Updated 2023 July 11
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 individual comets are given below, in ICQ format.
Comet 101P/Chernykh was discovered by Nikolaj Chernykh at the Crimean Astrophysical Observatory whilst scanning routine minor planet survey plates taken on 1977 August 19 and 22. It was a fairly bright object of 14th magnitude and at its best, at the end of September, it reached 12.5. The succeeding return was a little better, and this one is better again. The comet is an unusual one in playing celestial billiards with both Jupiter and Saturn and has made a number of approaches to both planets, most recently passing 0.35 AU from Jupiter in 1980, which reduced the period to 14 years.
The comet was observed to have split at the 1991 return, as reported on IAUC 5347 and IAUC 5391.
It comes into visual range in 2005 May, and reaches its brightest in the autumn, when it may get to 10th magnitude. It parallels the ecliptic, running from Aquarius into Pisces and remains visible into 2006.
The comet was recovered in July at 17th magnitude, and it seems likely that it won't get brighter than 15th magnitude, unless it has another outburst.
A secondary component was discovered at the end of November 2005, and this seems unlikely to be the same one that was seen in 1991.
Peter Birtwhistle recovered the comet at the 2006 return, allowing an improved orbit to be computed, that includes non-gravitational parameters and links the 1991 and 2000 returns. It is expected to fade from 14th magnitude in late July 2006.
Four electronic observations received at the 2013 return give a preliminary light curve of 11.9 + 5 log d +  log r however there are some indications that the light curve may be asymmetric, with the comet brighter after perihelion.
Comet 103P/Hartley In 1982 the comet made a close approach to Jupiter, and it was discovered by Hartley four years later, around nine months after perihelion. It was accidently recovered by T V Kryachko of Majdanak, USSR, on 1991 July 9.85, returning 5.6 days earlier than predicted. The orbit comes close to that of the Earth and it could produce a meteor shower at the descending node in November. Calculations by Harold Ridley gave a radiant of 19h56m +14ø, some 5ø Nf Altair, with a likely maximum around November 17. See also information from the IMO More recent calculations by Peter Brown of UWO suggest a likely maximum in early November, with a radiant in Cygnus.
It was well observed by the section at the 1991 return and observations showed that the brightness peaked around 13 days after perihelion.
The next return was also a good one and for the northern hemisphere it was likely to be the brightest predicted periodic comet of the year. It was an evening object throughout the apparition An observation on 1997 October 4 made it 13.5 and a further observation on October 7.8 with 0.33-m L approximately 13.0. By October 21.7 it had brightened to 12.6, but was very diffuse and difficult to see. At the end of the month, on October 31.76 it had reached mag 10.8 in my 0.20-m LX200, but was DC2, dia 2.7'. An observation in moonlight on November 10.77 put it at 10.6:, still very diffuse. On November 22.75 it had reached 9.9 in the same instrument. By November 30th it had become a little more condensed and was mag 9.5. Observations in early December put it at 9th magnitude and a binocular object.
The comet was a target for the extended mission of the Deep Impact spacecraft, renamed EPOXI. The encounter took place in October 2010, when the comet made a close approach to the Earth (0.12 au) and was a large diffuse naked eye object. The spacecraft made its closest approach to the comet on November 4 at 14:02 UT The spacecraft captured some spectacular images of this very unusual object. A report on ground based observations made in support of the spacecraft mission appears in Astrophysical Journal letters, though only the abstract is free to read. The authors note a change in the rotation period from 16.4 hours prior to 2010 August to 19 hours in December.
The section is collaborating with the Italian CARA group in a campaign to observe 103P/Hartley at the 2023 return. The comet has a linear light curve and is intrinsically brightest some 24 days after perihelion, which is in mid October. The comet passes 0.4 au from the Earth at the end of September, when it could be 9th magnitude. It could reach 8th magnitude in early November, but is then a morning object. VEM broadband and visual observations are desirable in addition to the more specialist observations used by the campaign.
Observations received in 1997 (289) give an uncorrected
preliminary light curve of
8.5 + 5 log d + 18.4 log r
8.3 + 5 log d + 0.042 abs (T-16.8) where T is the number of days after perihelion
nearly identical with that from the previous apparition
Observations in ICQ format, last observation 1998 April 24, updated 1998 June 26
Observations received in 2010 (119) give an uncorrected
preliminary light curve of
9.1 + 5 log d + 0.045 abs (T-16)
Observations in ICQ format, last observation 2010 October 29, updated 2010 November 3
David Jewitt notes that the nucleus has a diameter of around 600m and shows a rapid change in rotation period.
Leo Boethin discovered a comet from the Philippines in January 1973, however due to a slow postal service it took some time to get the details to the CBAT and it was never confirmed. The comet was formally discovered by Charles Kowal in 1979.
Calculations by Kazuo Kinoshita reveal that it frequently passes close by Jupiter, and it has been gradually getting closer to the sun. The perihelion distance was 1.5 au at the discovery in 1979, then reduced down to 1.4 au in 1998, 1.2 au in 2015, 1.1 au in 2022 and 0.98 au in 2033.
The comet was recovered by Spacewatch on 2003 August 31.20 with the
LPL/Spacewatch II 1.8-m telescope when magnitude 21. At the 2016 return it was
recovered by B Lutkenhoner using the Slooh.com 0.5m at the Canary Islands Observatory on
January 3.84 when it was 19th magnitude. Unless it outbursts again it is unlikely to
brighten further by more than a magnitude.
