BAA Comet Section : Comets discovered in 2008

Updated 2012 June 1

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.

Processed observations of 2008 comets [updated 2009 January] 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.

Brian Marsden notes in MPEC 2008-F33 [2008 March 26]:

R. Kracht suggested the identity of the Kracht group comets C/2002 Q8 and C/2008 E4 on the basis of the MPEC 2002-Q46 measurements of the former and his own measurements of the latter. He gave the previous perihelion date T = 1997 Feb. 14.9 but was unable to locate the comet on C2 images from that time. A linked orbit was computed by Brian Marsden and gives a period of 5.52 years.

Brian Marsden notes in MPEC 2008-L29 [2008 June 6]:

R. Kracht suggests that the Kracht-group comet C/2008 G6 is a return of comet C/2002 S11 (cf. MPEC 2002-T75).

Rainer Kracht also suggests that a comet he discovered on June 11 may be linked to 2002 R5, with a previous return on 1996 November 25.
Brian Marsden notes in MPEC 2008-O23 [2008 July 24]:

Comets C/2008 L6 and L7 appear to be members of the "Kracht 2" Group, and R. Kracht suggests that they represent a return of comet C/2002 R5 (cf. MPEC 2002-S35). The 15-deg shift in the line of nodes actually supports the likely correctness of this linkage, as it is consistent with the comet's passage within 1.1 AU of Jupiter in January 2007.

Brian Marsden notes in MPEC 2008-P60 [2008 August 12]:

R. Kracht suggests that the Kracht-group comet C/2008 N4 is a return of C/2002 S7, principally on the assumption that C/2002 S7 was itself a return of one of C/1996 X5, C/1996 X4 or C/1996 X3 (see MPEC 2006-C49). The derived orbit links C/2002 S7 and C/2008 N4. This gravitational linkage leads to a previous perihelion time of T = 1996 Dec. 6.00, earlier by a few hours than the values for the aforementioned 1996 comets.

Following up on MPEC 2008-P60, R. Kracht has suggested that the correct linkage for C/2002 S7 = C/2008 N4 is with C/1996 X3, on the assumption that the comet was affected by small nongravitational forces (see also MPEC 2009-H56). The nongravitational linkage, with parameters A1 = 0.0000, A2 = +0.0027, is based on Kracht's work.

Brian Marsden notes in MPEC 2008-S67 [2008 September 26]:

The Kracht-group comet C/2008 R7 is likely to be a return of one of the members of September 2002. R. Kracht himself suggests identity with C/2002 S5. Identity with C/2002 S11 is a distinct possibility, although this comet was associated with C/2008 G6 on MPEC 2008-L29. The published orbit links C/2008 R7 with C/2002 S4.

For further information on the discovery of these objects see this year's SOHO discoveries.

R. Kracht has suggested the identity of the Marsden-group comet C/2008 A3 with C/2002 R1 (cf. MPEC 2002-R57). The linkage (all the observations having been made with the C2 coronagraph), by Brian Marsden, yields for the previous perihelion passage T = 1997 Apr. 19.0.

Brian Marsden notes in MPEC 2009-F81 [2009 March 26] that Rainer Kracht suggested a linkage between 2003 Q1 and 2008 X6, and between 2003 Q6 and 2008 Y11. He further notes that the extrapolated orbits are very similar with perihelion around 1998 April 28:

These results suggest that the comets separated from each other around that time, although Kracht remarks that there is no trace of them then, at least in C2 data he inspected from 1998 Apr. 25. The dynamical situation is similar to that involving the likely linkages C/1999 J6 = 2004 V9 and C/1999 N5 = 2005 E4, where there is a comparable difference between the elements extrapolated back to 1993 (see MPEC 2005-E87).

Karl Battams has put together a probable family tree for the fragments.

For further information on the discovery of these objects see this year's SOHO discoveries.

Brian Marsden notes on MPEC 2008-E58 [2008 March 6] that

The parabolic orbit for C/2008 D3 satisfies 52 (10 from HI1-A, 12 from COR2-A and 30 from COR2-B spanning Feb. 20.66-22.21 UT, during which time the comet's heliocentric distance decreased from 0.154 to 0.032 AU) of the 97 observations shown with residuals no more than 15" in either coordinate. T and q are good to the quoted precision, while the uncertainties in the angular elements are substantially less than 0.1 deg. Elliptical orbit computations give e = 0.9998 and 120 < P < 180 years, results that are likely to be somewhat too small for a member of the Kreutz group. The STEREO-A and STEREO-B spacecraft were respectively 0.38 and 0.41 AU from the earth, the line between them subtending an angle of 155 deg at the earth.

