BAA Comet Section : Comets discovered in 2018

Updated 2018 January 17


  • 2018 A1 (PanSTARRS)
  • 2018 A2 (P/PanSTARRS)
  • 2018 A3 (ATLAS)
  • 2018 A4 (P/PanSTARRS)
  • 2018 A5 (P/PanSTARRS)

  • 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.


    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] The comet was at perihelion at 2.6 au in 2017 November.
    2018 A2 (P/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 25 years and JPL classify it as a Jupiter-family comet. The 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.
    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