BAA Comet Section : Comets discovered in 2019

Updated 2024 March 2


  • 2019 A1 (P/PanSTARRS)
  • 2019 A2 (P/ATLAS)
  • 2019 A3 (P/PanSTARRS)
  • 2019 A4 (P/PanSTARRS)
  • 2019 A5 (PanSTARRS)
  • 2019 A6 (P/Lemmon-PanSTARRS)
  • 2019 A7 (P/PanSTARRS)
  • 2019 A8 (P/PanSTARRS)
  • 2019 A9 (PanSTARRS)
  • A/2019 AB4 [A/PanSTARRS]
  • 2019 B1 (Africano)
  • 2019 B2 (P/Groeller)
  • 2019 B3 (PanSTARRS)
  • 2019 C1 (ATLAS)
  • 2019 D1 (Flewelling)
  • 2019 D2 (379P/Spacewatch)
  • 2019 E1 (377P/Scotti)
  • 2019 E2 (378P/McNaught)
  • 2019 E3 (ATLAS)
  • A/2019 EJ3 [A/Catalina]
  • 2019 F1 (ATLAS-Africano)
  • 2019 F2 (ATLAS)
  • 2019 G1 (380P/PanSTARRS)
  • 2019 G2 (PanSTARRS)
  • A/2019 G3 [A/PanSTARRS]
  • 2019 G4 (PanSTARRS)
  • 2019 GG21 (P/PanSTARRS)
  • 2019 GN22 [A/KMTM]
  • 2019 H1 (NEOWISE)
  • 2019 J1 (Lemmon)
  • 2019 J2 (Palomar)
  • 2019 J3 (ATLAS)
  • 2019 JU6 (ATLAS)
  • 2019 K1 (ATLAS)
  • 2019 K2 (P/LINEAR-Spacewatch)
  • 2019 K3 (P/Larson)
  • 2019 K4 (Ye)
  • 2019 K5 (Young)
  • 2019 K6 (A/PanSTARRS)
  • 2019 K7 (Smith)
  • 2019 K8 (ATLAS)
  • A/2019 KE7 [Catalina]
  • A/2019 KF7 [Palomar]
  • A/2019 KN19 [ATLAS]
  • 2019 L1 (PanSTARRS)
  • 2019 L2 (NEOWISE)
  • 2019 L3 (ATLAS)
  • 2019 LD2 (P/ATLAS)
  • 2019 LM4 (P/Palomar)
  • 2019 LB7 (Kleyna)
  • 2019 M1 (P/Christensen)
  • 2019 M2 (P/ATLAS)
  • 2019 M3 (ATLAS)
  • 2019 M4 (TESS)
  • 2019 N1 (ATLAS)
  • A/2019 N2 (TESS)
  • 2019 NJ3 (Lemmon)
  • 2019 O1 (P/Kowalski)
  • 2019 O2 (PanSTARRS)
  • 2019 O3 (Palomar)
  • A/2019 O4 (A/PanSTARRS)
  • 2019 OK [A/SONEAR-ASSASN-ATLAS]
  • 2019 P1 (P/Hill)
  • 2019 PN2 [A/PanSTARRS]
  • 2019 PR2 [A/PanSTARRS]
  • 2019 Q1 (Lemmon)
  • A/2019 Q2 (ATLAS)
  • 2019 Q3 (PanSTARRS)
  • 2019 Q4 (2I/Borisov)
  • 2019 QR6 [A/Lemmon]
  • 2019 R1 (387P/Boattini)
  • 2019 R2 (388P/Gibbs)
  • 2019 S1 (389P/Siding Spring)
  • 2019 S2 (P/PanSTARRS)
  • 2019 S3 (P/PanSTARRS)
  • 2019 S4 (Lemmon)
  • 2019 S5 (P/Spacewatch-Hill)
  • A/2019 T1 (A/PanSTARRS)
  • 2019 T2 (Lemmon)
  • 2019 T3 (ATLAS)
  • 2019 T4 (ATLAS)
  • 2019 T5 (P/ATLAS)
  • 2019 T6 (P/PanSTARRS)
  • 2019 U1 (390P/Gibbs)
  • 2019 U2 (391P/Kowalski)
  • 2019 U3 (P/LINEAR)
  • 2019 U4 (P/PanSTARRS)
  • 2019 U5 (PanSTARRS)
  • 2019 U6 (Lemmon)
  • 2019 V1 (Borisov)
  • 2019 V2 (P/Groeller)
  • 2019 W1 (P/PanSTARRS)
  • 2019 X1 (P/Pruyne)
  • 2019 X2 (P/PanSTARRS)
  • 2019 Y1 (ATLAS)
  • 2019 Y2 (407P/PanSTARRS-Fuls)
  • 2019 Y3 (P/Catalina)
  • 2019 Y4 (ATLAS)
  • 2019 Y5 (PanSTARRS)
  • 2019 YX6 [A/ATLAS]

  • 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 2019 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.


    2019 A1 (P/PanSTARRS)
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on January 3.63.  There were prediscovery observations from Mt Lemmon on December 4 and PanSTARRS on December 20. It was placed on the PCCP as P10KX4b.  [CBET 4591, MPEC 2019-A101, 2019 January 7]  The comet has a period of around 12 years and was at perihelion at 2.2 au in 2018 October. Remarkably PanSTARRS has discovered the first comet of the year for five years running. 
    2019 A2 (P/ATLAS)
    A 19th magnitude comet was discovered in images taken with the 0.5m Schmidt at Haleakala on January 4.48 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. There were pre-discovery images made in December from Purple Mountain Obervatory, ATLAS and Oukaimeden Observatory. It had been posted on the PCCP as A10b3Tk. [CBET 4595, MPEC 2019-A126, 2019 January 8]. The comet was at perihelion at 3.5 au in 2018 November and has a period of around 14 years.
    2019 A3 (P/PanSTARRS)
    A 22nd magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on January 3.27.  There were prediscovery observations from PanSTARRS 1 on August 8, 11 and 21 and PanSTARRS 2 on October 10, 18 and November 13. It was placed on the PCCP as P10KTLx.  [CBET 4598, MPEC 2019-A166, 2019 January 10]  The comet has a period of around 5.6 years and was at perihelion at 2.3 au in 2018 August.
    2019 A4 (P/PanSTARRS)
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on January 10.37.  There were prediscovery observations from PanSTARRS 1 on January 3. It was placed on the PCCP as P10Lm7w.  [CBET 4600, MPEC 2019-B44, 2019 January 17]  The comet has a relatively short period of 4.2 years and was at perihelion at 2.4 au in 2018 December.
    2019 A5 (PanSTARRS)
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on January 13.49.  There were prediscovery observations from PanSTARRS 1 on January 4. It was placed on the PCCP as P10LuEh.  [CBET 4601, MPEC 2019-B45, 2019 January 17]  The comet is at perihelion at 6.3 au in 2019 June and has a period of around 100 years.
    2019 A6 (P/Lemmon-PanSTARRS)
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on January 7.51.  It was placed on the PCCP as P10L7nx. Following confirmation, Gareth Williams identified it with an undesignated possible NEA reported by Mt Lemmon on December 19, with additional images on December 14 and 16.  [CBET 4602, MPEC 2019-B46, 2019 January 17]  The comet has a period of around 12 years and was at perihelion at 1.9 au in 2018 August.
    2019 A7 (P/PanSTARRS)
    A 20th magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on 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 around 5.7 years and was at perihelion at 2.7 au in 2018 January.
    2019 A8 (P/PanSTARRS)
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on January 11.64.  It was placed on the PCCP as P10LqGV.  [CBET 4608, MPEC 2019-C20, 2019 February 4]  The comet currently has a period of around 5.9 years and was at perihelion at 1.9 au in 2018 August.
    2019 A9 (PanSTARRS)
    A 20th magnitude object was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on January 14.27.  It was placed on the PCCP as P10Lwea. It was subsequently shown to have weak cometary features. There were prediscovery PanSTARRS images from December 18. [CBET 4610, MPEC 2019-C53, 2019 February 7]  The comet is at perihelion at 1.4 au in 2019 July.
    A/2019 AB4 [PanSTARRS]
    PanSTARRS discovered an asteroid in images taken with the 1.8m Ritchey-Chretien on January 3.2. The object, classified as a Main-belt Asteroid, is at perihelion at 2.0 au in 2019 March and has a period of around 3.5 years. It was briefly placed on the PCCP as P10KTPv. No cometary activity has been confirmed.
    2019 B1 (Africano)
    Brian Africano discovered a comet of 18th magnitude in Catalina Sky Survey images taken with the 0.68m Schmidt on January 19.48. Peter Birtwhistle was amongst the observers confirming the discovery, which was placed on the PCCP as C012RY1. [CBET 4604, MPEC 2019-B65, 2019 January 23]. The comet was at perihelion at 1.6 au in 2019 March.
    2019 B2 (P/Groeller)
    Hannes Groeller discovered a comet of 18th magnitude in Catalina Sky Survey images taken with the 0.68m Schmidt on January 26.31. Peter Birtwhistle was amongst the observers confirming the discovery, which was placed on the PCCP as C01N611. [CBET 4609, MPEC 2019-C21, 2019 February 4]. The comet is at perihelion at 2.4 au in 2019 June and has a period of around 7.6 years.
    2019 B3 (PanSTARRS)
    A 19th magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on January 24.58.  It was placed on the PCCP as P10LPUO.  [CBET 4611, MPEC 2019-D41, 2019 February 27]  The comet is at perihelion at 6.8 au in 2021 January.
    2019 C1 (ATLAS)
    An 18th magnitude object was discovered in images taken with the 0.5m Schmidt at Mauna Loa on February 5.46 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. There were pre-discovery images made in mid January from the Heleakala ATLAS. It had been posted on the PCCP as A10c3KV. [MPEC 2019-D42, 2019 February 27]. No cometary activity has been detected, however the object is in a long period orbit with perihelion at 6.6 au in 2020 May. It has therefore been given a cometary style asteroidal designation. It may show activity nearer perihelion, though this is only 0.7 au closer than its discovery distance.

    Reports of cometary features were made as early as 2019 March, however it wasn't until astrometry was reported at the end of 2020 January that an MPEC was issued to report this. [CBET 4721, MPEC 2020-C61, 2020 February 3/5] Curiously the CBET says "The object was given the designation "A/2019 C1" when announced on MPEC 2019-D42, due evidently to its comet-like orbit.", which implies that the MPC and CBAT don't talk to each other.


    2019 D1 (Flewelling)
    Heather Flewelling discovered a 17th magnitude comet in images taken with the ATLAS (Asteroid Terrestrial-impact Last Alert System) 0.5m Schmidt at Mauna Loa on February 26.65. It had been posted on the PCCP as A10ceJ9. [CBET 4614, MPEC 2019-F53, 2019 March 21]. The comet was at perihelion at 1.6 au in 2019 May. 
    2019 D2 (379P/Spacewatch)
    This comet, missed at its 2012 apparition, was recovered by Gareth Williams in incidental astrometry reported by the Mount Lemmon Survey, which was then linked to a single-night detection on the NEOCP. R. Weryk (F51) also suggested the linkage when he reported that the same NEOCP object had a FWHM of ~1".8 (compared to 1".15 +/- 0".04 for nearby stars) and a ~4" tail to the east. The indicated delta-T correction to the prediction, by B. G. Marsden, on MPC 56954 is -1.29 days (in 2012, the correction was -0.61 days). [CBET 4616, MPEC 2019-G21, 2019 April 3].
    2019 E1 (377P/Scotti)
    Erwin Schwab reported his recovery of 2003 L1 in images taken with the 1.0m reflector at the European Space Agency's Optical Ground Station at Teneriffe on March 9.11. The correction to T compared to the 2017 prediction on MPC 105247 is -0.39 days. [CBET 4612, MPEC 2019-E80, 2019 March 10]
    2019 E2 (378P/McNaught)
    Erwin Schwab reported his recovery of 2005 Y2 in images taken with the 1.0m reflector at the European Space Agency's Optical Ground Station at Teneriffe on March 10.14. The correction to T compared to the 2011 prediction on MPC 75706 is +0.04 days. [CBET 4613, MPEC 2019-F27, 2019 March 18]
    2019 E3 (ATLAS)
    A 19th magnitude comet was discovered in images taken with the 0.5m Schmidt at Mauna Loa on March 5.43. by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. It had been posted on the PCCP as A10ckQ4. [CBET 4615, MPEC 2019-F54, 2019 March 21]. The comet is at perihelion at 10.3 au in 2023 November.
    A/2019 EJ3 [A/Catalina]
    An object of 19th magnitude was discovered in Catalina Sky Survey images taken with the 0.68m Schmidt on March 4.30. Peter Birtwhistle was amongst the observers confirming the discovery, which was placed on the PCCP as C04HO51. [MPEC 2019-F118, 2019 March 28]. No cometary activity has been detected, but the object is on a very comet-like orbit. It was only observed over a short arc from March 4 to 12 and so the orbit remains uncertain. The object was at perihelion at 1.1 au in 2019 March and has a period of over 500 years in a retrograde orbit. JPL classify it as an Amor NEO asteroid, with an Earth MOID of 0.1 au.
    2019 F1 (ATLAS-Africano)
    ATLAS reported a possible 18th magnitude NEO on March 28.52, but it didn't have a high score and was not posted on the NEOCP. Brian Africano discovered the same object as a comet of 18th magnitude in Mt Lemmon Survey images taken with the 1.5m reflector on March 29.42. It was placed on the PCCP as C012RY1. [CBET 4619, 2019 April 10, MPEC 2019-G124, 2019 April 9]. The comet is at perihelion at 3.6 au in 2021 June.
    2019 F2 (ATLAS)
    A 18th magnitude comet was discovered in images taken with the 0.5m Schmidt at Mauna Loa on March 26.31 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. There were pre-discovery images made in February. It had been posted on the PCCP as A10cu6N. [CBET 4620, MPEC 2019-H29, 2019 April 22]. The comet is at perihelion at 2.2 au in 2019 September and has a period of around 70 years.
    2019 G1 (380P/PanSTARRS)
    A 23rd magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on April 3.51. Once the provisional orbit was better known it was possible for the PanSTARRS team to find prediscovery PanSTARRS observations from 2019 February, 2018 (when it was stellar) and 2011 (also stellar). There were also Mt Lemmon observations from 2019 March. With these observations, Gareth Williams then found further images from 2009 by Spacewatch and Purple Mountain Observatory. The comet was designated as 2011 O2 for the 2009 return. It was placed on the PCCP as P10MA2B.  [CBET 4610, 2019 April 10, MPEC 2019-G123, 2019 April 9]  The comet has a period of 9.6 years and was at perihelion at 3.0 au in 2009 October and 2019 June. It has a Jupiter MOID of 0.29 au and approached the planet to within 0.46 au in 1978 February; it will make a more distant approach in 2023, but a closer one has to wait until 2163.
    2019 G2 (PanSTARRS)
    PanSTARRS discovered an asteroid in images taken with the 1.8m Ritchey-Chretien on April 2.44. The object, classified as a Parabolic Asteroid, is at perihelion at 2.3 au in 2019 December and has a retrograde parabolic orbit with a Jupiter MOID of 0.20 au. It was placed on the PCCP as P10Mmzj. No cometary activity has been detected.

