BAA Comet Section Periodic Comets

BAA Comet Section : Periodic Comets 400 - 499

Updated 2020 September 15

P/Bressi	P/LINEAR-Hill	P/Novichonok-Gerke	P/LINEAR	P/PanSTARRS
P/PanSTARRS	P/McNaught
Comets 1 - 99	Comets 100 - 199	Comets 200 - 299	Comets 300 - 399	Comets 400 - 499	Not numbered objects

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.

P/Bressi = 2011 U2
Terry H Bressi discovered a 19th magnitude comet in Spacewatch images taken with the 0.9-m f/3 reflector at Kitt Peak on 2011 October 24.21. The comet reached perihelion at 4.8 au in May 2012 and has a period of around 13 years.

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 has not yet been given a designation for this return.

P/LINEAR-Hill = 2008 QP20
Rik Hill discovered an 18th magnitude comet on CCD images taken with the 0.68-m Catalina Schmidt telescope on 2008 September 23.63, which was confirmed as cometary by many observers following posting on the NEOCP. K Smalley of the MPC then identified the comet with an asteroidal object found by LINEAR on 2008 August 25.40. The comet was at perihelion at 1.7 au in early November 2008 and has a period of 6.5 years.

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.

P/Novichonok-Gerke = 2011 R3
MPEC 2011-R34 announced the discovery by Artyom Novichonok of a comet with the 0.4-m f/8 Ritchey-Chretien at Ka-Dar Observatory, TAU Station, Nizhny Arkhyz on images taken on 2011 September 7.02 by Vladimir Gerke. The comet has a period of 11 years with perihelion at 3.6 au in 2012 April.

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 the comet 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 has not yet been given a designation for the return.

P/LINEAR = 2002 T5
An apparently asteroidal object of mag 18.4 reported by LINEAR on 2002 October 5.39, posted on the NEO Confirmation Page due to unusual motion, has been found to be cometary in appearance. D. T. Durig and J. A. K. Blackwood, University of the South, Sewanee, TN, report that CCD images taken with a 0.30-m reflector on 2002 October 18.4 UT show the object to be diffuse with a hint of a tail 12"-15" long in p.a. 330 deg and a soft coma of diameter 5"-8". Images taken by G. Hug, Eskridge, KS, also with a 0.30-m reflector at about the same time, show a nearly stellar coma with extension about 10"-15" long in p.a. about 280 deg. [IAUC 7998, 2002 October 22]

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 has not yet been given a designation for the return.

P/PanSTARRS = 2013 O2 = 2020 O4
Pan-STARRS discovered a 21st magnitude comet on 2013 July 16.60 [MPEC 2013-O53, 2013 July 27] It reached perihelion at 2.1 au in 2013 December and has a period of around 7.5 years. It makes occasional approaches to Jupiter, most recently to within 0.3 au in 1994. This reduced the perihelion distance from 2.6 au to its present value.

Syuichi Nakano noticed that recovery observations of 2013 O2 had been published in recent MPECs listing observations of comets (2020-P19, Q175 and R04). The earliest observations (2020 July 30.36) were by Mt Lemmon, with several other observers/observatories including Werner Hasubick at Buchloe also observing the comet. Nakano then computed a linked orbit and an MPEC was issued giving a designation, followed by the CBET. [MPEC 2020-R32, CBET 4844, 2020 September 7]

P/PanSTARRS = 2013 PA104 = 2020 R1
PanSTARRS 1 discovered a 20th magnitude comet in images taken with the 1.8m Ritchey-Chretien on September 9.50. It was placed on the NEOCP with an unknown designation. Richard Weryk of the PanSTARRS team found pre-discovery images from 2013 August, 2014, 2015, 2016 and earlier in 2020. The MPC then gave it an asteroidal designation of 2013 PA104 and deleted it from the NEOCP but did not place it on the list of previous designations. In the meantime the Mt Lemmon Survey reported the detection of a comet on September 10.38 and this was placed on the PCCP as C35DT72. When follow-up observations were made it became obvious that the two objects were the same, but apart from admitting the goof, the MPC has not given further explanation of what went wrong. [CBET 4845, MPEC 2020-R101, 2020 September 13] The comet is at perihelion at 2.1 au in 2021 February and has a period of 6.7 years.

P/McNaught = 2006 H1 = 2020 R3
Rob McNaught discovered another comet, during the course of the Siding Spring Survey, on 2006 April 29.79. The object was 18th magnitude and was at perihelion in early May at 2.4 au. It is in a short period orbit, with period of 14 years.

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]

Published by Jonathan Shanklin. Jon Shanklin - jds@ast.cam.ac.uk