Updated 2015 October 24
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.
The comet was recovered by M. Masek, J. Cerny, J. Ebr, M. Prouza, P. Kubanek, M. Jelinek, K. Honkova and J. Jurysek at the Pierre Auger Observatory, Malarque with the 0.3m reflector on April 9.39. [MPEC 2014-G70, 2014 April 10]. The comet returns to perihelion 0.1 days earlier than predicted.
The comet can make close approaches to Venus, Earth and Mars. Its last close approach to Earth was at the discovery apparition in 2005, when it came to 0.10 au and in 2036 it will approach to 0.06 au. It will approach within 0.08 au of Mars in 2132 and approached Venus to 0.09 au in 1957.
2001 BB50 (P/LINEAR-NEAT) was recovered in images from PanSTARRS taken on 2014 May 17.28, with earlier images taken at the SATINO remote observatory, Haute Province on 2014 March 1.93. The comet will return to perihelion 1.76 days earlier than predicted and has a period of 13.7 years.
K. Lawrence, Jet Propulsion Laboratory, reports the discovery by the NEAT project of a 19th magnitude comet on 2003 October 22.29. Observations by J. Young at Table Mountain on October 23.2 UT show a 3" coma with a short, broad, fan-shaped tail about 8" long spanning p.a. 255-285 deg. [IAUC 8230, 2003 October 23]
2003 U3 (P/NEAT) was recovered in images taken at the ESA Optical Ground Station in Tenerife with the 1.0m reflector by P Ruiz. The comet will return to perihelion 1.80 days earlier than predicted and has a period of 11.4 years. [MPEC 2014-L12, 2014 June 2]
Michel Ory is a Swiss amateur astronomer and president of the Société jurassienne d'astronomie, which has a well equipped observatory in the foothills of the Jura.
The comet passed 0.3 au from Jupiter in November 2005, before which the perihelion distance was a little larger.
2008 Q2 was recovered by Hidetaka Sato in images taken with the iTelescope 0.51m astrograph at Siding Spring on 2014 June 2.79. The comet is very close to the prediction by B. G. Marsden on MPC 65935. It has a period of 5.8 years. [MPEC 2014-M10, CBET 3906, 2014 June 18]
B. Skiff, Lowell Observatory, reports his discovery of a comet on LONEOS images obtained on Nov. 4.1 UT with the 0.59-m Schmidt telescope, the object showing a moderately condensed coma of diameter 25" and a weak tail 50" long in p.a. 75 deg. Following posting on the "NEO Confirmation Page", B. L. Stevens (Las Cruces, NM, 0.3-m Schmidt-Cassegrain telescope) reports that his CCD images taken on Nov. 4.2 show a 30" tail in p.a. 55 deg. [IAUC 8426, 2004 November 4]
Gareth Williams found images of 2004 V1 (P/Skiff) in images taken taken with the PanSTARRS 1 1.8m Ritchey-Chretien on July 3.51. The comet will return to perihelion 0.32 days earlier than predicted and has a period of 9.9 years. [CBET 3918, MPEC 2014-N43, 2014 July 7]
An apparently asteroidal object reported by LINEAR, and posted on the NEO Confirmation Page, was found to be apparently cometary on CCD images taken by P. Birtwhistle (Great Shefford, U.K., 0.30-m reflector; very faint tail about 10" long in p.a. approximately 270-280 deg on July 31.10 and Aug. 2.08 UT; mag 18.1 and coma diameter about 5" on Aug. 2.08), by J. Ticha and M. Tichy (Klet, 1.06-m KLENOT telescope; diffuse with a wide tail in p.a. 260 deg on Aug. 3.01), and by J. McGaha (near Tucson, AZ; possible tail spike 5" long in p.a. 300 deg on Aug. 3.38 with a 0.30-m reflector; possible fan-shaped tail 5" long in p.a. 260 deg on Aug. 5.33 with a 0.62-m reflector). The preliminary orbital elements indicate that the comet passed 0.3 au from Jupiter in Nov. 1979. [IAUC 8174, 2003 August 5]
2003 O3 (P/LINEAR) was recovered by Hidetaka Sato in images taken with the iTelescope 0.51m astrograph at Siding Spring on June 21.77. The comet was missed at its 2009 return and is close to the prediction in the 2014 ICQ Handbook. It has a period of 5.5 years with perihelion at 1.3 au. [MPEC 2014-N76, CBET 3922, 2014 July 14]
A team of observers at the European Space Agency's Optical Ground Station recovered 2000 QJ46 (P/LINEAR) with the 1.0m reflector on 2014 July 25.15. The indicated correction to the prediction by B. G. Marsden on MPC 75735 is Delta(T) = -0.24 day. [CBET 3923, MPEC 2014-O44, 2014 July 27] The comet has a period of 14 years and reaches perihelion at 1.9 au in December.
