C/2017 U4 PANSTARRS
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Comet C/2017 U4 was discovered on 27 October 2017 with Pan-STARRS 1 telescope (Haleakala), that is about 11 months before its perihelion passage. Few prediscovery images of this comet were found: taken by the same survey from 2 January 2017.This comet was observed until 26 February 2020.

Comet had its closest approach to the Earth on 11 December 2018 (6.761 au), about 2.5 months after its perihelion passage.

The preferred solution given here is based on data spanning over 3.15 yr in a range of heliocentric distances: 8.64 au – 7.72 au (perihelion) – 8.36 au.

This near-parabolic comet suffers tiny planetary perturbations during its passage through the planetary system (original and future semimajor axes around 9,000 au).
solution description
number of observations 69
data interval 2017 01 02 – 2018 10 10
data arc selection data generally limited to pre-perihelion (PRE)
range of heliocentric distances 8.64 au – 7.72 au (perihelion) – 7.72 au
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 128
RMS [arcseconds] 0.34
orbit quality class 1b
orbital elements (barycentric ecliptic J2000)
Epoch 1707 07 12
perihelion date 2018 09 25.10558182 ± 0.01031205
perihelion distance [au] 7.73329693 ± 0.00005094
eccentricity 0.99908603 ± 0.00003532
argument of perihelion [°] 159.081031 ± 0.000696
ascending node [°] 245.932797 ± 0.000171
inclination [°] 158.212241 ± 0.000073
reciprocal semi-major axis [10-6 au-1] 118.19 ± 4.57
file containing 5001 VCs swarm
2017u4b1.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.