    On 2024 March 1, the MPC noted that cometary activity had been reported by David Rankin in images taken by the Catalina Sky Survey on 2020 January 14. Sam Deen had also found cometary activity in pre-discovery archival images from 2019 February and March and post discovery images from 2019 December. They therefore re-designated the object as a comet, though it is not clear why they took so long to do so. [MPEC 2024-E01, CBET 5361, 2024 March 1]


    A/2019 G3 [PanSTARRS]
    PanSTARRS discovered an asteroid in images taken with the 1.8m Ritchey-Chretien on April 4.49. The object, classified as a Centaur, was at perihelion at 2.9 au in 2018 December and has a retrograde orbit with a period of around 70 years. It was placed on the PCCP as P10MC3w. No cometary activity has been detected.
    2019 G4 (PanSTARRS)
    PanSTARRS discovered an asteroid in images taken with the 1.8m Ritchey-Chretien on April 9.25. The object was at perihelion at 5.9 au in 2018 September and has a retrograde orbit with a period of around 900 years. It was placed on the PCCP as P10N31R. No cometary activity was detected at the time and it was classified as a TNO.

    In 2022 Sam Deen found cometary activity in archival images taken in 2018 July with the Cerro Tololo-DECam prior to discovery and in 2019 and 2020 from Mauna Kea. [MPEC 2022-P69, CBET 5153, 5154 (correct elements), 2022 August 5/6]


    2019 GG21 (P/PanSTARRS)
    PanSTARRS discovered an asteroid in images taken with the 1.8m Ritchey-Chretien on April 4.40. The object was initially classified as a Centaur, and was at perihelion at 3.9 au in 2019 May and has a period of around 20 years. It was placed on the PCCP as P10MGql. Within a day of being given the asteroidal designation it was redesignated as a comet following the detection of a tail. [CBET 4621, MPEC 2019-H44, 2019 April 23]
    2019 GN22 [A/KMTN]
    An object discovered by the Korea Microlensing Telescope Network-CTIO with the 1.6-m f/3.22 reflector on April 5.1 was posted on the PCCP as JA0004. No cometary activity has been detected. It is a distant Centaur, with perihelion at 11.6 au in 2027 November.
    2019 H1 (NEOWISE)
    An 18th magnitude cometary object was discovered from the NEOWISE satellite on April 18.9. [MPEC 2019-J24, CBET 4623, 2019 May 4] It was posted on the PCCP as N00epwh. The comet was at perihelion at 1.8 au in 2019 April.
    2019 J1 (Lemmon)
    Richard Kowalski and David Rankin discovered a comet of 18th magnitude in Mt Lemmon Survey images taken with the 1.5m reflector on May 4.45. [CBET 4625, 2019 May 14, MPEC 2019-J122, 2019 May 12]. It was placed on the PCCP as C0M96K2. The comet was at perihelion at 2.5 au in 2019 April.
    2019 J2 (Palomar)
    The Zwicky Transient Facility discovered a 17th magnitude comet on May 9.47 with the 1.2m Oschin Schmidt.  Following posting on the PCCP they found pre-discovery images from April 27.5. [CBET 4626, 2019 May 14, MPEC 2019-J123, 2019 May 13]. It was placed on the PCCP as ZTF037w. It was at perihelion at 1.7 au in 2019 July.
    2019 J3 (ATLAS)
    A 19th magnitude comet was discovered in images taken with the 0.5m Schmidt at Haleakala on May 14.54 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team, and initially reported as an NEO candidate. It had been posted on the PCCP as A10dEHr. [CBET 4630, MPEC 2019-K14, 2019 May 23]. It re-appeared on the PCCP as P20P07C on July 24.3 until July 28 when S Nakano realised the identity. [CBET 4655, 2019 July 28, replaced by CBET 4656, 2019 July 29]  The comet is at perihelion at 2.4 au in 2019 August.  
    2019 JU6 (ATLAS)
    A 19th magnitude object was discovered in images taken with the 0.5m Schmidt at Haleakala on May 12.57 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. Subsequently other observers have noted cometary features and it has been re-designated. [CBET 4631, MPEC 2019-K18, 2019 May 24]. The comet is at perihelion at 2.0 au in 2019 June.
    2019 K1 (ATLAS)
    A 17th magnitude comet was discovered in images taken with the 0.5m Schmidt at Mauna Loa on May 16.48 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team, but apparently reported to the MPC without any details. It had been posted on the PCCP as A10dGSV. [CBET 4629, MPEC 2019-K13, 2019 May 23]. The comet is at perihelion at 2.0 au in 2020 February. It passed 1.2 au from Jupiter in 2019 February.
    2019 K2 (381P/LINEAR-Spacewatch)
    Gareth Williams found images of 2000 S4 (P/LINEAR-Spacewatch) in incidental astrometry submitted by PanSTARRS and the Mt Lemmon Survey taken on May 29.57 (PanSTARRS) and June 1.44 (Mt Lemmon). The indicated delta-T correction to the prediction on MPC 102107 is +0.25 days. [CBET 4633, MPEC 2019-L11, 2019 June 2/3]
    2019 K3 (382P/Larson)
    Gareth Williams found images of 2007 R1 (P/Larson) in incidental astrometry submitted by PanSTARRS taken on May 31.45. Erwin Schwab also reported the recovery in images taken with the 0.8m Schmidt at Calar Alto, Spain on May 29.09. The indicated delta-T correction to the prediction on MPC 75514 is -0.08 days. [CBET 4635, MPEC 2019-L42, 2019 June 3/4]
    2019 K4 (Ye)
    Quanzhi Ye discovered a possible 17th magnitude comet on May 30.46 in images taken with the Zwicky Transient Facility camera on the 1.2m Oschin Schmidt.  Following posting on the PCCP they found pre-discovery images from April 24.5. [CBET 4636 (given as 4626 in the subject header, with no name for the comet), MPEC 2019-M70, 2019 June 24]. It was placed on the PCCP as ZTF03N1. It was near perihelion at 2.3 au in 2019 June.
    2019 K5 (Young)
    David Young discovered a 17th magnitude comet in images taken with the ATLAS (Asteroid Terrestrial-impact Last Alert System) 0.5m Schmidt at Mauna Loa on May 25.59. It had been posted on the PCCP as A10dQbl and during a glitch in the MPC system was assigned the designation of 2015 XU100 as a main-belt asteroid. [CBET 4637, MPEC 2019-M86, 2019 June 27]. The comet was at perihelion at 2.0 au in 2019 June.
    2019 K6 (PanSTARRS)
    PanSTARRS 2 discovered an asteroid in images taken with the 1.8m Ritchey-Chretien on May 31.56. The object, classified by JPL as a Trans-Neptunian Object, is at perihelion at 3.9 au in 2020 May and has a retrograde near parabolic orbit with aphelion at 800 au. It was placed on the PCCP as P20Oqj5. This was another object affected by the MPC glitch, receiving the designation of 2014 QA41 as a main-belt asteroid. 

