Comet Section : Comets discovered in 2012
Updated 2017 April 5
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 new comets are given in ICQ format. More
recent ones may be available in TA format from the main page.
Full details of recently discovered objects will not appear until they are
available on the CBAT web pages, which is usually a fortnight after the
publication of the IAUC.
Meyer Group SOHO comets
were discovered with the SOHO LASCO coronographs and
have not been observed elsewhere. They were sungrazing comets of the
Meyer group. For further information on the discovery of
these objects see this year's SOHO discoveries. Twenty group
members were discovered this year, which is towards
the extreme tail of the normal distribution. There is speculation that a larger member
of the group might be on its way.
Kracht Group SOHO comets
2012 Bn (SOHO)
was discovered with the SOHO LASCO coronographs and
has not been observed elsewhere. It was a sungrazing comet of the
Kracht group.
Rainer Kracht suggests that this was a return of 2001 R8, and that it made
an approach of 1.02 AU to Jupiter on 2008 March 16
For further information on the discovery of
these objects see this year's SOHO discoveries.
Marsden Group SOHO comets
Several Marsden group comets have been
discovered with the SOHO LASCO coronographs this year and
have not been observed elsewhere. They were sungrazing comets of the
Marsden group. Rainer Kracht suggests possible linkages of
April 10 = 2006 E2 = 2000 C4 (or C3) and April 13 = 2005 W5 = 1999 U2. If this second
linkage is real he notes a substantial change in period from 5.9 years in 1999 to
6.4 years in 2012.
Karl Battams has put together a probable
family tree for the fragments.
The tree for the latest objects is not entirely clear, but a linkage to 2000 C3 or 2000 C4
seems probable. Rainer Kracht notes that the comet discovered on April 22 has similar
elements to the one found in March.
For further information on the discovery of
these objects see this year's SOHO discoveries.
Periodic SOHO comets
2012 M2 (P/SOHO)
2012 Q2 (P/SOHO)
Orbits for two periodic objects, 2012 M2 and 2012 Q2 were published on MPEC 2015-K01 [2015 May 16].
For further information on the discovery of
these objects see this year's SOHO discoveries and
cometary asteroids, potentially numberable comets and periodic SOHO comets.
2012 A1 (PanSTARRS)
Pan-STARRS discovered a 20th magnitude comet on January 2.45. It will reach perihelion at
7.6 AU
in 2013 December.
2012 A2 (LINEAR)
LINEAR discovered an 18th magnitude comet on January 15.41. It reached perihelion at 3.5 AU
in November. Visual observations show that it peaked at about 11th magnitude in November.
12 electronic and visual observations received so far
suggest a preliminary light curve of
m = 2.1 + 5 log d + 12.4 log r
2012 A3 (P/SOHO)
On January 19 Alan Watson discovered a fuzzy object with tail in STEREO H1b images from January 17.
William Thompson then found images in COR2B. It showed strong forward scattering brightening.
Man-To Hui (Cantonese, "Wentao Xu", "Wen-Tao Hsu" in Mandarin)
calculated a preliminary parabolic orbit and added astrometric measurements of the COR2B images. Rainer
Kracht added STEREO vectors and calculated a short period orbit, which he then linked to 2003 T12 (SOHO), which
Brian Marsden had noted might be a short period comet. He suggested that it should also be visible in STEREO images
from 2007, and Alan Watson found it in images from November that year. Rainer
notes that the comet made an approach to the Earth at 0.18 AU on 2008 January
26. At the time of closest approach it was around -50 declination and
near quadrature. The comet has a period of 4.1 years, with perihelion at 0.57 AU.
The comet was first observed from the ground by Hidetaka Sato, using the remote
facility at Mayhill, New Mexico. It was around 15th magnitude in the
images, but probably brighter visually.
Note the preliminary designation given by myself (2012 B1) was not issued by the MPC/IAUC. In the event they decided to ignore the discovery and orbit
computation sequence because pre-discovery observations made earlier in January became available,
and gave the designation of 2012 B1 to a comet discovered by PanSTARRS on January 25.
2012 B1 (P/PanSTARRS)
Pan-STARRS discovered a 20th magnitude comet on January 25.52. Pre-discovery images by the
University of Szeged, Piszkesteto Stn. (Konkoly) were found from
2011 December 31. It will reach perihelion at 3.8 AU
in 2013 July and has a period of around 17 years. Following improvements in the orbit, the comet was located in
observations made by NEAT in 1997.
6 observations received so far suggest a preliminary light curve of
m = 6.7 + 5 log d + [10] log r
2012 B2 (256P/LINEAR)
Comet 2003 HT15 was recovered at Geisei by observers T. Seki, S. Shimomoto and H. Sato
on 2012 January 26.5 using the
0.70-m f/7 reflector + CCD. The return to perihelion is 0.17 days later than the prediction
on MPC 69909.
2012 B3 (La Sagra)
The observing team at OAM Observatory, La Sagra (S. Sanchez, J. Nomen, M. Hurtado,
J. A. Jaume, W. K. Y. Yeung, P. Rios and F. Serra) using the 0. 45-m
f/2. 8 reflector discovered an 18th magnitude comet on January 29.18. It was at perihelion at 3.5 AU in 2011 December.
2012 BJ98 (Lemmon)
An object reported as asteroidal in images obtained in the second half of January, was identified as cometary in images taken
by the Mt Lemmon Survey on March 1, and then linked to images obtained by the Steward Observatory, Pan-STARRS and the Catalina
Sky Survey. The comet has perihelion at 2.2 AU in September and has a period of around 70 years.
2012 C1 (McNaught)
Rob McNaught discovered a 19th magnitude comet on CCD images taken with the 0.5-m Uppsala Schmidt telescope at Siding
Spring on February 5.56. The comet will reach perihelion at 4.8 AU in 2013 February.
