C/1991 F2 Helin-Lawrence
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Comet C/1991 F2 was discovered on 17 March 1991 by Eleanor F. Helin and Kenneth J. Lawrence (Mount Palomar, California, USA), that is about 10 months before its perihelion passage. This comet was last observed at the end of September 1992.
Comet had its closest approach to the Earth on 12 January 1992 (1.721 au), 8 days before perihelion passage.
Solutions given here are based on data spanning over 1.60 yr in a range of heliocentric distances: 4.25 au – 1.52 au (perihelion) – 3.52 au.
This Oort spike comet suffers tiny planetary perturbations during its passage through the planetary system; however, these perturbations lead to escape the comet on hyperbolic orbit from the planetary zone.
See also Królikowska 2014 and Królikowska 2020.

solution description
number of observations 113
data interval 1991 02 23 – 1992 09 30
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 4.25 au – 1.52 au (perihelion) – 3.52 au
type of model of motion NS - non-gravitational orbits for standard g(r)
data weighting YES
number of residuals 213
RMS [arcseconds] 0.78
orbit quality class 1b
next orbit statistics, both Galactic and stellar perturbations were taken into account
no. of returning VCs in the swarm 0
no. of escaping VCs in the swarm 5001
no. of hyperbolas among escaping VCs in the swarm 5001 *
next reciprocal semi-major axis [10-6 au-1] -103.29 – -93.90 – -84.54
next perihelion distance [au] 246 – 263 – 280
synchronous stop epoch [Myr] 1.46 S
percentage of VCs with qnext > 20100
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.
next orbit statistics, here only the Galactic tide has been included
no. of returning VCs in the swarm 0
no. of escaping VCs in the swarm 5001
no. of hyperbolas among escaping VCs in the swarm 5001 *
next reciprocal semi-major axis [10-6 au-1] -101.68 – -92.37 – -83.09
next perihelion distance [au] 0.15 – 0.19 – 0.26
synchronous stop epoch [Myr] 1.45 S
percentage of VCs with qnext < 10100