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 | 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+ | |
| orbital elements (barycentric ecliptic J2000) | ||
|---|---|---|
| Epoch | 1713 10 08 | |
| perihelion date | 2023 12 05.51554124 | ± 0.00400956 |
| perihelion distance [au] | 7.76122235 | ± 0.00002542 |
| eccentricity | 0.99979290 | ± 0.00001044 |
| argument of perihelion [°] | 211.629307 | ± 0.000301 |
| ascending node [°] | 314.852406 | ± 0.000028 |
| inclination [°] | 158.005519 | ± 0.000023 |
| reciprocal semi-major axis [10-6 au-1] | 26.68 | ± 1.35 |
| file containing 5001 VCs swarm |
|---|
| 2021a9n4.bmi |
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.
Six 2D-projections of the 6D space of original swarm including 5001 VCs. Each density map is given in logarithmic scale presented on the right in the individual panel.