0.25-m reflector); 14.74, 11.1 (Yoshimoto); 15.85, 11.4 (Bouma). [IAUC 7734, 2001 October 16]

    44 observations in 2001/2 give a rather unlikely preliminary uncorrected light curve of 5.5 + 5 log d + 41.0 log r, although this is a poor fit.

    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.

    The MPC then issued another MPEC stating that John Maikner had 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. The MPC gave a designation of 2023 X5, ignoring the confusion created with designations of 2023 S4 = 2023 X5 for P/Hogan. Until this is resolved I am using X5A for P/NEAT and X5B for P/Hogan. [MPEC 2024-B144, 2024 January 28]  This MPEC was later withdrawn [MPEC 2024-B152, 2024 January 29]


    479P/Elenin = 2011 NO1 = 2023 WM26
    An orbit for an unusual minor planet discovered by Leonid Elenin on 2011 July 3.0 using the remote 0.45m astrograph at ISON-NM Observatory, Mayhill, USA was published on MPEC 2011-O09 on July 18. The next MPEC published the following day gave a cometary designation. The object was at perihelion at 1.2 au in January and has a period of about 13 years.

    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.


    474P/Hogan = 2023 S4 = 2023 X5B = 2017 O4
    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.
    475P/Spacewatch-LINEAR = 2004 DO29 = 2023 V7
    An asteroidal object of 20th magnitude was discovered with the 0.9-m reflector at the Steward Observatory, Kitt Peak on 2004 February 17.22. It was in a 20 year orbit, with perihelion at 4.1 au and an eccentricity of 0.45. It reached perihelion in early October 2004. [discovery on MPEC 2004-D45, 2004 Feruary 28] The orbit was more typical of an intermediate period comet and it can approach within 0.7 au of Jupiter. Subsequent observations with the 2.2-m reflector of the University of Hawaii showed it to have a coma, thus confirming its true cometary nature.

    An apparently asteroidal object found by both the Spacewatch and LINEAR projects on CCD images taken on 2004 February 17 has been found to have a 5" centrally condensed coma (of mag R = 18.7) and a 15" tail in p.a. 220-270 deg on CCD images taken on 2004 March 16.3-16.6 by S. S. Sheppard, Y. R. Fernandez, and D. Jewitt with the University of Hawaii 2.2-m reflector. [IAUC 8305, 2004 March 15]

    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.


    476P/PanSTARRS = 2015 HG16 = 2023 W2
    A 22nd magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 2016 April 4.48. R Weryk from the PanSTARRS team then found the object in images taken the day before, and then from February 11. Gareth Williams linked these observations to an asteroid discovered by PanSTARRS on 2015 April 20.33. Weryk independently found further images from 2015 March 24 and April 9. [CBET 4270, MPEC 2016-G114, 2016 April 7] The comet was at perihelion at 3.1 au in 2014 June and has a period of 10.5 years.

    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.


    477P/PanSTARRS = 2018 P3 = 2023 V8
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 2018 August 8.54. It had been posted on the PCCP as P10IPdp. [CBET 4548, MPEC 2018-Q34, 2018 August 19] The comet was at perihelion at 1.8 au in 2018 October. It has a period of around 5.2 years and JPL classify it as a Encke-type comet.

    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.


    478P/ATLAS = 2023 Y3 = 2017 BQ100
    Sam Deen had identified 2017 BQ100 as a possible comet long before the MPC issued the discovery MPEC for 2023 Y3. He noted in a message to the comets-ml (#29577) on 2021 April 6:
    2017 BQ100 was discovered on 2017/01/28 by PANSTARRS and observed for just 5 days without being recovered. Although I failed to extend the arc, I found further observations from 01/28 by the Dark Energy Camera (W84) which still have not been published showing it with a faint but distinct tail in the antisolar direction. Furthermore, these observations showed that the previous orbit calculating it as a normal main-belt asteroid were due to bad measurements by J43 on 2017/01/29 (consistently about 2-3 arcseconds off) the resultant improved orbit has P=6.96 years and q=2.41 au.

    It bears vague orbital similarity to 94P/Russell but the orbit is too poor to make any definite claims off of that. I searched in the ITF as well and found no additional observations. It should next come to perihelion in late 2023 or early 2024, at which point the orbit is too poor to attempt any recovery. Times like these make me very much wish that PANSTARRS and Mount Lemmon would make their recent data available, because this comet is definitely somewhere in them.

    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.


    480P/PanSTARRS = 2014 A3 = 2023 X6
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 2014 January 9.51. [MPEC 2014-B02, 2014 January 16] The comet was at perihelion at 3.6 au in 2013 April and has a period of around 10 years.

    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.


    481P/Lemmon-PANSTARRS = 2012 WA34 = 2024 C5
    An asteroid was discovered during the Mt Lemmon survey on 2012 November 26.40 and by PanSTARRS on 2013 January 7.24 when cometary features were noted. Additional observations from PanSTARRS from 2011 September were then found. It has a period of 10.5 years, with perihelion at 3.2 au in 2013 January.

    Erwin Schwab recovered comet 2012 WA34 at 20th magnitude in images taken with the 1.0-m reflector at the ESA Optical Ground Station at Tenerife on February 12.97. Sam Deen then found images taken on 2023 September 18 and 19 taken with the 4.0-m DECam at Cerro Tololo. [MPEC 2024-D103, CBET 53xx, 2024 February 22]. The comet was at perihelion at 3.1 au in 2023 July and has a period of 10.1 years.


