C/2001 G1 LONEOS

Solar System
Dynamics &
Planetology
Group

C/2001 G1 LONEOS

General description

C/2001 G1 was discovered on 1 April 2001 by the LONEOS as an apparently asteroidal object. At once, its cometary apperance was reported [IAUC 7606, 2001 April 2]. Later, pre-discovery detections by Air Force Maui Optical and Supercomputing observatory (AMOS) from 28 and 29 December 2000 were found.

This comet made its closest approach to Earth on 8 April 2002 (7.309 au), six months after perihelion.

Solution given below is based on data span over 2.4 yr in a range of heliocentric distances: 8.41 au – 8.235 au (perihelion) – 8.98 au.

Figure caption: Time distribution of positional observations with corresponding heliocentric (red curve) and geocentric (green curve) distance at which they were taken. The horizontal dotted line shows the perihelion distance for a given comet whereas vertical dotted line — the moment of perihelion passage.

SSDP Cometary Note C2001G1A2-001

Comet C/2001 G1 LONEOS

number of observations	138
number of residuals	266
data interval	2000 Dec. 28 — 2003 June 1
rms [arcsec]	0.58
orbit quality class	1a

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT)	20011018.0	= JD 2452200.5
time of perihelion passage (TT)	20011009.141613	± 0.008279
perihelion distance	8.23542303	± 0.00003133
eccentricity	1.00244802	± 0.00002288
argument of perihelion [deg]	343.278402	± 0.000468
longitude of the ascending node [deg]	203.889833	± 0.000024
inclination [deg]	45.368344	± 0.000044
inverse semimajor axis [10^-6 au^-1]	-297.26	± 2.77

Note: Epoch is given in a format: yyyymmdd.d, time of perihelion passage in a format of yyyymmdd.dddddd.

Figure caption: Six 2D-projections of the 6D space of original swarm (5001 VCs) of C/2001 G1. Each density map is given in logarithmic scale presented on the right in the individual panel.
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Original orbital elements (barycentric; at 250 au from the Sun)

Epoch (TT)	16900829
time of perihelion passage (TT)	20011010.850895	± 0.008190
perihelion distance	8.23895535	± 0.00003115
eccentricity	0.99966545	± 0.00002270
argument of perihelion [deg]	343.332494	± 0.000464
longitude of the ascending node [deg]	203.944602	± 0.000024
inclination [deg]	45.357940	± 0.000043
inverse semimajor axis [10^-6 au^-1]	40.61	± 2.76

Note: Values of uncertainties of original/future orbital elements were derived using a swarm of 5001 osculating orbits of VCs (including the nominal osculating orbit given above) for original/future orbital evolution calclulations and then by fitting the distribution of a given orbital element of original/future swarm of VCs to Gaussian distribution.

Original barycentric positions and velocities of 5001 VCs at 250 au from the Sun are given here (data format), i.e. before entering the planetary zone.

Future orbital elements (barycentric; at 250 au from the Sun)

Epoch (TT)	23110308
time of perihelion passage (TT)	20011009.975832	± 0.008222
perihelion distance	8.23579001	± 0.00003120
eccentricity	1.00086239	± 0.00002267
argument of perihelion [deg]	343.306947	± 0.000465
longitude of the ascending node [deg]	203.917759	± 0.000024
inclination [deg]	45.353710	± 0.000043
inverse semimajor axis [10^-6 au^-1]	-104.71	± 2.75