Updated 2016 July 4
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.
J. V. Scotti recovered comet P/1997 V1 (Larsen) with the Spacewatch 1.8-m f/2.7 reflector at Kitt Peak on June 9.44. The indicated correction to the prediction on MPC 54170 is Delta T = -2.0 days. This is the 200th comet to be numbered, although several SOHO comets have been observed to return and not numbered.
Improved orbital elements were published on MPEC 2001-S05, including prediscovery observations on Aug. 19 by LINEAR by B. G. Marsden and these indicate that this comet passed only 0.014 AU from Mars on 2002 Jan. 10.7 TT, as first suggested by C.-I. Lagerkvist (Uppsala) and G. Hahn (German Aerospace Center, Berlin). [IAUC 7720, 2001 September 19] The comet has a period of 6.5 years and was at perihelion on 2002 February 17.
Comet 2001 R1 (P/LONEOS) was recovered by Michael Jaeger from Stixendorf, Austria on August 31.09 as a 17th magnitude object. It was confirmed by Giovanni Sostero and team from the Skylive Observatory, Catania, Italy the following night. The comet is a month past perihelion and will fade. Following posting of the recovery on the comet-ml Maik Meyer located NEAT images on frames from 2001 August. The indicated correction to the prediction on MPC 54169 is Delta T = -0.42 day.
Jim Scotti recovered his comet (P/2001 X2) on Spacewatch images taken with the 1.8-m reflector at Kitt Peak on 2008 September 5.43 as a 21st magnitude object. The indicated correction to the prediction on MPC 56802 is Delta(T) = -0.15 day. Pre-recovery images were found on Mt Lemmon frames from 2007 September and October, and Spacewatch from 2008 August.
The comet passed 0.67 AU from Jupiter on 1960 March 24.
An orbit by Syuichi Nakano links the comet with asteroid 1929 WW.
Gareth Williams identified images of 1999 WJ7 in incidental astrometry taken with the 0.9-m Spacewatch telescope on September 3.24. The comet was 20th magnitude, with perihelion in 2010 February. The indicated correction to the prediction on MPC 59598 is Delta(T) = -0.3 day.
The comet passed within about 0.1 AU of Jupiter in 1985, prior to which it was in a more distant, less eccentric orbit.
Gareth Williams identified images of 2001 TU80 in incidental astrometry taken with the 1.8-m Spacewatch telescope on September 8.43. The comet is at perihelion in December. The indicated correction to the prediction on MPC 54171 is Delta(T) = -0.3 day.
Koichi Itagaki (Teppo-cho, Yamagata) and Hiroshi Kaneda (Minami-ku, Sapporo) discovered a 13th magnitude comet on unfiltered CCD patrol frames taken on September 10.56 UT using a 0.21-m f/3 reflector. A confirming unfiltered CCD image was taken subsequently with a 0.60-m f/5.7 reflector at Yamagata, where the comet was diffuse with strong condensation, with a coma diameter of about 25" and a 2' tail toward the east-southeast.
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 10.21. It also suggests that Buckley's prediction was out by roughly six days.
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 D. 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. Zdenek Sekanina suggests that the two fragments separated from the parent some time ago. The one closest to the parent (B), separated in the second half of 2006, around 700 days before perihelion. Fragment C separated at the end of 1998, three years before the last return to perihelion. In both cases the comet was over 4.5 AU from the Sun at the time.
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.
As hinted on IAUC 7625, this is a short-period comet, and observations by C. W. Hergenrother, T. B. Spahr, and M. Nelson with the 1.8-m f/1 VATT Lennon telescope on May 27 make it clear that the orbital period is $P$ about 7.5-7.9 years. Spahr has also identified the comet with a very faint object (not described as cometary) discovered by A. E. Gleason with the Spacewatch telescope on 2000 Oct. 7 and placed on The NEO Confirmation Page but removed on Oct. 20 for lack of follow-up. The additional astrometry and orbital elements ($P$ = 7.64 yr) are given on MPEC 2001-K43. S. Nakano has noted some rough similarity to the orbit of comet 3D/Biela. [IAUC 7635, 2001 May 29]
Brian Marsden has provided some additional information about this possibility: While I cannot exclude with 100-percent certainty the possibility that the new comet P/2001 J1 (NEAT) is the long-lost 3D/Biela, I really don't think it is.
What, indeed, happened to 3D/Biela after 1852? Did it break up completely? Some 30 years ago I looked into the possibility of finding that comet again and published a number of different orbits based on different possibilities for the action of the nongravitational forces on the comet after 1852. For an epoch around 1971 these orbits all had perihelion distances under 0.83 AU and inclinations to the ecliptic under 8.1 degrees.
Coming now to the recent comet, although unusually large inconsistencies among the observations made it particularly difficult to establish the orbit, and given that the comet's position in the sky makes it difficult to observe, I note that some careful observations on May 27 by Carl Hergenrother and Tim Spahr with the Vatican Advanced Technology Telescope in Arizona isolated the revolution period to 7.5-7.9 years. Tim then realized that the object had in fact been reported as unusual--though not of cometary appearance--by Arianna Gleason at Spacewatch on October 7 last year. The object was then listed on The NEO Confirmation Page for almost two weeks, although it was obviously too faint for essentially all of the likely follow-up observers, and Spacewatch itself evidently just missed the comet's position when it recorded the region again on October 19. The October 7 linkage is clearly correct, and this pins down the current period as 7.64 years.
Running this orbit back gives a moderately close approach to Jupiter (0.8 AU) in 1972, before which the P/2001 J1 perihelion distance was 0.96 AU and the inclination 11 degrees. While there was tolerably good agreement in orbital eccentricity, argument of perihelion and nodal longitude, it is difficult to reconcile the perihelion distance and inclination with the 3D/Biela values. To get these elements to agree would require the nongravitational forces to act in some special way, together with the gravitational effects of occasional approaches to Jupiter.
Whether or not the comets are identical, why was the current comet not observed earlier in the twentieth century? After all, the perihelion distance of under 1 AU does allow moderately close approaches to the earth--with a minimum orbital distance of perhaps 0.15 AU and an actual minimum distance of perhaps 0.5 AU in 1955. Actually, it is quite clear that at many passages through perihelion the small elongation from the sun would completely preclude observations, and by the time the object had moved around to opposition it would be as faint as when Spacewatch fortuitously observed it last October. Even under the more favorable circumstances of the 1955 perihelion passage, the best one could hope for at a 90-degree elongation from the sun would be magnitude 15, and more typically (as this year), one would have to contend with a maximum elongation of 70-80 degrees and magnitude 16 if one were lucky. We _were_ lucky that NEAT was observing this year so far from opposition, and there would have been no observing program with the capability of making the discovery at the previous comparable elongation in 1985. Unless the comet is now anomalously faint, that it escaped prior detection is fully reasonable--a situation not a bit like that of 3D/Biela on several occasions in the late eighteenth and early nineteenth centuries.
Ken-ichi Kadota, Ageo, Saitama-ken, Japan recovered comet 2001 J1 (P/NEAT) on CCD images obtained with his 0.25-m f/6 reflector on October 15.78. Confirming observations were also made by H. Abe (Yatsuka-cho, Shimane-ken, Japan, 0.26-m reflector). The indicated correction to the prediction on MPC 54170 is Delta(T) = -0.6 day.
In 2008 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.
An apparently asteroidal object discovered by the LINEAR project on February 3.40 has been found to show a narrow 1'.1 tail in p.a. 274 deg (slightly expanding toward the end) on CCD images obtained by R. H. McNaught with the 1.0-m f/8 reflector at Siding Spring on Mar. 30.8 UT. Following a request by the Central Bureau, M. Kocer reports that CCD frames taken at Klet on Mar. 31.145 also show a narrow tail about 90" long in p.a. approximately 280 deg. [IAUC 8314, 2004 March 31]
Gary Hug recovered 2004 CB (P/LINEAR) on 2008 December 4.39 as an essentially stellar object of 20th magnitude. The indicated correction to the prediction on MPC 56803 is Delta(T) = +0.16 day.
