C/1986 P1-A Wilson
more info
Comet C/1986 P1-A was discovered on 5 August 1986 by Christine Wilson (Mount Palomar, California, USA), that is 8.5 months before its perihelion passage. This comet was last observed in mid-April 1989. Splitting event observed in comet Wilson was occured after perihelion passage.
Comet had its closest approach to the Earth on 1 May 1987 (0.623 au), less than two weeks after perihelion passage. According to Minor Planet Center, the main component A of this comet exhibits nongravitational acceleration in the time interval 5 August 1986 – 11 April 1989. Therefore, the non-gravitational orbit from the whole observational arc (spanning over 2.68 yr in a range of heliocentric distances: 3.64 au – 1.200 au (perihelion) – 7.83 au.) are given here as preferred orbit.

This Oort spike comet suffers large planetary perturbations during its passage through the planetary system; these perturbations lead to a more tight future orbit with semimajor axis of about 1,300 au.
See also Królikowska and Dybczyński 2010, Królikowska 2014 and Królikowska 2020.

solution description
number of observations 687
data interval 1986 08 05 – 1989 04 11
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 3.64 au – 1.20 au (perihelion) – 7.83 au
detectability of NG effects in the comet's motion comet with NG effects strongly manifested in positional data fitting
type of model of motion GR - gravitational orbit
data weighting YES
number of residuals 1364
RMS [arcseconds] 1.35
orbit quality class 1a+
orbital elements (barycentric ecliptic J2000)
Epoch 1688 09 08
perihelion date 1987 04 20.09862004 ± 0.00007920
perihelion distance [au] 1.19372426 ± 0.00000057
eccentricity 0.99998862 ± 0.00000098
argument of perihelion [°] 238.184415 ± 0.000046
ascending node [°] 111.413682 ± 0.000051
inclination [°] 147.182023 ± 0.000032
reciprocal semi-major axis [10-6 au-1] 9.53 ± 0.82
file containing 5001 VCs swarm
1986p1a1.bmi
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.
Six 2D-projections of the 6D space of original swarm including 5001 VCs. Each density map is given in logarithmic scale presented on the right in the individual panel.