The comet appeared on the PCCP as P11j29v in 2021 August, until Reinder Bouma pointed out that it was a return of the comet, some 25' off track thanks to the previous encounter with Jupiter. It appeared on the PCCP again, as C2WHJ51, in 2022 February.
Observations received at the 1998 return give a preliminary light
10.5 + 5 log d + 11.0 log r
However Seiichi Yoshida notes that the absolute magnitude is very variable from return to return, and that it outburst to 9.5 in 1972.
Observations in ICQ format, last observation 1998 April 23, updated 1998 October 5
Non- gravitational parameters A1 = +0.21 +/- 0.17, A2 = -0.0699 +/- 0.0025.
This was its third observed return and it remained at 13th - 14th magnitude from late October into January.
25 observations give an uncorrected preliminary light curve of 12.7 + 5 log d +  log r
Observations in ICQ format, last observation 2000 February 27, updated 2000 August 16.
Agustin Acosta reported a possible fragment in images taken on 2022 January 2. The fragmentation may have occurred between 2021 December 3 and 6, based on other reports. Further observations and reference to historical observations of a similar feature suggest that this was not a case of fragmentation. ATel #15177 suggests that a more likely explanation of the observation is from strong activity in a near polar active area, where the spin axis is directed towards the Sun at this point in the orbit. Denis Buczynski reported that the comet had become very diffuse with no photocentre on 2022 February 24, however other observers with larger telescopes and better seeing subsequently reported a faint nuclear condensation.
The comet suddenly starts brightening very rapidly several months prior to perihelion passage, and reaches maximum brightness only within two months or so. In 2008, the beginning of the rapid brightening was delayed and the maximum brightness was fainter than 2001.
Kazuo Kinoshita's calculations reveal that it passed 0.87 au from Jupiter in 1984, and the perihelion distance was reduced from 2.7 au down to 2.45 au. However, it passes only 0.71 au from Jupiter again in 2023, and the perihelion distance will be increased up to 2.8 au. The current feature of brightening rapidly may disappear in the returns after 2035, and the comet may be much fainter than now.
Kazuo Kinoshita's calculations reveal that it will pass 0.63 au from Jupiter in 2091, and the perihelion distance will be reduced down to 2.45 au.
Observations in ICQ format, last observation 2001 April 12, updated 2001 June 23.
7 observations at the 2014 return give an uncorrected preliminary light curve of 5.5 + 5 log d +  log r .
Calculations by Kazuo Kinoshita reveal that it passed extremely close to Jupiter in 1976, down to 0.012 A.U. It will pass extremely close to Jupiter again in 2071, down to 0.037 A.U. Seiichi Yoshida notes that during these two approaches to Jupiter, the comet effectively rotates around Jupiter for a while, however the perihelion distance and eccentricity do not change much.
29 observations received give an uncorrected preliminary light curve of 9.7 + 5 log d +  log r
Observations in ICQ format, last observation 2000 February 27, updated 2000 May 29.
Comet 116P/Wild was discovered on 1990 January 21.98 by Paul Wild with the 0.40-m Schmidt at the Zimmerwald station of the Berne Astronomical Institute at a photographic magnitude of 13.5. At its brightest the comet only reached 12m, but it was surprisingly well observed. The comet was perturbed into its present orbit after a close approach to Jupiter in mid 1987.
7 observations received give an uncorrected preliminary
light curve of 1.0 + 5 log d + 28.2 log r
12 observations received at the 2015 return give an uncorrected preliminary light curve of 3.4 + 5 log d + 23.4 log r
Observations in ICQ format, last observation 2003 July 26, updated 2003 October 25.
Comet 117P/Helin-Roman-Alu Seichi Yoshida provides the following notes:
The orbit is almost circular with an eccentricity of about 0.2. However, it tends to be brightest a long time after perihelion passage.
In the 1997 apparition it reached maximum brightness nearly one year after perihelion passage. At the discovery in 1989, it was already two years since the perihelion passage in 1987 October.
Kazuo Kinoshita's calculations reveal that the comet passed 0.68 A.U. from Jupiter in 2002 after the two apparitions, and the perihelion distance was reduced from 3.7 A.U. down to 3.0 A.U.
At the next return in 2005, it became brightest about 100 days after perihelion passage. The difference between the perihelion passage and the brightest day was reduced because the comet approached closer to the sun. But the asymmetric light curve with respect to perihelion passage still remains.
Kazuo Kinoshita's calculations reveal that the comet will pass near Jupiter twice at the end of 21st century, and the perihelion distance will be changed drastically. However it keeps the current orbit until that time.
At the 2014 return 25 visual and electronic observations give an uncorrected preliminary light curve of 0.3 + 5 log d + 22.7 log r
Comet 118P/Shoemaker-Levyis no longer observable at this apparition.
Observations received (28) give preliminary light curves of
8.8 + 5 log d +  log r or 7.3 + 5 log d +  log r
Observations in ICQ format, last observation 1997 March 31, updated 1997 July 7
Comet 121P/Shoemaker-Holt was discovered by Carolyn and Eugene Shoemaker and Henry Holt with the Palomar 0.46-m Schmidt on 1989 March 9 and at its brightest reached around 13th magnitude. It made a moderately close approach to Jupiter in 1984 and does not approach closer to the Earth than 1.7 AU. With a period of just over 8 years, circumstances do not change much from apparition to apparition so a similar performance was expected for the 2004 - 2005 apparition, however it seems to have been a couple of magnitudes fainter. It should remain around 15th magnitude for the first three months of the year as it retrogrades in Leo Minor.