A paper to be published in Icarus http://arxiv.org/abs/1509.00560 suggests that it is an aged comet that has been in its present orbit for around 10,000 years and is now only weakly active. The nucleus is reddish, similar to D type and Trojan asteroids. The comet may have been briefly more active in the 18th century.
Eric Christensen, Lunar and Planetary Laboratory, reports the discovery of a 15th magnitude comet on May 26.18 by the Catalina Sky Survey on CCD images taken with the 0.7-m Schmidt telescope. Following posting on the NEO Confirmation Page, many observers noted the obvious cometary nature of the object on CCD images taken during May 27.1-27.2 UT, including R. Elliot (Fall Creek, WI; coma diameter about 10"), P. R. Holvorcem and M. Schwartz (near Nogales, AZ; coma diameter about 35", with a 30" tail in p.a. 106 deg), J. Young (Table Mountain, CA; 10" coma and a very faint 40" tail in p.a. 115 deg with a slight curve halfway along its length to p.a. 130 deg), and J. McGaha (Tucson, AZ; coma diameter 12", with slight nuclear condensation and a 6" tail). [IAUC 8136, 2003 May 27]
It has been noted by numerous individuals that the preliminary orbital elements of comet C/2003 K2 (cf. IAUC 8136) place it close to the position of an unconfirmed object found on SWAN ultraviolet SOHO website images and reported to the Central Bureau on Apr. 14 by X.-m. Zhou (Bo-le, Xin-jiang, China). Measurements of the object on six dates, Apr. 5-19, were forwarded to the Central Bureau by Zhou (via D. H. Chen), by M. Mattiazzo, and by S. Hoenig; the positions differed considerably, due to the poor resolution of SWAN (uncertainty on the order of 1 degree). Two search ephemerides based on various positions were circulated by the Bureau to numerous visual and CCD observers in the hopes of optical confirmation, but the searches (undertaken during the last week of April by Zhou, A. Hale, Mattiazzo, Y. Kushida, and Y. Ezaki) revealed nothing to as faint as mag 14.5. The following improved parabolic orbital elements for C/2003 K2 (from MPEC 2003-K49) indicate that the search-ephemeris positions in late April for the SWAN object were no closer than about 2.5 degrees from C/2003 K2. The comet might be of short period. [IAUC 8138, 2003 May 30]
Attempts at recovery by Maik Meyer in November 2008 were unsuccessful, with the comet not being found down to 18th mag along the line of variation +/- 9 days.
Alan Watson found a 10th magnitude comet on SECCHI HI1-B images taken on December 8.24 Rainer Kracht made measurements of the object's position and computed a parabolic orbit, from which Maik Meyer suggested identity with comet P/2003 K2. The indicated correction to the prediction on MPC 56802 is Delta(T) = -22 days.
Rob Matson reports that the comet was visible in SWAN imagery from December 4, but was moving slowly in a location close to the occulting region. If anyone took an image of the planetary conjunction of Venus and Jupiter in early December it is just possible that they might have captured the comet, although for UK observers it would be very close to the horizon.
The comet passed through the SOHO LASCO C3 field between December 20 and 26, but at 9th magnitude would probably not have been detectable. However Piotr Guzik pointed out that the geometry is strongly forward scattering and the magnitude could be enhanced by 5 - 6 magnitudes around December 23. Joe Marcus suggested that the forward scattering could be sufficiently strong to enhance the brightness by as much as 6.5 magnitudes, making it a prominent object in the SOHO fields. On December 21.8 it was easily visible in the C3 field at about 8.2, along with two Kreutz comets. The comet emerged into the morning sky in January. Few observations have been made, but it appears to be fading relatively slowly.
5 observations give an uncorrected preliminary light curve of m = 9.4 + 5 log d +  log r.
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.
The comet suffered a minor encounter with Jupiter in 1925, but the orbit has been stable since then. It approaches Jupiter to 0.38 au in 2032 August, which will increase the perihelion distance from 2.3 to 2.7 au.
Observations in early January 2009 showed a coma, and so with observations over two returns and a secure orbit it was numbered 212.
Comet 2005 R2 (P/Van Ness) was recovered by Gary Hug with his 0.56-m reflector at Sandlot Observatory on January 31.36. It was 21st magnitude. The indicated correction to the prediction on MPC 62889 is Delta(T) = -0.1 day.
It became brighter than expected in 2011 and a secondary condensation was observed by Giovanni Sostero, Nick Howes, Helen Blyth and Ernesto Guido in images taken with the Haleakala-Faulkes Telescope North on August 5.5, and subsequently seen in images by J. Gonzalez at the end of July and early August. Orbital calculations by Hirohisa Sato suggest that the split occurred in 2007 or 2008. Following an alert from a Japanese observatory, the team observed an additional component in September. The continued fragmentation may explain why the comet has remained brighter than expected.
An object reported as asteroidal by LINEAR (discovery observation below), given the designation 2002 CW_134 on MPS 50314, and later placed on the NEO Confirmation Page, has been found to show cometary activity: Mar. 19.0 UT, diffuse with coma diameter 13" (M. Tichy and M. Kocer, Klet, 1.06-m reflector); Mar. 23.0, diffuse, faint coma extended about 30" in p.a. 330 deg (G. Masi and F. Mallia, Campo Catino, Italy, 0.8-m reflector).
2002 UT R.A. (2000) Decl. m2 Feb. 7.47271 12 52 46.90 - 5 33 17.2 20.1Jul 06 Bo Zhou reports a Kreutz group comet in C2 image Jul 07 Periodic comet 2011 N1 discovered Jul 07 Rob McNaught discovers comet 2011 N2 Jul 08 Sergey Shurpakov reports a Kreutz group comet in real time C3 images [IAUC 7858, 2002 March 23]
Comet 2002 CW134 (P/LINEAR) was also recovered by Gary Hug with his 0.56-m reflector at Sandlot Observatory on January 31.49. It was 20th magnitude. The indicated correction to the prediction on MPC 56802 is Delta(T) = -0.32 day.
It is in a periodic orbit of 8.1 years and perihelion at 3.2 AU and is a Jupiter family comet.
Comet 2002 O8 (P/NEAT) was also recovered by Gary Hug with his 0.56-m reflector at Sandlot Observatory, on January 22.49. The comet was 20th magnitude. The indicated correction to the prediction on MPC 59599 is Delta(T) = -0.34 day.
Comet 2001 CV8 (P/LINEAR) was recovered by Jim Scotti with the Spacewatch 1.8-m reflector on 2009 February 19.53. The indicated correction to the prediction on MPC 54170 is Delta(T) = -0.37 day.
The comet became about 5th magnitude at its brightest, with 39 visual observations giving a preliminary uncorrected light curve of 11.3 + 5 log d +  log r
The comet was recovered by Ernesto Guido, Giovanni Sostero and Paul Cammileri on 2009 March 17.50 using remote telescopes in the USA (the RAS Observatory 0.25-m reflector near Mayhill, NM) and in Australia (the 0.35-m reflector at Grove Creek Observatory, Trunkey, N.S.W.). The comet was 18th magnitude. The indicated correction to the predictions on MPC 56804 is Delta(T) = +0.01 day. It is a reasonably favourable return and the comet could reach 12th magnitude near the time of perihelion, coming into view for UK observers in August.
32 visual observations give a preliminary uncorrected light curve of 10.3 + 5 log d + 12.3 log r
M. Bezpalko, Lincoln Laboratory, Massachusetts Institute of Technology, reports the discovery by LINEAR of a comet with a tail in p.a. 270 deg on images taken on Apr. 29.3 UT. Following posting on the NEO Confirmation Page, other CCD observers have also reported the object as cometary, including G. J. Garradd (Tamworth, N.S.W., 0.45-m reflector; slightly diffuse on most images taken on Apr. 30.6), J. E. McGaha (Tucson, AZ, 0.30-m reflector; faint coma of size 5" x 10" and m_1 = 17.7-17.9, aligned north-south, with uniform brightness and no apparent nuclear condensation or core on May 2.2), and J. G. Ries (McDonald Observatory, 0.76-m reflector; 20" tail pointing slightly south of west on May 2.3; m_1 = 17.7-18.0). [IAUC 8127, 2003 May 1]
Orbital elements on MPEC 2003-K34, indicate that this comet passed 0.07 AU from Jupiter in June 1929, before which q and P were larger. [IAUC 8135, 2003 May 24]
On March 31 the LINEAR team reported a possible recovery of comet 2003 H4 (P/LINEAR) and this was confirmed by Giovanni Sostero, E Propsperi, Ernesto Guido and Paul Cammileri on April 15 using a remote telescope in Australia (the 0.35-m reflector at Grove Creek Observatory, Trunkey, N.S.W.). The comet was 20th magnitude. The indicated correction to the predictions on MPC 56804 is Delta(T) = -0.13 day.
An apparently asteroidal object with not-unusual motion recorded by the LINEAR project on 2002 June 5.30, and linked over 2002 June 5-13 and designated by the Minor Planet Center as 2002 LZ_11 (but indicated on MPEC 2002-L64 as having a cometary orbit), was accidentally reobserved by LINEAR on numerous occasions in July 2002 and during July-Nov. 2003 (and by LONEOS on 2003 Oct. 16). E. Christensen, University of Arizona, recognized 2002 LZ_11 as having cometary appearance yesterday in CCD images (mag 16.6-16.9) obtained accidentally by the Catalina Sky Survey (0.68-m f/1.8 Schmidt) on 2003 Oct. 29. Further images yesterday by Christensen apparently confirmed the cometary appearance, as did images obtained today at the request of the Minor Planet Center by J. Young (0.61-m reflector at Table Mountain Observatory), who described the object as having a round coma, 7" across, with a featureless fanshaped tail about 15"-20" long in p.a. 190-280 degrees. [IAUC 8240, 2003 November 18]
Ernesto Guido, Giovanni Sostero, Paul Cammileri and E Propsperi recovered comet 2002 LZ11 (P/LINEAR) on April 17.45 using a remote telescope in the USA (a 0.25-m reflector near Mayhill, New Mexico). The comet was 19th magnitude. The indicated correction to the predictions on MPC 59599 is Delta(T) = -0.4 day.
A comet has been discovered by R. H. McNaught on CCD images obtained with the 0.5-m Uppsala Schmidt telescope at Siding Spring. Following posting on the NEO Confirmation Page, J. Young reported that CCD images obtained with the 0.6-m reflector at Table Mountain on May 25.5 UT show an 8"-10" coma with no apparent central condensation and a straight, narrow tail 20"-30" long in p.a. 252 deg. CCD images taken by A. C. Gilmore and P. M. Kilmartin with the 0.6-m reflector at Mount John on May 25.7 show a circular 5" coma and no tail. [IAUC 8348, 2004 May 28]
Automatic analysis of data from 2009 April 28 provided to the Minor Planet Centre by Spacewatch identified comet P/2004 K2 (McNaught). The comet was also independently recovered by Gustavo Muler, J. M. Ruiz and Ramon Naves with the 0.30-m Schmidt-Cassegrain at the Observatorio Nazaret (Lanzarate, Spain) on May 1 and 3. The indicated correction to the prediction on MPC 56805 is Delta(T) = -0.08 day. The images from April 28 were stellar with no trace of coma or tail.
Perihelion is at 1.8 AU and the object is in a 6.6 year periodic orbit. It is a Jupiter family comet.
Leonid Elenin, Lyubertsy, Moscow region, Russia, recovered comet P/2002 JN16 as part of the ROCOT project. On June 1.40, he detected a diffuse object (~20.2m) with a small tail on 16 images obtained on 0.36-m f/3.8 Maksutov-Newtonian + ST-10XME (Tzec Maun observatory, Mayhill, NM, USA). The next day he requested confirmation of the recovery, and Michael Schwartz at Tenagra observatory imaged the comet on June 3 with 0.81-m f/7 Ritchey-Chretien + SITe. These images clearly show a tail at PA 248 degrees and length about 35". The correction to the predictions on MPC 56802 is Delta(T) = -0.2 day.
A. Milner, Lincoln Laboratory, reports the discovery by LINEAR of a comet with an apparent tail in p.a. 90 deg (discovery observation below). Following posting on the 'NEO Confirmation Page', other observers have confirmed the object's cometary nature from CCD images, including E. J. Christensen at Catalina (0.68-m Schmidt telescope, Dec. 9.10-9.11 UT; coma diameter about 8" with red mag 16.2-16.6 and faint 20" tail in p.a. 60 deg) and M. Tichy, M. Kocer, and J. Ticha at Klet (1.06-m KLENOT telescope, Dec. 9.70; diffuse with coma diameter 25" and a wide tail in p.a. 70 deg). It is possible that this comet is of short period. [IAUC 8449, 2004 December 9]
Rob McNaught discovered an 18th magnitude asteroid on images taken during the Siding Spring Survey with the 0.5-m Uppsala Schmidt on June 29.47. On a subsequent observing run on August 2.38 he noted that the object appeared cometary. Hirohiso Sato pointed out that the object appears to be comet P/LINEAR (2004 X1); the indicated correction to the prediction on MPEC 56804 being Delta_T = -2.2 days. The comet has a period of 4.83 years and reaches perihelion at 0.78 AU on September 1.1.
G. Sostero, E. Guido, P. Camilleri and E. Prosperi recovered P/Skiff (2002 S1) on June 15.61 from the co-addition of forty unfiltered 60-s CCD exposures obtained remotely on June 15.6 UT with the 0.35-m f/7 reflector at the Skylive-Grove Creek Observatory (near Trunkey, NSW, Australia). The recovery was confirmed by them on August 18.58. The comet was 20th magnitude and of stellar appearance. The indicated correction to the predictions on MPC 59600 is Delta(T) = -0.16 day.
An apparently asteroidal object with not-unusual motion reported on Dec. 4 and 5 by the LINEAR project, and designated 2003 XD_10 on MPS 92917, was independently discovered with the NEAT 1.2-m Schmidt telescope at Palomar on Dec. 14.4 and reported then to be cometary (with a faint short tail toward the east-southeast) by K. J. Lawrence. Following posting on the NEO Confirmation Page, several other CCD observers have also noted the object's cometary nature, including P. Birtwhistle (Great Shefford, Berkshire, England, 0.30-m reflector; on Dec. 14.9, from co-added images totaling 15 min exposure, diffuse coma of diameter 10", extended in p.a. about 260 deg, surrounding a central condensation of mag 19.4; on Dec. 15.9, 8" coma and 45" tail in p.a. 255 deg), J. E. McGaha (Tucson, AZ, 0.36-m reflector; on Dec. 16.3, three co-added 1-min frames show a small starlike condensation with a 8" coma), J. Young (Table Mountain, CA, 0.6-m reflector; on Dec. 17.3, 3" asymmetric coma with a hint of tail about 12" long in p.a. 250-260 deg), and R. Fredrick and R. Trentman (Louisburg, KS, 0.75-m reflector; on Dec. 17.4, broad fan-shaped tail 20" long in p.a. 240 deg). [IAUC 8257, 2003 December 17]
Jim Scotti recovered 2003 XD10 (P/LINEAR-NEAT) with the Spacewatch 1.8-m f/2.7 reflector at Kitt Peak on August 27.39. The comet was 21st magnitude and of stellar appearance. The indicated correction to the prediction on MPC 59598 is Delta(T) = -0.10 day.
