(6491) 1991 OA

(6491) 1991 OA

Discovery[1]
Discovered by	H. E. Holt
Discovery site	Palomar Obs.
Discovery date	16 July 1991
Designations
MPC designation	(6491) 1991 OA
Minor planet category	NEO · Amor · PHA[1]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	24.35 yr (8,895 days)
Aphelion	3.9772 AU
Perihelion	1.0227 AU
Semi-major axis	2.5000 AU
Eccentricity	0.5909
Orbital period (sidereal)	3.95 yr (1,444 days)
Mean anomaly	215.03°
Mean motion	0° 14^m 57.48^s / day
Inclination	5.9464°
Longitude of ascending node	301.90°
Argument of perihelion	323.60°
Earth MOID	0.0420 AU · 16.4 LD
Physical characteristics
Dimensions	0.52 km (derived)[2]
Synodic rotation period	2.69 h[3]
Geometric albedo	0.20 (assumed)[2]
Spectral type	S[2]
Absolute magnitude (H)	18.77[2][3] · 18.9[1]

(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.^[4]

Orbit and classification

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.^[1] Its minimum orbit intersection distance (MOID) with Earth is 0.0420 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).^[5]

A 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.^[4]

Physical characteristics

In 2000, a rotational lightcurve was published from photometric observations obtained by the Near-Earth Objects Follow-up Program during the early 1990s. The lightcurve rendered a rotation period of 2.69 hours with an brightness amplitude of 0.08 in magnitude (U=2).^[3] 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.^[2]

Naming

As of 2017, 1991 OA remains unnamed.^[4]

References

1. "JPL Small-Body Database Browser: 6491 (1991 OA)" (2015-07-25 last obs.). Jet Propulsion Laboratory. Retrieved 26 May 2017.
2. "LCDB Data for (6491)". Asteroid Lightcurve Database (LCDB). Retrieved 24 July 2016.
3. Erikson, A.; Mottola, S.; Lagerros, J. S. V.; Lindgren, M.; Piironen, J.; Oja, T.; et al. (October 2000). "The Near-Earth Objects Follow-up Program. III. 32 Lightcurves for 12 Objects from 1992 and 1995". Icarus. 147 (2): 487–497. Bibcode:2000Icar..147..487E. doi:10.1006/icar.2000.6457. Retrieved 1 January 2016.
4. "6491 (1991 OA)". Minor Planet Center. Retrieved 24 July 2016.
5. "JPL Close-Approach Data: 6491 (1991 OA)". Retrieved 24 March 2012. 2011-09-29 last obs

External links

• Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• (6491) 1991 OA at NeoDyS-2, Near Earth Objects—Dynamic Site
  • Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
• (6491) 1991 OA at ESA–space situational awareness
  • Ephemerides · Observations · Orbit · Physical properties · Summary
• (6491) 1991 OA at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters