87P/Bus

87P/Bus is a periodic comet with a current orbital period of 6.37 years around the Sun.

87P/Bus

Comet 87P/Bus photographed by the Hubble Space Telescope on 7 June 2001
Discovery[1]
Discovered by	Schelte J. Bus
Discovery site	UK Schmidt Telescope
Discovery date	2 March 1981
Designations
MPC designation	P/1981 E1, P/1987 B4
Alternative designations	1981 XI, 1987 XXXIV 1994 XVI 1981b, 1987f, 1993b
Orbital characteristics[2][3]
Epoch	31 May 2025 (JD 2459000.5)
Observation arc	39.57 years
Earliest precovery date	9 February 1981
Number of observations	801
Aphelion	4.776 AU
Perihelion	2.099 AU
Semi-major axis	3.438 AU
Eccentricity	0.38918
Orbital period	6.374 years
Inclination	2.603°
Longitude of ascending node	181.87°
Argument of periapsis	24.932°
Mean anomaly	3.356°
Last perihelion	9 May 2020
Next perihelion	7 June 2029[4]
TJupiter	3.009
Earth MOID	1.098 AU
Jupiter MOID	0.181 AU
Physical characteristics[5]
Mean radius	0.27±0.01 km
Synodic rotation period	32.0±9.0 hours
Comet total magnitude (M1)	12.7
Comet nuclear magnitude (M2)	16.1

Observational history

It was discovered by Schelte J. Bus in 1981 on a plate taken with the 1.2m UK Schmidt telescope at Siding Spring, Australia. The discovery was announced in IAU Circular 3578 on March 4, 1981.^[1] It has been observed on each of its subsequent apparitions, most recently in 2020.^[6]

Physical characteristics

Its nucleus is estimated to have an effective radius of 0.27±0.01 km and to be elongated, with an a/b ratio greater than 2.2. Its rotational period is estimated to be 32.0±9.0 hours.^[5]

Orbit

A close approach to Jupiter on 13 May 1952, at a distance of 0.0668 AU (9.99 million km), lowered the orbital period from 12.46 years and the perihelion distance from 4.43 AU to 6.43 years and 2.13 AU respectively. Another close approach to Jupiter on 24 February 2023, at a distance of 0.182 AU (27.2 million km), raised the perihelion to 3.62 AU and the orbital period to 9.58 years.^[7]