C/1987 H1 Shoemaker
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Comet C/1987 H1 was discovered by Carolyn S. and Eugene M. Shoemaker (with the 0.46-m Schmidt telescope at Palomar) on 25 April 1987 (IAUC 4384), when the comet was more than five months after its perihelion passage. The comet was last seen on 4 January 1992.
Comet had its closest approach to the Earth on 22 June 1986 (4.551 au), almost 5 months before its perihelion passage. After perihelion passage, it has second close approach to the Earth on 16 May 1987 (4.74 au), that was three weeks after its discovery.
Solution given here is based on data spanning over 4.7 yr in a range of heliocentric distances from 5.58 au to 13.40 au.
This Oort spike comet suffers slight planetary perturbations during its passage through the planetary system but these perturbations probably lead to escape of the comet from the solar system (see future barycentric orbit).
See also Królikowska 2014 and Królikowska and Dybczyński 2017.

solution description
number of observations 127
data interval 1987 04 25 – 1992 01 04
data type observed only after perihelion (POST)
data arc selection entire data set (STD)
range of heliocentric distances 5.58 au – 13.4au
detectability of NG effects in the comet's motion NG effects not determinable
type of model of motion GR - gravitational orbit
data weighting YES
number of residuals 242
RMS [arcseconds] 0.91
orbit quality class 1a+
orbital elements (heliocentric ecliptic J2000)
Epoch 1986 11 26
perihelion date 1986 11 17.10428200 ± 0.00405300
perihelion distance [au] 5.45751848 ± 0.00003120
eccentricity 1.00284157 ± 0.00001548
argument of perihelion [°] 16.995673 ± 0.000555
ascending node [°] 268.325863 ± 0.000079
inclination [°] 132.474265 ± 0.000057
reciprocal semi-major axis [10-6 au-1] -520.67 ± 2.83
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.