C/1990 K1 Levy
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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 88
data interval 1990 10 27 – 1992 04 01
data arc selection data generally limited to post-perihelion (POS)
range of heliocentric distances 0.94 au – 6.36au
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 167
RMS [arcseconds] 0.98
orbit quality class 1b
orbital elements (heliocentric ecliptic J2000)
Epoch 1990 11 05
perihelion date 1990 10 24.68470872 ± 0.00026493
perihelion distance [au] 0.93866901 ± 0.00000564
eccentricity 1.00053556 ± 0.00000545
argument of perihelion [°] 242.662082 ± 0.000403
ascending node [°] 139.363615 ± 0.000032
inclination [°] 131.582982 ± 0.000075
recip semi-major axis [10-6 au-1] -570.55 ± 5.80
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.