2008 O1 (SOHO) was visible in the total eclipse image taken by Miloslav Druckmuller (Brno University of Technology), Peter Aniol and Vojtech Rusin. Professor Druckmuller also provides a spectacular false colour image with frames taken 20 minutes apart in Novosibirsk (10:45) and Mongolia (11:04). The earlier image appears distinctly non-stellar. This is the first ground based imaging of one of the SOHO Kreutz comets.

I was able to locate it on October 22.8, when it 7.8 in 20x80B. Although well condensed it was a difficult object due to its low altitude.

78 observations received so far suggest an uncorrected preliminary light curve of m = 5.8 + 5 log d + 9.6 log r

Brian Marsden notes on MPEC 2008-F02 [2008 March 17] that

The "original" and "future" barycentric values of 1/a are +0.000105 and +0.000374 (+/- 0.000016) AU^-1, respectively.

Brian Marsden notes on MPEC 2008-H03 [2008 April 17] that

The "original" and "future" barycentric values of 1/a are +0.000017 and +0.000481 (+/- 0.000061) AU^-1, respectively.

The rapid rise in brightness described by the discoverers is not entirely consistent with the preliminary orbit. Subsequently published discovery magnitudes are however fainter, and visual observations suggest that the comet was around 13th magnitude. The comet reached perihelion in mid April at 1.3 AU. Visual observations in March suggested that the comet was around 10th magnitude, but was quite large and diffuse. By late April it had become poorly placed for easy observation from the UK and is now fading.

33 observations received so far suggest a preliminary light curve of m = 6.9 + 5 log d + 21.3 log r.

Observations in ICQ format, last observation 2008 April, updated 2008 May.

Further observations showed that the comet has a period of around 35 years, reaching perihelion at 4.8 AU in August.

Brian Marsden notes on MPEC 2008-K06 [2008 May 17] that

The "original" and "future" barycentric values of 1/a are +0.000253 and +0.000852 (+/- 0.000049) AU^-1, respectively.

Peter Jenniskens suggests that it may be a major fragment of the object that formed the kappa Cygnids meteor shower. Work with Jeremey Vaubaillon suggests a formation date for the shower between 4000 and 1600 BC.

Early orbit computations by Hirohisa Sato allowed the possibility of an elliptic orbit, with a period of around 200 years and this was subsequently confirmed, the latest orbit having an eccentricity of 0.95 and a period of around 350 years.

Orbit computation by Hirohisa Sato suggested that the orbit was a long period ellipse, and the latest orbit gives a period of around 2000 years. The comet could reach 11th magnitude around the time of perihelion.

Brian Marsden notes on MPEC 2008-N38 [2008 July 15] that

The "original" and "future" barycentric values of 1/a are +0.006961 and +0.006426 (+/- 0.000017) AU^-1, respectively.

37 observations received so far suggest a preliminary light curve of m = 5.1 + 5 log d + 17.6 log r

Observations in ICQ format, last observation 2008 June, updated 2008 July.

Orbit computation by Hirohisa Sato suggested that the orbit was of short period. The comet was at perihelion at 2.41 AU in late March and has a period of 6.5 years. It will fade. It is a member of the "Main Belt Comet" family.

Images obtained by Michal Jaeger on May 28 show the comet as a large, faint patch without central condensation. He suggests that the comet may have disintegrated. The most recent astrometric observations are from May 25.

Brian Marsden notes on MPEC 2008-N41 [2008 July 15] that

The "original" and "future" barycentric values of 1/a are +0.014802 and +0.014657 (+/- 0.000076) AU^-1, respectively.

Brian Marsden notes on MPEC 2008-N42 [2008 July 15] that

The "original" and "future" barycentric values of 1/a are +0.000031 and -0.000474 (+/- 0.000050) AU^-1, respectively.

