C/1987 F1 Torres
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Comet C/1987 F1 was discovered by Carlos Torres (at Cerro El Roble) on 28 March 1987 (IAUC 4355), two weeks before its perihelion passage. The comet was last seen on 27 December 1989.
The comet made its closest approach to the Earth on 24 April 1984 (2.73 au), that was two weeks after its perihelion passage.
Solution given here is based on data spanning over 2.75 yr in a range of heliocentric distances: 3.63 au – 3.62 au (perihelion) – 8.75 au.
This Oort spike comet suffers small planetary perturbations during its passage through the planetary system that lead to a more tight future orbit (see future barycentric orbit).
See also Królikowska 2014 and Królikowska and Dybczyński 2017.

solution description
number of observations 56
data interval 1987 03 28 – 1989 12 27
data type significantly more measurements after perihelion (POST+)
data arc selection entire data set (STD)
range of heliocentric distances 3.63 au – 3.62 au (perihelion) – 8.75 au
detectability of NG effects in the comet's motion NG effects not determinable
type of model of motion GR - gravitational orbit
data weighting NO
number of residuals 108
RMS [arcseconds] 1.14
orbit quality class 1a
orbital elements (heliocentric ecliptic J2000)
Epoch 1987 03 26
perihelion date 1987 04 10.27802900 ± 0.00234800
perihelion distance [au] 3.62460449 ± 0.00001506
eccentricity 1.00101531 ± 0.00001802
argument of perihelion [°] 329.089760 ± 0.000451
ascending node [°] 194.487714 ± 0.000055
inclination [°] 124.079942 ± 0.000075
recip semi-major axis [10-6 au-1] -280.12 ± 4.97
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