2012 C2 (Bruenjes)
Manfred (Fred) Bruenjes discovered a 15th magnitude comet in CCD data obtained at Moonglow Observatory, Warrensburg on February 11.14
Discovery story
Some follow-up observations suggested that it might be as bright as 12th magnitude. Further astrometric observations
initially suggested a link with comet 1943 R1 (Daimaca), however further
astrometry showed that this could not be the case. According to
calculations by Hirohisa
Sato the orbit is likely be hyperbolic. Perihelion was in mid March at 0.8 AU, but the comet was
receding from Earth and faded. The ephemeris suggests that it would have been brightest in late January, though
perhaps large and diffuse.
2012 C3 (P/PanSTARRS)
Pan-STARRS discovered a 21st magnitude comet on February 15.35. Following confirmation by Giovanni Sostero, Nick Howes
and Ernesto Guido using the Faulkes South telescope at Siding Spring, prediscovery images from late January were
found in Mt Lemmon Survey data. The comet was at perihelion at 3.7 AU in 2011 October and has a period of around 30 years.
2012 CH17 (MOSS)
The Morocco Oukaimeden Sky Survey (MOSS) discovered this comet on February 7.12, though it had earlier been flagged as an asteroid.
It reached perihelion at 1.3 AU in September. It could reach 13th magnitude, but is not well placed
for observation from the UK. One visual observation put it at 13th magnitude in
July.
A/2012 DG61 [PanSTARRS]
This unusual asteroid was discovered by the Pan-STARRS 1 1.8m Ritchey-Chretien reflector
on February 28.33. [MPEC 2012-E10, 2012 March 1, 3-day orbit]. It has an orbit with a
period of around 5.2 years and perihelion is at 0.8 AU in 2012 July. It can approach Jupiter within
0.25 AU and the Earth to 0.16 AU.
The orbit has a Tisserand criterion of 2.75 with respect to Jupiter.
2012 E1 (Hill)
Richard Hill discovered a 20th magnitude comet on March 2.48 on images taken during the Mt Lemmon Survey with
the 1.5m reflector. It was at perihelion in 2011 July at 7.5 AU.
2012 E2 (SWAN)
A comet was reported in SWAN images taken on March 4, 5 and 6 by Vladimir Bezugly on March 8 and was listed on the NEOCP as RMAT012.
The comet was another Kreutz group member, and had perihelion on March 15.03. When
the comet entered the SOHO field of view it appeared as a bright object, though not exceptional, and faded as it approached perihelion.
It is very unusual for a "normal" SOHO Kreutz comet to appear bright in SWAN images, and this might imply that it suffered some
disintegration ten days prior to perihelion. There is some speculation that the recent bright objects may imply more to come over
the next decade. After an orbit was published on MPEC 2012-F03, Terry Lovejoy re-processed his ground based images from March 10 and noted the presence
of a nearly starlike object of 9th magnitude.
2012 E3 (PanSTARRS)
Pan-STARRS discovered a 20th magnitude comet on March 14.60. The comet was at
perihelion at 3.7 AU in 2011 May.
2012 F1 (Gibbs)
Alex Gibbs discovered a 19th magnitude comet in images from the Catalina Sky Survey taken on March 16.28 with the 0.68-m Schmidt.
The comet was near perihelion at 2.6 AU.
2012 F2 (P/PanSTARRS)
Pan-STARRS discovered a 20th magnitude comet on March 16.49. The orbit published on the MPEC suggests that the comet was
at perihelion at 2.4 AU in 2011 July. Calculations
by Hirohisa Sato also allow the possibility that it is yet to reach perihelion or that it is in a periodic orbit. The latest
orbit has a period of around 16 years, with perihelion at 2.9 AU in 2013 April.
2012 F3 (PanSTARRS)
Pan-STARRS discovered a 21st magnitude comet on March 16.32. Following confirming images taken at Mauna Kea the next day,
images of the object were found in Pan-STARRS data from January 19. The comet is at perihelion at 3.5 AU in 2015 April.
21 observations received so far suggest a preliminary light curve of
m = 4.5 + 5 log d + 11.1 log r
2012 F4 (257P/Catalina)
G. Sostero, N. Howes, A. Tripp, E. Guido recovered comet 2005 JY126 (P/Catalina) using the 2.0-m Siding Spring-Faulkes Telescope South on
2012 March 21.60. The comet will reach perihelion 0.01 days later than the prediction on MPC 69910.
2012 F5 (331P/Gibbs)
Alex Gibbs discovered a 20th magnitude comet on March 22.29 on images taken during the Mt Lemmon Survey with
the 1.5m reflector.
The comet has a period of around 5.2 years and was at perihelion at 2.9 au in 2010 March. Given the interval
since perihelion, it may be in outburst. It was numbered in 2016.
2012 F6 (Lemmon)
Images taken during the Mt Lemmon Survey with the 1.5m reflector on March 23.21 showed another comet, of 21st magnitude.
It won't reach its perihelion of 0.7 AU until 2013 March. At discovery it was nearly 6 AU from the Sun.
The comet came into visual range in 2012 November though it is at a high southern
declination. It is poorly placed at perihelion, but UK observers may get it in May when it might be
7th magnitude, and will be able to follow it until the autumn.
A visual observation by Marco Goiato with a 0.22m reflector on November 18 made the comet
11.7, much brighter than expected. By mid February 2013 it had reached 5th
magnitude. The latest observations suggest that the comet reached 4.5 magnitude at perihelion. It
is now fading, but is a little brighter than the mean light curve.
172 visual observations received so far suggest a preliminary light curve of
m = 5.3 + 5 log d + 9.0 log r
2012 G1 (P/PanSTARRS)
Pan-STARRS discovered a 21st magnitude comet on April 13.35. Confirmation was made by other
astrometrists amongst whom was a team including Richard Miles, Giovanni Sostero, Nick Howes
and Ernesto Guido using the Faulkes North telescope at Haleakala.
The comet is at perihelion at 2.6 AU in 2012 June and has a period of around 8.5 years.
