BAA Comet Section : Comets discovered in 2019

Updated 2019 October 8


  • 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)
  • A/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)
  • A/2019 G2 [A/PanSTARRS]
  • A/2019 G3 [A/PanSTARRS]
  • A/2019 G4 [A/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)
  • A/2019 K6 [PanSTARRS]
  • 2019 K7 (Smith)
  • 2019 K8 (ATLAS)
  • 2019 KE7 [A/Catalina]
  • 2019 KF7 [A/Palomar]
  • 2019 L1 (PanSTARRS)
  • 2019 L2 (NEOWISE)
  • 2019 L3 (ATLAS)
  • 2019 LB7 (Kleyna)
  • 2019 M1 (P/Christensen)
  • 2019 M2 (P/ATLAS)
  • 2019 M3 (ATLAS)
  • 2019 N1 (ATLAS)
  • 2019 O1 (P/Kowalski)
  • A/2019 O2 (A/PanSTARRS)
  • A/2019 O3 (A/PanSTARRS)
  • A/2019 O4 (A/PanSTARRS)
  • 2019 OK [A/SONEAR-ASSASN-ATLAS]
  • 2019 P1 (P/Hill)
  • 2019 PN2 [A/PanSTARRS]
  • A/2019 Q1 (Lemmon)
  • A/2019 Q2 (ATLAS)
  • 2019 Q3 (PanSTARRS)
  • 2019 Q4 (2I/Borisov)
  • 2019 R1 (P/Boattini)
  • 2019 R2 (P/Gibbs)
  • 2019 S1 (P/Siding Spring)
  • 2019 S2 (P/PanSTARRS)
  • 2019 S3 (P/PanSTARRS)
  • A/2019 S4 (Lemmon)

  • 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.
    A/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.
    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 (A/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.
    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.
    A/2019 G4 [PanSTARRS]
    PanSTARRS discovered an asteroid in images taken with the 1.8m Ritchey-Chretien on April 9.25. The object, classified as a TNO, was at perihelion at 5.9 au in 2018 November and has a retrograde orbit with a period of around 900 years. It was placed on the PCCP as P10N31R. No cometary activity has been detected.
    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 Factory 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 (P/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 (P/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 Factory 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.
    A/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. No cometary activity has been detected yet.
    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 Factory 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.
    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.
    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 (P/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 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.
    2019 O1 (P/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]
    A/2019 O2 (A/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.
    A/2019 O3 (A/Palomar)
    A possible comet of 19th magnitude was found in images taken with the Zwicky Transient Factory 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. [CBET 46xx, MPEC 2019-P55, 2019 August 8] JPL class it as a Parabolic Asteroid. No cometary activity has been detected .
    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. [CBET 46xx, 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 (P/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 46xx, 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.
    A/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. [CBET 46xx, 2019 September, MPEC 2019-R92, 2019 September 9]. It was placed on the PCCP as C0V3RQ2. The object is at perihelion at 5.0 au in 2020 July and has a parabolic orbit.
    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. [CBET 46xx, 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.
    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 46xx, 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. The comet is not currently well placed but the initial observations suggest 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 increased eccentricity of 3.7+/-0.1.  The comet is due to reach 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.
    2019 R1 (P/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 (P/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 (P/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.
    A/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. [CBET 46xx, 2019 October, 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.
    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