BAA Comet Section : Periodic Comets

Updated 2011 December 18

Currently bright, numbered periodic comets

  • 21P/Giacobini-Zinner
  • 29P/Schwassmann-Wachmann in 2011
  • 41P/Tuttle-Giacobini-Kresak
  • 45P/Honda-Mrkos-Pajdusakova
  • 49P/Arend-Rigaux
  • 73P/Schwassmann-Wachmann
  • 78P/Gehrels
  • 213P/Van Ness

  • Note following the IAU convention announced in the 14th comet catalogue, numbers following the names of discoverers are no longer used.

    Numbered periodic comets

  • 2P/Encke
  • 4P/Faye
  • 6P/d'Arrest
  • 7P/Pons-Winnecke
  • 8P/Tuttle
  • 9P/Tempel
  • 10P/Tempel
  • 11P/Tempel-Swift-LINEAR
  • 15P/Finlay
  • 17P/Holmes
  • 19P/Borelly
  • 21P/Giacobini-Zinner
  • 22P/Kopff
  • 24P/Schaumasse
  • 26P/Grigg-Skjellerup
  • 27P/Cromellin
  • 29P/Schwassmann-Wachmann
  • 30P/Reinmuth
  • 32P/Comas Sola
  • 33P/Daniel
  • 37P/Forbes
  • 39P/Oterma
  • 41P/Tuttle-Giacobini-Kresak
  • 43P/Wolf-Harrington
  • 44P/Reinmuth
  • 45P/Honda-Mrkos-Pajdusakova
  • 46P/Wirtanen
  • 47P/Ashbrook-Jackson
  • 48P/Johnson
  • 49P/Arend-Rigaux
  • 50P/Arend
  • 51P/Harrington
  • 52P/Harrington-Abell
  • 53P/van Biesbroeck
  • 54P/de Vico-Swift-NEAT
  • 56P/Slaughter-Burnham
  • 57P/du Toit-Neujmin-Delporte
  • 59P/Kearns-Kwee
  • 60P/Tsuchinshan
  • 61P/Shajn-Schaldach
  • 62P/Tsuchinshan
  • 63P/Wild
  • 65P/Gunn
  • 66P/du Toit
  • 67P/Churyumov-Gerasimenko
  • 69P/Taylor
  • 71P/Clark
  • 73P/Schwassmann-Wachmann
  • 74P/Smirnova-Chernykh
  • 75P/Kohoutek
  • 76P/West-Kohoutek-Ikemura
  • 78P/Gehrels
  • 80P/Peters-Hartley
  • 81P/Wild
  • 83D/Russell
  • 84P/Giclas
  • 85P/Boethin
  • 88P/Howell
  • 92P/Sanguin
  • 93P/Lovas
  • 95P/Chiron
  • 96P/Machholz
  • 97P/Metcalf-Brewington
  • 101P/Chernykh
  • 102P/Shoemaker
  • 103P/Hartley
  • 104P/Kowal
  • 105P/Singer Brewster
  • 106P/Schuster
  • 110P/Hartley
  • 111P/Helin-Roman-Crockett
  • 114P/Wiseman-Skiff
  • 116P/Wild
  • 117P/Helin-Roman-Alu
  • 118P/Shoemaker-Levy
  • 121P/Shoemaker-Holt
  • 123P/West-Hartley
  • 128P/Shoemaker-Holt
  • 132P/Helin-Roman-Alu
  • 135P/Shoemaker-Levy
  • 136P/Mueller
  • 140P/Bowell-Skiff
  • 141P/Machholz
  • 144P/Kushida
  • 152P/Helin-Lawrence
  • 154P/Brewington
  • 155P/Shoemaker
  • 156P/Russell-LINEAR
  • 157P/Tritton
  • 158P/Kowal-LINEAR
  • 159P/LONEOS
  • 160P/LINEAR
  • 161P/Hartley-IRAS
  • 162P/Siding Spring
  • 163P/NEAT
  • 164P/Christensen
  • 165P/LINEAR
  • 166P/NEAT
  • 167P/CINEOS
  • 168P/Hergenrother
  • 169P/NEAT
  • 170P/Christensen
  • 171P/Spahr
  • 172P/Yeung
  • 173P/Mueller
  • 174P/Echeclus
  • 175P/Hergenrother
  • 176P/LINEAR
  • 177P/Barnard
  • 178P/Hug-Bell
  • 179P/Jedicke
  • 180P/NEAT
  • 181P/Shoemaker-Levy
  • 182P/LONEOS
  • 183P/Korlevic-Juric
  • 184P/Lovas
  • 185P/Petriew
  • 186P/Garradd
  • 187P/LINEAR
  • 188P/LINEAR-Mueller
  • 189P/NEAT
  • 190P/Mueller
  • 191P/McNaught
  • 192P/Shoemaker-Levy
  • 194P/LINEAR
  • 195P/Hill
  • 196P/Tichy
  • 197P/LINEAR
  • 198P/ODAS
  • 199P/Shoemaker
  • 200P/Larsen
  • 201P/LONEOS
  • 202P/Scotti
  • 203P/Korlevic
  • 205P/Giacobini
  • 206P/Barnard-Boattini
  • 207P/NEAT
  • 208P/McMillan
  • 209P/LINEAR
  • 210P/Christensen
  • 211P/Hill
  • 212P/NEAT
  • 213P/Van Ness
  • 214P/LINEAR
  • 215P/NEAT
  • 216P/LINEAR
  • 217P/LINEAR
  • 218P/LINEAR
  • 219P/LINEAR
  • 220P/McNaught
  • 221P/LINEAR
  • 222P/LINEAR
  • 223P/Skiff
  • 225P/LINEAR
  • 226P/Pigott-LINEAR-Kowalski
  • 227P/Catalina-LINEAR
  • 228P/LINEAR
  • 229P/Gibbs
  • 230P/LINEAR
  • 232P/Hill
  • 233P/La Sagra
  • 234P/LINEAR
  • 235P/LINEAR
  • 236P/LINEAR
  • 237P/LINEAR
  • 238P/Read
  • 239P/LINEAR
  • 240P/NEAT
  • 241P/LINEAR
  • 242P/Spahr
  • 243P/NEAT
  • 244P/Scotti
  • 245P/WISE
  • 246P/NEAT
  • 247P/LINEAR
  • 248P/Gibbs
  • 249P/LINEAR
  • 250P/Larson
  • 251P/LINEAR
  • 252P/LINEAR
  • 253P/Pan-STARRS
  • 254P/McNaught
  • P/Levy
  • Unnumbered periodic comets etc