A/2012 GS5 [PanSTARRS]
This unusual asteroid was discovered by the Pan-STARRS 1 1.8m Ritchey-Chretien reflector
on April 11.39. [MPEC 2012-G46, 2012 April 14, MPEC 2012-U119, 2012 October 29]. It has an orbit with a
period of 6.3 years and perihelion is at 0.5 AU in 2012 June. It can approach Jupiter within
0.5 AU and the Earth to 0.29 AU.
The orbit has a Tisserand criterion of 2.34 with respect to Jupiter.
2012 H1 (258P/PanSTARRS)
Pan-STARRS discovered a 22nd magnitude comet on April 27.43. Images of the comet were then
found in Mt Lemmon survey data from February 7 and March 28, and Spacewatch data from March 29.
The comet was at perihelion at 3.5 AU in 2011 March and has a period of around 9.2 years.
As the orbit became better defined, observations from 2002 were found, confirming the period.
2012 H2 (McNaught)
Rob McNaught discovered a 19th magnitude comet on CCD images taken with the 0.5-m Uppsala Schmidt telescope at Siding
Spring on April 29.37. The comet was near perihelion at 1.7 AU.
A/2012 HD2 [Spacewatch]
This unusual asteroid was discovered at the Steward Observatory, Kitt Peak by Jim Scotti with the 0.9m
Spacewatch reflector on April 18.28. It has a period of around 28
years and perihelion is at
2.5 AU in 2012 September. It has a retrograde orbit, with aphelion at 16 AU. [MPEC 2012-H32, 2012 April 20, 2-day orbit].
The orbit has a Tisserand criterion of -0.94 with respect to Jupiter.
2012 J1 (Catalina)
A 17th magnitude object found in images from the Catalina Sky Survey taken on May 13.44 with the 0.68-m Schmidt
was found to show cometary features by other observers.
The comet reaches perihelion at 3.2 AU in December, when it may be 13th magnitude.
13 observations received so far
suggest a preliminary light curve of
m = 3.2 + 5 log d + [15] log r
2012 K1 (PanSTARRS)
Pan-STARRS discovered a 19th magnitude comet on May 17.55.
Calculations by Hirohisa Sato suggested a more interesting perihelion distance of around 1
au in 2014 August or September, compared to the original MPEC orbit.
This was confirmed by further observations, which gave perihelion at 1.1 au in 2014 August.
By March 2014 it was under visual
observation. By April it was well placed for observation, entering Ursa Major, and
by the end of the month was high in the sky in the early evening. The comet was near its brightest at 7th magnitude in mid
October 2014 and is fading.
398 visual and CCD observations received so far suggest a preliminary light curve of
m = 6.2 + 5 log d + 6.9 log r
2012 K2 (260P/McNaught)
Comet 2005 K3 (P/McNaught) was recovered by M Masek with the 0.3m reflector
at the Pierre Auger Observatory, Malargue on May 15.38. It will reach perihelion in September, 0.22 days earlier than predicted.
2012 K3 (P/Gibbs)
Alex Gibbs discovered a 19th magnitude comet on May 21.35 on images taken during the Mt Lemmon Survey with
the 1.5m reflector.
The comet has a period of around 6.9 years and is at perihelion at 2.1 AU in 2012 September.
2012 K4 (261P/Larson)
Comet 2005 N3 (P/Larson) was recovered by Nick Howes, Giovanni Sostero and Ernesto Guido on May 22.57
using the 2.0-m Faulkes Telescope North. The comet was 20th magnitude. It reaches perihelion
in September, 0.27 days earlier than predicted.
2012 K5 (LINEAR)
LINEAR discovered an 18th magnitude comet on May 25.33. It reached perihelion at 1.1 AU
in November. It reached 8th magnitude at the end of the year, but will fade rapidly. The preliminary orbit has
some similarities with that of 1995 O1 (Hale-Bopp), but this is a completely different
comet. I observed it from a dark site outside Cambridge with 20x80B on December
13.18 it was an easy well-condensed object of 9.9.
27 observations received so far
suggest a preliminary light curve of
m = 9.8 + 5 log d + 6.2 log r, though there are systematic residuals, with the
comet fainter than the mean curve during December. There are some indications that
there might be a discontinuity in the light curve between the end of August and early
September.
2012 K6 (McNaught)
Rob McNaught discovered a 19th magnitude comet on CCD images taken with the 0.5-m Uppsala Schmidt telescope at Siding
Spring on May 27.78. The comet is at perihelion at 3.4 AU in 2013 May.
2012 K7 (262P/McNaught-Russell)
Comet 1994 X1 (P/McNaught-Russell) was recovered by Giovanni Sostero, Nick Howes and Ernesto Guido on May 29.61
using the 2.0-m Faulkes Telescope North. It reaches perihelion in December, 0.02 days earlier than predicted.
2012 K8 (Lemmon)
A distant periodic object discovered during the Mt Lemmon Survey on May 30.35, was shown to have cometary features
by other observers. The comet is at perihelion at 6.5 AU in 2014 August.
2012 K9 (263P/Gibbs)
H Sato recovered 2006 Y2 on May 16.14, though confirmatory images were not taken until June, when the
recovery was announced. The comet was near perihelion at 1.3 AU at recovery.
2012 L1 (LINEAR)
LINEAR discovered a 19th magnitude comet on June 1.33. It will reach perihelion at 2.3 AU in December.
2012 L2 (LINEAR)
LINEAR discovered a 20th magnitude comet on June 1.37. It will reach perihelion at 1.5 AU in 2013 May.
Maik Meyer noted that the preliminary orbit had similarities with the orbit of 1785 A1
(Messier-Mechain). The comet was around 12th magnitude in 2013 January and February.
It may reach 10th magnitude in 2013 April/May but is poorly placed.
612observations received so far suggest a preliminary light curve of
m = 7.3 + 5 log d + 9.8 log r The comet is near its peak brightness.
