BAA Comet Section : Comets discovered in 2018

Updated 2018 June 15


  • 2007 KP2 [A/ATLAS]
  • 2018 A1 (PanSTARRS)
  • 2018 A2 (364P/PanSTARRS)
  • 2018 A3 (ATLAS)
  • 2018 A4 (P/PanSTARRS)
  • 2018 A5 (P/PanSTARRS)
  • 2018 A6 (Gibbs)
  • 2018 AS18 [A/Mt Lemmon]
  • 2018 B1 (Lemmon)
  • 2018 BJ11 [A/PanSTARRS]
  • 2018 C1 (P/Lemmon-Read)
  • 2018 C2 (Lemmon)
  • 2018 DE4 [A/Lemmon]
  • 2018 DF4 [A/Lemmon]
  • 2018 DO4 [A/Lemmon]
  • 2018 E1 (ATLAS)
  • 2018 E2 (Barros)
  • 2018 EN4 (NEOWISE)
  • 2018 EF9 (Lemmon)
  • 2018 F1 (Grauer)
  • 2018 F2 (366P/Spacewatch)
  • 2018 F3 (Johnson)
  • 2018 F4 (PanSTARRS)
  • 2018 H1 (P/Catalina)
  • 2018 H2 (P/PanSTARRS)
  • 2018 K1 (Welland)
  • 2018 KH3 [A/Lemmon]
  • 2018 KJ3 [A/Lemmon]
  • 2018 KA4 [A/PanSTARRS]
  • 2018 KB4 [A/PanSTARRS]
  • 2018 L1 (P/PanSTARRS)
  • 2018 L2 (ATLAS)
  • 2018 L3 (P/NEAT)

  • When observing a comet please try to forget how bright you think the comet should be, what it was when you last viewed it, what other observers think it is or what the ephemeris says it should be.

    The equations for the light curves of comets that are currently visible use only the raw observations and should give a reasonable prediction for the current brightness. If the comet has not yet been observed or has gone from view a correction for aperture is included, so that telescopic observers should expect the comet to be fainter than given by the equation. The correction is about 0.033 per centimetre. Values for the r parameter given in square brackets [ ] are assumed. The form of the light curve is either the standard m = H0 + 5 log d + K0 log r or the linear brightening m = H0 + 5 log d + L0 abs(t - T + D0) where T is the date of perihelion, t the present and D0 an offset, if L0 is +ve the comet brightens towards perihelion and if D0 is +ve the comet is brightest prior to perihelion.

    Observations of comets made in 2018 are given in ICQ format. 

    Full details of recently discovered objects will not appear until they are available on the CBAT web pages. The actual accuracy of preliminary orbits is often (nearly always) much worse than the published accuracy implies.  In part this is because each orbital solution is treated as a mathematical construct and does not take account of observational error.  JPL does publish the errors, whereas the MPECs do not.