The comet was periodic and was near perihelion. The period is around 6.7 years and the perihelion distance 1.2 AU. BAA Member Peter Birtwhistle was amongst the first to confirm its cometary nature.
Jim Scotti recovered 2002 T1 (P/LINEAR) with the Spacewatch 1.8-m f/2.7 reflector at Kitt Peak on August 28.49. The comet was 21st magnitude and of near-stellar ("soft") appearance. The indicated correction to the prediction on MPC 56804 is Delta(T) = +0.04 day.
Orbital calculations by Maik Meyer tend to confirm the identity of the object with D/1783 W1. Nakano has computed a linked orbit:
If the comet has made 33 revolutions from 1783 to 2003, this provides a good linkage between D/1783 W1 and P/2003 A1. Because the period of the comet is not certain, the number of revolutions of the comet could be between 37 and 29. Furthermore, in the case of 33 revolutions, the comet made close approaches to Jupiter: on 1923 9 16.0 to 0.35 AU, on 1864 6 1.5 to 0.57 AU, and on 1852 7 3.0 to 0.98 AU with an approach to 0.67 AU on 1793 4 7.5. The closest approach to the earth during this time was at the appearance of 1783.
An apparently asteroidal LINEAR object discovered on 2003 January 5.07 with m2 18.4), posted on the NEO Confirmation Page, has been found to be diffuse by CCD observers elsewhere, including at Haleakala (1.2-m reflector, with K. Lawrence reporting the object as slightly diffuse on NEAT images taken on Jan. 7.3 UT, and again somewhat diffuse on Jan. 8.3), at Klet (where M. Tichy found a coma diameter of 8" on images taken on Jan. 8.7 with the 1.06-m KLENOT reflector), and at Ondrejov (where P. Pravec found a faint, small coma that was "marginally apparent", on images taken close to the moon on Jan. 8.8 with the 0.65-m f/3.6 reflector). The object is likely of short period, with the angular orbital elements quite similar to those of D/1783 W1. [IAUC 8044, 2003 January 8]
Rich Kowalski discovered a very diffuse comet during the Catalina Sky Survey with the 0.68m Schmidt on 2009 September 10.4, which was confirmed by several observers including Peter Birtwhistle, following posting on the NEOCP as 9R1E5E6. Dimitry Chestnov linked the object to comet 2003 A1, although the linked orbit had considerably different orbital elements (notably T and q) to those predicted for 2003 A1. Brian Marsden notes on IAUC 9072: "it is meaningless to indicate a Delta(T) value because the prediction is strongly influenced by a very close approach to Jupiter (nominally 0.0605 AU on 2006 Sept. 10.4 TT)." He then computed a linked orbit that satisfactorily included observations of comet Pigott, seen in 1783. The comet was at perihelion in May.
Following publication of the new orbit, Maik Meyer was able to locate images of the comet on Siding Spring images taken on 1995 October 29.
An apparently asteroidal object reported independently by the Catalina and LINEAR surveys (discovery observations on MPS 102307; linked by G. V. Williams) has been found to be cometary on CCD images obtained at two Arizona observatories. Observations (via independent discovery) on Apr. 14.3 UT by M. T. Read and J. A. Larsen, using the 0.9-m f/3 Spacewatch reflector at Kitt Peak, show a tail 100" long in p.a. 300 deg, extending asymmetrically from the south part of the nuclear condensation. Exposures taken to look for cometary appearance on Apr. 14.32 by C. W. Hergenrother with the 1.2-m reflector at Mt. Hopkins show a very condensed 9" coma and a narrow tail 210" long in p.a. 295 deg. [IAUC 8322, 2004 April 15]
Jim Scotti recovered P/2004 EW38 with the 1.8-m Spacewatch telescope at Kitt Peak on 2009 September 21.37, noting only stellar appearance. The indicated correction to the orbit prediction on MPC 59600 is Delta(T) = +0.02 day.
Following publication of the new orbit, Maik Meyer was able to locate images of the comet on Haleakala-NEAT images taken on 1997 January 15.
An apparently asteroidal object of 20th mag discovered by LINEAR on December 17.32 and designated 2001 YX_127 (cf. MPS 47220, MPO 24028) has been found to have a broad, fan-shaped extension in p.a. 100 deg on CCD images obtained on Feb. 14.2 UT by T. B. Spahr with the 1.2-m reflector at Mount Hopkins. Co-added CCD R-band images taken at about the same time by C. W. Hergenrother with the Catalina 1.54-m reflector show a 7" coma and a broad tail 8" long in p.a. 100 deg. [IAUC 7828, 2002 February 14]
Jim Scotti recovered P/2001 YX127 with the 1.8-m Spacewatch telescope at Kitt Peak on October 18.45, noting that it was very faintly diffuse with a short tail. The indicated correction to the orbit prediction on MPC 62881 is Delta T = -0.36 day. It reaches perihelion in 2011 August.
Following improved astrometry S. Nakano identified observations of the comet among single-night data from NEAT at the two preceding apparitions in 1997 and 2002, with it being assigned the identifications 1997 A2 and 2002 Q15. Rob Matson independently located the images corresponding to these observations, together with some additional ones and provided measurements. The comet's approach to a distance of 0.88 AU from Jupiter in September 2007 means that the orbital period, currently 6.27 years, was previously 6.48-6.49 years, with the comet's previous two perihelion passages occurring on 2003 Mar. 3 and 1996 Sept. 4.
The comet was recovered by Gary Hug with his 0.56-m reflector at Sandlot Observatory on 2009 December 11.32. The indicated correction to the prediction on MPC 62880 is Delta(T) = -0.5 day.
F. Manca, Bosisio Parini (LC), Italy, has suggested that the comet was observed at its previous perihelion passage as 1999 XO188, the observations of which, all by LINEAR, were given on MPS 9249 and 82876. The object was first observed on 1999 December 12.34. An orbit was published on MPO 50446. [CBET 2083, 2009 December 17]
The comet was then identified with asteroid 2005 JR71 by Gareth Williams.
An apparently asteroidal object discovered by the LINEAR project on 2003 October 29.32 has been found to show cometary appearance on CCD images taken with the Mt. Hopkins 1.2-m reflector on Nov. 30.25 UT by C. W. Hergenrother; his co-added 1200-s R-band exposures show a highly condensed 16" coma and a narrow tail 100" long in p.a. 280 deg (mag 18.5 determined by T. B. Spahr). Also, R. S. McMillan noted the object as diffuse in Spacewatch incidental observations made on Nov. 30.4. [IAUC 8247, 2003 December 2]
Jim Scotti recovered comet 2003 UY275 on May 20.44 with the Spacewatch 1.8-m f/2.7 reflector at Kitt Peak. The indicated correction to the orbit on MPC 59600 is Delta(T) = -0.70 day. There are suggestions that images taken in late October and early November show that the comet has split into two components.
At the 2016 return the comet brightened quite rapidly during the first half of the year and reached 13th magnitude in late June, much brighter than expected.
Jana Pittichova recovered P/2005 U1 on images obtained with the 2.2-m University of Hawaii reflector at Mauna Kea on 2010 July 7.43. The comet was around mag 24. The indicated correction to the prediction on MPC 62880 is Delta(T) = -0.2 day.
In 2010 August, images from WISE taken in early February were linked by Gareth Williams to P/1999 XB69 (LINEAR). This then allowed images from the Mt Lemmon Survey taken at the end of 2008 October to be included in the orbital solution. The comet has a period of 9.5 years and was at perihelion in 2009 July.