2012 L3 (LINEAR)
LINEAR discovered a 19th magnitude comet on June 10.31. Although the initial orbit
suggested a small perihelion distance, the latest orbit suggests that it was near
perihelion at 3.0 AU.
2012 L4 (264P/Larsen)
K Sarneczky recovered 2004 H3 on June 15.92 with the University of Szeged 0.60-m Schmidt at Piszekesteto Station
(Konkoly), when the comet was some seven months past perihelion.
The comet has a period of 7.7 years, and returned to perihelion 1.29 days earlier than predicted.
2012 LP26 (Palomar)
An object discovered by the Palomar Transient Factory with the 1.2m Oschin Schmidt on 2012 June 10.19
was found to show cometary features by Jim Scotti in Spacewatch images taken in early 2013 February.
The comet is at perihelion at 6.5 au in 2015 August.
2012 M1 (265P/LINEAR)
H Sato recovered 2003 O2 on June 18.43 using the 0.51-m f/6.8 astrograph at the RAS Observatory, Mayhill.
The comet was near perihelion and has a period of 8.7 years.
2012 N1 (P/Machholz-C)
Prafull Sharma discovered a SOHO comet on July 15, which at the time was thought to be a Meyer group comet. Later
orbit calculations showed that it was a fragment of P/Machholz. Another fragment (B), discovered in SOHO
images on the same day by Liang Liu, has a period of 7.36 years but has not been given a
separate designation. The main comet and fragment C have a period of 5.2 years.
2012 NJ (P/La Sagra)
The La Sagra team reported an asteroid found on images taken on July 13.03, and their positions combined
with those from several other observatories lead to the automatic determination of an orbit, which had a
high inclination and a period of around 50 years. This was published on July 14. Further observations
and indications that the object had a tail lead Gareth Williams to compute a manual orbit for the comet, which was
published on July 18. The comet was around a month past perihelion at 1.3 AU and the period is around 25 years.
2012 O1 (P/McNaught)
Rob McNaught discovered a 19th magnitude comet on CCD images taken with the 0.5-m Uppsala Schmidt telescope at Siding
Spring on July 18.74. The comet was near perihelion at 1.5 AU and has a period of 6.7 years.
2012 O2 (P/McNaught)
Rob McNaught discovered a 19th magnitude comet on CCD images taken with the 0.5-m Uppsala Schmidt telescope at Siding
Spring on July 20.60. The comet was around a month past perihelion at 1.7 AU and has a period of around 6.8 years.
2012 O3 (P/McNaught)
Rob McNaught discovered an 18th magnitude comet on CCD images taken with the 0.5-m Uppsala Schmidt telescope at Siding
Spring on July 23.69. The comet was near perihelion at 1.6 AU and has a period of 9.7 years.
2012 OP (Siding Spring)
This unusual asteroid was discovered during the Siding Spring Survey with the 0.5-m Uppsala Schmidt
on July 16.62. [MPEC 2012-O12, 2012 July 19, 2-day orbit]. The orbit has a Tisserand criterion of -0.76 with respect to Jupiter.
Cometary characteristics were noted in images taken by Hidetaka Sato in 2013 March
using the remote 0.51m telescope at the iTelescope Observatory at Siding Spring, and confirmed
by other amateur observers in 2013 April. The comet has a retrograde orbit with perihelion at
3.6 AU in 2012 December.
2012 P1 (266P/Christensen)
Images taken at Majdanak on August 15 by O. Burhonov with the 1.5m Ritchey-Chretien, with confirmation images taken on
August 28, and measured by Artyom Novichonok recovered 2006 U5 (P/Christensen). The comet will reach perihelion 0.21 days
early compared to predictions on the MPC.
2012 P2 (268P/Bernardi)
David Tholen's team recovered 2005 V1 (P/Bernardi) with the 8.2m reflector at Mauna Kea on August 13.55, when the comet was
24th magnitude. It doesn't return to perihelion until 2015.
2012 Q1 (Kowalski)
Richard Kowalski discovered a 19th magnitude comet during the course of the Mt Lemmon Survey with the 1.5m reflector on
August 28.20. It was near perihelion at 9.5 AU at discovery and has a period of
around 150 years. The CBET
announcing the discovery gave the comet name as LEMMON, whilst the name used here is from the MPEC. The latest orbit
from Hirohisa Sato gives the period as around 130 years, with perihelion at 9.5 AU in 2012
February.
2012 R1 (267P/LONEOS)
2006 Q2 (P/LONEOS) was recovered by V. Nevski, D. Ivanov,
A. Novichonok and I. Kondratenko on images taken on September 11.9 with the 0.4m reflector at the
ISON-Kislovodsk Observatory. Additional images were taken by Robert Holmes on September 12.3 with the 0.61m astrograph
at the Astronomical Research Observatory, Westfield. The comet reached perihelion 0.8 days
late in 2012 August compared to predictions on the MPC.
2012 R2 (269P/Jedicke)
1996 A1 (P/Jedicke) was recovered on images taken on September 11.86 by O Burhonov with the 1.5m Ritchey-Chretien at the
Majdanak Observatory and measured by Artyom Novichonok. Additional observations were made at the Steward Observatory
later in the month, and the recovery allowed identification of further pre-discovery images taken at the Observatory
in 1993 October.
The comet will reach perihelion 0.74 days early in 2014 November compared to predictions on the MPC.
2012 S1 (ISON)
An 18th magnitude comet was discovered with
the 0.4-m f/3 reflector of the International Scientific Optical Network (ISON)
at Kislovodsk Observatory, Russia, by observers Vitali Nevski and Artyom Novichonok
. Following further positions taken by various astrometrists, including Peter Birtwhistle, the preliminary
orbit allowed pre-discovery detections from the Mt Lemmon survey in 2011 December and Pan-STARRS in 2012 January.
The comet has a perihelion at 0.012 AU in 2013 November, when it will briefly be a brilliant object.
It passed within 0.1 AU of Mars on 2013 October 3. It is a Sun-skirting comet.