Comet 123P/West-Hartley was discovered by Richard West on an ESO survey plate taken on March 14 and independently by Malcolm Hartley on a UK Schmidt plate taken on May 28. The comet has made no recent close approaches to Jupiter. It reached between 13th and 14th magnitude at the last return in 1996. It should achieve a similar brightness this time round, but is at its brightest early in the New Year after its 2003 December perihelion.
Comet 128P/Shoemaker-Holt Seiichi Yoshida notes:
Kazuo Kinoshita's calculations reveal that it passed only 0.13 A.U. from Jupiter in 1982, and the perihelion distance was reduced from 4.2 A.U. down to 3.1 A.U. It was discovered in 1987 when it came into inner part of the solar system and became bright for the first time.The comet is one of those known to have undergone nuclear splitting according to the list of Marcos & Marcos [Dynamically correlated minor bodies in the outer solar system, MNRAS, 474, 838, 2018 February]
In the next return in 1997, it became much fainter than at the discovery, by 3 mag when recovered. But it started brightening rapidly 4 months prior to the perihelion passage. After the perihelion passage, it reached to the same brightness as at the discovery.
In the next return in 2007, it was as bright as the previous apparition before the perihelion passage. But it kept faint, did not brighten as shown in the previous apparition, even after the perihelion passage.
The nucleus split into two pieces in 1997 apparition. The unusual brightening in that apparition was probably a temporary event due to the nuclear split. The comet should be usually 18-19 mag at best.
Kazuo Kinoshita's calculation revealed that it will pass only 0.28 A.U. from Jupiter in 2029, and the perihelion distance will be increased up to 4.1 A.U. again. The comet will be extremely faint, fainter than 22 mag at best, after that.
132P/Helin-Roman-Alu is no longer visible at this apparition.
Observations in ICQ format, only observation 1997 December 31, updated 1998 February 4
This was the first Main Belt Comet to be discovered.
Observations received in 2014 give a preliminary light curve of
8.5 + 5 log d +  log r
Comet 135P/Shoemaker-Levy Seiichi Yoshida provides the following information
Kazuo Kinoshita's calculations reveal that the comet approached Jupiter to 0.08 A.U. in 1988, and the perihelion distance was reduced from 5.2 A.U. to 2.7 A.U. It was discovered in 1992, when it passed perihelion at the new distance for the first time, when it reached to 16 mag. But at the next return in 1999, it only reached 18 mag. It has not yet been recovered at the 2007 return, and must be fainter still. The absolute magnitude of the comet has been fading, 7.5 mag in 1992, 8.5 mag in 1999, and fainter than 9.5 mag in 2007. Kazuo Kinoshita's calculations reveal that it will approach Jupiter again in 2047, and the perihelion distance will be increased to 3.6 A.U.
Comet 136P/Mueller The comet was recovered at its third apparition by the Remanzacco and Zvezdno Obshtestvo teams in 2007 July.
Observations in ICQ format , last observation 1999 May 1, updated 1999 August 12.
Donald Machholz discovered 141P/Machholz (1994 P1) with his 0.25-m reflector at 10m in August 1994. It proved to have multiple components, first reported by Michael Jager (Vienna, Austria). The four secondary components could all be described by the same orbit, but with perihelion delayed by up to half a day from the primary. At times there seemed to be a faint trail of material linking the components. The comet has a short period of 5.2 years with a perihelion distance of 0.75 au and aphelion just inside the orbit of Jupiter. The orbit has been slowly evolving, with progressive changes occurring about every 50 years, thanks to approaches to Jupiter. The most recent close approach was in 1982. With a relatively stable perihelion distance, which is slowly increasing, it is perhaps surprising that the comet was not discovered earlier. There was a favourable return in autumn 1978 when it might have reached 8th magnitude and very favourable returns in the autumns of 1920, 1937 and 1957 when it might have reached 6th magnitude. The fact that it was not discovered at any of these returns suggests either that the orbital evolution is slightly inaccurate, or that the absolute magnitude at the 1994 return was not typical. At present the earth passes about 0.25 au outside the descending node and the orbital evolution will slowly decrease this distance, raising the possibility of meteor shower from the comet in a few hundred years time.
Zdenek Sekanina has published a paper on the 'Multiple fragmentation of comet Machholz 2 (P/1994 P1)' in Astronomy and Astrophysics, v.342, p.285-299 (1999). The abstract states:
Discovered in August of 1994, periodic comet Machholz 2 consisted of five condensations, A-E, of which D later became double. They were lined up along their common heliocentric orbit (with A being the leading and brightest component) and connected by a trail of material, suggesting that the comet's nuclear fragmentation was accompanied by a copious release of large dust particles. The earliest breakup is found to have occurred in late 1987, ~ 600 days before the comet's 1989 perihelion, giving birth to fragment B and the grand precursor of A. The precursors of A and D and fragments A and C appear to have originated, respectively, ~ 5 days prior to and right at perihelion. The last breakup episode during that same return to the Sun was the separation of E, probably from the precursor of D, ~ 600 days after perihelion. The division of D into D_1 and D_2 is the only event analyzed in this paper that occurred one revolution later, in 1994. The circumstances and implications of this fragmentation sequence are examined in detail and predictions are presented for 1999/2000.
Robert H. McNaught recovered component A of the comet on CCD images obtained with the 1.0-m f/8 reflector at Siding Spring on 1999 August 3.55. This periodic comet was predicted to be the brightest return in 1999, though it didn't live up to expectation and only reached 10th magnitude.