It is a moderately distant and intrinsically faint periodic comet. It has a period of 8.1 years and a perihelion distance of 2.5 AU.
The comet was independently recovered between August 9 and 11 by H. Taylor (Rayle, GA, U.S.A., 25-cm reflector), by H. Sato (Tokyo, Japan; remotely, 25-cm reflector, RAS Observatory, Mayhill, NM, U.S.A.; 20" coma and 30" tail in p.a. 260 deg), by L. Elenin (Lyubertsy, Russia; remotely, 45-cm f/2.8 astrograph, ISON-NM Observatory, Mayhill; 50" tail), and by T. Yusa (telescope data same as for Sato; faint 25" tail in p.a. 252 deg). The indicated correction to the prediction by S. Nakano (ICQ 2009/ 2010 Comet Handbook, p. 108) is Delta(T) = -0.63 day. [IAUC 9159, 2010 August 12)
H. Sato, Tokyo, recovered P/1999 U3 on 2010 August 12.44 on CCD images obtained remotely with a 0.25-m f/3.4 reflector located at the RAS Observatory near Mayhill, NM, U.S.A when it showed a 15" coma. The indicated correction to the prediction by S. Nakano on MPC 59600 is Delta(T) = -0.22 day. [IAUC 9160, 2010 August 13]
Gary Hug recovered comet 1998 U4 (P/Spahr) on August 14.41 on images taken with a 0.56-m reflector located near Scranton, KS, U.S.A. The indicated correction to the prediction by B. G. Marsden on MPC 65938 is Delta(T) = +0.04 day. The perihelion distance has migrated out a little to 4.0 AU and the period is now 13.0 years.
Ernesto Guido and Giovani Sostero recovered comet 2003 S2 (P/NEAT) on August 15.31 on images taken with a 0.25-m f/3.4 reflector located at the RAS Observatory near Mayhill, NM, U.S.A. The indicated correction to the prediction by B. G. Marsden on MPC 62880 is Delta(T) = -0.33 day.
Additional astrometry, including prediscovery observations by LINEAR on Nov. 29 and Dec. 21 identified by B. G. Marsden, appear on MPEC 2000-Y47, together with the following orbital elements showing this to be a short-period comet. The elements indicate an approach to within 0.05 AU of Jupiter in Sept. 1998. Further to IAUC 7552, J. V. Scotti notes that the comet showed a 7" coma and a 1'.16 tail in p.a. 270 deg on a Spacewatch CCD image taken on Dec. 31.174 UT. An image obtained at Klet on Dec. 30.79 shows a coma diameter of 8" and m_1 = 17.5. [IAUC 7553, 2000 December 31]
Jim Scotti recovered comet 2000 Y3 (P/Scotti) as an essentially stellar object on images obtained on August 19.38 and 20 with the 0.9-m Spacewatch reflector at Kitt Peak. The indicated correction to the prediction on MPC 65937 is Delta(T) = -0.46 day.
In September 2010 Rob Matson identified the comet on NEAT images from Palomar taken in August and September 2002, and the comet was given the identity 2002 Q16 for this return.
The NEAT program reports the discovery of a comet on images taken with the 1.2-m reflector at Haleakala, with a tail about 5" long toward the west. Following WWW posting on the NEO Confirmation Page, numerous observers have reported on the object's cometary appearance on CCD images taken during Mar. 28.9-29.4 UT, including F. Hormuth, J. Ticha and M. Tichy, P. Kusnirak, B. L. Stevens, J. Young, and G. Hug -- the object generally showing a coma diameter of 8"-30", total magnitude as bright as 16, and a faint tail approximately 20"-40" long spanning p.a. 240-285 deg.
The comet passed about 0.37 AU from Jupiter in July 2001, causing the perihelion distance to decrease. [IAUC 8313, 2004 March 29]
Kazuo Kinoshita calculates that this passage reduced the perihelion distance from 3.8 AU to 2.9 AU. The comet will approach Jupiter again in 2024, when the perihelion will be increased to 3.5 AU. The returns of 2005, 2013 and 2021 are the closest over the last 200 years. The comet should have been bright enough for discovery at earlier returns, which suggests that the change in perihelion distance has enhanced the activity of the comet.
The comet was recovered by E. Romas (Rostov-na-Donu, Russia), A. Novichonok (Kondopoga, Russia), and Dmitry Chestnov (Saransk, Russia) on forty stacked 120-s images obtained on November 2.0 UT with the 0.5-m f/8.3 Maksutov-Cassegrain reflector at the Kislovodsk Mountain Astronomical Station of Pulkovo Observatory. Gary Hug (Scranton, KS, U.S.A.) found the comet to be slightly diffuse on images taken with a 0.56-m reflector on November 3.5. The indicated correction to the prediction on MPC 69908 is Delta(T) = -0.02 day. Although not due to reach perihelion until 2013 January, Juan Jose Gonzalez reported it at 12th magnitude on 2012 March 15.
36 observations received so far suggest a preliminary light curve of m = 8.1 + 5 log d +  log r
It was refound by LINEAR on 2010 November 15.39 at 18th magnitude. It was finally confirmed as a comet in 2010 December when observations at the Haute Province Observatory as part of the T2 prject showed that it had a tail. This was confirmed by follow-up observations and announced on MPEC 2010-Y29 on December 27. The comet reaches perihelion in early January at this return, at a distance of 1.48 AU and has a period of 7.9 years.
Leonid Elenin (Lyubertsy, Russia) recovered 2006 U1 (P/LINEAR) using the ISON-NM Observatory near Mayhill, New Mexico, USA. The indicated correction to the prediction by S. Nakano (2010/2011 Comet Handbook) is Delta(T) = +0.24 day.
Images of the comet have been found in Spacewatch images from 1995 and 2004 and NEAT images from 2002.
Jim Scotti recovered 2004 HC18 (P/LINEAR) using the Spacewatch 1.8m reflector on May 1.47. The indicated correction to the prediction in the 2010/2011 Comet Handbook) is Delta(T) = -0.10 day.
It has a 6.5 year period with perihelion at 1.7 AU.
Jim Scotti recovered comet 2000 G1 (P/LINEAR) with the Spacewatch telescope on 2011 June 9.42, when it was 23rd magnitude. It was not recovered at its previous return in 2005. The most recent perihelion was in November 2010. The indicated correction to the prediction on MPC 59601 is Delta(T) = -0.24 day.
The comet was moved into its present orbit in February 1987 when an encounter to within 0.15 au of Jupiter made significant changes to the elements. It made a close approach to the Earth in 2016, passing 0.036 au from us on March 21, when it was best seen from the Southern Hemisphere. Interestingly, recently discovered 2016 BA14 has a very similar orbit and made an even closer approach a day later.
The first observations were made in 2016 February, but it brightened very quickly in March and had reached 6th magnitude by mid month, peaking at 4th magnitude around the time of closest approach. The comet was a large, very diffuse, object. The observations are best fitted by a linear light curve, with the comet at peak output some 39 days after perihelion and brightening unusually rapidly. The rapid brightening gave reports of an outburst, but the degree of condensation has remained low. A standard light curve does not fit the observations.
89 observation received so far suggest a preliminary uncorrected light curve of m = 9.3 + 5 log d + 0.1006 * abs(t-T-39) .
The comet could potentially have an associated meteor shower. This would be maximum around March 30 and the meteors would appear to radiate from 5h 08m -16.
Subsequently S Nakano was able to identify the comet with LINEAR images of asteroid 1998 RS22 and then with 2005 observations by Spacewatch. The comet has a period of 6.5 years.