  • P/Blanpain
  • (596) Scheila
  • (3200) Phaethon
  • S01P/SOHO
  • S02P/SOHO
  • S03P/SOHO
  • S04P/SOHO
  • S05P/SOHO
  • 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 2P/Encke

    2000 saw comet 2P/Encke's 58th observed return to perihelion since its discovery by Mechain in 1786. The orbit is quite stable, and with a period of 3.3 years apparitions repeat on a 10 year cycle. There is some evidence for a secular fading, however this is not shown in BAA data over the last 50 years. Another suggestion is that Encke has two active regions, an old one with declining activity, which operates prior to perihelion and a recently activated one present after perihelion. The comet is the progenitor of the Taurid meteor complex and may be associated with several Apollo asteroids.

    Observations received in 1997 (15) give a preliminary light curve of 11.8 + 5 log d + 18.6 log r

    Observations in ICQ format, last observation 1997 July 7, updated 1997 July 28 .

    A few observers spotted the comet in early 2000 August, estimating it at around 11th mag. Pepe Manteca imaged the comet on August 10 and August 14. The comet was visible in the SOHO C3 coronagraph, but was fainter than expected and was only 8.8 on September 7.1. It suddenly brightened on September 14 around 15:00 to 6.5.

    2003 The comet was picked up visually at the 2003 return in October, however it was initially very diffuse and significantly fainter than expected. In the Northumberland 0.30-m refractor x230 I estimated it 12.9 on October 24.89 with a 0.8', DC1 coma. It was half a magnitude brighter a couple of nights later. Following reports on the comet mailing list that it was significantly brighter in binoculars, I visited a dark sky site on October 27.94 and found it at 9.9 in 20x80B with a 4.5' DC3 coma. It was a very easy object in 25x100B. On November 16.81 I estimated it at 7.7 in 20x80B, with a 10' diameter DC2 coma. On November 26.73 it was 6.8 in 10x50B with a 13' DC3 coma. Many observers comment on the pronounced fan of material coming from a stellar nucleus. Most observers lost it in early December, but Juan José González Suárez was able to view it from a mountain location on December 24.28, estimating it as a stellar object of approx 4.7 in 25x1000B.

    For the 2003 return 52 observations give a preliminary corrected light curve of 10.7 + 5 log d + 12.3 log r.

    L. M. Woodney, University of Central Florida; and T. C. Owen and Y. R. Fernandez, University of Hawaii, report the detection of HCN from comet 2P/Encke. The HCN J(4-3) transition was observed during Nov 9-11 UT at the James Clerk Maxwell Telescope. The line had a FWHM of 1.4 km/s and an integrated line strength of 0.057 +/- 0.011 K km/s. Assuming a rotational temperature of 43 K, and using a Haser model, a production rate of Q(HCN) = 9.8 x 10**23 molecules/s was derived. [IAUC 8239, 2003 November 17]