The return was moderately favourable with the comet moving rapidly eastwards, through Aquarius, Cetus, Eridanus and Orion as it faded. The A component brightened significantly in the last week of 1999 and reached around 10th mag, then faded and become more diffuse. The D component was several magnitudes fainter. The comet remained several magnitudes fainter than expected. Martin Mobberley imaged the comet on December 29.75. and January 9 . David Strange also imaged it on January 9 . Visually it is a rather diffuse object and I made it 9.7 in my 0.33-m Dobsonian on January 9.74.
42 observations at the 1999 return give an uncorrected preliminary light curve of m = 11.7 + 5 log d + 0.0511 abs(t-T-20.6).
Observations in ICQ format , Last observation 2000 February 8, updated 2000 August 16.
The comet was recovered at its 2015 return by the NEOWISE space observatory in 2015 May. In August it was reported in outburst, brightening from around 15th magnitude at the beginning of the month to 12th magnitude on the 22nd. In addition a secondary component was discovered some 22 minutes from the primary. Gareth Williams noted in MPEC 2015-R12 [2015 September 6]:
Initially reported as a new comet, this object was immediately recognized as being a potential fragment of 141P. The current astrometry is rather noisy, which precludes an unambiguous linkage to a known fragment. Computations by both Gareth Williams and S. Nakano suggest that this object can be linked to either fragment C or fragment D (equally well), or to fragment B (less satisfactorily). Fragment D was observed in both 1994 and 1999, while fragment B faded rapidly over the course of a week in November 1994. In no case is the linkage to a known fragment satisfactory. Therefore, in the absence of a definitive linkage, the new fragment designation "H" is being assigned. Also, the opportunity is being taken to publish rough orbits for three other fragments seen in 1994 that have not been published previously.
4 observations at the 2015 return gives an uncorrected preliminary light curve of m = 13.2 + 5 log d +  log r.
PanSTARRS 2 discovered an apparently asteroidal object on 2020 August 13.27 which was posted on the NEOCP as PP213Rbq. The MPC noted that it had the motion expected of 141P and it is assumed that this is component A. The comet passed 0.93 au from Jupiter in 2017 October and passes 0.53 au from Earth in 2021 January. [CBET 4834, 2020 August 19]. Michael Jaeger imaged the comet on December 7.7, noting the main body and two much fainter fragments. The main body was about 13th magnitude, which is a bit fainter than predicted, though the next day JJ Gonzalez was able to see it visually at 12th magnitude. The comet reached 10th magnitude between the time of perihelion in December and closest approach in January, this was slightly fainter than originally expected, but perhaps a consequence of the perihelion distance being slightly greater than at the last return. Some time between 2021 March 2.2 and 3.2 the comet brightened by about four magnitudes in an outburst and grew a tail [CBET 4940, 2021 March 7].
C. E. Delahodde, European Southern Observatory, reported the recovery by O. R. Hainaut and herself of comet P/1994 A1 (= 1994a = 1993 XX) with the 3.6-m reflector on 2000 July 25.33. The indicated correction to the prediction by S. Nakano on MPC 31664 was Delta(T) = -0.10 day. [IAUC 7467, 2000 July 27]. No visual observations were made, but the comet was numbered.
The comet was recovered in 2008 with the Keck II telescope at Mauna Kea by K. Meech and J. Pittichova on June 18.51. It was observed with the Spitzer Space Telescope in July. It brightened extremely rapidly, reaching binocular visibility in winter 2008/9.
68 observations give an uncorrected preliminary light curve of m = -2.8 + 5 log d + 75 log r.
On 2001 Dec. 25, S. Nakano (Sumoto, Japan) reported that T. Oribe had apparently recovered comet P/1993 K2 (= 1993 XI = 1993l) the night before (December 24.86) with the 1.0-m reflector at the Saji Observatory. The position was within 2" of the prediction by B. G. Marsden on MPC 34423 (ephemeris on MPC 43696). No information was provided about the object's appearance other than m_1 = 19.5. The comet has now been independently reported by K. Sarneczky and Z. Heiner in 2002 Jan. 11 data obtained with the 0.6-m Schmidt at Piszkesteto, at m_1 = 20, but again with no information about the appearance. These observations confirm a tentative single-night detection by C. W. Hergenrother and D. Means of an object of stellar appearance (in an 840-s co-added exposure) at the comet's expected position a year ago with the Steward Observatory's 2.3-m reflector at Kitt Peak. [IAUC 7790, 2002 January 14]
Further to IAUC 7790, K. Sarneczky reports that his 300-s unfiltered CCD images taken on Jan. 11.2 UT show a diffuse, 8" coma and a faint, narrow, 13" tail in p.a. 283 deg. [IAUC 7792, 2002 January 15] Further to IAUC 7790, T. Oribe reports that his CCD images taken on 2001 Dec. 24.86 UT show a 0'.15 coma and an 8" tail in p.a. 295 deg. [IAUC 7794, 2002 January 17]
F. Artigue, H. Cucurullo, and G. Trancredi, Observatorio Astronomico Los Molinos, Montevideo, report the recovery of comet P/1992 Q1 (= 1992p = 1992 XIV), mag 16.8, with a diffuse coma of diameter 20" and central condensation, on CCD images taken with a 0.46-m telescope in the course of the 'BUSCA' project on August 26.98 and 27.98. Further astrometry and orbital elements (from observations 1992 Aug. 28-2002 Aug. 28) appear on MPEC 2002-Q41; the correction to the prediction on MPC 40670 is Delta(T) = +0.52 day.[IAUC 7961, 2002 August 28]
Observations in ICQ format Last observation 2002 December 7, updated 2003 January 23.