    2007 KP2 [A/ATLAS]
    An object was discovered in images taken with the 0.5m Schmidt at Haleakala on April 13 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. It was posted on the PCCP as A106HZo. The object was linked by the MPC with 2007 KP2, an Outer Main-belt Asteroid observed between 2007 April 22 and May 20.
    2018 A1 (PanSTARRS)
    A 19th magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on January 6.58.  It was placed on the PCCP as P10FSoC.  Peter Birtwhistle confirmed the cometary nature of the discovery. [CBET 4471, MPEC 2018-A43, 2017 January 11]  Astrometry from Nick James and Peter Carson later in January allowed Nick to compute a revised orbit which suggested that the comet had a period of around 130 years and was at perihelion at 2.4 au in 2017 October.  This was confirmed in an MPEC that came out a few days later.
    2018 A2 (364P/PanSTARRS)
    Erwin Schwab reported the recovery of 2013 CU129 to the Central Bureau in remotely obtained images that he had taken with the 0.8m Schmidt at Calar Alto, Spain, on January 16.92. In the meantime Gareth Williams of the Minor Planet Centre had identified the comet in incidental astrometry from Mt Lemmon on January 12.38. As is becomming commonplace, two CBETs were required to correctly announce the recovery. [CBET 4474, 4475, MPEC 2018-B14, 2018 January 17] The indicated correction to the prediction by S. Nakano in the ICQ's 2018 Comet Handbook is Delta(T) = +0.02 day.
    2018 A3 (ATLAS)
    An 18th magnitude comet was discovered in images taken with the 0.5m Schmidt at Mauna Loa on January 10.61 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. It had been posted on the PCCP as A105UPd. [CBET 4476, MPEC 2018-B18, 2018 January 17]. The comet will reach perihelion at 3.3 au in 2019 January.
    2018 A4 (P/PanSTARRS)
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on January 12.29.  It had been posted on the PCCP as P10G1vh.  [CBET 4477, MPEC 2018-B19, 2018 January 17] The comet is at perihelion at 2.4 au in 2018 May. It has a period of around 45 years (calculated by Hirohisa Sato) and JPL classify it as a Jupiter-family comet. The preliminary orbit has a Jupiter MOID of 0.15 au, though there have been no recent close passes.
    2018 A5 (P/PanSTARRS)
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on January 13.47.  There were pre-discovery PanSTARRS images from 2017 November and December. It had been posted on the PCCP as P10G50L.  [CBET 4478, MPEC 2018-B20, 2018 January 17] The comet was at perihelion at 2.7 au in 2017 September. It has a period of 13.4 years and JPL classify it as a Jupiter-family comet.
    2018 A6 (Gibbs)
    Alex Gibbs discovered a 19th magnitude comet in Mt Lemmon Survey images taken with the 1.5m reflector on January 15.38. It was placed on the PCCP as ZAA01CF. [CBET 4479, MPEC 2018-B100, 2018 January 23] The comet is at perihelion at 2.9 au in 2019 May.  Hirohisa Sato suggests that the comet is periodic, with perihelion at 3.1 au in 2019 August and a period of around 40 years.
    A/2017 AS18 [Mt Lemmon]
    The Mt Lemmon Survey discovered an asteroid in images taken with the 1.5m reflector on January 13, which was posted on the PCCP as ZA398B0. There is currently no evidence for cometary activity. The asteroid is classified as a Centaur by JPL. It is at perihelion at 1.7 au in 2018 March and has a period of around 50 years, though unusually JPL do not give any error bars.
    2018 B1 (Lemmon)
    An apparently asteroidal object of 19th magnitude was found in Mt Lemmon Survey images taken with the 1.5m reflector on January 25.14. It was placed on the PCCP as ZBB6FE2 and follow up observations by astrometrists, including Peter Birtwhistle, showed that it was slightly diffuse and elongated. With a preliminary orbit, Gareth Williams was then able to find pre-discovery PanSTARRS images from 2017 January. [CBET 4484, MPEC 2018-C27, 2018 February 7] The comet is at perihelion at 5.1 au in 2018 March. 
    A/2018 BJ11 [PanSTARRS]
    PanSTARRS discovered an asteroid in images taken with the 1.8m Ritchey-Chretien in January. The object, classified as an Outer Main-belt Asteroid, was at perihelion at 3.3 au in 2015 November and has a period of around 9 years. It was placed on the PCCP as P10GpOj. No cometary activity has been confirmed.
    2018 C1 (P/Lemmon-Read)
    Mike Read discovered a comet in images taken with the 0.9-m Spacewatch telescope at Kitt Peak on February 9.29.   It was also discovered as an apparently asteroidal object of 19th magnitude and possible NEO, in Mt Lemmon Survey images taken with the 1.5m reflector on February 4.42. It was placed on the PCCP as SW40xg.  After posting it was also found in PanSTARRS images from January 16.42.  [CBET 4487, MPEC 2018-C76, 2018 February 11]  The comet is near perihelion at 2.59 au and has a period of around 13 years. 
    2018 C2 (Lemmon)
    An asteroidal object of 20th magnitude was found in Mt Lemmon Survey images taken with the 1.5m reflector on February 5.55. It was placed on the PCCP as ZC82561, because it had a slightly hyperbolic orbit, but no cometary activity had been detected. It was therefore given a cometary letter designation with an A/ prefix. [MPEC 2018-E18, 2018 March 4] On March 22.6 images taken with the 3.6m Canada-France-Hawaii showed a broad faint tail, though with only a marginal coma. The designation was therefore changed to C/ [MPEC 2018-F136, CBET 4501, 2018 March 28] The comet is at perihelion at 2.0 au in 2018 June.
    2018 DE4 [A/Lemmon]
    An asteroidal object of 21st magnitude was found in Mt Lemmon Survey images taken with the 1.5m reflector on February 17.43. It was placed on the PCCP as ZD8BAB2, but no cometary activity has been detected. [MPEC 2018-E15, 2018 March 4] The asteroid is at perihelion at 2.4 au in 2018 April and has a period of around 180 years. It is classified as a TransNeptunian Object by JPL.  
    2018 DF4 [A/Lemmon]
    An asteroidal object of 21st magnitude was found in Mt Lemmon Survey images taken with the 1.5m reflector on February 23.22. It was placed on the PCCP as ZD92B16, but no cometary activity has been detected. [MPEC 2018-E16, 2018 March 4] The asteroid is at perihelion at 1.6 au in 2018 October and has a period of around 1000 years. It is classified as a TransNeptunian Object by JPL.  
    2018 DO4 [A/Lemmon]
    An asteroidal object of 21st magnitude was found in Mt Lemmon Survey images taken with the 1.5m reflector on February 25.31. It was placed on the PCCP as ZD9686E, but no cometary activity has been detected. [MPEC 2018-F13, 2018 March 16] The asteroid is at perihelion at 2.4 au in 2019 August and has a retrograde orbit with a period of around 100 years. It is classified as a Centaur by JPL.  
    2018 E1 (ATLAS)
    A 17th magnitude comet was discovered in images taken with the 0.5m Schmidt at Haleakala on March 10.23 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. Pre-discovery images from PanSTARRS were found in data from 2015 August and October and 2016 August to October. It had been posted on the PCCP as A106x1X. [CBET 4493 and quickly revised on 4494, MPEC 2018-F10, 2018 March 16]. The comet will reach perihelion at 2.7 au in 2018 April and has a period of around 400 years.
    2018 E2 (Barros)
    Brazilian amateur astronomer Joćo Ribeiro de Barros discovered a 19th magnitude comet in images taken with the 0.45m f/2.9 reflector of the SONEAR observatory on March 12.93. [CBET 4495, MPEC 2018-F11, 2018 March 16] It had been posted on the PCCP as S091272. The comet was at perihelion at 3.9 au in 2017 December.
    2017 EN4 (NEOWISE)
    A 20th magnitude object was discovered from the NEOWISE satellite on March 9.09. [MPEC 2018-F12, 2018 March 16] It had been posted on the PCCP as N00ctza. The object, originally classified as a Centaur asteroid, was at perihelion at 1.4 au in 2018 June and has a highly inclined orbit with a period of around 80 years. The orbit has a Jupiter MOID of 0.57 au and a Tisserand invariant of 0.43. As it approached perihelion it developed cometary activity, and was redesignated as a comet. [MPEC 2018-L53, CBET 4524, 2018 June 11 and CBET 4525 the same day with replacement text]
    2018 EF9 (Lemmon)
    An asteroidal object of 21st magnitude was found in Mt Lemmon Survey images taken with the 1.5m reflector on March 9.30. It was placed on the PCCP as ZE9BC93, but no cometary activity was detected at the time. [MPEC 2018-F138, 2018 March 28]