    F. Bensch, Harvard Smithsonian Center for Astrophysics (CfA); E. Bergin, University of Michigan; and G. Melnick, CfA, write: "We have monitored the 1(10)-1(01) emission of water vapor at 556.936 GHz toward comet 2P using the Submillimeter Wave Astronomy Satellite (SWAS). Between Nov. 7.04 and 15.21 UT, the line- integrated antenna temperature within the 3'.2 x 4'.5 elliptical SWAS beam varied between I < 0.252 (3-sigma upper limit for observations on Nov. 7.04-7.99) and I = 0.98 K km/s (Nov. 12.03- 12.99). The average line-integrated intensity for this period is I = 0.55 +/- 0.03 K km/s. The water-production rate, Q(H_2O), is derived using a spherical outflow model (Haser model) with a water photo-destruction rate of 1.366 x 10**-5 s**-1 and an assumed ortho-para ratio of 3. The uncertainty in the resulting Q(H_2O) is governed by the finite S/N ratio of the observations and the uncertainty in the electron abundance in the coma. (In addition to infrared fluorescence and H_2O-H_2O collisions, H_2O-electron collisions provide a significant contribution to the 1(10)-1(01) line excitation; our modeling of the electron abundance uses the same parameterization as Biver et al. 1999, A.J. 118, 1850). For observations made between Nov. 9.06 and 9.96 (I = 0.53 +/- 0.07 K km/s), we derive Q(H_2O) = (2.9 +/- 0.4) x 10**27 s**-1 for an electron abundance similar to those derived by in-situ measurements in the coma of 1P/Halley, and Q(H_2O) = (4.0 +/- 0.5) x 10**27 s**-1 for an electron abundance reduced by a factor of 0.2. Previous studies of this transition toward several other comets by SWAS and by the (sub)millimeter-wavelength satellite Odin have indicated that the electron density in cometary comae might be smaller by a factor of about 0.2, compared to the electron density in 1P/Halley (Biver, private communication, based on data from Lecacheux et al. 2003, A.Ap. 402, L55)." [IAUC 8249, 2003 December 4]

    Observations in ICQ format, last observation 2003 December 24, updated 2003 December 29.

    Comet 2P/Encke in 2007 2P/Encke put on a brief showing in the UK evening sky in late March and early April just before perihelion, when it was a binocular object in Pisces and Aries. After perihelion it was visible passing through the SOHO LASCO field and that of its successor, STEREO. STEREO imaged a disconnection event in the ion tail, and a NASA press release was issued in October.

    This was comet Encke's 60th observed return to perihelion since its discovery by Mechain in 1786. This year the comet was briefly seen from the Northern Hemisphere prior to perihelion, with rather better views from the Southern Hemisphere after perihelion, when the comet is often brighter.

    Martin Mobberley made an early image of the comet at its 2007 return, imaging it on 2006 December 9.81 when it was still only around 18th magnitude.

    5 observations received give an uncorrected preliminary light curve of m = 10.7 + 5 log d + 8.3 log r

    Observations in ICQ format, last observation 2007 April 13, updated 2007 April 16.

    Comet 2P/Encke in 2010 This is comet 2P/Encke's 61st observed return to perihelion since its discovery by Mechain in 1786. The orbit is quite stable, and with a period of 3.3 years apparitions repeat on a 10-year cycle. This year it has a poor elongation prior to perihelion, but it will be visible passing through the SOHO LASCO field and that of its successors, the twin STEREO satellites in late July and early August. After perihelion the comet becomes visible from the Southern Hemisphere in mid August as a fading binocular object, and can be followed throughout September. BAA Members have been observing the comet for over 50 years and there is little evidence for a secular fading, although the comet is often brighter post perihelion than it is before. The comet is the progenitor of the Taurid meteor complex and may be associated with several Apollo asteroids.

    The comet was first picked up in the SOHO C3 field on August 4. It became visible to Southern Hemisphere observers mid-month.

    34 observations received give an uncorrected preliminary light curve of m = 10.2 + 5 log d + 6.4 log r

    Observations in ICQ format, last observation 2010 September 13, updated 2010 November 3.

    Comet 4P/Faye Hervé A Faye discovered 4P/Faye in 1843 during a visual search with a small telescope at the Paris Observatory. It reached 5m, though this has never been reached at subsequent returns. It is possible that this was a one off caused by a slight reduction in perihelion distance from 1.8 to 1.7 AU following a close encounter with Jupiter in 1841. Several authors have suggested that the absolute magnitude of the comet is declining rapidly, but it reaches a similar magnitude at all favourable apparitions. This return is very similar to the 1991 return, when it reached 10th magnitude. It has behaved much as predicted and was at its brightest in early November 2006 at just brighter than 10th magnitude. It will slowly fade. By mid January 2007 it was around 12th magnitude and had only faded a little further by April.

    126 observations received give an uncorrected preliminary light curve of m = 9.4 + 5 log d + 7.2 log r

    Observations in ICQ format, last observation 2007 April 5, updated 2007 April 16.

    Comet 6P/d'Arrest 6P/d'Arrest makes its 19th observed return in 2008, and it is a good one with the comet reaching perihelion when near opposition. It was first observed by La Hire in 1678 and only four other periodic comets (Halley, Tempel-Tuttle, Swift-Tuttle and Ikeya-Zhang) have a longer observational interval. At previous good returns it has reached naked eye brightness, but orbital perturbations have increased the perihelion distance over the past few returns and predictions suggest that it is unlikely to get brighter than 9m at this return. It should come within visual range in June and reaches perihelion just after opposition in August. It heads south and will become invisible to UK observers, but Southern Hemisphere observers will be able to follow it as it fades out of visual range in October. It spends June and July in Aquila, but rapidly heads south in August and is in Microscopium by the end of the month.