    Francois Kugel suggested activity in images from 2020 March and this was confirmed by other observers.  The object was then redesignated as a comet.  [CBET 4784, MPEC 2020-K171, 2020 May 26]
    2019 K7 (Smith)
    A 17th magnitude object was discovered by Ken Smith in images taken with the 0.5m Schmidt at Haleakala on May 30.56 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. It was posted on the PCCP as br4203 [not as A10xxxx as might be expected]. [CBET 4645, MPEC 2019-N12, 2019 July 1.  CBET 4648 was issued on July 4 with corrected ephemeris magnitudes.]. The comet is at perihelion at 4.5 au in 2020 June.
    2019 K8 (ATLAS)
    An 18th magnitude comet was discovered in images taken with the 0.5m Schmidt at Mauna Loa on May 27.57 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. It had been posted on the PCCP as A10dGSV and as A10eo6k. [CBET 4646, MPEC 2019-N13, 2019 July 1]. The comet was at perihelion at 3.2 au in 2019 July.
    A/2019 KE7 [Catalina]
    An object of 20th magnitude was discovered in Catalina Sky Survey images taken with the 0.68m Schmidt on May 26.4. It was was placed on the PCCP as C0P3xJ2. No cometary activity has been detected and it is classed by JPL as a Centaur. The object was at perihelion at 3.5 au in 2018 December and has a period of 40 years in a retrograde orbit. It was another object affected by the MPC glitch, being designated as 2014 KH21 and classed as a main-belt asteroid.
    A/2019 KF7 [Palomar]
    An object of 19th magnitude was found in images taken with the Zwicky Transient Facility camera on the 1.2m Oschin Schmidt on May 31.2.  It was placed on the PCCP as ZTF03Pd and during a glitch in the MPC processing system was given the main-belt asteroid designation of 2014 HW46. No cometary activity was detected and an orbit was published on MPEC 2019-M84, 2019 June 27. It reaches perihelion at 2.9 au in 2019 October and has a period of around 15 years. JPL class it as a Centaur.
    A/2019 KN19 [ATLAS]
    An object was discovered in images taken with the 0.5m Schmidt at [Mauna Loa ?] by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team on 2020 May 28.6. Earlier observations back to 2018 were found. The object, classified by JPL as a Centaur, was at perihelion at 2.9 au in 2020 April and has an orbit with a period of around 45 years. It has a Saturn MOID of 0.2 au. It was placed on the PCCP as A10mV7e. No cometary activity has been detected.
    2019 L1 (PanSTARRS)
    A 20th magnitude comet was discovered in PanSTARRS 2 images taken with the 1.8m Ritchey-Chretien on June 12.53. Once the provisional orbit was better known it was possible to find prediscovery PanSTARRS 1 observations from 2019 May 30 and there were also Mt Lemmon images from early June. It was placed on the PCCP as P20OYq5. During a glitch in the MPC processing system the object was designated as 2015 XF315 and classed as a main-belt asteroid, before being added back to the PCCP. [CBET 4639 corrected on 4640, 2019 June 28, MPEC 2019-M77, 2019 June 26]  The comet has a period of around 30 years and was at perihelion at 2.9 au in 2019 August. It has a Jupiter MOID of 0.64 au.
    2019 L2 (NEOWISE)
    An 18th magnitude cometary object was discovered from the NEOWISE satellite on June 11.78. [MPEC 2019-M93, CBET 4641, 2019 June 28] It was posted on the PCCP as N00ez6d. The comet was at perihelion at 1.6 au in 2019 April and has a period of around 120 years.
    2019 L3 (ATLAS)
    An 18th magnitude object was discovered in images taken with the 0.5m Schmidt at Haleakala on June 10.56 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. It was posted on the PCCP as A10eeCl. Other observers then detected cometary features. [CBET 4644, MPEC 2019-N11, 2019 July 1]. The comet is at perihelion at 3.6 au in 2022 January.  Although quite a distant object the comet has a bright absolute magnitude.  It has reached 9th magnitude and shows a well condensed coma.  It was the easiest of four comets seen with the Northumberland refractor on January 4, and was later visible in25x100B from the centre of Cambridge.
    2019 LD2 (P/ATLAS)
    An 18th magnitude object was discovered in images taken with the 0.5m Schmidt at Mauna Loa on June 10.41 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. Alan Fitzsimmons and David Young detected a coma and this was confirmed with follow-up observations. It may have fallen through the cracks of the glitch in the processing system that occurred around this time and no formal acknowledgement of the cometary nature was published. A message posted by Sam Deen to the comet-ml on 2020 May 22 pointed out the cometary nature and unusual orbit of the object. It is in a temporary Jupiter orbit (behaving like a Trojan asteroid), having been in a near encounter to 0.092 au on 2017 February 17. It will again approach Jupiter on 2028 May 13, to 0.119 au, which will again transform the orbit. Finally a very close approach to Jupiter will occur in 2063 January, with the orbit currently unknowable after that time, though possibly transitioning to a Jupiter Family Comet.  The cometary nature was acknowledged with the publication of MPEC 2020-K133 and CBET 4780 the following day.