A team of observers at the European Space Agency's Optical Ground Station recovered 1997 T3 (P/Lagerqvist-Carsenty) with the 1.0m reflector on 2014 July 29.08. The indicated correction to the prediction by B. G. Marsden on MPC 79348 is Delta(T) = -1.28 days. [CBET 3925, MPEC 2014-O65, 2014 July 30] The comet has a period of 17 years and reaches perihelion at 4.2 au in 2015 May.
Krisztian Sarneczky recovered 2005 Q4 (P/LINEAR) with a 0.6m Schmidt on 2014 August 23.00, with PanSTARRS images from the same night later found by Gareth Williams. The indicated correction to the prediction by Gareth Williams on MPC 75706 is Delta(T) = -0.26 day. [CBET 3937, MPEC 2014-Q39, 2014 August 24] The comet has a period of 9.4 years and reaches perihelion at 1.7 au in 2015 February.
Krisztian Sarneczky recovered 2006 S6 (P/Hill) with a 0.6m Schmidt at the Piszkesteto Station of Konkoly Observatory on 2014 August 24.98. The indicated correction to the prediction by Gareth Williams on MPC 79348 is Delta(T) = -0.32 day. [CBET 3938, MPEC 2014-Q53, 2014 August 26] The comet has a period of 8.5 years and reaches perihelion at 2.4 au in 2015 April.
2001 Q11 (P/NEAT) was recovered in images taken by Eric Christensen at Mt Lemmon with the 1.5m reflector on September 6.45. After the object was posted on the PCCP, Hidetaka Sato was able to find the comet in images taken on July 28.82. The comet will return to perihelion 0.68 days earlier than predicted and has a period of 6.4 years. It was discovered by Maik Meyer in 2010 in images taken in 2001, though no images could be found from the 2007 return. [CBET 3971, MPEC 2014-R91, 2014 September 12]
With an improved orbit, it was linked to an object found in LONEOS images from September and November 2003 and was designated 2003 S10 for that return. [MPEC 2014-U24, 2014 October 20]
The comet was at perihelion at 2.4 au in 2014 August and has a period of 5.6 years.
1997 G1 (P/Montani) was recovered on October 13.31 at the Steward Observatory, Kitt Peak by Terry Bressi and A F Tubbiolo with the 0.9m reflector.
An apparently asteroidal object discovered by LONEOS, designated 2004 VR_8 (cf. MPS 118755, MPEC 2004-V48), was found to show a 10"-diameter coma and a tail 16" long in p.a. 140 deg on R-band CCD observations taken by C. W. Hergenrother (Lunar and Planetary Laboratory) with the 1.54-m Kuiper reflector at Catalina on November 19.3 UT. Also, A. Nakamura (Kuma, Ehime, Japan) reports that 240-s unfiltered CCD frames taken with a 0.60-m reflector on December 8.55 and 9.55 shows to object's image to be slightly 'softer' than other field stars of similar brightness, and a possible very faint tail is visible to the southeast. [IAUC 8451, 2004 December 10]
A possible recovery of 2004 VR8 (P/LONEOS) with the 3.5m Apache Point reflector on 2013 November 6.15 was confirmed with the same telescope on 2014 December 8.09. The indicated correction to the prediction by G. V. Willliams on MPC 84327 is Delta(T) = -0.71 day. [CBET 4038, MPEC 2014-Y45, 2014 December 24]
The comet approaches Jupiter every few orbits, most recently on 2007 August 22 when it passed 0.40 au from the planet. The encounter made small changes to the orbital elements and increased the orbital period to 11.2 years.