    Further observations in April, first by NEOWISE and then confirmed from the ground showed a coma and faint tail, so the object was redesignated as a comet. [CBET 4511, MPEC 2018-H55, 2018 April 20]

    The comet is at perihelion at 1.6 au in 2018 May and has a period of around 12,000 years. The inclination of the orbit is near perpendicular. It has a Jupiter MOID of 0.24.

    Juan Jose Gonzalez found it much brighter than expected when it reached perihelion, making it 11th magnitude in his 20cm SCT from his mountain observing site.
    2018 F1 (Grauer)
    Al Grauer discovered a comet of 19th magnitude in Mt Lemmon Survey images taken with the 1.5m reflector on March 17.35. It was independently discovered a few hours later in PanSTARRS images [So why isn't it Grauer-PanSTARRS ?] and they also found pre-discovery images from 2017 December 22, 2018 January 17 and March 10. [CBET 4496, MPEC 2018-F42, 2018 March 19] The comet is at perihelion at 3.0 au in 2018 December. It has a period of around 5000 years.
    2018 F2 (366P/Spacewatch)
    2005 JN was recovered with the 1.0m f/4.4 reflector at the ESA Optical Ground Station at Tenerife on March 17.18. It was 20th magnitude.
    2018 F3 (Johnson)
    Jess Johnson discovered a comet of 20th magnitude in Mt Lemmon Survey images taken with the 1.5m reflector on March 20.27. It was placed on the PCCP as ZFAB135. [CBET 4500, MPEC 2018-F137, 2018 March 28] The comet was at perihelion at 2.5 au in 2017 August.
    2018 F4 (PanSTARRS)
    PanSTARRS discovered a 20th magnitude asteroid in images taken with the 1.8m Ritchey-Chretien on March 17.53. It was placed on the PCCP as P10HIgx but no cometary activity was confirmed at the time. The object was classified as a Hyperbolic Asteroid by JPL.