The comet was recovered at the 2013 apparition on 2013 August 2.02 by F Fratev with the 0.35m reflector at the Zvezdno Obshtestvo Observatory, Plano. It will return to perihelion 0.25 days later than expected. The recovery magnitude was about 4m fainter than predicted.
39 electronic and visual observations received so far in 2013 suggest a preliminary uncorrected light curve of m = 2.9 + 5 log d + 36.0 log r The error bars remain quite large.
S. Nakano, Sumoto, Japan, reports the CCD recovery of comet P/1986 A1 (= 1986a = 1985 XVIII) independently by T. Oribe (1.03-m reflector, Saji; diffuse coma of diameter 10", hint of tail toward the west on R-band images, mag 18.0) on September 9.78 and by A. Nakamura (0.60-m reflector, Kuma; diffuse with some central condensation, coma diameter 12", unfiltered images, mag 18.6) on September 12.81.
The indicated correction to the prediction on MPC 34423 is Delta(T) = -0.14 day. [IAUC 7969, 2002 September 13]
Observations in ICQ format Last observation 2002 December 11, updated 2003 January 13.
The comet was reported as around 2 magnitudes brighter than expected by Taras Prystavski at 13th magnitude in early October 2020. This is likely to be a consequence of the reduced perihelion distance, which has increased the activity of the comet. It passes 0.48 au from the Earth at the end of October.
Keith Tritton provides the following information about the original discovery:
I'm amazed (and delighted) it's been recovered. It's quite a story - it was very faint on discovery in 1978 (I think it may even have been the faintest comet ever discovered at that time), when I was working on the Southern UK Schmidt Sky Survey. The orbit was observed over only a very short arc. The first return was very unfavourable, so it couldn't be seen, and the orbital inaccuracy was so large that the predictions for the second return had huge uncertainties. Nevertheless I got some plates taken at the Schmidt (this was about 1990) and sent to me in Cambridge for searching. But I never got them, they were lost in transit from Australia!
So I never expected to hear anything more about it. It must be rather rare to pick up a lost comet on its fourth return, mustn't it?
P. Holvorcem, Campinas, Brazil, has reported that the co- addition of three 45-s unfiltered CCD images of a fast-moving object found by C. Juels, Fountain Hills, AZ, with a 0.12-m f/5 refractor and a 0.5-m f/4.8 reflector on October 6.44 show a coma of diameter 2' and a hint of a 1'.5 tail at p.a. roughly 257 deg. Following posting on the NEO Confirmation Page, additional CCD observers noted the object's cometary appearance, including R. Trentman (Louisburg, KS, 0.75-m reflector; mag 13.1 and very faint evidence of a tail approximately 10" long in p.a. approximately 280 deg on Oct. 7.4 UT), D. T. Durig (Sewanee, TN, 0.30-m f/5.86 reflector; teardrop-shaped coma of mag 10.1 with a tail at least 2'-2'.5 long in p.a. about 285 deg on Oct. 7.4), and J. Young (Table Mountain, CA, 0.6-m reflector; 36" coma elongated to 48", with a 3' tail in p.a. 289 deg with a very straight and extremely thin jet of length about 1'.5 in its center on Oct. 7.5).
Following a suggestion by S. Hoenig (Dossenheim, Germany) from orbital computations by M. Meyer (Kelkheim, Germany), B. G. Marsden (Smithsonian Astrophysical Observatory) has shown that this comet is identical to the lost comet 1978d = 1977 XIII = D/1978 C2 (Tritton), which was observed for only a month (cf. IAUC 3175, 3186, 3194, 3198). The available astrometry, including Sept. 22 prediscovery observations, and the orbital elements by Marsden appear on MPEC 2003-T37. [IAUC 8215, 2003 October 7]
Observations in ICQ format, last observation 2003 October 8, updated 2003 October 25.
In 2022 Michael Jager noted a secondary condensation in images taken on September 18 and 23, suggesting that further fragmentation has occurred. The comet was near perihelion at the time. The fragment had also been seen by ZTF between August 21 and September 2, but the observations had been put into the MPC ITF and had gone un-reported. Orbital calculations by Syuichi Nakano suggest that the split occurred during this return. An orbit for the fragment was published in MPEC 2022-T23 [2022 October 2].
S Nakano has identified the comet with 1979 O1, observed by Charles Kowal on three occasions between July 24 and 27 and then lost. The orbit was uncertain, but noted as possibly being periodic due to the low inclination.
An apparently asteroidal object with not-unusual motion, found by LONEOS on October 16.40 (the discovery observation together with other astrometry appeared on MPS 88336, 90581, and 91035 with the designation 2003 UD_16; initial orbit on MPO 53844), has been found by C. W. Hergenrother to show a circular, condensed 11" coma and no tail on co-added 900-s R-band CCD exposures taken on Nov. 30 with the Mt. Hopkins 1.2-m reflector (astrometry below measured by T. B. Spahr). [IAUC 8248, 2003 December 3]
Maik Meyer found images of the comet on Palomar plates taken in 1989 and 1991, thus allowing a secure orbit to be determined.
