C/2021 A9 PanSTARRS
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Comet C/2021 A9 was discovered on 12 January 2021 with the Pan-STARRS 1 telescope (Haleakala), that is almost two years before its perihelion passage. a few pre-discovery measurements were next found extending the data arc one month back. Comet is still observed as in April 2025.
Comet had its closest approach to the Earth on 3 January 2024 (6.80 au), about one month after its perihelion passage.
Preferred NG solution given here is based on data span over 4.15 yr in a range of heliocentric distances: 10.15 au – 7.76 au (perihelion) – 8.20 au; also GR orbits based on the same data arc as NG orbit and pre-perihelion orbital leg are given.
This Oort spike comet suffers tiny planetary perturbations during its passage through the planetary system; and its future orbit have semimajor axis notable longer than 10,000 au.
Comet had its closest approach to the Earth on 3 January 2024 (6.80 au), about one month after its perihelion passage.
Preferred NG solution given here is based on data span over 4.15 yr in a range of heliocentric distances: 10.15 au – 7.76 au (perihelion) – 8.20 au; also GR orbits based on the same data arc as NG orbit and pre-perihelion orbital leg are given.
This Oort spike comet suffers tiny planetary perturbations during its passage through the planetary system; and its future orbit have semimajor axis notable longer than 10,000 au.
| solution description | ||
|---|---|---|
| number of observations | 466 | |
| data interval | 2020 12 12 – 2025 02 04 | |
| data type | perihelion within the observation arc (FULL) | |
| data arc selection | entire data set (STD) | |
| range of heliocentric distances | 10.15 au – 7.76 au (perihelion) – 8.2 au | |
| type of model of motion | NC - non-gravitational orbits for symmetric CO-g(r)-like function | |
| data weighting | YES | |
| number of residuals | 914 | |
| RMS [arcseconds] | 0.29 | |
| orbit quality class | 1a+ | |
| next 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 | |
| next reciprocal semi-major axis [10-6 au-1] | 8.54 – 10.54 – 12.58 | |
| next perihelion distance [au] | 39.4 – 40.6 – 41.7 | |
| next aphelion distance [103 au] | 160 – 190 – 230 | |
| synchronous stop epoch [Myr] | 3.45 | S |
| percentage of VCs with qnext > 20 | 100 | |
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.
| next_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 | |
| next reciprocal semi-major axis [10-6 au-1] | 8.41 – 10.42 – 12.46 | |
| next perihelion distance [au] | 23.8 – 25 – 26.2 | |
| next aphelion distance [103 au] | 160 – 190 – 240 | |
| synchronous stop epoch [Myr] | 3.44 | S |
| percentage of VCs with qnext > 20 | 100 | |