C/2001 OG108 (LONEOS)

C/2001 OG₁₀₈ (LONEOS) is a Halley-type comet with an orbital period of 48.51 years.^[3] It was discovered on 28 July 2001 by the LONEOS telescope at Lowell Observatory.^[2] Of the short-period comets with known diameters and perihelion inside the orbit of Earth, C/2001 OG₁₀₈ is the second largest after Comet Swift–Tuttle.^[5]

For other comets of the same name, see Comet LONEOS.

C/2001 OG₁₀₈ (LONEOS)

Discovery[1][2]
Discovered by	M. E. Van Ness
Discovery site	Lowell Observatory (LONEOS)
Discovery date	28 July 2001
Orbital characteristics[3]
Epoch	5 December 2001 (JD 2452248.5)
Observation arc	340 days
Number of observations	882
Aphelion	25.606 AU
Perihelion	0.994 AU
Semi-major axis	13.300 AU
Eccentricity	0.92526
Orbital period	48.51 years
Inclination	80.245°
Longitude of ascending node	10.555°
Argument of periapsis	116.42°
Last perihelion	15 March 2002
Next perihelion	7 June 2050 [4]
TJupiter	0.597
Earth MOID	0.301 AU
Jupiter MOID	0.968 AU
Physical characteristics[3]
Dimensions	13.6 ± 1.0 km (8.45 ± 0.62 mi)
Synodic rotation period	57.12 hours
Geometric albedo	0.054
Comet total magnitude (M1)	13.3

Orbit

Observations taken in January and February 2002 showed that the "asteroid" had developed a small amount of cometary activity as it approached perihelion.^[1] It was subsequently reclassified as a comet.^[1] The comet came to perihelion (closest approach to the Sun) on 15 March 2002.^[3] It will come to aphelion in 2026 and the next perihelion passage is calculated to be on 7 June 2050.^[4] On 23 March 2147 the comet will pass about 0.42 AU (63 million km; 160 LD) from Earth^[3] with an uncertainty region of about ±2 million km.^[6]

C/2001 OG108 (LONEOS) Closest Earth Approach on 2147-Mar-23 11:20 UT^[3]

Date & time of closest approach	Earth distance (AU)	Sun distance (AU)	Velocity wrt Earth (km/s)	Velocity wrt Sun (km/s)	Uncertainty region (3-sigma)	Reference
2147-03-23 11:20 ± 13:38	0.42 AU (63 million km; 39 million mi; 160 LD)	1.35 AU (202 million km; 125 million mi; 530 LD)	40.3	35.3	± 2 million km	Horizons

This comet probably represents the transition between typical Halley-family/long-period comets and extinct comets.^[1] Damocloids have been studied as possible extinct cometary candidates due to the similarity of their orbital parameters with those of Halley-family comets.^[1]

Physical properties

The comet has a rotational period of 2.38 ± 0.02 days (57.12 hr).^[1][3]

In 2003, the comet was estimated to have a mean absolute V magnitude (H) of 13.05 ± 0.10, with an albedo of 0.03, giving an effective radius of 8.9 ± 0.7 km (5.53 ± 0.43 mi).^[1] Using data from Fernandez (2004–2005) JPL lists the comet with an albedo of 0.05 and a diameter of 13.6 ± 1.0 km (8.45 ± 0.62 mi)^[3]

See also

• List of Halley-type comets