    482P/PanSTARRS = 2014 VF40
    2014 VF40 was discovered on 2014 November 10.41 by PANSTARRS and has been observed over one orbit. It has a period of 7.3 years and perihelion at 1.9 au. It passed 0.3 au from Jupiter in 2021 February. Mike Kelley reported on the comets-ml on 2024 January 19 that it was showing active behaviour in ZTF images from 2023 October onwards. It wasn't given a PCCP designation, but was (and on February 29 still was) listed on the PCCP as possibly showing cometary activity. It was subsequently re-designated as a comet. [MPEC 2024-D133, CBET 5359, 2024 February 29]
    483P/PanSTARRS = 2016 J1-A = 2016 J1-B = 2020 Y6-A = 2020 Y6-B = 2021 K5-B = 2010 M9
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 2016 May 5.46. Confirmatory images taken with the Canada-France-Hawaii telescope on May 6.43 showed a second comet in the field, moving in an identical fashion. This was designated component B. [CBET 4276, MPEC 2016-J90, 2016 May 8] The comets are at perihelion at 2.4 au in 2016 June and have a period of around 5.6 years.  It/they is a Main Belt Comet.

    Marco Micheli recovered fragment A of 2016 J1 in images taken with the 8.1-m Gemini North telescope on 2020 December 24.52, and in additional images taken on 2021 February 17, April 11, 14, 15, 17, May 16, 17, 2022 March 13, April 8, 25 and June 19. At recovery the comet was 25th magnitude. [MPEC 2024-E142, CBET 5367, 2024 March 11/13]

    Marco Micheli recovered fragment B of 2016 J1 in images taken with the 8.1-m Gemini North telescope on 2021 May 20.28, and in additional images taken on May 30, 31, 2022 June 24 and July 7 and with Gemini South on 2022 July 7. At recovery the comet was 24th magnitude. [MPEC 2024-E143, CBET 5367, 2024 March 11/13]  The CBET suggests that the 2021 K5-B designation should not have been made and instead designates it as 2020 Y6-B. It also notes that following recovery and computation of a linked orbit, Syuichi Nakano was able to find images of the comet made on 2004 June 20 by the Catalina Sky Survey. Sam Deen was also able to find additional observations from 2010 and 2011. The splitting likely occured at or after the 2004 return.

    To add to the confusion, the MPC published additional observations found by Sam Dean from WISE in 2010 June and by PanSTARRS in 2011 August under the designation 2010 M9. [MPEC 2024-F76, 2024 March 22] Whether this will lead to other cometary returns getting a designation prior to numbering is uncertain.

    I am not certain whether the two objects will be given separate numbers, or retain their A and B designations. It may depend on who does the numbering. The answer seems to be that the comet is numbered as 483, and eventually separate orbits for the two components were given.


    484P/Spacewatch = 2005 XR132
    This outer main-belt asteroid was discovered by Spacewatch on 2005 December 5.47. It has perihelion at 2.1 au and a period of 7.3 years. Lulin Observatory report in ATel 14522 [2021 April 7] that a tail was present in images taken on 2021 April 5 and 6. They suggest that activity had begun about 100 days earlier. They do not say whether a coma was also present, so the tail may represent an impact event. Sam Deen notes that the perihelion distance has slowly been decreasing since 1200 when it was around 3.6 au. Before then it was a quasi-Hilda type orbit. This object was (and of February 29 is) listed on the PCCP as possibly showing cometary activity or having a cometary orbit. Some considerable time later it was re-designated as a comet. [MPEC 2024-D135, CBET 5360, 2024 February 29]. Although the announcement MPEC for this comet was issued before that for 483P/PanSTARRS, the comet was numbered after it.
    485P/Sheppard-Tholen = 2022 U6 = 2006 AH2
    In 2024 April the MPC reported that David Tholen had reported a possible comet in images taken with the 8.2 m Subbaru telescope at Mauna Kea on 2022 October 28.46. They identified this as a return of the minor planet 2006 AH2, which had been discovered by the Mt Lemmon Survey on 2006 January 2.37. It seems that this was acutally reported to the MPC in 2023 January with confirming images soon coming in. It appears as if the MPC then forgot about it for over a year. [MPEC 2024-H65, CBET 5387, 2024 April 23] The comet has a period of 17.9 years and was at perihelion at 4.0 au in 2023 August. Sam Deen suggests that it may have made a close (0.009 au) approach to Saturn in 1782 August.
    P/Leonard = 2018 L5 = 2024 H1
    Greg Leonard discovered a comet of 19th magnitude in Mt Lemmon Survey images taken with the 1.5m reflector on 2018 June 14.42. It was placed on the PCCP as ZLB3D4B. [CBET 4528, MPEC 2018-N04, 2018 July 1] The comet was at perihelion at 2.3 au in 2018 May and has a period of around 6.9 years.

    Erwin Schwab recovered comet 2018 L5 at 21st magnitude in images taken with the 1.0-m reflector at the ESA Optical Ground Station at Tenerife on April 18.o7. He confirmed the recovery with images taken by the Sutherland LCO 1-m Schmidt on April 21. [MPEC 2024-K145, CBET 5400, 2024 May 31]. The comet is at perihelion at 2.3 au in 2025 April and has a period of 6.9 years. It passed 0.4 au from Jupiter in 1978 July and 2014 September. There is a possible identification with 1937 BG


    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.

    Published by Jonathan Shanklin. Jon Shanklin - jds@ast.cam.ac.uk