|Discovered by H. E. Holt|
MPC designation (6491) 1991 OA
Observation arc 24.35 yr (8,895 days)
Discovered 16 July 1991
Discovery site Palomar Observatory
|Discovery date 16 July 1991|
Minor planet category NEO · Amor · PHA
Perihelion 1.0233 AU
Aphelion 3.98 m
Discoverer Henry E. Holt
Asteroid group Amor asteroid
|Similar Sun, 6489 Golevka, 4179 Toutatis|
(6491) 1991 OA is a highly eccentric, stony asteroid, classified as near-Earth object and potentially hazardous asteroid, approximately half a kilometer in diameter. It was discovered on 16 July 1991, by American astronomer Henry E. Holt at the U.S. Palomar Observatory in California.
The S-type body is an Amor asteroid – a subgroup of near-Earth asteroids that approach the orbit of Earth from beyond, but do not cross it. It orbits the Sun at a distance of 1.0–4.0 AU once every 3 years and 11 months (1,444 days). Its orbit has an eccentricity of 0.59 and an inclination of 6° with respect to the ecliptic. Its minimum orbit intersection distance (MOID) with Earth is 0.0429 AU, and on 1 August 2086, it will make a close approach and pass by Earth at a distance of 0.09 AU (13,000,000 km). The first precovery was taken at the Australian Siding Spring Observatory in March 1991, extending the asteroid's observation arc by 4 months prior to its discovery.
In 2000, a rotational light-curve was published from photometric observations obtained by the Near-Earth Objects Follow-up Program during the early 1990s. The light-curve rendered a rotation period of 2.69 hours with an brightness amplitude of 0.08 in magnitude (U=2). The Collaborative Asteroid Lightcurve Link (CALL) assumes an albedo of 0.20 and derives a diameter of 0.53 kilometers, based on an absolute magnitude of 18.77.