C/1991 F2 Helin-Lawrence
more info
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
orbital elements (heliocentric ecliptic J2000)
Epoch 1992 01 19
perihelion date 1992 01 20.02697569 ± 0.00012191
perihelion distance [au] 1.51771129 ± 0.00000327
eccentricity 1.00040745 ± 0.00000888
argument of perihelion [°] 271.159246 ± 0.000035
ascending node [°] 11.834904 ± 0.000028
inclination [°] 95.456595 ± 0.000089
recip semi-major axis [10-6 au-1] -268.47 ± 5.85
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
non-gravitational parameters
A1 [10-8au\day-2] 0.65566 ± 0.22993
A2 [10-8au\day-2] -0.34009 ± 0.13367
A3 [10-8au\day-2] 0.072405 ± 0.037893
m -2.15
n 5.093
k -4.6142
r0 [au] 2.808
α 0.1113