C/2021 Y1 ATLAS
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Comet C/2021 Y1 was discovered on 26 December 2021 by ATLAS-MLO (Mauna Loa), that is a year and five months before its perihelion passage. Next, two series of pre-discovery images taken by M Holbroook at Pleasant Groves Observatory on two days in November (8 and 24) were found.
Comet had its closest approach to the Earth on 12 December 2022 (1.69 au), about 5.5 months before its perihelion passage.
The preferred NG solution given here is based on data span over 1.61 yr in a range of heliocentric distances: 5.91 au – 2.032 au (perihelion) – 2.11 au. However, even this NG solution exhibits some trends in [O-C] within a few months before perihelion passage. Thus, we also offer the solution 'd5' for past orbital study.
This Oort spike comet suffers rather small planetary perturbations during its passage through the planetary system that lead to escape the comet from the planetary zone on a hyperbolic orbit.
Comet had its closest approach to the Earth on 12 December 2022 (1.69 au), about 5.5 months before its perihelion passage.
The preferred NG solution given here is based on data span over 1.61 yr in a range of heliocentric distances: 5.91 au – 2.032 au (perihelion) – 2.11 au. However, even this NG solution exhibits some trends in [O-C] within a few months before perihelion passage. Thus, we also offer the solution 'd5' for past orbital study.
This Oort spike comet suffers rather small planetary perturbations during its passage through the planetary system that lead to escape the comet from the planetary zone on a hyperbolic orbit.
| solution description | ||
|---|---|---|
| number of observations | 1809 | |
| data interval | 2021 11 08 – 2023 04 24 | |
| data arc selection | data generally limited to pre-perihelion (PRE) | |
| range of heliocentric distances | 5.91 au – 2.03au | |
| type of model of motion | NC - non-gravitational orbits for symmetric CO-g(r)-like function | |
| data weighting | YES | |
| number of residuals | 3567 | |
| RMS [arcseconds] | 0.32 | |
| orbit quality class | 1a | |
| previous orbit statistics, both Galactic and stellar perturbations were taken into account | ||
|---|---|---|
| no. of returning VCs in the swarm | 0 | |
| no. of escaping VCs in the swarm | 5001 | * |
| no. of hyperbolas among escaping VCs in the swarm | 0 | |
| previous reciprocal semi-major axis [10-6 au-1] | 4.10 – 5.87 – 7.64 | |
| previous perihelion distance [au] | 1400 – 1460 – 1530 | |
| previous aphelion distance [103 au] | 260 – 340 – 490 | |
| synchronous stop epoch [Myr] | -3.33 | S |
| percentage of VCs with qprev > 20 | 100 | |
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).
| previous_g orbit statistics, here only the Galactic tide has been included | ||
|---|---|---|
| no. of returning VCs in the swarm | 0 | |
| no. of escaping VCs in the swarm | 5001 | * |
| no. of hyperbolas among escaping VCs in the swarm | 0 | |
| previous reciprocal semi-major axis [10-6 au-1] | 8.15 – 9.76 – 11.36 | |
| previous perihelion distance [au] | 28.3 – 30.5 – 32.8 | |
| previous aphelion distance [103 au] | 180 – 200 – 250 | |
| synchronous stop epoch [Myr] | -3.58 | S |
| percentage of VCs with qprev > 20 | 100 | |