    The comet was recovered at its 2008 apparition in late April by observers at Lowell Observatory's Anderson Mesa Station and Kachina Observatory, Flagstaff. It was around 19th magnitude. It appears to have undergone something of an outburst around the time of perihelion

    65 observations received so far at the 2008 return cannot be fitted into a normal light curve.

    Comet 7P/Pons-Winnecke 7P/Pons-Winnecke was discovered by Jean Louis Pons with a 0.12-m refractor at Marseilles in 1819, but was then lost until rediscovered by Friedrich August Theodor Winnecke with a 0.11-m refractor in Bonn in 1858. He demonstrated the identity and recovered the comet in 1869. The perihelion distance has slowly been increasing since the early 1800s. It can make close approaches to the Earth and did so in 1927 (0.04 AU), 1939 (0.11), 1892 (0.12), 1819 (0.13) and 1921 (0.14). An outburst of the meteor shower associated with the comet, the June Bootids, occurred on 1998 June 27.6.

    In 2002 it will be a morning object, becoming visible in February and reaching 11th magnitude in May after which it is unfavourably placed for observation from the UK. Observers at lower latitudes will be able to follow it until September. It moves eastwards, being in Aquarius in May.

    Although few confirmed observations have been received, reports circulating on the internet suggest that the comet entered visual range in April. It is currently several magnitudes fainter than expected.

    Observations in ICQ format, last observation 2002 August 13, updated 2002 November 6.

    Comet 8P/Tuttle 8P/Tuttle is likely to be one of the brighter objects for visual observers in 2008. It could be a binocular or even naked eye object at the beginning of the New Year as it makes a close pass of the Earth at 0.25 AU. It begins the year in Pisces, but is rapidly heading south and UK observers will lose it after the third week of January. Southern Hemisphere observers should be able to follow it for another three months. The comet was discovered by Pierre Mechain in January 1790 from Paris, but the available observations were insufficient to compute an elliptical orbit and it was lost until a comet was discovered by Horace Tuttle at Harvard, USA in February 1858. When an accurate orbit was computed it was found to be identical to Mechain's comet and it has been observed at every return since 1871 except for a very unfavourable one in 1953. The most favourable returns are those with a perihelion in December, January or February. The orbit is quite stable, due to the high inclination and the value of the argument of perihelion, and it intersects the earth's producing the Ursid meteor shower which peaks on December 23. Rates at maximum are usually only 10 - 15 per hour, but strong displays of around 100 per hour occurred in 1945 and 1986; in both cases the parent comet was near aphelion.

    The comet was recovered in April 2007, with delta T of +0.13 days compared to the prediction on MPC 54167. Observations in early November suggested that it had reached 14th magnitude.

    P. Jenniskens, Ames Research Center, supplied a prediction (Jenniskens and Lyytinen 2000, WGN, submitted) of enhanced activity in 2000 of the meteor stream associated with comet 8P/Tuttle. Notable Ursid outbursts near the time of 8P's aphelion occurred in 1945 and 1986. Maximum activity is anticipated around Dec. 22.31 UT from material ejected from the comet in 1405. Ejections in 1392 and 1378 could expand this activity over an interval of 4-5 hours. [IAUC 7455, 2000 December 18] P. Jenniskens, Ames Research Center, reports that preliminary results show that there was an enhancement of Ursid meteors visible between Dec. 22.2 and 22.4 UT, including several brighter than mag 1, with a peak (ZHR > 50) near the predicted time of Dec. 22.31 [IAUC 7548, 2000 December 23]

    Observations by D. Schleicher, Lowell Observatory; and L. Woodney, California State University, San Bernardino, using CN narrowband imaging on Dec. 14 with the Hall 1.1-m telescope at Lowell Observatory show three radial arcs. If these are from the same jet, it implies a rotation period of 4.9 - 5.0 hours.

    216 observations received give a preliminary light curve of m = 6.8 + 5 log d + 0.0429 abs(t-T-27.1)

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

    Comet 9P/Tempel was first observed in 1867, but was lost between 1879 and 1967 following an encounter with Jupiter in 1881 which increased the perihelion distance from 1.8 to 2.1 AU. Further encounters in 1941 and 1953 put q back to 1.5 AU and calculations by Brian Marsden allowed Elizabeth Roemer to recover it in 1967. Alternate returns are favourable, but an encounter with Jupiter in 2024 will once again increase the perihelion distance to 1.8 AU. The 2000 return was an unfavourable one and no observations were made. It is an important comet to observe as it is a potential spacecraft target and a special request for observations has been made. It may come within visual range as early as 2005 February, when it is visible in the morning sky in Virgo and remains in the constellation until July. It should be at its best in May and June, when it may reach 10th magnitude in the evening sky, but it heads south as it fades and UK observers will loose it after mid-summer, although elsewhere it should remain visible until 2005 October.

    I was finally able to observe the comet on 2005 April 4.9, finding it an easy object in the N'land refractor. It was mag 11.7, DC4 and diameter 0.7'. Observations in late May were putting it at around 10.5 - 11th magnitude.

    Comet 9P/Tempel is the target for the Deep Impact mission and observations are requested.

