76P/West–Kohoutek–Ikemura

76P/West–Kohoutek–Ikemura is a Jupiter-family periodic comet in the Solar System with a current orbital period of 6.47 years.^[2]

76P/West–Kohoutek–Ikemura

76P/W–K–I photographed from the Zwicky Transient Facility on 29 December 2019
Discovery
Discovered by	Richard M. West Lubos Kohoutek Toshihiko Ikemura
Discovery site	Geneva, Switzerland Hamburg, Germany Shinshiro, Japan
Discovery date	January–March 1975
Designations
MPC designation	P/1975 D1 P/1980 V2
Alternative designations	1975 IV, 1981 VIII 1987 XV, 1993 XXI 1975b, 1980r 1987x, 1993o
Orbital characteristics[1][2]
Epoch	21 January 2022 (JD 2459600.5)
Observation arc	48.44 years
Earliest precovery date	15 October 1974
Number of observations	1,281
Aphelion	5.341 AU
Perihelion	1.603 AU
Semi-major axis	3.472 AU
Eccentricity	0.53829
Orbital period	6.469 years
Inclination	30.466°
Longitude of ascending node	84.109°
Argument of periapsis	359.95°
Mean anomaly	124.62°
Last perihelion	26 October 2019
Next perihelion	13 April 2026
TJupiter	2.685
Earth MOID	0.617 AU
Jupiter MOID	0.049 AU
Physical characteristics[1][3]
Dimensions	0.62 km (0.39 mi)
Synodic rotation period	6.6±1.0 hours
Comet total magnitude (M1)	15.4
Comet nuclear magnitude (M2)	17.2

Discovery and observations

The comet was initially spotted on a photographic plate by Richard M. West at the European Southern Observatory Sky Atlas Laboratory, Geneva in January 1975, when it had a brightness of magnitude 12.^[4] Inability to predict its movement from a single image meant the comet had to be presumed lost.

In late February it was accidentally rediscovered by Lubos Kohoutek at the Hamburg Observatory, Germany and independently on 1 March by Toshihiko Ikemura in Shinshiro, Japan. After further observations the comets parabolic orbit was computed, which gave a perihelion date of 23 March 1975 and proved that all three sightings were of the same object, which was accordingly designated 76P/West–Kohoutek–Ikemura.

The comet has been observed at its successive returns in 1987, 1993, 2000, 2006 and 2013.

Orbit

Further calculations by Brian G. Marsden determined the comet's elliptical orbit^[5] and revealed that it had passed only 0.012 AU (1.8 million km) from Jupiter on 22 March 1972.^[4] This close approach had reduced its orbital frequency from some 30 years to the current 6.48 years and its perihelion distance from 4.78 AU to 1.60 AU.

Physical characteristics

Its nucleus is estimated to have an effective radius of 0.31 ± 0.01 kilometers and its rotational period is estimated to be 6.6±1.0 hours.^[3]

See also

• List of numbered comets