    Prediscovery observations made by the Dark Energy Camera (DECam) on 2018 August 10 were reported on CBET 4821 [2020 August 2]. These, taken together with non-detections from 2017, suggest that cometary activity was then taking place. The non-detections are consistent with an upper limit of the nucleus size of around 3km.
    2019 LM4 (P/Palomar)
    An asteroid discovered by the Zwicky Transient Facility using the 1.2-m Oschin Schmidt at Palomar on June 4.17 was rediscovered as a comet in images obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on 2020 May 12.34 and posted on the PCCP as P1101sd. It had previously been independently discovered with the 1.04-m f/1.8 Schmidt telescope at the XuYi Station of Purple Mountain Observatory on 2020 May 11.65 in the course of the "Chinese Near Earth Object Survey". It was also independently discovered with the 0.5-m f/2 Schmidt reflector at Haleakala, Hawaii, in the course of the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) search program on May 9.52, though not reported as cometary. Other astrometrists, including Peter Birtwhistle confirmed the cometary nature of the object. The comet is likely in outburst. [CBET 4775, MPEC 2020-J68, 2020 May 14] The comet has a period of 13.7 years with perihelion at 2.4 au in 2019 June. It approached to 0.36 au from Jupiter in 2007 June, although following the encounter the Jupiter MOID is now 0.38 au.
    2019 LB7 (Kleyna)
    A 23rd magnitude object was discovered by Jan Kleyna in images taken with the Hyper Suprime-Cam on the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea on June 7.59. It was posted on the NEOCP as HSCNEO2, although reported as a comet, and was inadvertantly designated as an asteroid on MPEC 2019-N20 [2019 July 2]. Later the same day it was re-designated as a comet. [CBET 4647, MPEC 2019-N32, 2019 July 2]. The comet was at perihelion at 2.5 au in 2019 March and has a period of around 200 years.
    2019 M1 (383P/Christensen)
    Krisztian Sarneczky recovered 2006 S1 with the 0.6m Schmidt at the University of Szeged, Piszkesteto Station (Konkoly) on June 25.90. It was 20th magnitude. The prediction for the return by Brian Marsden on MPC 102108 required a correction to T of +0.71 days, which corresponds to about half a degree from the expected position. [MPEC 2019-N62, 2019 July 5, CBET 4649, July 6]. The MPEC did not give a designation, but this was given on the CBET. The comet was missed at the 2013 return.
    2019 M2 (P/ATLAS)
    An 18th magnitude object was discovered in images taken with the 0.5m Schmidt at Mauna Loa on June 29.58 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. After posting on the PCCP it was found to show cometary features by other observers. It had been posted on the PCCP as A10evjB. [CBET 4651, MPEC 2019-O08, 2019 July 17]. The comet was near perihelion at 1.1 au in 2019 June. It is a near earth object and passed 0.21 au from us on June 16.  On CBET 4657 [2019 July 29] Dan Green discusses the possible identity with 1884 O1 (D/Barnard).  With further astrometry available S Nakano has integrated the orbit backwards in time, noting several close approaches to Jupiter.  The likely perihelion dates however do not coincide with that of D/Barnard.  Further astrometry may allow confirmation of the identity, or there may be two comets that are related to each other.
    2019 M3 (ATLAS)
    A 19th magnitude object was discovered in images taken with the 0.5m Schmidt at Haleakala on June 30.52 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. After posting on the PCCP it was found to show cometary features by other observers. It had been posted on the PCCP as A10evjM. [CBET 4653, MPEC 2019-O23, 2019 July 18]. The comet was at perihelion at 2.4 au in 2019 January.
    2019 M4 (TESS)
    In 2022 June TESS reported astrometry of an apparently asteroidal object discovered on 2019 June 27.11. P Veres of the MPC noted that the orbit was highly elliptical and it was posted on the PCCP as LTN63ix. Sam Deen then found archival images from Cerro Tololo DECam taken between 2019 July and December. [MPEC 2023-J102, CBET 5257, 2023 May 12] The comet was at perihelion at 9.2 au in 2019 September.
    2019 N1 (ATLAS)
    A 19th magnitude object was discovered in images taken with the 0.5m Schmidt at Mauna Loa on July 5.54 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. After posting on the PCCP it was found to show cometary features by other observers and pre-discovery images found in ATLAS (Haleakala) and Faulkes-North images from June. It had been posted on the PCCP as A10eGy8. [CBET 4650, MPEC 2019-N160, 2019 July 15]. The comet is at perihelion at 1.7 au in 2020 December and may come within visual range.
    A/2019 N2 (TESS)
    An object of around 16th magnitude was found in TESS data from 2019 July 4.95. There were pre-discovery images in TESS data back to JUne 20 and it was followed until July 10. Sam Deen found the object in ZTF data at 20th magnitude between October 20 and 30. It was posted on the PCCP as LTMQ6Ga in 2022 August, where it languished until 2023 February. [MPEC 2023-C138, 2023 February 14]. The exact sequence of events is not clear on the MPEC. The object was at perihelion at 1.9 au in 2019 August and is in a near parabolic high inclination orbit.
    2019 NJ3 (Lemmon)
    Sam Dean suggests that an asteroid of 20th magnitude discovered during the Mt Lemmon Survey with the 1.5m reflector on July 5.40 may be a comet. He has found additional observations which suggest that the orbit is parabolic and near perpendicular with the object at perihelion at 4.4 au in 2020 October. [comets-ml 2020 July 25]. Alan Hale used an LCO telescope the same day to take images at the expected position based on Sam's orbit and noted the presence of a comet close to the expected position. The MPC issued MPEC 2020-P41 on 2020 August 11, which credited Ernesto Guido and Hirohisa Sato with reporting cometary features on July 30 and August 1. CBET 4828 gives the more detailed story, giving due credit.
    2019 O1 (384P/Kowalski)
    Hirohisa Sato recovered 2014 U2 in images taken with an iTelescope 0.51-m f/6.8 astrograph at Siding Spring, NSW on July 27.81. The indicated delta-T correction to the prediction on MPC 102108 is -0.02 days. [CBET 4654, MPEC 2019-O84, 2019 July 28]
    2019 O2 (PanSTARRS)
    PanSTARRS 1 discovered a possible comet in images taken with the 1.8m Ritchey-Chretien on July 24.52. The object, classified as a Trans-Neptunian Object, is at perihelion at 9.8 au in 2023 April and has a slightly retrograde orbit with a period of around 300 years. It was placed on the PCCP as P10POWX. No cometary activity has been detected. The MPC designated it as 2019 O1 on MPEC 2019-P54 [2019 August 8], despite this designation already being used for P/Kowalski. They quickly realised the error and re-issued the MPEC with the correct designation as A/2019 O2.

    Cometary activity was noted in images taken by Roberto Haver in images taken on 2020 May 24, with occasional subsequent reports of activity. The MPC eventually re-designated it as a comet [MPEC 2024-E07, CBET 5362, 2024 March 2] The orbital period is around 440 years.


