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 | |
| detectability of NG effects in the comet's motion | comet with determinable NG~orbit | |
| type of model of motion | GR - gravitational orbit | |
| data weighting | YES | |
| number of residuals | 914 | |
| RMS [arcseconds] | 0.31 | |
| orbit quality class | 1a+ | |
| next orbit statistics, both Galactic and stellar perturbations were taken into account | ||
|---|---|---|
| no. of returning VCs in the swarm | 10 | |
| no. of escaping VCs in the swarm | 4991 | * |
| no. of hyperbolas among escaping VCs in the swarm | 0 | |
| next reciprocal semi-major axis [10-6 au-1] | 14.84 – 15.39 – 15.97 | |
| next perihelion distance [au] | 39.2 – 39.7 – 40.2 | |
| next aphelion distance [103 au] | 125 – 130 – 135 | |
| synchronous stop epoch [Myr] | 4.81 | 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 | 3 | |
| no. of escaping VCs in the swarm | 4998 | * |
| no. of hyperbolas among escaping VCs in the swarm | 0 | |
| next reciprocal semi-major axis [10-6 au-1] | 14.70 – 15.26 – 15.84 | |
| next perihelion distance [au] | 42.7 – 43.9 – 45.2 | |
| next aphelion distance [103 au] | 126 – 131 – 136 | |
| synchronous stop epoch [Myr] | 4.85 | S |
| percentage of VCs with qnext > 20 | 100 | |