Gareth Williams notes on MPEC 2012-T08 [2012 October 3] that
The "original" and "future" barycentric values of 1/a are
(1/a)_orig = +0.000058, (1/a)_fut = +0.000008.
The small "original" value suggests that this comet has not made a previous
visit to the inner solar system, and is a "new" comet from the Oort cloud.
The comet emerged from solar conjunction in 2013 September as an 11th magnitude object in the morning
sky, as seen by Juan Jose Gonzalez on September 1. By early October it had brightened to
10th magnitude, but it was clear that the comet was not brightening very quickly. I
glimpsed it in late October in 25x100B at about magnitude 9.5. Reports on November 6
suggested a possible increase in brightness and change in appearance, however nothing
further developed. Tail rays did form, but this was a solar effect. A tail
disconnection event occurred on November 13. Dynamical tail activity is likely to
increase as the comet approaches the Sun and these effects should not be confused with
activity on the comet nucleus. Professional observers suggested a rapid increase in
gaseous output between November 12 and 13. The comet became more active on November 14, developing
a near stellar appearance and reaching magnitude
6. It brightened further to 5th magnitude by November 15, but has remained near this
brightness according to ground based observers. German scientists suggest that
the November 12 to 14 sequence was caused by a minor
fragmentation event, which also created coma wings. General tail activity also
increased, with a disconnection event seen on November 13, but beware of confusing solar effects with events on the
comet nucleus. I observed it on November 19.25 when it was 5.3 in 20x80B. Its absolute
magnitude was close to or fainter than the Bortle survival limit, and the comet did not survive
long after perihelion.
The
comet entered the
SOHO C3 field
on November 27 and continued brightening until some 12 hours prior to perihelion, when it
was around -2. It then faded. It showed two tails, the longest over 4° long.
It was also visible in the STEREO H1A field. The brightest portion
of the comet became elongated. A tail feature survived perihelion in the C2 field, and then the comet reappeared
as a bright, well condensed object in the C3
field on November 29. On November 30 the comet appeared
very diffuse and significantly fainter in the C3 field and this progressed further as the
comet left the field. The transit through the C3 field is shown in this movie.
A possible explanation is that the intense solar wind and
radiation
when very near the Sun stripped
all material from the nucleus, causing the fade. As the thermal wave penetrated the
bare nucleus it disintegrated, leaving a ghostly remnant.
The remnant was detected from the
ground by
Juan Jose Gonzalez on December 7.26, when it was 7.2 in his 200mm SCT. He also
noted faint tails. The remnant will be visible in the
evening sky from mid month, when any tail might be at its greatest length. However the tails seen in C3
did not lie along the
radius vector and the tails seen by Juan Jose are only 0.3° long. The debris rapidly moves north,
passing five degrees from M13 on December 22 and 4° from the pole in early January 2014.
Speculation and hysteria about the comet thrived throughout the apparition. Shortly
after discovery some in the media suggested that the comet would be
12 times brighter than the full moon and therefore visible in daylight. The evidence
to date suggests otherwise, however the behaviour of comets is unpredictable and a sudden rejuvenation
is not impossible. One analyst suggested for several weeks that the light curve had flattened to such
an extent that the comet's complete disintegration was imminent, but the comet continued
to slowly brighten. Image flaws were interpreted as effects in the comet. There was also speculation (NASA Science News) that the comet could cause
a meteor shower, or as the dust would be exceedingly fine, a display of noctilucent clouds
around 2014 January 12. On November
20, BBC Radio 4 News had a short item at 06:50 which had at least three errors:
Contrary to what their science correspondent said, 2012 S1 will not get higher in the sky
over the next week, Mars is not in Virgo and comets did not form in the Oort Cloud.
The BBC TV lunchtime news on November 28 presented several misleading simulations without
identifying them as such. The comet was never easily visible to the general public, so be prepared to disappoint your
non-astronomer friends.
See also 2012 S1 (ISON).
126 electronic and visual observations received until (December 20) suggest a preliminary aperture corrected light curve of
m = 7.3±0.1 + 5 log d + 6.3±0.3 log r Internet reports
showed considerable confusion over whether it was brightening or not, but in general the
comet did not deviate much from the mean light curve until the final fade began.
2012 S2 (P/La Sagra)
The observing team at OAM Observatory, La Sagra (S. Sanchez, J. Nomen, M. Hurtado,
J. A. Jaume, W. K. Y. Yeung, P. Rios, F. Serra and T. Valls) using the 0. 45-m
f/2. 8 reflector discovered an 18th magnitude comet on September 23.07. It was at perihelion at 1.4 AU in mid August
and has a period of 9.3 years.
2012 S3 (PanSTARRS)
Pan-STARRS discovered a 20th magnitude comet on September 27.30. It will reach perihelion at
2.3 AU in 2013 August.
2012 S4 (PanSTARRS)
Pan-STARRS discovered a 19th magnitude comet on September 28.41. It will reach perihelion at
4.3 AU in 2013 June.
2012 S5 (270P/Gehrels)
1997 C1 (P/Gehrels) was recovered on images taken on September 25.38 by the Mt Lemmon Survey with the 1.5-m reflector.
The comet will reach perihelion 1.74 days later in 2013 July compared to predictions on the MPC.
2012 SB6 (P/Lemmon)
An asteroidal object of 19th magnitude found during the Mt Lemmon Survey with the 1.5m reflector on September 17.42, was later seen to have
cometary characteristics. Images taken shortly before discovery by the Catalina Sky Survey were also found. The comet
was
near perihelion at 2.4 AU and has a period of around 7.7 years.
2012 T1 (282P/PanSTARRS)
Pan-STARRS discovered a 21st magnitude comet on October 6.53. Confirmation was made by
astrometrists from the T3 group. Archival observations from Pan-STARRS were found from 2011 July.
The comet was at perihelion at 2.4 AU in 2012 September and has a period of around 5.6 years. It is a
Main Belt Comet.