    2019 O3 (Palomar)
    A possible comet of 19th magnitude was found in images taken with the Zwicky Transient Facility camera on the 1.2m Oschin Schmidt on July 26.22. It was placed on the PCCP as ZTF055N. It reaches perihelion at 8.8 au in 2021 March and has a nearly perpendicular parabolic orbit. [MPEC 2019-P55, 2019 August 8] JPL classed it as a Parabolic Asteroid. No cometary activity was detected until 2020 May, when it was observed by the 3.6-m Canada-France-Hawaii Telescope on Mauna Kea and then confirmed by several other observers. It was redesignated as a comet [CBET 4817, MPEC 2020-O64, 2020 July 21].
    A/2019 O4 (A/PanSTARRS)
    PanSTARRS 1 discovered a possible comet in images taken with the 1.8m Ritchey-Chretien on July 27.59. The object, classified as a Trans-Neptunian Object, is at perihelion at 3.6 au in 2020 February and has a retrograde orbit with a period of around 190 years. [MPEC 2019-P56, 2019 August 8] It was placed on the PCCP as P10Q0Eb. No cometary activity has been detected.
    2019 OK [A/SONEAR-ASSASN-ATLAS]
    The SONEAR team discovered a 14th magnitude object with the 0.28-m astrograph at Oliviera on July 24.05, which was posted on the NEOCP as S511618. The All-Sky Automated Survey for Supernovae (ASASSN) discovered a 14th magnitude object with the "Henrietta-Leavitt" 0.14-m refractor at McDonald Observatory on July 24.42, which was posted on the PCCP as asassn3 before being linked to the SONEAR object. ATLAS-Haleakala then found a 17th magnitude object in data from July 21.5, which appeared on the NEOCP as A10f1QW before being linked to the SONEAR object. [MPEC 2019-O56, 2019 July 24]  No confirmed cometary activity was detected and the object, classed as an Apollo NEO passed 0.0005 au from the Earth on July 25.0 after which it faded dramatically. It will be at perihelion at 0.5 au in 2019 September and has a period of 2.7 years. It makes frequent close approaches to the Earth and Venus.
    2019 P1 (385P/Hill)
    Krisztian Sarneczky recovered 2010 U2 with the 0.6m Schmidt at the University of Szeged, Piszkesteto Station (Konkoly) on August 2.05, with confirming images on the 7th. It was 21st magnitude. The indicated delta-T correcton to the prediction, by Gareth Williams, on MPC 102107 is -0.47 days. [MPEC 2019-P61, CBET 4658, 2019 August 9].
    2019 PN2 [A/PanSTARRS]
    PanSTARRS 1 discovered an asteroid in images taken with the 1.8m Ritchey-Chretien on August 5.60 The object, classified by JPL as a Centaur, is at perihelion at 2.0 au in 2019 October and has a retrograde orbit with a period of around 130 years. It was placed on the PCCP as P10QhFM. No cometary activity has been detected yet.
    2019 PR2 [A/PanSTARRS] and 2019 QR6 [A/Lemmon]
    PanSTARRS 1 discovered an asteroid of 21st magnitude in images taken with the 1.8m Ritchey-Chretien on August 10.60. The Mt Lemmon Survey discovered an object of 21st magnitude in images taken with the 1.5m reflector on August 30.40. They were around a degree apart at discovery. The objects are classified by JPL as Amor-type NEOs. Both were at perihelion at 1.2 au in 2019 October and have a period of around 13.9 years and a Jupiter MOID of 0.4 au. The two objects are clearly related. In a paper submitted to MNRAS Petr Fatka et al suggest that the pair separated around 300 years ago, and that non-gravitational forces are required to explain their motion, ie they showed cometary activity at one time. The observations from the Mt Lemmon Survey on which they base this result are not yet in the MPC database.
    2019 Q1 (Lemmon)
    The Mt Lemmon Survey discovered an object of 21st magnitude in images taken with the 1.5m reflector on August 28.40. [MPEC 2019-R92, 2019 September 9]. It was placed on the PCCP as C0V3RQ2. The object was at perihelion at 5.0 au in 2020 July and has a parabolic orbit.  It was reported to have a tail at the end of July 2020.  This was confirmed in MPEC 2020-R14 and CBET 4843 [2020 September 6] when it was redesignated as a comet.
    A/2019 Q2 (ATLAS)
    A 19th magnitude object was discovered in images taken with the 0.5m Schmidt at Mauna Loa on August 24.58 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. It had been posted on the PCCP as A10fGxh. [MPEC 2019-R101, 2019 September 10]. The comet was at perihelion at 1.3 au in 2019 July and is in a retrograde long period orbit.  Alan Hale reports that he has detected a cometary appearance in images, so it should be re-classified.
    2019 Q3 (PanSTARRS)
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on August 29.25. Once the provisional orbit was better known it was possible to find prediscovery PanSTARRS 1 and 2 observations from July and August. [CBET 4665, MPEC 2019-R102, 2019 September 10] It was placed on the PCCP as P10R3Vi. The comet was at perihelion at 7.2 au in 2018 August.
    2019 Q4 (2I/Borisov)
    Gennady Borisov discovered a comet in images taken with the MARGO 0.65-m f/1.5 astrograph at Nauchnij, Crimea on August 30.04. It was placed on the PCCP as gb00234. Initial observations suggested a very hyperbolic orbit with an eccentricity of 3.1, implying an interstellar origin. [CBET 4666, MPEC 2019-R106, 2019 September 11] The latest JPL orbit has an eccentricity of 3.36.  The comet reached perihelion at 2.0 au in 2019 December.  

    MPEC 2019-S72 [2019 September 24] notes: Continued observation and analysis of this object has confirmed its hyperbolic orbit and interstellar origin. The Minor Planet Center has therefore assigned the permanent interstellar designation 2I to it. The IAU Working Group for Small Body Nomenclature has decided to retain the name Borisov for the permanent designation.

    Observations by the Hubble Space Telescope in late March 2020 suggest a possible splitting of the nucleus between March 23 and 28.
    2019 R1 (387P/Boattini)
    Gennady Borisov recovered 2008 Y1 in images taken with the MARGO 0.65-m f/1.5 astrograph at Nauchnij, Crimea on September 2.01. It was placed on the PCCP as gb00239. The indicated delta-T correction to the prediction, by Brian G. Marsden on MPC 102107, is -4.38 days. [CBET 4663, MPEC 2019-R83, 2019 September 9]
    2019 R2 (388P/Gibbs)
    Hirohisa Sato recovered 2007 T4 in images taken with an iTelescope 0.43-m f/6.8 astrograph near Mayhill, New Mexico on September 5.48. The indicated delta-T correction to the prediction on NK 1629 is -0.02 days. [CBET 4662, 2019 September 8, MPEC 2019-R84, CBET 4664, 2019 September 9]
    2019 S1 (389P/Siding Spring)
    2006 R1 was recovered independently by Gareth Williams and R. Weryk in images from Pan-STARRS 1 taken on September 25.53. The indicated delta-T correction to the prediction, by Gareth Williams, on MPC 105244, is -6.6 days. [CBET 4671, MPEC 2019-S105, 2019 September 27]
    2019 S2 (P/PanSTARRS)
    A 22nd magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on September 28.37. Once the provisional orbit was better known it was possible to find prediscovery PanSTARRS 1 observations from July and August. [CBET 4673, MPEC 2019-T80, 2019 October 4/5] It was placed on the PCCP as P10Scgl. The comet was at perihelion at 3.8 au in 2019 February and has a period of around 10 years.
    2019 S3 (P/PanSTARRS)
    A 21st magnitude comet was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on September 25.54. Once the provisional orbit was better known it was possible to find prediscovery PanSTARRS 1 and 2 observations from August and September and Mt Lemmon images from September. [CBET 4674, MPEC 2019-T82, 2019 October 4] It was placed on the PCCP as P10RRZi. The comet was at perihelion at 1.8 au in 2019 August and has a period of around 6 years. Given that it was discovered before 2019 S2 the designation guidelines indicate that the two comets should be designated in the opposite order.
    2019 S4 (Lemmon)
    The Mt Lemmon Survey discovered an object of 21st magnitude in images taken with the 1.5m reflector on September 17.45. [MPEC 2019-T83, 2019 October 4/5]. It was placed on the PCCP as C0ZBYY2. The object is at perihelion at 3.4 au in 2020 April and has a near perpendicular long period orbit.

