Updated 2020 November 28
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.
This should have been numbered 405 if given in sequential order.
Erwin Schwab recovered the comet in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain. on 2020 September 11.09. The indicated delta-T correction to the prediction, by Gareth Williams, on MPC 58118 is -0.15 days. [CBET 4847, MPEC 2020-R159, 2020 September 14]
This should have been numbered 406 if given in sequential order.
The comet is a distant object and reached perihelion at the end of June 2003. The period is 18.5 years and the perihelion distance 3.93 au. Observers contributing to the preliminary orbit included BAA Member Peter Birtwhistle.
Erwin Schwab recovered the comet in images taken with the 0.8-m f/3 Schmidt reflector at Calar Alto, Spain. on 2020 August 18.11. The comet was some 5' from the expected position. [CBET 4835, 2020 August 19] It was finally given a designation for the return in MPEC 2020-S155 [2020 September 23].
This should have been numbered 403 if given in sequential order.
D Carson Fuls discovered a comet of 19th magnitude in Mt Lemmon Survey images taken with the 1.5m reflector on 2019 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 was at perihelion at 2.1 au in 2020 January and has a period of around 6 years.
Sam Deen has shown that the two comets are identical. The comet passed 0.34 au from Jupiter in 2010 in an encounter that significantly changed the orbit. [CBET 4792, 2020 June 8].
The comet should have been numbered 397, but the MPC have ignored the convention of numbering in order of orbit determination and returns. An MPEC announcing the identity was finally published on 2020 November 11 [MPEC 2020-V67].
Seiichi Nakano found images of the comet in PanSTARRS 1 data taken with the 1.8m Ritchey-Chretien on 2020 June 17.55 and on July 17 and 20. The comet was close to the expected position. The comet passed 0.97 au from Jupiter in 2020 February in an encounter that reduced the perihelion distance from 4.8 to 4.1 au and the period from 12.7 to 10.3 years. [CBET 4831, 2020 August 16] It was finally given a designation for the return in MPEC 2020-U182 [2020 October 23]. It has not yet been numbered, though it should have been 400.
In 2020 Sam Deen found images of the comet in DECam data taken with the 4.0m reflector at Cerro Tololo on 2016 January 15.26 and 2016 March 1.14. These were identified by Seiichi Nakano as being a return of 2008 QP20. The comet was close to the expected position. [CBET 4832, 2020 August 17] It has not yet been given a designation for the return.
Only the name Novichonok was originally given to the comet, however the discoverer was clear that it was a team effort with Gerke, and the name was later amended.
Denis Denisenko noted
As usual, there's a whole story behind the new discovery. This comet was caught just 63 (!!!) pixels from the edge of 1330x890 CCD image in 3x3 binning mode in the first night. Upon posting at NEO Confirmation Page most people (including myself) originally thought it to be identical to 111P (whose predicted position was less than 5' away, yet the magnitude was almost identical to the new object). But the direction of motion of the Comet Novichonok was totally different from Comet Helin-Roman-Crockett, and the new object was about twice slower.Congratulations to Artyom with the first Russian periodic comet since the breakup of USSR! If you remember, two Comets Elenin were discovered on the telescope installed in USA. This time the observation was made in southern Russia, in the Republic of Karachay-Cherkessia in northern Caucasus, not far away from the 6-meter BTA telescope.
Seiichi Nakano found images of 2011 R3 in PanSTARRS 1 data taken with the 1.8m Ritchey-Chretien on 2020 June 20.49 and July 18.36. The comet was close to the expected position. The comet was put into its present orbit during a series of encounters with Jupiter: 0.87 au in 1992 October, 0.11 au in 1993 August and 0.45 au in 2005 April. Prior to these encounters the comet was in a more distant orbit with perihelion at 5.2 au and a period of 19.4 years. [CBET 4833, 2020 August 17] It was finally given a designation for the return in 2020 November [MPEC 2020-V78, 2020 November 12].
The Mt Lemmon Survey discovered a comet on 2020 October 15.45, which was placed on the PCCP as C3HU5C2. Hirohisa Sato subsequently realised that this was a return of 2007 VQ11 and it was withdrawn from the PCCP. CBET 4869 and MPEC 2020-U169 were issued on October 22. The comet was some 22' from the expected position, corresponding to a delta T of around -1.9 days.
An object briefly appeared on the PCCP as P218YG3 before being transferred to the "Previous NEOCP Objects" page having been identified as a return of comet 2013 TL117, though it was given on the page as 2013 TL17. The PCCP recovery was by by PanSTARRS 2 on 2020 October 25.6. Shortly afterwards further details were given in MPEC 2020-U231 and CBET 4874 [2020 October 25/26]. These reveal the continuing tensions between the MPC and CBET. Erwin Schwab had recovered the comet on October 17.13 with the Calar Alto 0.8m Schmidt (not Calar Alto-Schmidt as given in the MPEC). Additional independent recoveries were made at the Dominion Astrophysical Observatory on October 22 and by T. Ikemura and Hirohisa Sato on October 23/24.
Comet 2007 R2 was recovered during observations with the Korea Microlensing Telescope Network-SSO 1.6m reflector on 2020 September 11.64, when it was around 22nd magnitude. PanSTARRS 2 recorded it two days later and the Korean group made further observations on September 15. All these observations were published in MPEC 2020-S188 as observations of 2007 R2, though none of the observers realised that it was a recovery. [2020 September 25] Seiichi Nakano of the CBAT later noticed the observations and drew attention to the recovery. T. Ikemura and Hirohisa Sato made follow-up observations on October 10 and 12, with PanSTARRS 1 observing it on October 20. The comet was missed at the 2014 return and passed 0.74 au from Jupiter in 2016 March. The encounter increased the perihelion distance to 1.6 au and the period to 6.8 years. The comet was at perihelion in September. [CBET 4884, MPEC 2020-U269, 2020 October 30/31]. The CBET yet again hints at the tensions between the CBAT and MPC.
According to the MPEC the comet was recovered on 2020 November 3.49 by the Zwicky Transient Facility with the 1.2m Oschin Schmidt and by the Mt Lemmon Survey with the 1.5m reflector on November 16.51. The indicated delta-T correction to the prediction by G. V. Williams on MPC 75706 is -1.08 days and it was some 30' from the expected position. The CBET gives priority to the Mt Lemon Survey for reporting a new comet and then drawing attention to the likely identity with 2005 XA54. [CBET 4885, MPEC 2020-W25, 2020 November 17] The comet has perihelion at 1.8 au in 2021 January and a period of 14.9 years.
Published by Jonathan Shanklin. Jon Shanklin - jds@ast.cam.ac.uk