On 2013 January 26 Rob Matson found images of the comet in frames taken by NEAT with
the Palomar 1.2m Schmidt on 2001 December 9.
Although the comet has been numbered, the latest MPC does not give it a name.
2012 T2 (P/PanSTARRS)
Pan-STARRS discovered a 21st magnitude comet on October 10.36. Confirmations included measurements by
several amateur astrometrists.
The comet was at perihelion at 4.9 AU in 2011 August and has a period of around 13 years. It is a
Main Belt Comet. Hirohisa Sato provides an improved orbit which has perihelion at 4.8 AU in 2013 April and a period
of around 14 years.
2012 T3 (P/PanSTARRS)
Pan-STARRS discovered a 21st magnitude comet on October 10.35. Confirmations included measurements by
several amateur astrometrists.
The comet was at perihelion at 2.4 AU in 2012 April and has a period of around 15 years.
2012 T4 (McNaught)
Rob McNaught discovered an 18th magnitude comet on CCD images taken with the 0.5-m Uppsala Schmidt telescope at Siding
Spring on October 13.43. The comet was near perihelion at 2.0 AU.
2012 T5 (Bressi)
Terry Bressi discovered a 19th magnitude comet on October 14.42 on CCD images taken with the 0.9m
Spacewatch reflector at Kitt Peak. The comet reaches perihelion at 0.3 AU in 2013
February, when it may be 8th magnitude, however its behaviour suggests that it may be
fragmenting. It brightened to 9th magnitude and became well condensed in early
February, but then faded to 10th magnitude. It is intrinsically faint. It will be too far south for UK observers prior to perihelion,
and perhaps 11th magnitude when it emerges from solar conjunction in March. No
observations had been reported by April 9.
13 observations received so far suggest a preliminary light curve of
m = 11.3 + 5 log d + 5.3 log r
2012 T6 (Kowalski)
Richard Kowalski discovered a 17th magnitude comet on October 16.46 on CCD images taken
during the Mt Lemmon Survey with the 1.5m reflector. Pre-discovery images were found in
Catalina Sky Survey and LINEAR data from the day before. The comet was at perihelion at
1.8 AU in August. It has a period of around 50 years.
2012 T7 (P/Vorobjov)
Tomas Vorobjov discovered a 20th magnitude comet on October 15.37 on CCD images taken with
the 0.81m f/7 Ritchey-Chretien at the Mount Lemmon SkyCenter. The comet is at perihelion at
3.9 AU in 2013 January and has a period of 12.5 years. As the orbit improved,
pre-discovery images taken by the Mt Lemmon Survey in 2011 November were found. Rob
Matson then found and measured images taken by NEAT in 2000 December and 2001 January.
2012 TK8 (P/Tanagra)
A 20th magnitude asteroidal object discovered at the Tanagra Observatory on October 6.32 by
Michael Schwartz and Paulo Holvorcem was subsequently shown to be a comet.
It reaches perihelion at 3.1 AU in 2013 May and has a period of around 8.6 years.
2012 TB36 (271P/van Houten-Lemmon)
An asteroidal object of 21st magnitude found during the Mt Lemmon Survey with the 1.5m reflector on September 17.35, was later
seen to have cometary features.
Immediately following publication of the MPEC announcing the discovery, Maik Meyer suggested an identity with
P/van Houten (1960 S1), and Gareth Williams then computed a linked orbit. The comet is
at perihelion at 4.2 AU in 2013 July and has a period of 18 years. Jovian perturbations have increased the period
from 15.8 years in 1960, and increased the perihelion distance from 3.9 AU. The comet was only observed for
a month in 1961 and the date of perihelion was 6 days out, and the period 70 days too short.
A/2012 TA53 [Mt Lemmon]
This unusual asteroid was discovered the Mt Lemmon Survey with the 1.5-m reflector
on October 8.24. [MPEC 2012-T38, 2012 October 10, 2-day orbit]. It has an orbit with a
period of around 6.1 years and perihelion was at 1.4 AU in 2012 September. It can approach Jupiter within
0.22 AU and the Earth to 0.42 AU.
The orbit has a Tisserand criterion of 2.85 with respect to Jupiter.
A/2012 TL139 [PanSTARRS]
This unusual asteroid was discovered by the Pan-STARRS 1 1.8m Ritchey-Chretien reflector
on October 9.56. [MPEC 2012-T75, 2012 October 13, 4-day orbit]. It has a retrograde orbit with a
period of around 200 years and perihelion was at 3.5 AU in 2012 October.
The orbit has a Tisserand criterion of -2.00 with respect to Jupiter.
A/2012 TO139 [Mt Lemmon]
This unusual asteroid was discovered the Mt Lemmon Survey with the 1.5-m reflector
on October 11.25. [MPEC 2012-T78, 2012 October 13, 2-day orbit]. It has an orbit with a
period of around 4.8 years and perihelion was at 0.2 AU in 2012 July. It can approach Jupiter within
0.4 AU and the Earth to 0.0007 AU.
The orbit has a Tisserand criterion of 2.42 with respect to Jupiter.
2012 U1 (PanSTARRS)
Pan-STARRS discovered a 21st magnitude comet on October 17.39. It will reach perihelion at
5.3 AU in 2014 July.
2012 U2 (P/PanSTARRS)
Pan-STARRS discovered a 19th magnitude comet on October 20.35. It reached perihelion at 3.5 AU in 2012 August
and has a period of around 20 years. The latest orbit by Hirohisa Sato gives
perihelion at 3.6 AU in 2012 December.
2012 US27 (P/Siding Spring)
This unusual asteroid was discovered during the Siding Spring Survey with the 0.5-m Uppsala Schmidt
on October 17.58. [MPEC 2012-U49, 2012 October 20, 2.5-day orbit]. It has a
period of 12 years and perihelion was at 1.8 AU in 2013 February.
The orbit has a Tisserand criterion of 2.20 with respect to Jupiter.
In November, further observations at Siding Spring showed that it had cometary features and it was reclassified.
