C/2020 U4 PanSTARRS
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Comet C/2020 U4 was discovered on 22 October 2020, about 1.5 yr before its perihelion passage; later a series of prediscovery images was found going back to 9 November 2019. This comet was observed until 11 September 2024 (as in February 2025).
Comet had its closest approach to the Earth on 30 November 2021 (4.47 au); a bit more than four months before the perihelion passage.
Solution given here is based on data span over 4.84 yr in a range of heliocentric distances: 8.24 au – 5.35 au (perihelion) – 8.26 au. Orbits based on pre-perihelion and post-perihelion data independently were also obtained.
This Oort spike comet suffers small planetary perturbations during its passage through the planetary system; however, they lead to escape the comet from the solar system on hyperbolic barycentric orbit.
Comet had its closest approach to the Earth on 30 November 2021 (4.47 au); a bit more than four months before the perihelion passage.
Solution given here is based on data span over 4.84 yr in a range of heliocentric distances: 8.24 au – 5.35 au (perihelion) – 8.26 au. Orbits based on pre-perihelion and post-perihelion data independently were also obtained.
This Oort spike comet suffers small planetary perturbations during its passage through the planetary system; however, they lead to escape the comet from the solar system on hyperbolic barycentric orbit.
solution description | ||
---|---|---|
number of observations | 1060 | |
data interval | 2019 11 09 – 2024 09 11 | |
data type | perihelion within the observation arc (FULL) | |
data arc selection | entire data set (STD) | |
range of heliocentric distances | 8.24 au – 5.35 au (perihelion) – 8.26 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 | 2086 | |
RMS [arcseconds] | 0.38 | |
orbit quality class | 1a+ |
orbital elements (heliocentric ecliptic J2000) | ||
---|---|---|
Epoch | 2022 04 11 | |
perihelion date | 2022 04 07.99509661 | ± 0.00015139 |
perihelion distance [au] | 5.35367876 | ± 0.00000100 |
eccentricity | 1.00135032 | ± 0.00000166 |
argument of perihelion [°] | 69.535035 | ± 0.000022 |
ascending node [°] | 120.013691 | ± 0.000017 |
inclination [°] | 167.035857 | ± 0.000004 |
reciprocal semi-major axis [10-6 au-1] | -252.22 | ± 0.31 |

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).
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).