Maik Meyer provides the following information on the linkage with the NEAT images:
Comet precovery by Maik Meyer [from http://www.hohmanntransfer.com/mn/0409/20.htm]
It came right after my little son went to bed and I was preparing for a comet observing session, so I had time without family duties. I quickly checked for earlier images of this comet and SkyMorph indicated two days in 1996 in NEAT data with an asteroidal brightness of 18 mag. I was not very hopeful but almost fell off my seat when I saw the bright 16-mag. comet with a coma and a tiny tail on my screen.
I quickly measured the two days, composed the message to the MPC, and, when I came back from my comet observing, MPEC 2004-S18 had been issued containing the observations and updated orbits for the 1996 and 2004 apparitions. I still wonder why this one slipped through NEAT's detection, because it is so obvious. Now this comet will become numbered ? my second precovery which leads to a permanent numbering after 159P/LONEOS.
Observations in ICQ format, last observation 2004 October 13, updated 2004 October 19.
Rob McNaught has recovered comet P/Hartley-IRAS (1983v=2004 V2) with the Siding Spring 1-m reflector. The comet was 4.8 days behind the prediction in the 2004 ICQ Handbook. At 19th magnitude it is a little fainter than might be expected.
For the 2005 return 17 observations give a preliminary light curve of 9.0 + 5 log d +  log r.
The 14th magnitude object was discovered by Rob McNaught during the Siding Spring Survey on October 10.55. It will fade. It has been linked to objects seen in 1990 (by the Palomar Sky Survey), 2000 (by LINEAR and LONEOS) and by ESO, AMOS and NEAT in following years, so the orbit is secure and it was numbered 162. It has a period of 5.32 years, with perihelion at 1.23 AU and was at perihelion on November 10.
Maik Meyer has found images of the comet on Palomar DSS plates from 1990 and 1991, and NEAT images from 1997. This gives a secure orbit and lead to the comet being numbered 163.
David Herald recovered comet 1998 W2 (P/Hergenrother) on images taken with his 0.36m f4 SC reflector on 2005 July 4 & 5. The comet was 0.27 days ahead of the prediction on MPC 45658. Following recovery it has been numbered 168.
The comet outburst at its 2012 return, suddenly brightening from around 11th magnitude in September to around 9.5 in early October. After the outburst it faded quite normally.
42 observations received give an uncorrected preliminary light curve post outburst of m = 10.0 + 5 log d + 8.2 log r
In November 2009 Alan Watson spotted a bright comet in STEREO images, which was identified with 169P. Ground based observations by Juan Jose Gonzalez on November 18.8 gave a magnitude of 9.2. He noted that he had also observed it as a 10th magnitude object at its return in September 2005. An article on the likely brightness of 169P/NEAT by Joe Marcus in ICQ suggests that part of the anomolous brightening was due to forward scatter.
The comet is one of those known to have undergone nuclear splitting according to the list of Marcos & Marcos [Dynamically correlated minor bodies in the outer solar system, MNRAS, 474, 838, 2018 February]. They link it with 2003 T12 (P/SOHO).
Further observations show that it is a periodic comet with period of 8.6 years and will reach perihelion at 2.93 au in late January 2006. It has been identified in observations made by NEAT in 1997, so the orbit is now secure and the comet has received a numeric designation.
Gennadi Borosov recovered it in July 2022 and it briefly appeared on the PCCP as gb00355.
Comet P/Spahr was recovered as 2005 R3 by F. Fratev and E. Mihaylova of Zvezdno Obshtestvo Obsevatory, Plana, with a 0.25-m f/4.7 reflector and by E. J. Christensen with the Catalina 0.68-m Schmidt telescope. The prediction in the 2005 Handbook requires a correction of delta T = -0.2 day. Following recovery the comet was numbered 171.
An apparently asteroidal object of 20th mag discovered by William Kwong Yeung, Benson, AZ, on CCD images taken with a 0.45-m reflector near Apache Peak on Jan. 21.49 UT was identified by the Minor Planet Center with additional apparently asteroidal observations (including some in 1998 and 2000-2001) made at several observatories through its routine processing. Noting the unusual nature of its orbit, T. Spahr obtained unfiltered CCD observations with M. Calkins at the 1.2-m reflector on Mount Hopkins on May 5, 6, and 7 that show the object (m_1 about 17) larger than nearby stars of similar brightness and with a persistent faint tail about 5" long in p.a. 315 deg. [IAUC 7986, 2002 May 9]
It was numbered 172 in September 2005 following identification of images on Palomar Sky Survey plates from the previous apparition in October 1993. Pre-discovery images by Spacewatch in 1998, and LINEAR in 2000 were also identified.
The case seems similar to that of Chiron, which is (2060) 95P/Chiron, so the object should receive a cometary number. Roll on comet Pluto!
The Committee on Small Bodies Nomenclature has agreed to give the comet P/2000 EC_98 (cf. IAUC 8656, 8660) the same name as the centaur minor planet (60558), Echeclus (cf. MPC 55988), which has been assigned also the permanent comet number 174P (MPC 55911). [IAUC 8677, 2006 February 22]
Observations made since December 2005 appear to indicate that the main source of activity is a secondary body moving independently of the primary, possibly on a hyperbolic orbit. The object was at maximum elongation from the primary around February 25. It may be an escaped satellite or a debris fragment.
Michael Jaeger imaged the comet on 2011 May 30, finding it to be in outburst at 15th magnitude. Paul Camilleri caught the comet in outburst on 2016 August 28.68, finding it had brightened by about two magnitudes. J J Gonzalez was able to see it visually at 14.8.
