BAA Comet Section : Comets discovered in 2023

Updated 2023 January 26


  • 2023 A1 (Leonard)
  • 2023 B1 (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 magnitude parameters [ updated 2023 January 3] of comets that are currently visible should give a reasonable prediction for the current brightness.   The evidence shows that VEM magnitudes do not require a correction for aperture.  Visual observations however do, and are therefore now corrected to a standard aperture of 30cm. The correction is about 0.033 per centimetre.  Visual observers using smaller apertures may find a comet to be brighter than indicated by the equation.  Values for the r parameter given in square brackets [ ] are assumed. The form of the light curve is either the standard m = H0 + 5 log d + K0 log r or the linear brightening m = H0 + 5 log d + L0 abs(t - T + D0) where T is the date of perihelion, t the present and D0 an offset, if L0 is +ve the comet brightens towards perihelion and if D0 is +ve the comet is brightest prior to perihelion.

    Observations of new comets in 2023 are given in ICQ format. 

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


    2023 A1 (Leonard)
    Gregory Leonard discovered a comet of 19th magnitude in images taken with the 1.5-m reflector of the Mt Lemmon Survey on 2023 January 9.54. It was placed on the PCCP as C8T3Z82. [MPEC 2023-B66, CBET 5204, 2023 January 22]. The comet is at perihelion at 1.8 au in 2023 March.
    2023 B1 (P/PanSTARRS)
    PanSTARRS 2 discovered an 18th magnitude comet in images taken with the 1.8 m Ritchey-Chretien on January 21.48. It was placed on the PCCP as P21D3Eu. There were prediscovery images with ATLAS-HKO on January 13 and Xingming Observatory #3, Nanshan on January 19. Alan Fitzsimmons suggests that it may be a Centaur asteroid that is undergoing an outburst. [MPEC 2023-B118, CBET 5209, 2023 January 25/26] The comet is at perihelion at 6.1 au in 2023 June and has a period of around 20 years.  It may have passed around 1 au from Jupiter in 1930. October.
    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 gives a stellar limiting magnitude of around 15 at the zenith on very good nights. The Thorrowgood refractor was built in 1864 and has a 0.20-m f14 doublet lens.
    Published by Jonathan Shanklin. Jon Shanklin - jds@ast.cam.ac.uk