C/2020 S4 PanSTARRS
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Comet C/2020 S4 was discovered on 16 September 2020, about 2.5 yr before its perihelion passage. This comet was observed until 5 June 2024 (as in February 2025).

Comet had its closest approach to the Earth on 6 February 2023 (2.39 au); about 3 days before the perihelion passage.

Currently, the preferred NG solution given here is based on data span over 3.65 yr in a range of heliocentric distances: 8.04 au – 3.37 au (perihelion) – 5.29 au. This comet shows large trends in the O-C distribution for a purely gravitational orbit, which are substantially reduced when NG acceleration is included in the model of motion. Orbits based on pre-perihelion and post-perihelion data independently were also obtained.

This Oort spike comet suffers moderate planetary perturbations during its passage through the planetary system that lead to escape this comet from the solar system on hyperbolic orbit.
solution description
number of observations 992
data interval 2020 09 16 – 2023 02 09
data arc selection data generally limited to pre-perihelion (PRE)
range of heliocentric distances 8.04 au – 3.37 au (perihelion) – 3.37 au
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 1975
RMS [arcseconds] 0.53
orbit quality class 1a+
orbital elements (barycentric ecliptic J2000)
Epoch 1720 03 25
perihelion date 2023 02 08.92407272 ± 0.00044300
perihelion distance [au] 3.36949274 ± 0.00000317
eccentricity 0.99984440 ± 0.00000298
argument of perihelion [°] 20.953576 ± 0.000102
ascending node [°] 117.865720 ± 0.000019
inclination [°] 20.580834 ± 0.000007
reciprocal semi-major axis [10-6 au-1] 46.18 ± 0.88
file containing 5001 VCs swarm
2020s4pa.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.
Middle panel(s): O-C diagram for a given solution (sometimes in comparison to another solution available in CODE), where residuals in right ascension are shown using magenta dots and in declination by blue open circles.
Lowest panel: Relative weights for a given data set(s).
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.