    Observations from the HST and the onboard Deep Impact camera show what appear to be minor outbursts of the comet during June. These are promoted as major events by the NASA Deep Impact site, although they are of short duration (dissipating in less than 12 hours) and are of small size (about 2000 km). Interestingly stars passing through the field appear to brighten during the event shown by the DI camera.

    Following the impact, there was no obvious increase in visual magnitude, however the coma did become more condensed.

    The Stardust-NExT spacecraft encountered 9P/Tempel at 03:40 UT on 2011 February 15. It returned images showing the effects of the Deep Impact hit on the comet in 2005 July.

    192 observations give a preliminary light curve of m = 6.8 + 5 log d + 23.1 log r. The H10 magnitude is 9.4. The light curve this year is very similar to those in 1983 and 1994 and taking all together gives an aperture corrected equation of m = 5.7 + 5 log d + 21.9 log r

    Observations in ICQ format, 47 observations, updated 2005 June 1.

    Comet 10P/Tempel made its 20th observed return in 1999. It was discovered by William Tempel (Milan, Italy) as a 9th magnitude object in 1873. Several unfavourable returns were missed in the earlier years. The orbit is very stable, which is one reason why it is a favoured target for planned spacecraft missions. In 1983 the IRAS satellite detected an extensive dust trail behind the comet.

    Traditionally the light curve is regarded as highly asymmetric with a late turn on. There is a rapid rise in brightness as perihelion approaches, which continues more slowly for a couple more weeks after perihelion, followed by a slow decline until activity switches off. An alternative view is that the light curve is linear with a peak about a month after perihelion.

    With a 5.5 year period alternate returns are favourable and the 2010 return is one of them.

    1999 David Strange obtained an image of the comet on July 10. Jose Carvajal estimated it at 10.6 in 32cm L on August 5.9, but I was unable to see it with 20cm R on the same night. On Aug 10.9 Andrew Pearce and I observed it with 14x100B from just outside Penzance, Cornwall, my estimate was 8.7 (HS) and Andrew made it a little fainter. Back in Cambridge it was a very difficult object in the 0.20-m refractor, though it was observed during the IWCA. Andrew Pearce now back in Australia reported that the comet has faded to near 10th mag at the end of August. It faded very slowly and it was still 12th mag in December. 2010 Deep images of 10P/Tempel showed a dust trail in the plane of the comet's orbit. Francois Kugel and C Rinner obtained a mosaic on July 14. Further images on July 24 show the trail extending over 20 degrees from the nucleus.

    111 observations received at the 1999 return give an uncorrected preliminary light curve of m = 10.4 + 5 log d + 0.0295 abs(t-T-18.1) or 6.1 + 5 log d + 29.3 log r.

    Observations in ICQ format , last observation 2000 January 30, updated 2000 August 16.

    73 observations received at the 2010 return give an uncorrected preliminary light curve of m = 9.4 + 5 log d + 0.0152 abs(t-T-28)

    Observations in ICQ format , last observation 2010 October 28, updated 2010 November 3.

    Comet 11P/Tempel-Swift-LINEAR C. Hergenrother, Lunar and Planetary Laboratory; and K. Muraoka, Kochi, Japan, suggested a link between comet 11D (last seen in 1908) and P/2001 X3 (cf. IAUC 7778) -- a linkage confirmed at the Minor Planet Center and by S. Nakano (Sumoto, Japan). Nakano has computed orbital elements (from 43 observations, 1908-2001, mean residual 0".8; nongravitational parameters A_1 = +0.13 +/- 0.01, A_2 = -0.0134 +/- 0.0007). The comet was not found in 1963 despite a prediction by B. G. Marsden (IAUC 1838, 1839, 1840). More recent predictions were made by Marsden and Sekanina (1971, A.J. 76, 1142), by Nakano (Comet Handbooks for 1989, 1995, and 1996, Oriental Astronomical Association; and NK 686), and by Muraoka (Comet Handbook for 2001, OAA). The indicated correction to Nakano's 2001 prediction (1998, NK 686) is Delta(T) = +3.4 days. [IAUC 7779, 2001 December 20] A prediction for the return also appeared in the BAA Journal, under predictions for comets in 2001.
    Comet 15P/Finlay William Henry Finlay discovered this comet from the Cape Observatory on 1886 September 26, with an 18cm refractor. It was around 11th magnitude at this and the following return. In 1906 it passed 0.3 AU from the Earth and reached 6th magnitude. Jupiter perturbations in 1910 gave an unfavourable return in 1913, but a good one in 1919, though they were unfavourable after that until 1953, when it was recovered. It has been observed at every return since 1953, and this is its 14th return. It is an intrinsicaly faint object and there are usually few visual observations. A September perihelion would give favourable observing circumstances, under which the comet could reach 5th magnitude.

    4 observations received so far at the 2008 return suggest an uncorrected preliminary light curve of m = 8.7 + 5 log d + [15] log r

    Comet 17P/Holmes Pepe Manteca imaged this faint comet on 2000 August 10.