M. Meyer, Limburg, Germany, identified observations of comet P/2010 T1 (cf. IAUC 9172) on NEAT images obtained at Palomar on 2001 October 23.5 (when the comet was slightly diffuse) and December 18.4 UT, as well as a single trail on a Digitized Sky Survey image obtained with the 1.2-m Schmidt telescope at Siding Spring on 1980 October 5; the identity of the astrometry (published on MPC 76729) was confirmed by S. Nakano (Sumoto, Japan) and by G. V. Williams (Minor Planet Center), leading to the assignment of the permanent number 254P to this comet. Orbital elements by Nakano suggest T = 1980 September 25.59, 1990 October 15.69, 2000 October 9.30, and 2010 October 26.64 TT. [IAUC 9240, 2011 November 14]
Calculations by Hirohisa Sato suggested a periodic orbit, and an MPEC was issued on October 7 confirming this. The period is 5.2 years, which perhaps suggests that it was discovered in outburst. Several people, including CÚdric Bemer, have suggested the possibility of a meteor shower from the comet around December 31/January 1. The orbit is however still a little uncertain, so it is not clear how much meteoric material is likely to be present. At its next return in 2011 the comet makes a close approach to the Earth. Calculations by Andrew Lowe suggest an approach to 0.024 AU, with the comet perhaps visible to the naked eye. If the comet is fragmenting it may be more likely to have a significant dust trail present.
The object was at perihelion at 1.0 AU on 2006 October 7. Initial visual and CCD observations suggested that the comet was perhaps a magnitude brighter than the discovery magnitude.
Maik Meyer has suggested a possible link with C/1743 C1. The orbit is rather chaotic, but further observations at the 2011 return may help refine the orbit.
P/2006 T1 was recovered by the Mt Lemmon Survey on December 17.06 and quickly confirmed by other astrometrists, including Peter Birtwhistle and Richard Miles. At 18th magnitude the comet is much fainter than expected (10 magnitudes) and 2.6 days from the expected perihelion. It was clearly in outburst at discovery in 2006, and there is always a chance that there will be repeat at this return. Unless this happens, or the light curve is unusual it will not get within visual range.
An apparently asteroidal object reported by LINEAR (discovery observation published on MPS 78496; prediscovery LINEAR observations published on MPS 80247; orbital elements on MPO 48372) was found cometary by C. Hergenrother, who reported a diffuse coma of diameter 15" (and mag 18.6 within an aperture of radius 8") and a broad tail 60" long in p.a. 115 deg on co-added 900-s R-band images taken on June 24.3 UT with the Mount Hopkins 1.2-m reflector. [IAUC 8156, 2003 June 25]
The comet 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. The current period is 10.0 years.
The comet was recovered by G. Sostero, N. Howes, A. Tripp, E. Guido 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.
As the orbit became better defined, observations from 2002 were found, confirming the period.
Few observations of the comet were 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.
Observations by Henry Hsieh in 2012 confirmed observations made in 2010 and 2011 and give a perihelion date in 2013 January, 0.10 days earlier than predicted. With observations made near aphelion it was not given a designation for the 2013 return.
The comet was recovered by M Masek with the 0.3m reflector at the Pierre Auger Observatory, Malargue on 2012 May 15.38 and it will reach perihelion in September, 0.22 days earlier than predicted. It reached a peak near 11th magnitude in 2012 October.
21 visual observations give a preliminary uncorrected light curve of 10.7 + 5 log d +  log r but this is not a good fit, and a linear fit of m = 12.9 + 5 log d + 0.0077 abs(t-T-24) is not much better.
The comet was recovered by Nick Howes, Giovanni Sostero and Ernesto Guido on 2012 May 22.57 using the 2.0-m Faulkes Telescope North when it was 20th magnitude. It reaches perihelion in September, 0.27 days earlier than predicted.
Although not observed visually at the discovery apparition, its brightness on the Schmidt plates suggests that it might have been within range and the predictions are based on this assumption. These suggested that it might become visible in 2012 July, and would be at its brightest in November and December, when it is well placed in the evening sky. In the event it wasn't seen visually until early November, when it was 13th magnitude. A month later it had brightened further to 11th magnitude. This change suggests that it may be a comet that shows a linear brightening, so could brighten further.
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.
J. A. Larsen, Lunar and Planetary Laboratory, University of Arizona, reports the discovery of a comet on Spacewatch CCD images taken with the 0.9-m f/3 reflector at Kitt Peak, reporting a 17" tail in p.a. 280 deg. Following posting on the NEO Confirmation Page, J. E. McGaha (Tucson, AZ, 0.62-m f/5.1 reflector) reported that his stacked 3-min CCD frames taken on Apr. 24.22 UT show a soft coma with diameter 6" and a 8" tail in p.a. 270 deg. [IAUC 8332, 2004 April 24]
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.
M. Bezpalko, Lincoln Laboratory, reports the LINEAR discovery of a comet, showing a tail approximately 42" long in p.a. 230 deg. Other CCD observers report mag 16.9-17.9 and a tail of up to 6' long in p.a. 245-250 deg on July 30-31 (including S. Sanchez, R. Stoss, and J. Nomen at Mallorca; R. Trentman and R. Frederick at Louisburg, KS; and P. Birtwhistle at Great Shefford, U.K., who also noted a 9" central condensation of mag 17.9, adding that the tail was very diffuse and wide). [IAUC 8172, 2003 July 31]
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 now has a period of 8.7 years.
The comet had a period of 6.6 years, with perihelion at 2.3 AU in mid 2007 January.
Recovery mages were taken at Majdanak on 2012 August 15 by O. Burhonov with the 1.5m Ritchey-Chretien, with confirmation images taken on August 28, and measured by Artyom Novichonok. The comet will reach perihelion 0.21 days early compared to predictions on the MPC.
The comet was recovered by V. Nevski, D. Ivanov, A. Novichonok and I. Kondratenko on images taken on 2012 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.
David Tholen's team recovered the comet with the 8.2m reflector at Mauna Kea on 2012 August 13.55, when it was 24th magnitude. It doesn't return to perihelion until 2015.
The comet was recovered on images taken on 2012 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, Kitt Peak, 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, and has a period of 19.8 years.
The comet was recovered on images taken on 2012 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.
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.
2004 F1 (P/NEAT) was recovered on images taken on 2012 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.
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.
The latest orbit by Hirohisa Sato, based only on the 2012 observations, gives a period of 196 years, ie the last perihelion was in 1819. Forcing a fit to 1827 M1 increases the residuals of the modern observations. This could imply that there are significant non-gravitational forces acting, or that possibly the comet split at some point in the past and this is not a return of the comet seen in 1827. This might explain the apparent discrepancy in absolute magnitude.
Richard Miles demonstrated that CCD imagers can image comets in conditions that defeat visual observers with images taken from the UK on December 5, when the comet was very low in the sky. The comet emerged from conjunction towards the end of January as a 9th magnitude object, a little brighter than expected, but in line with suggestions of a linear light curve, with the comet brightest about 22 days after perihelion. More observations are required.
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.
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 reaches perihelion at 1.6 AU on December 27.3 and has a period of around 14 years.
Further observations showed cometary characteristics. Perihelion was at 1.9 AU in early November 2005, and it has a period of 7.6 years.
Jim Scotti recovered 2005 YQ127 in Spacewatch II images taken with the 1.8-m f/2.7 reflector at Kitt Peak on January 7.10. Perihelion is in June, 0.12 days later than predicted from the discovery apparition. [MPEC 2013-B18, 2013 January 18]
Jim Scotti recovered 2006 K2 in Spacewatch II images taken with the 1.8-m f/2.7 reflector at Kitt Peak on 2013 January 19.53. Perihelion is in August, 0.17 days earlier than predicted from the discovery apparition. [MPEC 2013-B58, 2013 January 21]
Reiner Stoss notes the following discovery story on behalf of the LSSS team
Exactly one year ago fellow asteroid hunter Patrick Wiggins posted on MPML his joy about his latest asteroid discovery. You can find the thread in the MPML archive (subject: "It's still possible"). His conclusion was that it is still possible for amateurs to find "bright" asteroids, despite the huge sky coverage by the NASA NEO surveys.In early 2013 Rob Matson found the comet in NEAT images taken with the Palomar 1.2m Schmidt in 2002 July, and other images were found in frames from the Apache Point 2.5m telescope.