A/2012 UU27 [LINEAR]
This unusual asteroid was discovered during the LINEAR Survey with the 1.0-m reflector
on October 16.31. [MPEC 2012-U52, 2012 October 20, 3-day orbit]. It has a
period of around 9.3 years and perihelion is at 1.6 AU in 2012 December.
The orbit has a Tisserand criterion of 2.00 with respect to Jupiter and approaches
to within 0.5 AU of the planet.
A/2012 US136 [Mt Lemmon]
This unusual asteroid was discovered the Mt Lemmon Survey with the 1.5-m reflector
on October 21.09. [MPEC 2012-U84, 2012 October 24, 3-day orbit]. It has an orbit with a
period of around 9.6 years and perihelion was at 0.38 AU in 2012 September. It can approach the Earth to 0.0850 AU.
The orbit has a Tisserand criterion of 1.61 with respect to Jupiter.
2012 V1 (PanSTARRS)
Pan-STARRS discovered a 20th magnitude comet on November 3.34. It will reach perihelion at 2.1 AU in 2013 July.
2012 V2 (LINEAR)
LINEAR discovered a 19th magnitude comet on November 5.08, at relatively high northern declination.
It will reach perihelion at 1.5 AU
in 2013 August. It is poorly placed at perihelion and then moves
to high southern declination.
The comet was spotted by Vladimir Bezugly in SWAN imagery in 2013 July,
suggesting that it was at least two magnitudes brighter than expected. It become visible to southern hemisphere observers in mid
August, when it was about 9th magnitude and was still this bright in early October.
It is now fading, with recent reports giving a magnitude around 10.5.40 electronic and visual observations received so far suggest a preliminary uncorrected light curve of
m = 5.3 + 5 log d + 10.2 log r
2012 V3 (272P/NEAT)
2004 F1 (P/NEAT) was recovered on images taken on November 12.49 by the Mt Lemmon Survey with the 1.5-m reflector.
The comet will reach perihelion 1.0 days earlier in 2013 February compared to predictions on the MPC.
2012 V4 (273P/Pons-Gambart)
Rob Matson discovered a comet in SWAN images taken on November 7, 10, 11, 13 and 19 on November 29, and this was quickly
confirmed in ground based images taken by Terry Lovejoy on November 29.40. The comet is around 10.5 in his images.
Maik Meyer and independently, Gareth Williams, suggested an identity with D/Pons-Gambart (1827 M1), which itself
was linked to a comet seen in 1110 in China and Korea. At the 1827 return the comet had an absolute
magnitude of 7, whereas the preliminary estimate for the current return is 9.5. A possible explanation, first suggested
by Jakob Cerny, is that the
comet has a linear light-curve and is brightest after perihelion. The comet
reached perihelion at 0.81 AU on December 19 and is in a retrograde orbit with a period of 188 years. Despite the computation
of an orbit based on the SWAN data, the name SWAN has not been incorporated into the comet name.
Gareth Williams notes on MPEC 2012-X14 [2012 December 5] that
These orbital elements, like those on MPEC X02, assume that
C/2012 V4 is a return of D/1827 M1 (Pons-Gambart). Whereas that earlier
orbit assumed that there were two missed returns between 1827 and 2012,
the above orbit assumes no missed returns. The much longer period
was suggested by the current observations not being well fit to
orbital periods of ~62 and ~94 years. Noting the obvious discordance
between the two E27 observations on Nov. 29, the semi-major axis fit by
the 2012 observations alone is at least 26 AU, discounting the two-
and three-missed revolution solutions. At the present time, the solution
presented here is believed to be correct, as the fit of the bulk of the
1827 observations (known to be grossly inaccurate by modern standards) is
far better than earlier attempts with shorter orbital periods. There is
a slight systematic trend in the current residuals, which may be related to
observation weighting. Continued observation is clearly desirable.
It emerged from conjunction towards the end of January as an 9th magnitude object. CCD imagers may be able to get
it when conditions are impossible for visual observers (eg twilight, low altitude), and Richard Miles
demonstrated this with images taken from the UK on December 5.
2012 WX32 (274P/Tombaugh-Tenagra)
An asteroid was discovered at the Tenagra II observatory by Michael Schwartz and Paulo Holvorcem with the 0.41m astrograph on
November 27.50. On December 3 they noted cometary features during follow-up
observations and these were confirmed by other observers.
Syuichi Nakano then linked the comet to asteroid 2003 WZ141 which was observed
by Spacewatch and LINEAR in 2003, and to a comet discovered by Clyde Tombaugh in 1932 on plates taken in 1931 January
and which was originally logged as asteroid 1931 AN. Details of the chain of events surrounding 1931 AN are given by
Gary Kronk in Volume 3 of Cometography. Gareth Williams then computed an orbit linking the three apparitions.
The new orbit is very different to that calculated for 1931 AN, largely on
account of large errors in the position from the first of its three plates. The new orbit has the 1931 perihelion at 2.4 AU
cf the 0.9 AU calculated from four positions, and is periodic rather than parabolic. The current period is 9.1 years, and this is the 10th return, reaching
perihelion in 2013 February. It seems likely that the comet may have outburst in 1931, as it was estimated at 12th magnitude
on the plates, some 6 magnitudes brighter than suggested by the ephemeris. Alternatively it may have
a linear type light curve.
2012 WA34 (P/Lemmon-PanSTARRS)
An asteroid was discovered during the Mt Lemmon survey on November 26.40 and by PanSTARRS on 2013 January 7.24
when cometary features were noted. Additional observations from PanSTARRS from 2011 September were then found.
It has a period of 10.5 years, with perihelion at 3.2 AU in 2013 January.
A/2012 WJ4 [LINEAR]
This unusual asteroid was discovered during the LINEAR Survey with the 1.0-m reflector
on November 19.13. [MPEC 2012-W35, 2012 November 23, 3-day orbit]. It has a
period of around 5.8 years and perihelion is at 1.3 AU in 2012 December.