    The comet was discovered by Edwin Holmes from London on 1892 November 6. He had been observing in poor conditions, and decided to have a look at the Andromeda galaxy with his 32cm reflector before stopping for the night. He found an unexpected object that wasn't M31. Other observers were initially skeptical, but the comet was soon confirmed. It remained bright for several weeks before slowly fading, and then underwent another outburst in mid January, which again brought it within naked eye range.

    At its eight following returns the comet was a faint object. It was reported in outburst by Spanish amateurs on 2007 October 24, when near opposition, but well past perihelion. The brightest estimates so far suggest that it reached 2.5. It is fading very slowly, and by mid November was still 3rd magnitude, although it had expanded to 40' diameter.

    Observations with the Super-WASP wide-field imaging system at La Palma captured the start of the comet's outburst, and show that it brightened from 9.7 to 8.6 over 2.6 at a rate consistent with the linear expansion of an optically thick coma. Extrapolating backwards in time suggests that the outburst commenced on October 23.8.

    Richard Miles has produced an explanation for the outburst involving the catalytic decomposition of H2O2.

    Comet 19P/Borrelly Alphonse Borrelly discovered comet 19P/Borrelly in 1904 from Marseilles, France, during a routine comet search with a 160mm refractor. It was put into its discovery orbit by an encounter with Jupiter in 1889, which only made minor changes, and subsequent returns slowly became more favourable. Despite having had several further moderately close approaches to Jupiter the orbit has only changed a little and the comet will next approach Jupiter in 2019. This will be its 13th observed return, with two poor ones having been missed. At its best return in 1987 it reached 7.5m. This return is only a little worse and the brightness should peak at around 9.5m towards the end of September, shortly after perihelion. UK observers are likely to first pick up the comet as it passes through Orion in mid August when 10m, though more southerly observers will already have had it under observation for a couple of months. The solar elongation only slowly increases, but the comet moves north, although remaining a morning object. Slowly fading as it passes through Gemini (September), the Leos (October) and into Ursa Major (November), the comet begins to move north more rapidly and ends the year at 11m in Canes Venatici.

    The comet was picked up by Michael Mattiazzo, who estimated it at 13th mag in mid June 2001. By July 22 it had brightened to 11.4, a bit fainter than expected. Observing on August 28.11 with my 0.20-m SCT x75 I made it 10.3, DC4, diameter 1.7'. It reached a peak of around 10th magnitude in September and then slowly faded. By late November it was around mag 11.5 and by early January around 12.5.

    The spacecraft Deep Space 1 successfully imaged comet 19P/Borrelly on September 22.

    D. Schleicher, Lowell Observatory, writes: ``I obtained narrowband photometry of comet 19P on Sept. 18 and 19 using the Hall 1.1-m telescope at Lowell Observatory, yielding the following averaged production-rate results: log Q(OH) = 28.34; equivalent log Q(water; vectorial) = 28.41; log Af(rho) = 2.50 (cf. IAUC 7342). The radial fall-off of the dust is significantly steeper than the canonical 1/(rho), with Af(rho) decreasing by 1.9 times between rho = 20 000 and 110 000 km." [IAUC 7722, 2001 September 21]

    Visual m_1 estimates: Sept. 1.11 UT, 10.0 (R. J. Bouma, Groningen, The Netherlands, 0.25-m reflector); 28.14, 9.9 (W. Hasubick, Buchloe, Germany, 25x100 binoculars); Oct. 11.08, 10.1 (B. H. Granslo, Fjellhamar, Norway, 0.20-m reflector); 18.68, 10.3 (Y. Nagai, Yamanashi, Japan, 0.32-m reflector); 24.96, 10.7 (V. S. Nevski, Vitebsk, Belarus, 0.30-m reflector). [IAUC 7739, 2001 October 25]

    In 2009 Bernhard Haeusler imaged the comet between March 20 and June 12, detecting a sunward pointing tail, with a condensation possibly coming from jets active on the opposite pole to those seen by DS1.

    120 observations received give an uncorrected preliminary light curve of m = 6.8 + 5 log d + 18.4 log r

    Observations in ICQ format, last observation 2002 May 18, updated 2002 September 29.

    Comet 21P/Giacobini-Zinner is the parent comet of the October Draconid meteors. On this occasion we pass just inside the comet's orbit 92 days after the comet, with any shower taking place on October 8.7.

    The comet was first discovered by Michael Giacobini at Nice observatory in December 1900 and was thought to have a period of 6.8 years. The next two returns were expected to be difficult to observe, but in October 1913, Ernst Zinner, of Bamberg, Germany, discovered a comet whilst observing variable stars in Scutum. This turned out to be the same comet, but the period had been incorrectly determined. The comet was missed at three unfavourable returns, so the 1998 return was the thirteenth apparition of the comet. It will come within visual range in 2005 March, but is not well placed for the UK until April, when it may be 12th magnitude. It is a morning object, and draws back into the Sun, so that we will lose it again in 2005 May, by which time it may have brightened to 10th magnitude. For most of this period it is in Pegasus.

    Martin Mobberley imaged the comet on 1998 October 14 and October 25 .

    In 1998 223 observations received gave an uncorrected preliminary light curve of 8.9 + 5 log d + 13.6 log r
    In 2005 22 observations give an uncorrected preliminary lightcurve of 8.5 + 5 log d + 19.9 log r

    Observations in ICQ format , last observation 1999 April 29, updated 1999 July 7.

    Comet 22P/Kopff

    22P/Kopff was discovered photographically by A Kopff at Konigstuhl Observatory in 1906, when it was around 11m. The next return was unfavourable, but it has been seen at every return since then. Following an encounter with Jupiter in 1942/43 its period was reduced and the perihelion distance decreased to 1.5 AU. The following return was one of its best and it reached 8m. The next return was unusual, in that it was 3m fainter than predicted until perihelion, when it brightened by 2m. It suffered another encounter with Jupiter in 1954, but this made significant changes only to the angular elements. 1964 was another good return and the comet reached 9m.

    The 2002 return was not favourable and only a few observations were received. Although now near its brightest it is poorly placed.

    An analysis of the data from 1996 gave a light curve of 7.5 + 5 log d + 10 log r, but this was very indeterminate. The 2009 data (62 observations) suggest 8.3 + 5 log d + 8.9 log r

    1996 Observations in ICQ format reported to 1997 October 30.

    2002 Observations in ICQ format reported to 2002 November 6, last observation 2002 September 29.

    Comet 24P/Schaumasse Alexandre Schaumasse discovered comet 24P/Schaumasse during a visual search with the 400mm coude equatorial at Nice, France in 1911 December as a 12m diffuse object and it reaches a similar magnitude at average returns. The 1952 return was very favourable and the comet reached 5m, though there may have been an outburst. The orbit is relatively stable and this will be its 10th observed return. UK observers may pick up the 13m comet in the evening sky in February as it brightens on its way to perihelion. Moving northwards in Aries, it passes into Taurus in mid March when it should be a magnitude brighter. It is at its brightest tracking through Auriga at the end of April and early May when it should be at nearly 10m. Passing into Gemini we will loose it low in the summer twilight by the end of the month.

    Martin Mobberley imaged the comet on February 13 and estimates the CCD magnitude as around 15 - 16. I observed on February 14.8 with the Northumberland refractor and immediately saw a diffuse object in the expected position, which I estimated at 13.6. This is rather brighter than the CCD magnitude and will need further confirmation. A further observation on March 12.8 put the comet at 13.2. I was able to glimpse it in the Thorrowgood refractor on April 24, estimating it at around 11.9.

    78 observations received give an preliminary light curve of 7.7 + 5 log d + 29.2 log r

    Observations in ICQ format reported to 2002 June 26, last observation 2001 June 20.

    Comet 26P/Grigg-Skjellerup On 2008 June 12 NASA resulted a news bulletin announcing the discovery of a new mineral in dust particles captured in the Earth's atmosphere, which were possibly from 26P.

    Comet 27P/Crommelin 27P/Crommelin has a poor return ijn 2011 and will not be visible from the UK. Its maximum elongation whilst brighter than 14th magnitude is only 37°, and it is then at a northern declination. The comet is named for the BAA Comet Section Director, A C Crommelin, who first computed a linked orbit for comets seen in 1818, 1873 and 1928. It was quite well observed in 1984 when it served as a test comet for the International Halley Watch.

    A few observations were made in early July 2011 when the comet was around 10th magnitude.

    Comet 29P/Schwassmann-Wachmann 1997 In February and early March 1997 the comet was in outburst, peaking at around 12th mag. It was not seen in April, but returned to visibility in early May, rising to 12th mag late in the month. I observed it at 13.7: on May 12.95 with the Northumberland 0.30-m refractor. On May 29.97 it was 12.0: in my 0.20-m T x 75, dia 1.8', DC3. Andrew Pearce reports glimpsing it at around 14th mag in his 0.41-m reflector at the end of December 1997.

    1998 Further reports suggest that the comet brightened to around 12th mag visually and then faded to 14th mag. Another outburst commenced in mid March 1998 according to IAUC 6844 and the comet is now around 13th mag, though I was unable to see it on April 28.9, when it was fainter than 13.2. It may be undergoing another outburst at around 13th mag (May 30).

    1999 Andrew Pearce discovered it in outburst on 1999 March 31. It was well condensed and so relatively easy to see, but faded below 14th mag. Reports suggest another outburst to around 13th magnitude in early June. Jose Aguiar reported it in outburst once again at the beginning of July.

    2000 Jose Aguiar reported as possibly being in outburst on July 1

    2001 The comet is undergoing another outburst, as shown by the following total magnitudes (CCD unless otherwise indicated): Apr. 22.80 UT, 15.5 (A. Nakamura, Kuma, Ehime, Japan, 0.60-m reflector); 28.44, 15.7 (A. Hale, Cloudcroft, NM, 0.2-m reflector); May 17.69, 13.2 (K. Kadota, Ageo, Saitama, Japan, 0.18-m reflector); 18.71, 13.4 (Kadota); 19.73, 12.0 (K. Yoshimoto, Hirao, Yamaguchi, Japan, 0.25-m reflector; visual); 27.77, 13.5 (Nakamura). [IAUC 7640, 2001 June 1] Further outbursts have taken place and the comet remains at around 12th magnitude into August.