2005 RV25 (P/LONEOS-Christensen) was recovered on 2014 October 22.98 at the ESA Optical Ground Station, Tenerife by D Abreau with the 1.0m reflector. The recovery was confirmed by J D Armstrong with the Faulkes-North [CBET 40nn, MPEC 2014-W19, 2014 November 19] The comet has perihelion at 3.6 au in 2015 October and a period of 8.9 years. The perihelion date was around xx days earlier than those published for the equinox of perihelion.
PanSTARRS recovered P/2010 K2 in images taken with the 1.8m Ritchey-Chretien on 2015 January 26.46, with further images on March 18.35. The comet now has a period of 5.1 years and will reach perihelion 3.2 days earlier than previously predicted. It passed 0.71 au from Jupiter in 2012 November.
1994 N2 (P/McNaught-Hartley) was recovered by PanSTARRS in images taken with the 1.8m Ritchey-Chretien on 2014 June 29.32, though it took further images taken at the MASTER-SAAO Observatory, Sutherland with the 0.4m reflector on 2015 March 31.1 to confirm the recovery. The comet reaches perihelion at 2.45 au in October and has a period of 20.6 years.
5 visual observations received so far suggest a preliminary light curve of m = 9.0 + 5 log d +  log r
An object found in infra-red images from the NEOWISE satellite on 2015 April 5.67 was identified as the return of 2008 S1 (P/Catalina-McNaught) by Gareth Williams. The indicated correction to the prediction on MPC 79350 is Delta(T) = -0.11 day. The comet reaches perihelion at 1.20 au in 2015 July and has a period of 6.8 years.
R. H. McNaught reports his discovery of a comet on CCD images taken by himself with the 0.5-m Uppsala Schmidt telescope at Siding Spring on Sept. 2.4 UT, when the object was diffuse with a hint of a tail to the southeast. Images taken by McNaught with the Siding Spring 1.0-m f/8 reflector on Sept. 4.4 show the comet to be diffuse with a 10" coma and a tail 15" long in p.a. 110 deg. [IAUC 8398, 2004 September 4]
J. Young (Table Mountain, 0.6-m reflector + CCD) reports that images taken in poor seeing (and at low altitude) on Sept. 6.13- 6.16 UT show a coma diameter of about 5". Additional CCD images by R. H. McNaught with the Siding-Spring 1.0-m reflector on Sept. 6.5 show an ill-defined center of brightness that is elongated in the direction of tail (and of the comet's motion). [IAUC 8400, 2004 September 6]
An apparently asteroidal object found on images taken with the Cerro Tololo 4-m reflector by L. Allen and D. James (measured by F. Valdes) was posted on the Minor Planet Center's NEOCP webpage and then announced on MPEC 2015-H82 with the minor-planet designation 2015 HC10. Gareth Williams, F. Manca, and P. Sicoli then each identified it with comet P/2004 R1. The comet was missed at its 2010 return. The indicated correction to the prediction by S. Nakano on MPC 79350 is Delta(T) = +5.0 days.
Brian Marsden published a linked orbit on MPEC 2009-H56 [2009 April 26] and noted:
The above computation, using nongravitational parameters A1 = +0.0002, A2 = -0.0002, is based on work by R. Kracht. Despite the poor quality of the SOHO observations, a purely gravitational computation from the four apparitions appears to leave significantly systematic residuals.This suggests that the object really is a comet, and should therefore be numbered as such. The comet was again observed from SOHO in 2012, eventually being designated 2012 M2 in 2015 May and then subsequently numbered.
The identification is by R. Kracht. The observations, all obtained with the LASCO C2 coronagraph, are on MPEC 2006-L20, 2004-M42 and 2008-O16. The The object passed 0.058 AU from the earth on 2000 Jan. 13, 0.032 AU from Mars on 2004 May 19 and 1.17 AU from Jupiter on 2003 Feb. 1.The comet was again observed from SOHO in 2012, eventually being designated 2012 Q2 in 2015 May and subsequently numbered as 323P/SOHO.