    Cometary activity was reported by several observers, begining in 2019 October and the object was re-designated as a comet [CBET 4738, MPEC 2020-F168, 2020 March 28]


    2019 S5 (P/Spacewatch-Hill)
    A 21st magnitude comet was reported by Scott Sheppard on 2019 November 8 in images taken with the 4.0m reflector at the Cerro Tololo observatory on 2019 September 24.29 and 26.23. The MPC then identified it as a recovery of 2009 SK280 and found additional PanSTARRS and Mt Lemmon images from 2019 October. The indicated delta-T correction to the prediction on MPC 102108 by Gareth Williams is +0.87 days. Syuichi Nakano notes that prior to a close approach of the comet to Jupiter on 1994 May 2 at a distance of 0.13 au, the comet had a slightly closer perihelion and slightly more eccentric orbit. [CBET 4697, MPEC 2019-V147, 2019 November 12]
    A/2019 T1 (A/PanSTARRS)
    PanSTARRS 2 discovered a 21st magnitude object in images taken with the 1.8m Ritchey-Chretien on October 8.43. Prediscovery images from PanSTARRS taken in 2017, 2018 and 2019 were soon found. It was placed on the PCCP as P20SCgd. [CBET 46xx, MPEC 2019-U08, 2019 October 16] The object, classified as a Trans-Neptunian Object by JPL, is at perihelion at 4.3 au in 2021 January and has a retrograde orbit with a period of around 240 years. No cometary activity has been detected so far.
    2019 T2 (Lemmon)
    The Mt Lemmon Survey discovered an object of 21st magnitude in images taken with the 1.5m reflector on October 9.14. There were pre-discovery observations from Mt Lemmon in August and PanSTARRS in September. [MPEC 2019-U09, 2019 October 16]. It was placed on the PCCP as C152W42. The object is at perihelion at 2.6 au in 2021 April and has a near perpendicular long period orbit. JPL class it as a Trans-Neptunian object. Cometary activity was detected in 2020 June and it was redesignated as a comet [CBET 4809, MPEC 2020-N14, 2020 July 4].
    2019 T3 (ATLAS)
    A 19th magnitude object was discovered in images taken with the 0.5m Schmidt at Mauna Loa on October 6.61 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. It had been posted on the PCCP as A10gzoN. There were pre-discovery PanSTARRS 1 and 2 images from January. [CBET 4678, MPEC 2019-U10, 2019 October 16]. The comet is at perihelion at 5.9 au in 2021 March and is in a retrograde orbit.
    2019 T4 (ATLAS)
    A 19th magnitude object was discovered in images taken with the 0.5m Schmidt at Mauna Loa on October 9.58 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. It had been posted on the PCCP as A10glCS. There were pre-discovery PanSTARRS 1 images from February and other observers noted its cometary nature. [CBET 4681, MPEC 2019-U99, 2019 October 22]. The comet is at perihelion at 4.2 au in 2022 June, when it could reach 11th magnitude.
    2019 T5 (P/ATLAS)
    A 19th magnitude comet was discovered in images taken with the 0.5m Schmidt at Mauna Loa on October 8.61 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. It had been posted on the PCCP as A10gFB1. [CBET 4682, 4683, MPEC 2019-U116, 2019 October 23/24]. The comet was at perihelion at 1.5 au in 2019 August and has a period of around 20 years.
    2019 T6 (P/PanSTARRS)
    PanSTARRS 2 discovered a 20th magnitude comet in images taken with the 1.8m Ritchey-Chretien on October 8.47. It was placed on the PCCP as P20SzGs. [CBET 4684, MPEC 2019-U140, 2019 October 24] The comet is at perihelion at 2.1 au in 2019 November and has an orbit with a period of around 13 years.
    2019 U1 (390P/Gibbs)
    A comet discovered in images taken with the 0.5m Schmidt at Haleakala on October 21.25 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team was identified as a return of 2006 W1 by the MPC and Hirohisa Sato. The indicated delta-T correction to the prediction on  NK 3401 is -9.5 days.  The comet passed 1.4 au from Saturn in 2010 July.  [CBET 4685, MPEC 2019-U163, 2019 October 25] The comet is at perihelion at 1.7 au in 2020 March.
    2019 U2 (391P/Kowalski)
    BAA Member Kevin Hills recovered 2006 F1 (P/Kowalski) on October 22.01 in images taken with his 0.5-m f/2.9 astrograph at Tacande Observatory, La Palma. It was also recovered by PanSTARRS on October 25.35, with both sites reporting additional pre-recovery images. The indicated delta-T correction to the prediction on MPC 94677 was -0.06 days. [CBET 4686, MPEC 2019-U193, 2019 October 26/28]
    2019 U3 (P/LINEAR)
    Krisztian Sarneczky recovered 2004 WR9 with the 0.6m Schmidt at the University of Szeged, Piszkesteto Station (Konkoly) on October 26.96, with confirming images on the 27th. It was 19th magnitude. The indicated delta-T correcton to the prediction, by Gareth Williams, on MPC 105245 is -0.75 days. [MPEC 2019-U245, CBET 4687, 2019 October 28].
    2019 U4 (P/PanSTARRS)
    PanSTARRS 1 discovered a 21st magnitude comet in images taken with the 1.8m Ritchey-Chretien on October 25.53. It was placed on the PCCP as P10TjRi. Subsequently earlier PanSTARRS images from September and October were found. [CBET 4688, MPEC 2019-U246, 2019 October 28] The comet was at perihelion at 1.8 au in 2019 September and has an orbit with a period of around 7 years.
    2019 U5 (PanSTARRS)
    PanSTARRS 1 discovered a 21st magnitude object in images taken with the 1.8m Ritchey-Chretien on October 22.22. It was placed on the PCCP as P10ST2o. [MPEC 2019-V10, 2019 November 1] The object, preliminary classified as a Parabolic Asteroid by JPL, is at perihelion at 3.6 au in 2023 March and has a retrograde orbit. No cometary activity was detected at discovery, but it was still over 10 au from the Sun, and might develop cometary features when it was closer, so was given an A/ designation. It duly developed a coma, first noted in 2021 February and then by several amateurs including Werner Hasubick in early April [MPEC 2021-G80, 2021 April 7].  Werner Hasubick observed it at 13.6 in 2022 April, so it may reach 11th magnitude around the time of perihelion.
    2019 U6 (Lemmon)
    The Mt Lemmon Survey discovered an object of 21st magnitude in images taken with the 1.5m reflector on October 31.43. [MPEC 2019-V131, 2019 November 8]. It was placed on the PCCP as C1CKPL2.  Several observers subsequently reported that they had detected a cometary appearance in images.  Michael Mattiazzo imaged it on March 11, when it showed a clear coma.  It was reclassified as a comet following the reports made since December [CBET 4735, MPEC 2020-F136, 2020 March 25]   The object was at perihelion at 0.9 au in 2020 June and has a parabolic orbit.   It brightened quite rapidly and reached 6th magnitude around perihelion in June, but began fading sooner than expected from a standard light curve.  A linear light curve is a better fit to the observations.  It won't become visible to UK observers until mid July, when it may be fading from 8th magnitude.
    2019 V1 (Borisov)
    Gennady Borisov discovered a comet in images taken with the MARGO 0.65-m f/1.5 astrograph at Nauchnij, Crimea on November 1.99. It was placed on the PCCP as gb00246. Nick James was amongst those contributing early astrometry. [CBET 4696, MPEC 2019-V130, 2019 November 8/9] The comet is due to reach perihelion at 3.1 au in 2020 July.
    2019 V2 (P/Groeller)
    Hannes Groeller discovered a comet of 21st magnitude in Mt Lemmon Survey images taken with the 1.5m reflector on November 3.50. It was placed on the PCCP as C1DN7J2. [CBET 4700, MPEC 2019-W132, 2019 November 25]. The comet is at perihelion at 5.0 au in 2020 October and has a period of around 21 years.
    2019 W1 (P/PanSTARRS)
    A 20th magnitude comet was discovered in PanSTARRS 2 images taken with the 1.8m Ritchey-Chretien on November 29.54. There were prediscovery observations from PanSTARRS 1 in 2018 August and 2019 January. Confirming imagery was obtained by Peter Birtwhistle amongst others. It was placed on the PCCP as P20VIIH. It seems to have been several magnitudes brighter after perihelion, than it was pre-perihelion.  [CBET 4707, MPEC 2019-Y37, 2019 December 21]  The comet has a period of around 10 years and was at perihelion at 3.3 au in 2019 May.
    2019 X1 (P/Pruyne)
    Teddy (Theodore) Pruyne discovered a comet of 19th magnitude in Mt Lemmon Survey images taken with the 1.5m reflector on December 2.37. It was placed on the PCCP as C1HKHZ2. [CBET 4702, MPEC 2019-X103, 2019 December 10]. The comet was at perihelion at 4.3 au in 2019 July and has a period of around 15 years.  There may be pre-discovery images from 2003, in which case the comet could be numbered.
    2019 X2 (P/PanSTARRS)
    A 22nd magnitude comet was discovered in PanSTARRS 2 images taken with the 1.8m Ritchey-Chretien on December 4.58. There were prediscovery observations from PanSTARRS 2 2019 November. It was placed on the PCCP as P20VUDB. [CBET 4713, MPEC 2020-A121, 2020 January 12/13]  The comet has a period of around 7 years and was at perihelion at 1.8 au in 2019 December.
    2019 Y1 (ATLAS)
    An 18th magnitude object was discovered in images taken with the 0.5m Schmidt at Haleakala on December 16.23 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. Confirmations came from several amateur observers. It had been posted on the PCCP as A10iMHA. [CBET 4708, MPEC 2020-A72, 2020 January 5/6]. The comet was at perihelion at 0.8 au in 2020 March. Maik Meyer suggests that it is a member of the "Liller" family of comets, which include 1988 A1 (Liller), 1996 Q1 (Tabur) and 2015 F3 (SWAN).  The orbit has an Earth MOID of 0.083 au.