    Evidence for a cometary nature came in April, when follow up images showed a coma and tail. [MPEC 2018- H21, CBET 4508, 2018 April 17]. The comet is at perihelion at 3.4 au in 2019 December and has a current eccentricity of 1.011 in a near perpendicular orbit. The Jupiter MOID is 0.60, but the object is not currently near the planet. If the orbit is confirmed it could be a candidate for a second interstellar object. Although the latest orbit remains strongly hyperbolic, the eccentricity is quite uncertain.


    2018 H1 (P/Catalina)
    Erwin Schwab recovered 2011 CR42 during remote observations with the Calar Alto 0.8m Schmidt on April 17.01. No tail or coma was detected in total exposures of 600s.
    2018 H2 (P/PanSTARRS)
    A 20th magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on April 16.53.  There were pre-discovery PanSTARRS images from 2017 November. It had been posted on the PCCP as P10Hq33.  [CBET 4512, MPEC 2018-H93, 2018 April 26] The comet was at perihelion at 2.0 au in 2018 January. It has a period of 9.2 years and JPL classify it as a Jupiter-family comet.
    2018 K1 (Weiland)
    Henry Weiland discovered a 17th magnitude comet in images taken with the 0.5m Schmidt at Mauna Loa on May 25.54 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) program. Pre-discovery images from PanSTARRS were found in data from 2017 November 6 and 2018 May 24. It had been posted on the PCCP as A1072Wf. [CBET 4518, MPEC 2018-K117, 2018 May 31]. The comet was at perihelion at 1.8 au in 2018 April and has a period of around 160 years.
    A/2018 KH3 [Lemmon]
    An asteroidal object of 21st magnitude was found in Mt Lemmon Survey images taken with the 1.5m reflector on May 16.43. It was placed on the PCCP as ZKA7A2D, but no cometary activity has been detected. [MPEC 2018-K115, 2018 May 31] The asteroid was at perihelion at 3.7 au in 2017 May and has a period of around 1000 years. It is classified as a Trans Neptunian Object by JPL.  
    A/2018 KJ3 [Lemmon]
    An asteroidal object of 20th magnitude was found in Mt Lemmon Survey images taken with the 1.5m reflector on May 17.41. It was placed on the PCCP as ZKA8FB3, but no cometary activity has been detected. [MPEC 2018-K116, 2018 May 31] The asteroid is at perihelion at 3.6 au in 2019 September and has a retrograde orbit with a period of around 2000 years. It is classified as a Trans Neptunian Object by JPL.  
    A/2018 KA4 [PanSTARRS]
    PanSTARRS discovered an asteroid in images taken with the 1.8m Ritchey-Chretien on May 23. The object, classified as a Mars-crossing Asteroid, was at perihelion at 1.6 au in 2018 June and has a period of around 3.9 years. It was placed on the PCCP as P10HxLa. No cometary activity has been confirmed.
    A/2018 KB4 [PanSTARRS]
    PanSTARRS discovered an asteroid in images taken with the 1.8m Ritchey-Chretien on May 26.57. The object, classified as a Apollo Asteroid, was at perihelion at 1.0 au in 2018 April and has a period of around 3.3 years. It was placed on the PCCP as P10Hy2h. No cometary activity has been confirmed.
    2018 L1 (P/PanSTARRS)
    A 20th magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on June 3.28.  It was placed on the PCCP as P10HyFo.  [CBET 4521, MPEC 2018-L36, 2018 June 8]  The comet had a period of around 6.9 years and was at perihelion at 1.9 au in 2018 November.  
    2018 L2 (ATLAS)
    An 16th magnitude comet was discovered in images taken with the 0.5m Schmidt at Mauna Loa on June 6.33 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. It had been posted on the PCCP as A1077xy. [CBET 4522, MPEC 2018-L37, 2018 June 9]. The comet will reach perihelion at 1.7 au in 2018 December.
    2018 L3 (P/NEAT)
    2005 R1 was recovered in images taken at the European Space Agency's Optical Ground Station at Teneriffe with the 1.0m reflector on June 13.19. It was 19th magnitude. The indicated correction to the prediction by S. Nakano in the ICQ's 2018 Comet Handbook is Delta(T) = -0.07 day. [CBET 4526, MPEC 2018-L76, 2018 June 14]
    Ephemerides of current comets are available on the CBAT ephemeris page and positions of newly discovered comets are on the NEO confirmation page.
    More information on LINEAR. A list of comets discovered by selected search programs.
    The Northumberland refractor is the telescope that was used in the search for Neptune. It now has a 0.30-m f20 doublet lens which used to give a stellar limiting magnitude of around 15 at the zenith on good nights. The Thorrowgood refractor was built in 1864 and has a 0.20-m f14 doublet lens.
    Published by Jonathan Shanklin. Jon Shanklin - jds@ast.cam.ac.uk