The comet was recovered by S. S. Sheppard with the Magellan-Baade telescope in images taken in 2015 March and April, but the recovery was first reported by Jim Scotti in images taken with the Spacewatch 1.8-m telescope at Kitt Peak on 2015 May 22.43. The indicated correction to the prediction by S. Nakano is Delta(T) = -0.03 day. [CBET 4107, MPEC 2015-K101, 2015 May 26]. The Magellan-Baade images showed a tail, which was confirmed by CFH images, according to IAUC 9276 [2015 August 3]. This notes that the object is the fourth main belt comet to show recurrent activity when near perihelion after being inactive at aphelion.
Hidetaka Sato recovered 2009 L2 with the 0.51m iTelescope at Siding Spring on 2015 May 11.38 with confirming images taken on June 9 and 10. [MPEC 2015-L28, 2015 June 10].
Krisztian Sarneczky recovered 2007 V2 (P/Hill) with the 0.6m Schmidt at Piszkesteto Station of Konkoly Observatory on August 8.02. [CBET 4134, MPEC 2015-P21, 2015 August 10].
A possible comet found by PanSTARRS on August 6.39 was tentatively identified as 2002 Q1 (P/Van Ness) by Gareth Williams. Krisztian Sarneczky independently recovered the comet on images taken with the 0.6m Schmidt at Piszkesteto Station of Konkoly Observatory on August 10.87 by A Sodor. The indicated correction to the prediction by S. Nakano on MPC 79352 is Delta(T) = +1.5 days. [CBET 4135, MPEC 2015-P24, 2015 August 11].
Alex Gibbs discovered an 18th magnitude comet during the Catalina Sky Survey with the 0.68m Schmidt on 2015 September 30.13. He suggested that it might be a recovery of P/LONEOS-Tucker, which had been missed at its 2007 return. Other astrometrists, including Peter Birtwhistle confirmed the comet, and Gareth Williams computed a linked orbit. The correction to the predicted time of perihelion in published elements for the return was -1.9 days. [CBET 4146, MPEC 2015-T06, 2015 October 5]
An apparently asteroidal object was discovered by the LINEAR project on 2003 November 18 (observed on only two nights) and given the designation 2003 WC_7 (MPS 91151). The object was discovered independently on January 31 by the Catalina Sky Survey and then posted on the NEO Confirmation Page. As a result, it has been found to show cometary appearance on CCD exposures taken by J. Young (Table Mountain, 0.6-m reflector, Feb. 1.15 UT; very diffuse coma of mag 17.5 and diameter 5", very little central condensation, and a straight, narrow 10" tail in p.a. 345 deg) and by G. J. Garradd and R. H. McNaught (Siding Spring, 1.0-m f/8 reflector, Feb. 1.46; coma diameter 3".5 in 2".5 seeing; no obvious tail visible in five co- added 40-s frames). [IAUC 8280, 2004 February 1]
PanSTARRS discovered what was thought to be an unknown 20th magnitude comet on October 10.53, though the discovery report did suggest that it might be a recovery of 2003 WC7 (P/LINEAR-Catalina). Further astrometry confirmed the identification. The indicated correction to the prediction by G. V. Williams on MPC 79352 is Delta(T) = +0.70 day; the indicated correction to the prediction by S. Nakano in the ICQ's 2015 Comet Handbook is Delta(T) = +0.37 day. CBET 4148, MPEC 2015-T72, 2015 October 12]. The indicated ICQ Handbook does not appear to have any functional web links and is apparently not on the internet.
Krisztian Sarneczky recovered 1999 V1 on 2015 October 22.98 with the 0.6m Schmidt at Piszkesteto station of Konkoly Observatory. Following the observation he was able to identify images from September 13. The indicated correction to the prediction by Gareth Williams on MPC 84326 is Delta(T) = -0.74 day. [CBET 4155, MPEC 2015-U49, 2015 October 24]
Published by Jonathan Shanklin. Jon Shanklin - firstname.lastname@example.org