    A visual observation from Alan Hale suggested that it was already around 13th magnitude in mid January 2020.  It brightened rapidly and reached 9th magnitude in February. Observations in mid April suggested that it was still brightening, so it is either in outburst or following a linear light curve making it brighter post perihelion. On April 19 it was an easy, well condensed object of 8th magnitude in 20x80B from central Cambridge. It has since faded quite rapidly.
    2019 Y2 (407P/PanSTARRS-Fuls)
    D Carson Fuls discovered a comet of 19th magnitude in Mt Lemmon Survey images taken with the 1.5m reflector on 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 is at perihelion at 2.1 au in 2020 January and has a period of around 6 years.

    Sam Deen has shown that the the comet is identical with 2013 J4 (P/PanSTARRS). The comet passed 0.34 au from Jupiter in 2010 in an encounter that significantly changed the orbit. [CBET 4792, 2020 June 8].  An MPEC announcing the identity was finally published on 2020 November 11 [MPEC 2020-V67].


    2019 Y3 (P/Catalina)
    A possible comet of 18th magnitude was discovered in Catalina Sky Survey images taken with the 0.68m Schmidt on December 17.53. It was was placed on the PCCP as C0TUEG1 and confirmed by other observers including Michael Jaeger. [CBET 4711, MPEC 2020-A109, 2020 January 9]. The comet was near perihelion at 0.9 au in 2019 December and has a period of around 5 years.
    2019 Y4 (ATLAS)
    A 19th magnitude object was discovered in images taken with the 0.5m Schmidt at Mauna Loa on December 28.60 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. Confirmations came from several amateur observers including Michael Jaeger and Eric Bryssinck. It had been posted on the PCCP as A10j7UG. [CBET 4712, MPEC 2020-A112, 2020 January 10/11]. The comet is at perihelion at 0.3 au in 2020 May. Maik Meyer noted that its orbit is very similar to that of the Great Comet 1844 Y1.   It will remain well placed for UK observers into May.

    Michael Jaeger reported it at 14th magnitude on February 15.  It brightened rapidly and became a binocular object by mid March.  During the second half of March the rate of brightening appeared to slow for many observers, however those using the smallest aperture that showed the comet clearly reported the comet as brighter than those using larger apertures.   It was clear by early April that the comet had faded.  Astrometric observations appeared to show large non-gravitational effects and the coma had became elongated.  Separate condensations then began to appear in the coma, with one offset from the coma and placed where expected from the original orbit.  This strongly suggested that the comet had undergone a major disruption event.  In CBET 4751 [2020 April 13] Zdenek Sekanina suggests that a major fragmentation event occurred on or before mid March at about 1.8 au from the Sun, with the rapid brightening terminating around March 17.  The component produced in this event itself fragmented in late March or early April. The detached coma began to fade.  HST images suggested that this scenario was not viable and in CBET 4763 [2020 April 29] Sekanina suggested that the comet was in the process of stochastic fragmentation, which began when the comet was a long way from perihelion. 

     Overall the comet remained at around 9th magnitude during April. The comet suddenly brightened to 8th magnitude around May 8/9, suggesting another phase in the break-up and is showing day to day changes in morphology.  This appears to have been the final event in the complete disintegration of the comet.

    A possible alternative view to the mid March break-up (posted on April 13) is that the disruption event began in mid February when the rapid brightening commenced.  Only further observations will show the future evolution of this interesting object.


    2019 Y5 (PanSTARRS)
    A 22nd magnitude object was discovered in PanSTARRS 1 images taken with the 1.8m Ritchey-Chretien on December 28.24. There were prediscovery observations from PanSTARRS 1 in 2019 September, October and November. It was placed on the PCCP as P10VI2g. No cometary activity was detected. [MPEC 2020-A120, 2020 January 12]  The object was at perihelion at 4.9 au in 2019 August.  JPL classified it as a Trans-Neptunian Object with a period of nearly 1000 years.  In 2020 February and again in 2020 July it was seen to show cometary features and was redesignated as a comet.  [CBET  4819, MPEC 2020-O118, 2020 July 26]
    2019 YX6 [A/ATLAS]
    An 18th magnitude object was discovered in images taken with the 0.5m Schmidt at Mauna Loa on December 21.35 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) team. It was posted on the PCCP as A10iY9L, but no confirmation of any cometary nature was reported. [MPEC 2020-A111, 2020 January 10]. The object was at perihelion at 0.38 au in 2019 November. It is an Apollo asteroid, an NEO and a PHA. It passed 0.030 from the Earth on 2019 December 16, close to its MOID. It can also pass close to Venus and Jupiter.
    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 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