In an attempt to underline this and to motivate other fellow observers I had then posted some experiences made in the first few months of our own sky survey. After just three months of permanently scanning the skies we had received around one thousand designations from MPC and the sky seemed to be full of unidentified asteroids, some of them as bright as magnitude 17.
Now, exactly one year later, the situation has not changed significantly. At J75 we keep scanning with the 45-cm and we find lots of new stuff ranging from magnitude 18 to 20. Sometimes as many as a few hundred possibly new objects per night. It shows that finding new asteroids is not a matter of luck, just a function of search area and limiting magnitude... and more or less the same applies to comets I guess.
We have missed a few of them in the past, either because they were just outside the search area. Or because of some other "constraints" (see below). Now we finally scored one and this one would have gone unnoticed too if MPC wouldn't have linked it to other survey observations so that it showed a cometary orbit and drew special attention therefore. Finding one is way more difficult than finding an asteroid, even a NEO. But I guess it comes too more or less guaranteed after a lot of searching, like with asteroids.
Definitely the times are much harder now compared to the age when Dennis di Cicco wrote his famous "Hunting Asteroids From Your Backyard" article 15 years ago. At that time nearly every mover on the sky was a new one, even at magnitude 16. The big surveys are now in operation since more than 10 years and the number of objects that have been discovered and have received orbits has virtually exploded, from around 29,000 in early January 1996 to more than 460,000 objects now (out of these were 6,800 numbered then vs. 220,000 numbered objects now).
I am not into visual comet hunting, but I think to remember that these folks invested on average hundreds of hours per discovery. Clearly their work was very difficult, learning all those faint galaxies to distinguish them from possible comets without using star maps and a light to not destroy the adaption of the eyes. Today's work is rather different. Being outside with the telescope under the sky was replaced by endless sessions on the computer screen watching CCD images scroll by. Judge yourself what is easier and more pleasurable :o)
I am therefore not able to tell how many hours it took us to score the first one, but here are a few numbers that might help evaluate how much "asteroid work" was done (=sky was scanned) until the first new comet showed up. They are from more or less one year of LSSS operations.
Earlier this month I did extract some numbers for J75 LSSS from the MPC observations database and I noticed that we had meanwhile published more than 500,000 observations for a total of 75,000 individual objects. Thirty percent of all numbered asteroids to date were observed by J75. And the number of designations received from the MPC is now at 3300.
And still, compared to the numbers delivered by Catalina, LINEAR and Spacewatch ours are rather humble. We know that we can't compete with them and it isn't our goal at all. LSSS is working different than the big surveys. It is an amateur survey done entirely remotely. Only one operator is permanently at the observatory, while all others are up to several thousand kilometers away. As all of us have day jobs, it is only possible to run this survey by using every free minute, being connected remotely no matter where we currently are.
My LSSS colleague Jaime Nomen is sometimes working via laptop and 3G card while he is travelling in a high-speed train (AVE) between Barcelona and Madrid. If you ever happen to use that train and you see someone getting anxious when the 3G signal is getting weak in one of the tunnels, you know who it is and what some people do at over 300km/h :o)
Anyway, no matter if you are after asteroids or comets, I think that the closing sentence of Dennis di Cicco's 1996 article is still true:
"There's a lot of stuff out there waiting to be discovered, and it doesn't take long to find it!"
... except with some comets :o)
P.S.: As mentioned above, here is one sure way to lose a comet discovery: Travel to a remote island without taking a 3G card with you! Some of us were on the island of Lastovo in the Adriatic Sea around New Year's Eve 2008/2009, unfortunately without Internet. When we returned on Jan. 2, I checked my email inbox to see the detections made of possibly new asteroids by our telescopes in the past days. I ran them through MPChecker just to find this: ----- The following objects, brighter than V = 23, were found in the 5.0-arcminute region around the following observation:8CTB133 C2008 12 30.16450 10 03 12.59 +20 00 29.2 18.3 V J75 Object designation R.A. Decl. V Offsets Motion/min Orbit Further observations? h m s ░ ' " R.A. Decl. Mot. PA Comment (Elong/Decl/V at date 1) P/2008 Y2 (Gibbs) 10 03 12.6 +20 00 30 0.0W 0.0N 0.6 128.6 cmt (r = 1.65 AU)----- We had a comet in the inbox waiting to be reported, right when we were out of town for a couple of days without Internet. And then of course comes what must come... Catalina picks it up, reports it and gets the credit in IAUC 9008 from Jan. 1 Sometimes you lose, sometimes you win :o)
J. A. Larsen, Lunar and Planetary Laboratory, reports his discovery of a comet on Spacewatch images taken with the 0.9-m telescope at Kitt Peak; the object showed a coma diameter of 7" and a 15" tail in p.a. 240 deg. Following posting on the NEO Confirmation Page, other CCD observers also noted the object's cometary appearance, including J. G. Ries (McDonald Observatory, 0.76-m reflector; Apr. 21.24-21.43 UT; object extended with a hint of tail to the southwest), G. Hug (Scranton, KS, 0.3-m reflector; Apr. 21.4; diffuse), and J. Young (Table Mountain, 0.6-m reflector; Apr. 21.42-21.45; small central condensation in a round 4" coma, with a hint of elongation about 8" long in p.a. 290 deg). [IAUC 8328, 2004 April 21]
Jim Scotti recovered 2004 H2 in Spacewatch II images taken with the 1.8-m f/2.7 reflector at Kitt Peak on 2013 February 5.50. It has a period of 9.6 years and is at perihelion at 2.6 au in December, 0.58 days earlier than predicted from the discovery apparition. [MPEC 2013-C25, 2013 February 6]
With further astrometry leading to an improved orbit, Maik Meyer found and measured the comet in NEAT images from February and March 2002, and the comet was also found in Spacewatch images from 2000 November.
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.
Jim Scotti recovered 2007 H1 with the Spacewatch 1.8m reflector on May 1.41. The comet will return 0.22 days earlier than predicted in 2014 September, when it may again reach 13th magnitude.
F. Shelly, Lincoln Laboratory, Massachusetts Institute of Technology, reported the discovery of a comet with a diffuse coma and a very wide, fan-shaped tail in p.a. 85 deg on LINEAR images on October 19.09. Following posting on the NEO Confirmation Page, other CCD observers also commented on the cometary appearance on October 21.1-21.2, including J. Young at Table Mountain (0.6-m reflector; 5" coma without central condensation and with a fan-shaped tail about 25" long spanning p.a. 70-95 deg) and R. Fredrick and T. Medlock at Louisburg, KS (0.75-m reflector; 30" tail in p.a. 80 deg). [IAUC 8229, 2003 October 21]
Hidetaka Sato recovered 2003 U2 with the remote iTelescope 0.51m astrograph at Mayhill Observatory on 2013 May 8.45. Perihelion is 0.18 days earlier than predicted. [MPEC 2013-K37, 2013 May 24]
Hidetaka Sato recovered 2005 L4 with the remote iTelescope 0.51m astrograph at Siding Spring on 2013 May 19.70. Perihelion is 0.18 days earlier than predicted. [MPEC 2013-K47, 2013 May 31]
Jim Scotti recovered 2006 R2 with the Spacewatch 1.8m reflector on 2013 June 1.29. The comet will return 0.75 days earlier than predicted. [MPEC 2013-L19, 2013 June 4]
As noted above the preliminary announcement of this asteroid suggested that it could be a Jupiter family comet, and this has proved to be the case. M Micheli (Italy) and Peter Jenniskens both suggested an identity with the lost periodic comet Blanpain (D/1819 W1), and Brian Marsden has now conclusively linked the asteroid with the comet. Harold Ridley has also tentatively linked the comet with the Phoenicid meteor shower of 1956 December 5. [IAUC 8485, 2005 February 13]
At discovery the comet was around 6.5, with a coma of 6 - 7 ' diameter. It was observed for 59 days. Although Vsekhsvyatskij gives an absolute magnitude of 8.5, this doesn't fit the ephemeris very well and 10.5 is more likely.
