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 1912
data interval 2020 09 16 – 2024 06 05
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 8.04 au – 3.37 au (perihelion) – 5.46 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 3787
RMS [arcseconds] 0.51
orbit quality class 1a+
previous orbit statistics, both Galactic and stellar perturbations were taken into account
no. of returning VCs in the swarm 5001 *
no. of escaping VCs in the swarm 0
no. of hyperbolas among escaping VCs in the swarm 0
previous reciprocal semi-major axis [10-6 au-1] 43.17 – 43.21 – 43.22
previous perihelion distance [au] 219 – 243 – 267
previous aphelion distance [103 au] 46.032 – 46.04 – 46.081
time interval to previous perihelion [Myr] 2.78 – 2.82 – 2.85
percentage of VCs with qprev > 20100
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).
previous_g orbit statistics, here only the Galactic tide has been included
no. of returning VCs in the swarm 5001 *
no. of escaping VCs in the swarm 0
no. of hyperbolas among escaping VCs in the swarm 0
previous reciprocal semi-major axis [10-6 au-1] 49.38 – 49.81 – 50.25
previous perihelion distance [au] 8.06 – 8.24 – 8.42
previous aphelion distance [103 au] 39.79 – 40.14 – 40.49
time interval to previous perihelion [Myr] 2.79 – 2.83 – 2.87
percentage of VCs with qprev < 10100