It was refound as 2008 JL14, also at Kitt Peak. The linked orbit has a period of 5.0 years, with perihelion at 1.28 AU in mid December 2007. The earth MOID is 0.46 AU. [MPEC 2008-O29, 2008 July 26]

The identification is by R. Kracht. The observations, all obtained with the LASCO C2 coronagraph, are on MPEC 2006-L20, 2004-M42 and 2008-O16. The The object passed 0.058 AU from the earth on 2000 Jan. 13, 0.032 AU from Mars on 2004 May 19 and 1.17 AU from Jupiter on 2003 Feb. 1.

Brian Marsden notes on MPEC 2008-O45 [2008 July 29] that further [astrometric] observations of this comet are very desirable.

Brian Marsden notes on MPEC 2008-R70 [2008 September 15] that

The "original" and "future" barycentric values of 1/a are +0.001193 and +0.001252 (+/- 0.000033) AU^-1, respectively.

Brian Marsden notes on MPEC 2008-Q07 [2008 August 18] that the orbit indicates a very close approach to Jupiter (to 0.1 AU) in 2003 and that the previous perihelion distance was around 5.8 AU.

Brian Marsden notes on MPEC 2008-U16 [2008 October 20] that

The "original" and "future" barycentric values of 1/a are +0.000132 and +0.000222 (+/- 0.000047) AU^-1, respectively.

Brian Marsden notes on MPEC 2008-U17 [2008 October 20] that

The "original" and "future" barycentric values of 1/a are +0.001786 and +0.001851 (+/- 0.000023) AU^-1, respectively.

Michel Ory is a Swiss amateur astronomer and president of the Société jurassienne d'astronomie, which has a well equipped observatory in the foothills of the Jura.

The comet passed 0.3 AU from Jupiter in November 2005, before which the perihelion distance was a little larger.

Brian Marsden notes on MPEC 2009-G07 [2009 April 3] that

The "original" and "future" barycentric values of 1/a are +0.000283 and +0.000744 (+/- 0.000006) AU^-1, respectively.

Few observations of the comet are being made, but those available suggest a periodic orbit of 4.5 years, with perihelion at 1.8 AU in July.

Akimasa Nakamura notes that it has the smallest aphelion distance (3.7 AU) of any comet and Carl Hergenrother notes:

P/2008 R1 (Garradd) is the latest example of a 'Main-Belt Comet' or an 'Activated Asteroid'.

Current theory suggests that traditional comets formed between 5 AU and the edge of the proto-solar disk. Most of these proto-comets were absorbed into the rapidly growing outer planets. As the outer planets migrated, the remainder of the proto-comet population was either thrown out of the solar system, thrown into the Oort Cloud, or trapped in the Kuiper Belt / Scattered Disk Population. These populations now give us our usual assortment of comets, the Jupiter-Family Comets, Halley-types and Long-Period Comets.

The Main-Belt Comets are volatile-rich bodies that either formed in the asteroid belt or were trapped there during the era of planet migration. One theory, the Nice theory, suggests that all carbonaceous asteroids (C,B,D,F,G type asteroids) in the Main Belt and Jupiter Trojan population originally formed between 5 AU and the outer edge of the Kuiper Belt. This means that objects such as Ceres and Pallas are related to Kuiper Belt Objects and were trapped in stable orbits much closer to the Sun.

There are at least 5 known Main Belt Comets: 133P/Elst-Pizarro 176P/LINEAR P/2005 U1 (Read) P/2008 J2 (Beshore) P/2008 R1 (Garradd)

It is possible that many asteroids in the outer part of the Main Belt are capable of occasional cometary activity.

There are also objects on Near-Earth asteroid orbits that more likely originated in the Main Belt rather than from the Kuiper Belt or Oort Cloud, such as: 2P/Encke 107P/Wilson-Harrington (3200) Phaethon

The main point is there may no longer be a clear cut boundary between comets and asteroids. Many objects in the solar system have moved a long way from where they originally formed.

Henry Hsieh's research really expanded our knowledge of these objects. He has a good website devoted to his work.

The comet was observed in 2010, 2011 and 2012, so was not given a designation for the 2013 return, which has perihelion at 1.8 AU in January, with a period of 4.5 years.

The comet passed 0.67 AU from Jupiter on 1960 March 24.

An orbit by Syuichi Nakano, published in 2004, linked the comet with asteroid 1929 WW, however some of the 1929 positions were unsatisfactory. These have now been re-measured, and the identification confirmed, indeed the 1929 object does appear cometary on closer examination. Perihelion was on 1930 January 8.7.

