4341 Poseidon

4341 Poseidon (prov. designation: 1987 KF) is a rare-type asteroid classified as near-Earth object of the Apollo group, approximately 2.3 kilometers (1.4 miles) in diameter. It was discovered by American astronomer Carolyn Shoemaker at Palomar Observatory on 29 May 1987.^[7] The asteroid was named after Poseidon from Greek mythology.^[2]

4341 Poseidon

Discovery [1]
Discovered by	C. Shoemaker
Discovery site	Palomar Obs.
Discovery date	29 May 1987
Designations
MPC designation	(4341) Poseidon
Named after	Poseidon (Greek mythology)[2]
Alternative designations	1987 KF
Minor planet category	Apollo · NEO
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	30.05 yr (10,975 days)
Aphelion	3.0819 AU
Perihelion	0.5881 AU
Semi-major axis	1.8350 AU
Eccentricity	0.6795
Orbital period (sidereal)	2.49 yr (908 days)
Mean anomaly	93.192°
Mean motion	0° 23m 47.4s / day
Inclination	11.852°
Longitude of ascending node	108.11°
Argument of perihelion	15.652°
Earth MOID	0.1941 AU · 75.6 LD
Physical characteristics
Mean diameter	2.32 km (derived)[3]
Synodic rotation period	6.262 h[4] 6.2656 h[5]
Geometric albedo	0.18 (assumed)[3]
Spectral type	SMASS = O [1][3]
Absolute magnitude (H)	15.65[3][5] · 16.0[1] · 16.11±0.80[6]

Orbit and classification

Poseidon orbits the Sun at a distance of 0.6–3.1 AU once every 2 years and 6 months (908 days). Its orbit has an eccentricity of 0.68 and an inclination of 12° with respect to the ecliptic.^[1]

As no precoveries were taken, the asteroid's observation arc begins with its discovery in 1987.^[7] Poseidon may be associated with the Taurid Complex of meteor showers.^[8] It has an Earth minimum orbital intersection distance of 0.1941 AU (29,000,000 km), which corresponds to 75.6 lunar distances.^[1]

Naming

This minor planet was named for the "God of the Sea", Poseidon, one of the Twelve Olympians in Greek mythology. He was also referred to as "Earth-Shaker" due to his role in provoking earthquakes, which were then thought to be caused by ocean waves beating on the shore. He was the brother of Zeus (see 5731 Zeus), and an enemy of the Trojans in the Trojan War.^[2] The naming citation was published by the Minor Planet Center on 30 January 1991 (M.P.C. 17656).^[9]

Physical characteristics

In the SMASS classification, Poseidon is an O-type asteroid.^[1]

Diameter and albedo

The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.18 and derives a diameter of 2.32 kilometers with an absolute magnitude of 15.65.^[3] As of 2017, no other estimates for its diameter and albedo have been published.^[1][3]

Lightcurves

In 1998, a rotational lightcurve of Poseidon was published from photometric observations made by Czech astronomer Petr Pravec at Ondřejov Observatory. It gave a period of 6.262 hours with a brightness variation of 0.08 magnitude (U=2).^[4]

A second lightcurve was obtained during the Near-Earth Objects Follow-up Program which gave a concurring period of 6.2656 hours and an amplitude of 0.07 magnitude (U=2).^[5] A low brightness variation typically indicates that the body has a nearly spheroidal shape.