C/1990 K1 Levy
more info
Comet C/1990 K1 was discovered on 20 May 1990 by David Levy (Arizona), that is about 5 months before its perihelion passage. This comet was last observed at the beginning of April 1992.
Comet had its closest approach to the Earth on 26 August 1990 (0.430 au), less than 2 months before perihelion passage.
This is a comet with nongravitational effects strongly manifested in positional data fitting.
Preferred solution given here is based on data spanning over 1.86 yr in a range of heliocentric distances: 2.57 au – 0.939 au (perihelion) – 6.36 au. However, also two other non-gravitational solutions are given: bn solution based on pre-perihelion data, and rn solution based on post-perihelion data.
This comet with semimajor axis of about 10,000 au (preferred orbit) or even shorter (see solution bn) suffers rather large planetary perturbations during its passage through the planetary system; 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 590
data interval 1990 05 21 – 1990 10 21
data arc selection data generally limited to pre-perihelion (PRE)
range of heliocentric distances 2.57 au – 0.94au
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 1144
RMS [arcseconds] 0.92
orbit quality class 2a
orbital elements (barycentric ecliptic J2000)
Epoch 1688 02 21
perihelion date 1990 10 24.56245105 ± 0.00052728
perihelion distance [au] 0.93920752 ± 0.00000632
eccentricity 0.99962299 ± 0.00001663
argument of perihelion [°] 242.657385 ± 0.000830
ascending node [°] 139.299456 ± 0.000055
inclination [°] 131.571295 ± 0.000175
reciprocal semi-major axis [10-6 au-1] 401.41 ± 17.71
file containing 5001 VCs swarm
1990k1b9.bmi
Upper panel: 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.
Lower panel (panels): O-C diagram for this(two) solution (solutions) given in this database, where residuals in right ascension are shown using magenta dots and in declination by blue open circles.
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.