The original orbit for comet Blanpain appears to have been relatively good, however the period was around a month out. Since its discovery apparition it made a further 34 returns prior to its recovery as an asteroid in 2003. Perihelion distance has varied between 0.87 and 1.04 AU, and it passed 0.31 AU from Jupiter in 1995. There were close approaches to the Earth at the discovery in 1819 (0.11 AU in October before discovery), 1866 (0.08 AU in November), 1919 (0.06 AU in November/December). It will make future close approaches in 2020 (0.09 AU in January) and 2035 (0.09 AU in November). [Orbits calculated by Kenji Muraoka and myself]
Already more than a year ago, S. Foglia, Milan, Italy, reported a suggestion by M. Micheli that backward integration of the orbit of 2003 WY25 given on MPEC 2003-Y78 (Catalina Sky Survey discovery announcement on MPEC 2003-W41) suggested possible identity -- though showing discordances extending up to 17 deg in the argument of perihelion (Peri.) -- with the lost comet D/1819 W1 = 1819 IV, which was itself tentatively shown by H. B. Ridley (1957, BAA Circ. No. 382) to be related to the one-time Phoenicid meteor shower of 1956 Dec. 5. P. Jenniskens, NASA Ames Research Center, has now independently suggested the 1819-2003 identity with a Peri. discordance of 0.2 deg. Computations by B. G. Marsden, Harvard- Smithsonian Center for Astrophysics, that included reexamination of the 1819-1820 observations confirm a best-fit gravitational linkage with Peri. discordance 0.2 deg. He also showed that the discordances in all three angular elements can be reduced to 0.01 deg by starting from the following orbital elements for 2003 WY25 (which had H = 21.1 and was consistently of stellar appearance despite a passage only 0.025 AU from the earth on 2003 Dec. 12):
Epoch = 2003 Dec. 27.0 TT T = 2003 Dec. 11.5776 TT Peri. = 9.0695 e = 0.675583 Node = 69.3827 2000.0 q = 1.000069 AU Incl. = 5.9292 a = 3.082662 AU n = 0.1821022 P = 5.412 yearsAlthough backward integration of this orbit gives T too late in 1819, adjustment by Delta(T) = -4.28 days and modification of the angular elements within the range indicated above yield the result
Epoch = 1819 Nov. 22.0 TT T = 1819 Nov. 20.27 TT Peri. = 349.65 e = 0.7028 Node = 80.02 2000.0 q = 0.8893 AU Incl. = 9.23 a = 2.9928 AU n = 0.19036 P = 5.18 yearswhich satisfactorily represents 10 of the 13 observations made at Paris, Bologna, and Milan during 1819 Dec. 14-1820 Jan. 15 within 90 arcsec. The integrated orbital elements at the time of the Phoenicid shower are T = 1956 Oct. 25.32 TT, Peri. = 0.14 deg, Node = 74.37 deg, i = 9.60 deg (equinox 2000.0), q = 0.9914 AU, e = 0.6767, a = 3.0669 AU, P = 5.37 years. [IAUC 8485, 2005 February 13]
The comet was recovered by PanSTARRS on July 4.46, when it was found in outburst at 20th magnitude, some five magnitudes brighter than expected. [MPEC 2013-N20, 2013 July 6]. A new linked orbit was published in MPEC 2013-N21 [2013 July 7] and it was then numbered. Although expected to be renamed Blanpain-Catalina, it has reverted to just 289P/Blanpain.
Jonathan Shanklin observed it on 1998 October 29.1, making it around 12.5 in the Northumberland refractor x105, DC s3 and diameter around 1'. Nick James imaged the comet on October 26. Observations with the Northumberland in 1999 March put the comet at 12 - 13th magnitude. Observing on 1999 April 9/10 Shanklin could barely see the comet in the Northumberland, estimating it 13.6.
The 157 Observations in ICQ format gave an uncorrected light curve of 9.8 + 5 log d + 0.0151 abs(t-T-46.0)
K Sarneczky and G Marschalko recovered 1998 U3 with the 0.6m Schmidt at Konkoly Observatory on July 8.04. Perihelion is 1.96 days earlier than predicted. [MPEC 2013-N46, 2013 July 13]
9 observations at the 2014 return give an uncorrected light curve of 1.2 + 5 log d + 29.3 log r
Hidetaka Sato imaged comet 1998 Y2 (P/Li) on 2013 May 9.80 with the 0.51m astrograph of the iTelescope at Siding Spring, but confirmation of the recovery was not made until 2013 July 16.39 when it was imaged by M Masek with the 0.3m reflector at the Pierre Auger Observatory, Malargue. [MPEC 2013-O52, 2013 July 27] Perihelion is 0.85 days later than predicted.
Jim Scotti recovered 2006 XG16 with the 1.8-m Spacewatch II reflector on September 14.48 when it was 22nd magnitude. [MPEC 2013-S01, 2013 September 16] Perihelion is 0.07 days later than predicted.
Hidetaka Sato recovered 2008 A2 with the remote iTelescope 0.43m astrograph at Mayhill, New Mexico on December 11.51. Perihelion is 0.24 days earlier than predicted. [MPEC 2013-X72, 2013 December 14]
An apparently asteroidal object reported by LINEAR in early January 2002 and considered of only moderate interest was also recognized at the Minor Planet Center to have been accidentally reobserved by LINEAR on three isolated nights in February and March, after which the orbit calculation suggested the object might be a comet. It was therefore listed on the NEO Confirmation Page. Observations with the 1.2-m reflector at Mt. Hopkins Observatory by P. Berlind and T. B. Spahr on April 6.1 UT in poor conditions (high thin cirrus) showed that the images were softer than those of stars of similar brightness, and observations on April 7.2 showed the slightly diffuse images of a definite comet. [IAUC 7869, 2002 April 7]
Jim Scotti recovered 2002 AR2 with the 0.9m Spacewatch telescope at Kitt Peak on September 14.2, and it was also imaged by the Mount Lemmon Survey during September and October, but it wasn't finally confirmed until Scotti imaged it with the 1.8-m Spacewatch II reflector on December 25.15 when it was 21st magnitude. [MPEC 2013-Y30, 2013 December 25] The comet returns to perihelion 0.7 days earlier than predicted.
The comet was recovered by an observing team at the Pierre Auger Observatory, Malargue using the 0.3m f/10 reflector on January 6.31. Following recovery prediscovery NEAT images from 2001 June were identified. The comet was close to the predicted time of return.
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 2008 and has a period of 6.5 years. It is a member of the "Main Belt Comet" family.
The comet was recovered at the Cordell-Lorenz Observatory with their 0.3m Schmidt-Cassegrain on February 27.40, with pre-recovery images then found in Mt Lemmon data from January 2. The comet returns to perihelion 0.3 days earlier than predicted.
Jim Scotti recovered 2007 C1 (P/Christensen) in images taken with the 1.8m Spacewatch II reflector on February 9.54. The comet returned to perihelion 0.52 days earlier than predicted.
When the orbit improved the comet was linked to asteroid 2005 EL284 observed by LONEOS and LINEAR in 2005 March and by the Siding Spring Survey in 2005 July.
Published by Jonathan Shanklin. Jon Shanklin - firstname.lastname@example.org