The comet outburst again in 2017 December, brightening by around 5 magnitudes. Nick James reports that the coma expanded at about 3.4 arcsec per day from around December 6.5, corresponding to an expansion speed of 95 m/s. His analysis of the total magnitude suggests a fading of 0.011 magnitudes per day.
The Committee on Small Bodies Nomenclature has announced that P/2000 C1 = P/2006 A3 (Hergenrother) has been assigned the number 175P (cf. IAUC 8664). [IAUC 8677, 2006 February 22]
In June 2006 the Committee on Small Bodies Nomenclature agreed to name and number the comet, although the asteroidal designation will be used for archiving any astrometry.
As is often the case, early magnitude estimates by CCD observers were approximating to m2 rather than the published m1 and by mid July the comet was reported at around 10th magnitude.
50? observations received give an uncorrected preliminary light curve of m = 9.2 + 5 log d + 21.7 log r
D Tibbets and Gary Hug recovered comet 1999 X1 (Hug-Bell) on July 16.40 with the 0.7-m relector at the Farpoint Observatory Eskridge, Kansas. The correction to the perihelion time predicted on MPC 48383 was -0.12 day.
Following recovery it was numbered 178P.
J. L. Ortiz and A. Mora recovered comet 2001 K1 (P/NEAT) on CCD images obtained with the 2.5-m Isaac Newton Telescope at La Palma. The images were measured by Reiner Stoss. The comet was essentially stellar and magnitude 22. The indicated correction to the prediction on MPC 54169 is Delta(T) = -0.4 day. This confirms a tentative identification made by Reiner of the comet on Palomar Sky Survey plates from 1955.
Eric Christensen recovered comet 2001 WF2 (P/LONEOS) with the Catalina Sky Survey 0.68-m Schmidt on 2006 November 18.27. The comet was 20th magnitude and the indicated correction to the elements on MPC 51822 is Delta(T) = -0.05 day.
Eric Christensen recovered 1999 DN3 (P/Korlevic-Juric) with the Mt Lemon 1.5-m on December 16.36. The comet was 20th magnitude, and the indicated correction to the prediction on MPC 54168 is Delta(T) = -2.0 days. Perihelion is at 3.9 AU in May 2008 and the comet has a period of 9.6 years.
Maik Meyer found some prediscovery observations in archive imagery from 1996 and 1975, which should lead to numbering of the comet.
I managed to find this comet in three DSS images after playing around with orbits and finding the anchor point with the 1996 images. It should be visible in a plate of 1995, but was not seen. Also I could not find it in some NEAT images. In the 1975 images the comet is quite bright, probably due to the slow motion. The appearance is almost the same in the two different plates, although at a different position. I have taken the position of the center of the short trail. The 1996 image is involved with a star. Here I could only measure the end of the trail.Hirohisa Sato has computed a new orbit linking the apparitions. Subsequently to Maik's identification, Gareth Williams identified a comet, reported by Russell Eberst in 1978 from UK Schmidt plates taken at Siding Spring in 1977 and designated as 1977 O1 as being the same comet. With observations at three returns the comet is now likely to be numbered 186P. The brightness of the object does seem rather more variable than expected for such a distant object, so it may be subject to occasional outbursts, much as 29P/Schwassmann-Wachman.
Seiichi Yoshida notes that:
The perihelion distance is large at 4.3 A.U., and the orbit is almost circular with an eccentricity of 0.12. Kenji Muraoka's calculation revealed that this orbit does not change significantly for 200 years in the 20th and 21st centuries.
It reaches 17.5 mag at best based on the brightness at the discovery in 2007 January. The brightness in 1996 February was similar, however, the comet was unexpectedly bright at 15.5 mag in 1975 May and June. It seems to have been a temporary outburst, as the comet returned to its normal brightness in 1977 July at 18 mag.
This comet is similar to 111P/Helin-Roman-Crockett; large perihelion distance, almost circular orbit, and a record of unexpected brightening in temporary outburst.
Eric Christensen recovered comet 1999 J5 (P/LINEAR) in images taken on March 9 during the course of the Mount Lemmon Survey, with additional images taken by R A Kowalski on March 10. The indicated correction to the prediction on MPC 54170 is Delta(T) = -0.8 day.
Seiichi Yoshida notes:
This is a new periodic comet discovered in 1999. At the next return in 2008, it became fainter by 2 mag.
Kazuo Kinoshita's calculations reveal that the perihelion distance has been almost constant at 3.6 - 3.7 A.U. since 1952. Therefore, the brightness of the comet should be also stable.
In the 1999 apparition, the comet was not observed in 2000, one year after the discovery, although it must have been almost as bright as at the discovery. It suggests that the comet was temporarily bright in outburst in 1999.
Rob McNaught recovered comet P/1998 S1 with the 0.5-m Uppsala Schmidt at Siding Spring on 2007 May 13 and Jim Scotti independently recovered it with the Spacewatch 1.8-m f/2.7 reflector at Kitt Peak on June 26.5. The indicated Delta(T) correction to the prediction on MPC 51824 is +0.03 day.
The preliminary orbit suggested that it was in a short period orbit with P around 5 years and was near perihelion. It is intrinsically very faint (H0=19). The orbital period is the third shortest of current P/ comets. At a favourable return it can pass 0.2 AU from the Earth.
Comet 2002 O5 (P/NEAT) was recovered independently at three observatories in mid July as 2007 N2: by LINEAR in New Mexico, and by G. Lombardi and E. Pettarin at Farra d'Isonzo, Italy and F. Fratev and E. Mihaylova at Plana, Bulgaria. It was around 16th magnitude. The correction to the predictions on MPC 51823 was Delta(T) = -0.36 day.