The orbit has a Tisserand criterion of 2.83 with respect to Jupiter and approaches
to within 0.5 AU of the planet.
2012 X1 (LINEAR)
LINEAR discovered a 19th magnitude comet on December 8.39. It reached perihelion at
1.6 AU in 2014 February, when
it was expected to reach 12th magnitude. On October 20 Hidetaka Sato imaged the comet in
outburst at 8.5, some 5 magnitudes brighter than expected. Richard Miles suggested that the outburst
was similar to
those seen in 29P/Schwassmann-Wachmann, in which case the expectation was an expanding coma
becoming more diffuse, with a slow decline in brightness as the outer coma was lost to the
background. Astronomy Now provided a commentary.
Images (eg by Damian Peach on January 11) suggested that it
became a
very normal looking object, and stayed at 8th magnitude for several
months. After perihelion it showed a perfectly ordinary light curve, remaining
steady in brightness into late April, then gradually fading more quickly.
Using 151 visual observations post perihelion suggests a preliminary light curve of
m = 4.5 + 5 log d + 10.9 log r
2012 X2 (PanSTARRS)
Pan-STARRS discovered a 19th magnitude comet on December 12.53. It reaches perihelion at 4.4 AU in 2013 October.
The latest orbit gives it a period of about 90
years, with perihelion at 4.7 AU in 2013 March.
A/2012 XE55 [LINEAR]
This unusual asteroid was discovered during the LINEAR Survey with the 1.0-m reflector
on December 6.39. [MPEC 2012-X41, 2012 December 10, 4-day orbit]. It has a
period of around 6.2 years and perihelion is at 1.3 AU in 2013 January.
The orbit has a Tisserand criterion of 2.64 with respect to Jupiter and approaches
to within 0.3 AU of the planet.
A/2012 XF112 [PanSTARRS]
This unusual asteroid was discovered by the Pan-STARRS 1 1.8m Ritchey-Chretien reflector
on December 10.46. [MPEC 2012-X74, 2012 December 13]. It has an orbit with a
period of 5.7 years and perihelion is at 1.2 AU in 2013 January. It can approach Jupiter within
0.1 AU and the Earth to 0.19 AU.
The orbit has a Tisserand criterion of 2.83 with respect to Jupiter.
A/2012 XM134 [Mt Lemmon]
This unusual asteroid was discovered the Mt Lemmon Survey with the 1.5-m reflector
on December 13.18. [MPEC 2012-X93, 2012 December 14, 1-day orbit]. It has an orbit with a
period of around 6.2 years and perihelion was at 1.0 AU in 2012 November. It can approach the Earth to 0.0382 AU
and Jupiter to 0.3 AU.
The orbit has a Tisserand criterion of 2.68 with respect to Jupiter.
2012 Y1 (LINEAR)
LINEAR discovered a 19th magnitude comet on December 18.26. It was at perihelion at 2.0
AU in 2013 January.
2012 Y2 (275P/Hermann)
Pan-STARRS discovered a 20th magnitude comet on December 22.61. Following posting on the NEOCP and confirmation by
T. Linder and R. Holmes at Cerro Tololo with the 0.41-m f/11
Ritchey-Chretien, Gareth Williams and Maik Meyer linked it to 1999 D1 (P/Hermann).
The comet was near perihelion at 1.6 AU and has a period of around 14 years.
2012 Y3 (McNaught)
Rob McNaught discovered a 15th magnitude comet on CCD images taken with the 0.5-m Uppsala Schmidt telescope at Siding
Spring on December 30.58. The comet was at perihelion at 1.8 AU in August, when it might have been around 13th magnitude.
It has a period of around 150 years. This was the 100th comet discovered by the Siding Spring search programme.
A/2012 YN3 [Catalina]
This unusual asteroid was discovered the Catalina Sky Survey with the 0.68-m Schmidt
on December 20.32. [MPEC 2012-Y22, 2012 December 23, 3-day orbit]. It has an orbit with a
period of around 6.5 years and perihelion was at 1.3 AU in 2012 December. It can approach the Earth to 0.4 AU
and Jupiter to 0.2 AU.
The orbit has a Tisserand criterion of 2.74 with respect to Jupiter.
A/2012 YO6 [PanSTARRS]
This unusual asteroid was discovered by the Pan-STARRS 1 1.8m Ritchey-Chretien reflector
on December 22.40. [MPEC 2012-Y36, 2012 December 29, 7-day orbit]. It has a retrograde orbit with a
period of about 15 years and perihelion is at 3.3 AU in 2012 July.
The orbit has a Tisserand criterion of 0.30 with respect to Jupiter.
A/2012 YE8 [Mt Lemmon]
This unusual asteroid was discovered the Mt Lemmon Survey with the 1.5-m reflector
on December 21.52. [MPEC 2013-A13, 2013 January 4, 13-day orbit]. It has a retrograde orbit with a
period of around 19 years and perihelion is at 3.8 AU in 2013 August. It can approach Saturn to 1.1 AU.
Aphelion is at 10.6 AU. The orbit has a Tisserand criterion of -0.76 with respect to Jupiter.
Ephemerides of current comets are available on the CBAT
ephemeris page and positions of newly discovered comets are on the
NEO confirmation page.
More information on LINEAR. A list of comets
discovered by selected search programs.
The Northumberland refractor
is the telescope that was used in the search for Neptune.
It now has a 0.30-m f20 doublet lens which gives a stellar limiting magnitude of around
15 at the zenith on good nights.
The Thorrowgood refractor was
built in 1864 and has a 0.20-m f14 doublet lens.
Published by Jonathan Shanklin. jds@ast.cam.ac.uk
126 electronic and visual observations received until (December 20) suggest a preliminary aperture corrected light curve of
m = 7.3±0.1 + 5 log d + 6.3±0.3 log r Internet reports
showed considerable confusion over whether it was brightening or not, but in general the
comet did not deviate much from the mean light curve until the final fade began.
