C/2021 A9 PanSTARRS
more info
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 | 311 | |
| data interval | 2020 12 12 – 2023 11 21 | |
| data arc selection | data generally limited to pre-perihelion (PRE) | |
| range of heliocentric distances | 10.15 au – 7.76au | |
| 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 | 607 | |
| RMS [arcseconds] | 0.27 | |
| 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] | 23.50 – 26.51 – 27.52 | |
| previous perihelion distance [au] | 1700 – 2000 – 2400 | |
| previous aphelion distance [103 au] | 71 – 73.4 – 82.8 | |
| time interval to previous perihelion [Myr] | 7.22 – 7.68 – 8.15 | |
| percentage of VCs with qprev > 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.
| 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] | 25.72 – 26.71 – 27.70 | |
| previous perihelion distance [au] | 0.82 – 0.85 – 1.01 | |
| previous aphelion distance [103 au] | 72.2 – 74.9 – 77.8 | |
| time interval to previous perihelion [Myr] | 6.91 – 7.3 – 7.74 | |
| percentage of VCs with qprev < 10 | 100 | |