Comet 1998 U2 was recovered by L. Buzzi and F. Luppi, Varese, Italy on 2007 July 26 on CCD images obtained with a 0.60-m reflector. Peter Birtwhistle made confirming CCD observations on July 27. The indicated correction to the predictions on MPC 51823 is Delta(T) = +0.3 day.
Images from August and November 2000 were found in archival LONEOS and NEAT observations by Syuichi Nakano in early September and it was given the designation 2000 P3 for this return. Following publication of the identification on MPEC 2007-R04 further images from September and December 2000 were found in the NEAT archives by Maik Meyer and Reinder Bouma.
192P is a bright periodic comet, which was not discovered until 1990. At the discovery, it had already passed perihelion two months before, and faded out rapidly. So, it was supposed to be a temporary outburst. But it was observed at the same brightness in the next return in 2007.
This comet tends to brighten and fade out rapidly, and the light curve is asymmetric to the time of perihelion. It reaches maximum brightness about 50 days after perihelion passage.
Kazuo Kinoshita's calculations show that the orbital elements of this comet have not changed much since 1888. So it is expected to show the same light curve in every apparition.
Additional astrometry and orbital elements by B. G. Marsden (from 35 observations, Aug. 17-29) appear on MPEC 2001-Q69 [IAUC 7697, 2001 August 29] The comet was at perihelion in June and will not get significantly brighter. It has a period of 6.6 years. This is LINEAR's 65th comet.
Observations in ICQ format, last observation 2001 October 10, updated 2001 October 17.
Comet 2001 Q5 (P/LINEAR-NEAT) was recovered by K. Sarneczky and L. L. Kiss with the 2.3-m reflector at Siding Spring on October 21.45. The indicated correction to the prediction on MPC 54167 is Delta(T) = -0.5 day.
Comet 2000 B3 (P/LINEAR) was recovered by L. Buzzi and F. Luppi on CCD frames taken with a 0.60-m f/4.64 reflector at Varese, Italy on November 17.07. The indicated correction to the prediction on MPC 54167 is Delta(T) = +0.16 day.
Following further observations in 2007 September and December, and the publishing of new elements on MPEC 2007-X14 [2007 December 3], S. Foglia, R. Matson, and M. Tombelli identified images of the comet on two UK Schmidt plates from 1993 and 1994. The linked orbit has a period of 16.5 years.
M. Tichy and J. Ticha, Klet Observatory, recovered comet P/2000 U6 (cf. IAUC 7515) on CCD images obtained on February 3rd with the 1.06-m KLENOT Telescope. They subsequently identified earlier images from January 11. The indicated correction to the prediction on MPC 54167 is Delta(T) = -0.16 day.
Another apparently asteroidal LINEAR object found on May 23.16, announced on MPEC 2003-K27 as 2003 KV_2 (see also MPEC 2003-K38 and 2003-K47), has been found cometary on R-band images taken by C. Brinkworth and M. Burleigh on May 28.9 and 29.9 UT with the 1-m Jacobus Kapteyn Telescope on La Palma (communicated by A. Fitzsimmons), in which the object shows a tail about 4"-5" long in p.a. 125 deg and a small coma that is somewhat larger than the surrounding field stars. The preliminary orbit shows a passage 0.55 AU from Jupiter in Jan. 2001, before which the perihelion distance was somewhat larger. [IAUC 8139, 2003 May 30]
After posting an asteroidal object discovered by the Catalina Sky Survey on the NEOCP Sergio Foglia suggested an identity with comet 2003 KV2 (LINEAR), indicating a correction of Delta(T) = +0.8 day to the prediction by Nakano on MPC 56801.
In March 2008, Gareth Williams identified images of comet P/1998 X1 taken at its 2006 return. He found that Spacewatch images taken between January and March and Mt Lemmon images from March show the comet, which was around 21st magnitude. The indicated correction to the orbital elements on MPC 45656 is Delta(T) approximately -2 days. The observations from the two apparitions do not fit together very well, leaving residuals of up to 5".
Brian Marsden notes on MPEC 2008-G10 [2008 April 2]
The rediscovery of this comet by G. V. Williams in 2006 astrometric survey data was announced on 2008 Mar. 31 on IAUC 8929-8930, with the 2006 observations simultaneously published on MPEC 2008-F63, together with another triplet of 1999 observations. This rediscovery appears to be consistent with E. J. Christensen's tentative single-night recovery observations in 2005 October. As noted on IAUC 8929, however, the linked orbit computation was decidedly unsatisfactory. This was also true of attempts to include the A1 and A2 nongravitational parameters. Following a demonstration by S. Nakano of the apparent need also to include the A3 parameter, linked orbital elements were obtained by G. V. Williams from such a solution. The resulting nongravitational parameters are A1 = -2.79 +/- 0.27, A2 = +1.1966 +/- 0.2612, A3 = -2.2588 +/- 0.0268.
Spanish CCD observers reported the comet in outburst in early August, and this was confirmed by other CCD observers. Juan Jose Gonzalez Suarez made a visual observation on August 4.92, estimating it as a nearly stellar object of magnitude 14.4.
The comet appeared as C7F3352 on the PCCP in 2022 March. It reaches perihelion in 2023 August.
Published by Jonathan Shanklin. Jon Shanklin - firstname.lastname@example.org