Maik Meyer, Limburg, Germany, suggested that the comet was identical to comet 1896 R2 (D/Giacobini), which had not been seen since January 1897 and for which a prediction by Nakano gave T = 2008 September 9.89. This prediction was included in the BAA listing for the comets expected in 2008. Richard Buckley made a prediction for its return in 1975, which was published in the Journal in 1977. The identity has been confirmed by Nakano, who notes that the comet has made 17 revolutions and passed only 0.51 AU from the earth on 1962 September 9 and 0.81 AU from Jupiter on 1992 January 14. The linked orbit shows that the comet was at perihelion on September 10.08.

The fact that the comet was not recovered on previous occasions, and that it is now past its brightest for this return, suggests that the comet might have been found in outburst, although it was expected to reach 11th magnitude based on the discovery apparition. Further confirmation of this suggestion was made when Douglas T. Durig and K. N. Hatchett, Cordell-Lorenz Observatory, Sewanee, Tennassee, USA reported observations of two additional components, which have perihelion times differing by Delta(T) = +0.014 and +0.133 day.

Brian Marsden published a linked orbit on MPEC 2008-S82 [2008 September 27] and notes:

The object passed 1.29 AU from Jupiter on 2003 October 14.

Brian Marsden notes on MPEC 2008-X59 [2008 December 8] that

The "original" and "future" barycentric values of 1/a are -0.000501 and -0.000490 (+/- 0.000507) AU^-1, respectively.

An image taken by Martin Mobberley on 2009 January 18.8 suggested that the comet was about 12th magnitude. It had faded below 14th magnitude by 2009 December.

Brian Marsden notes on MPEC 2008-X60 [2008 December 8] that

The "original" and "future" barycentric values of 1/a are -0.000018 and +0.000245 (+/- 0.000043) AU^-1, respectively.

56 observations received so far suggest a preliminary light curve of m = 6.5 + 5 log d + 11.9 log r

The comet was the first one to be discovered photographically, by E E Barnard from the Mount Wilson Observatory on 1892 October 12. It was very faint and only followed until December 8. The apparition was not a particularly favourable one and the comet was last observed a few days before perihelion. The calculated orbit suggested that no favourable returns were likely for some years and the comet was lost. Richard Buckley published a paper on missing comets in the BAA Journal in 1977 (BAAJ, 87, No3) and gave a prediction for a return in 1976.

In December, S Nakano linked the comet with previously unreported observations of an 18th magnitude object obtained by LONEOS in September and October 2000. This return is now designated 2000 S7. The new orbit shows that the comet passed 0.18 AU from Jupiter on 2004 July 8.

Calculations by Hirohisa Sato allow for the possibility of an elliptic orbit of period 11 years and perihelion at 2.0 AU in early June 2009. This was confirmed by subsequent orbits, which give a period of 6.7 years and perihelion 2.4 AU in 2009 May.

With an improved orbit, Maik Meyer subsequently found previously unidentified images of the comet on frames taken by NEAT on 2003 March 24 and LONEOS on 2003 April 1. The comet was given the designation 2003 F6 at this return, which had perihelion on 2002 August 19.1.

Hirohisa Sato has calculated an improved elliptical orbit, which suggests a period of around 250 years. The elliptical orbit was confirmed on a subsequent MPEC, which gives a period of around 290 years.

The comet will pased through the SOHO LASCO C3 field between December 20 and 26. It will emerge into the morning sky for UK observers around January 10, by which time it will have faded to around 10.5. It will fade quite rapidly.

4 observations received so far suggest an uncorrected preliminary light curve of m = 13.9 + 5 log d + 10.7 log r

Brian Marsden notes on MPEC 2009-E04 [2009 March 1] that further [astrometric] observations of this comet are very desirable.

Unfortunately further observations suggested a radically different orbit. It is likely that perihelion was at over 4 AU in 2008. The latest MPEC gives perihelion at 3.9 AU in 2008 April. Computations by both Hirohisa Sato and Kenji Muraoka suggest a short period orbit of around 25 years, with perihelion at 4.5 AU in autumn 2008. The latest orbit gives perihelion at 4.4 AU in mid January 2009 and a period of around 23 years.

Brian Marsden notes on MPEC 2009-A43 [2009 January 7] that further [astrometric] observations of this comet are desirable.