143P/Kowal–Mrkos

For other comets of the same name, see Comet Kowal and Comet Mrkos.

143P/Kowal–Mrkos is a periodic comet in the Solar System.

143P/Kowal–Mrkos

Discovery[1]
Discovered by	Charles T. Kowal Antonín Mrkos
Discovery site	Palomar Observatory Klet' Observatory
Discovery date	2 May 1984
Designations
MPC designation	D/1984 H1 P/1984 JD P/2000 ET90
Alternative designations	1984 X, 1984n
Orbital characteristics[2][3]
Epoch	5 May 2025 (JD 2460800.5)
Observation arc	40.83 years
Earliest precovery date	23 April 1984
Number of observations	1,231
Aphelion	6.618 AU
Perihelion	2.942 AU
Semi-major axis	4.780 AU
Eccentricity	0.38458
Orbital period	10.451 years
Inclination	5.472°
Longitude of ascending node	242.62°
Argument of periapsis	304.32°
Mean anomaly	303.47°
Last perihelion	7 May 2018
Next perihelion	28 December 2026[4]
TJupiter	2.864
Earth MOID	1.537 AU
Jupiter MOID	0.019 AU
Physical characteristics[5]
Mean radius	5.7±0.6 km
Synodic rotation period	17.21±0.10 hours
Spectral type	(V–R) = 0.58±0.02
Comet total magnitude (M1)	14.5

Observational history

Discovery and loss

Antonín Mrkos first reported the discovery of this comet as an asteroid named 1984 JD, after spotting it as a 16th-magnitude object on the night of 2 May 1984.^[6] In September 1984, Charles T. Kowal analyzed photographic plates exposed on the night of 23 April 1984 and he noted the comet as almost stellar-like, with a faint but discernible coma.^[6] Brian G. Marsden immediately recognized that Kowal's object is identical to that of Mrkos' discovery, allowing him to calculate an elliptical orbit for the object,^[1] which allowed Mrkos to notice that he indeed captured faint cometary activity on images he took on 19 May.^[7] However, it was not observed beyond that date, and was initially considered lost, subsequently redesignated as D/1984 H1.^[6]

Recovery

It was not observed during the comet's predicted apparition in 1992.^[8] Shuichi Nakano later revised his orbital calculations for the comet in 1997, which allowed him to predict that the comet may next return by 2000.^[6] It was successfully recovered on 9 March 2000, when LINEAR and LONEOS spotted an asteroid-like object with a comet-like orbit (2000 ET₉₀), which Marsden noted matched those predicted for Kowal–Mrkos.^[9]