    2002 This comet appears again to be in outburst, as indicated by the following total-magnitude estimates (visual unless otherwise noted): Mar. 20.83 UT, [16: (T. Kojima, Chiyoda, Japan, 0.25-m reflector + CCD); 27.80, 14.4 (Kojima); May 8.46, 13.5 (A. Hale, Cloudcroft, NM, 0.41-m reflector); 9.46, 13.3 (Hale); 21.45, 13.3 (Hale); June 8.39, 12.3 (Hale; near-stellar appearance); 9.75, 12.0 (A. Nakamura, Kuma, Ehime, Japan, 0.60-m reflector + CCD; strong condensation). [IAUC 7918, 2002 June 13]

    Carlos Labordena (Spain) reported the comet in outburst on November 1, at 12th magnitude with a well condensed coma. Michael Mattiazzo (Australia) also reported the comet bright, with the comet at around 14th magnitude through most of October, brightening at the end of the month. The degree of condensation was quite variable suggesting a series of outbursts, with perhaps one around October 27 and another around November 4.

    2003 Salvador Sanchez, Jaime Nomen and Reiner Stoss observed the comet on the morning of May 22 with the remotely controlled 30-cm telescope of the Observatorio Astronomico de Mallorca. The comet looked to be in outburst. The measured magnitude was 13.5 N on 80s CCD frames at an SNR of 30. Juan Jose Gonzalez reported the comet at 13.1 on July 23.02. A further outburst was reported at the end of September.


    Seichi Yoshida notes the following pattern of activity:

    The high level activities in 2002 and 2004, and the low level activity in 2000 are remarkable.
  • 1997 Two outbursts occured, but faint in general.
  • 1998 After outburst in late January, it kept bright for a while though diffused. Only one outburst. Not visible visually in the latter half.
  • 1999 Not visible visually in the former half. After outburst in late March, it kept bright for a while though diffused. Only one outburst.
  • 2000 No outburst. Not visible visually almost at all.
  • 2001 Major outburst occured in August. Some other small outbursts occured, too. Every outburst was short, and it became invisible soon.
  • 2002 Outbursts often occured. It was brighter than 13 mag in many times. It became so faint temporarily in July.
  • 2003 Outbursts often occured, but small, and only 13 mag at best.
  • 2004 Outbursts frequently occured. It kept bright around 12 mag all through the year.
  • 2005 The comet was reported in outburst in July. A second outburst was reported in mid August. Another outburst began in mid September and I estimated it at 12.1 and DC6 in the N'land refractor x185 on September 18.96 There was another outburst in mid December and it was an easy object in the N'land refractor on December 17.9


    The comet was reported in outburst at around 13th magnitude in mid July 2006. An image taken by Martin Mobberley on December 16.8 showed the comet at around 12th magnitude.

    2007 It spent the first quarter of the year in Taurus before sinking into solar conjunction. It emerged into the morning sky of Auriga in August, reaching opposition there at the end of the year. Generally outbursts seem not to have been so frequent in 2007, however it was reported in outburst at 13th magnitude in late December.


    It spent the first third of the year in Auriga before sinking into solar conjunction. It emerged into the morning sky of Gemini in August, and spent the last third of the year in Cancer. Unusually there was no opposition in 2008. A major outburst occurred in January and it reached 11th magnitude mid-month. A further outburst occurred in mid September, when it again reached 11th magnitude. It seems to have spent most of this year within visual range. Another outburst commenced around December 18.

    Comet 29P/Schwassmann-Wachmann in 2009

    This annual comet has frequent outbursts and over the past few years seems to be more often active than not, though it rarely gets brighter than 12m. It is possible that its pattern of behaviour is changing. In early 1996 it was in outburst for several months. In the first half of 1998 it was in outburst on several occasions and this also occurred in 1999. The randomly spaced outbursts may be due to a thermal heat wave propagating into the nucleus and triggering sublimation of CO inside the comet. This comet is an ideal target for those equipped with CCDs and it should be observed at every opportunity.

    The comet begins the year retrograding in Cancer and passes into Gemini around the time of opposition on January 17. It resumes direct motion around the time of the northern spring equinox and will be lost to UK observers in early May. It is in solar conjunction on August 1. For UK observers it will become observable in the morning sky in October, by which time it is in Leo.

    Richard Miles notes that it was at opposition on January 17, when it had a phase angle of only 0.5 degrees and this may have lead to an opposition effect brightening. Some jet structure was observed in the coma around this time, and he further notes that it will be important to follow their evolution as the comet is reported to be a slow rotator (about 60 days).

    2010 The comet underwent a major outburst in February, reaching 10th magnitude. This was around the time of opposition, when the phase angle was 0.3 degrees.

    Comet 29P/Schwassmann-Wachmann in 2011 29P/Schwassmann-Wachmann underwent a minor outburst at the end of February reaching 12th magnitude. Another outburst took place in late March, with the comet again reaching 12th magnitude.

  • 1997 Observations in ICQ format, last observation 1997 June 2, updated 1997 June 23 .