C/2021 S3 (PANSTARRS)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2021 S3 (PANSTARRS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2024-02-14T17:02:55.976640Z |
| Orbit solution date (soln_date, UTC) | 2026-01-07T15:42:41Z |
| Obs used | 4855 |
| NEO | - |
| M1 | 10.700 |
| K1 | 4.500 |
| PC | - |
| Discovery observation (MPC, UTC) | 2021-09-24T13:27:42.969600Z |
| Discovery magnitude (MPC) | 20.17 i |
| Discovery observatory (MPC) | F52 · Pan-STARRS 2, Haleakala |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2024-03-19.0000000 |
| e | 1.00024544 |
| q (au) | 1.320205 |
| a (au) | -5378.855450 |
| i (deg) | 58.532818 |
| Ω (om, deg) | 215.620806 |
| ω (w, deg) | 6.853898 |
| M (ma, deg) | 0.000083 |
Magnitude
Scatter + Global Linear
$$ M_a = (9.812 + 3.233\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 9.812 |
| n | 3.233 |
| gf | 0.991 |
| gb | -0.915 |
| k | 0.980 |
| δ90 | 9.884 |
| Parameter | Symbol | Range | Description |
|---|---|---|---|
| Absolute magnitude at 1 AU from Sun and Earth | H0 | -5 to 20 | Intrinsic brightness of the comet |
| Photometric slope parameter | n | 2 to 6 | Rate of brightness change with heliocentric distance |
| Forward scattering asymmetry factor | gf |
0.8 to 1 | Degree of forward scattering |
| Backward scattering asymmetry factor | gb |
-1 to -0.5 | Degree of backward scattering |
| Partitioning coefficient | k | 0.8 to 1 | Ratio between forward/backward scattering contributions |
| Dust-to-gas brightness ratio | δ90 | 1 to 10 | Relative contribution of dust scattering to gas emission |
Reference: EPSC-DPS2025-160
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) | End (UTC) | a | b |
|---|---|---|---|
| 2020-12-06 | 2023-05-02 | +6.6906 | -5.821 |
| 2023-05-02 | 2024-02-14 | -0.5527 | -1.219 |
| 2024-02-14 | 2024-11-13 | +1.6110 | -0.826 |
| 2024-11-13 | 2025-12-27 | +6.1193 | -3.554 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Finding Chart
Ephemeris
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-06-01 00:00 | 00:14:41.20 | +35:16:15.7 | HIP 1137 | 10.52 |
| 2026-06-01 12:00 | 00:14:48.99 | +35:18:00.6 | HIP 1137 | 10.18 |
| 2026-06-02 00:00 | 00:14:56.68 | +35:19:45.3 | HIP 1137 | 10.36 |
| 2026-06-02 12:00 | 00:15:04.26 | +35:21:30.0 | HIP 1137 | 11.03 |
| 2026-06-03 00:00 | 00:15:11.74 | +35:23:14.5 | HIP 1137 | 12.10 |
| 2026-06-03 12:00 | 00:15:19.12 | +35:24:58.8 | HIP 1137 | 13.46 |
| 2026-06-04 00:00 | 00:15:26.40 | +35:26:43.0 | HIP 1137 | 15.02 |
| 2026-06-04 12:00 | 00:15:33.57 | +35:28:27.1 | HIP 1137 | 16.74 |
| 2026-06-05 00:00 | 00:15:40.63 | +35:30:11.0 | HIP 1137 | 18.54 |
| 2026-06-05 12:00 | 00:15:47.59 | +35:31:54.8 | HIP 1137 | 20.42 |
| 2026-06-06 00:00 | 00:15:54.44 | +35:33:38.3 | HIP 1137 | 22.34 |
| 2026-06-06 12:00 | 00:16:01.19 | +35:35:21.7 | HIP 1137 | 24.29 |
| 2026-06-07 00:00 | 00:16:07.83 | +35:37:05.0 | HIP 1137 | 26.25 |
| 2026-06-07 12:00 | 00:16:14.36 | +35:38:48.0 | HIP 1297 | 28.12 |
| 2026-06-08 00:00 | 00:16:20.78 | +35:40:30.8 | HIP 1297 | 29.86 |
| 2026-06-08 12:00 | 00:16:27.10 | +35:42:13.5 | HIP 1492 | 31.32 |
| 2026-06-09 00:00 | 00:16:33.30 | +35:43:55.9 | HIP 1492 | 29.33 |
| 2026-06-09 12:00 | 00:16:39.40 | +35:45:38.1 | HIP 1492 | 27.39 |
| 2026-06-10 00:00 | 00:16:45.39 | +35:47:20.1 | HIP 1492 | 25.50 |
| 2026-06-10 12:00 | 00:16:51.26 | +35:49:01.8 | HIP 1492 | 23.67 |
| 2026-06-11 00:00 | 00:16:57.03 | +35:50:43.4 | HIP 1492 | 21.90 |
| 2026-06-11 12:00 | 00:17:02.68 | +35:52:24.6 | HIP 1492 | 20.20 |
| 2026-06-12 00:00 | 00:17:08.22 | +35:54:05.7 | HIP 1492 | 18.60 |
| 2026-06-12 12:00 | 00:17:13.65 | +35:55:46.5 | HIP 1492 | 17.12 |
| 2026-06-13 00:00 | 00:17:18.96 | +35:57:27.0 | HIP 1492 | 15.77 |
| 2026-06-13 12:00 | 00:17:24.17 | +35:59:07.2 | HIP 1492 | 14.60 |
| 2026-06-14 00:00 | 00:17:29.25 | +36:00:47.2 | HIP 1492 | 13.64 |
| 2026-06-14 12:00 | 00:17:34.23 | +36:02:26.8 | HIP 1492 | 12.92 |
| 2026-06-15 00:00 | 00:17:39.09 | +36:04:06.2 | HIP 1492 | 12.49 |
| 2026-06-15 12:00 | 00:17:43.83 | +36:05:45.3 | HIP 1492 | 12.37 |
| 2026-06-16 00:00 | 00:17:48.46 | +36:07:24.0 | HIP 1492 | 12.55 |
| 2026-06-16 12:00 | 00:17:52.97 | +36:09:02.5 | HIP 1492 | 13.03 |
| 2026-06-17 00:00 | 00:17:57.36 | +36:10:40.6 | HIP 1492 | 13.75 |
| 2026-06-17 12:00 | 00:18:01.64 | +36:12:18.4 | HIP 1492 | 14.69 |
| 2026-06-18 00:00 | 00:18:05.80 | +36:13:55.8 | HIP 1492 | 15.78 |
| 2026-06-18 12:00 | 00:18:09.84 | +36:15:32.9 | HIP 1492 | 17.01 |
| 2026-06-19 00:00 | 00:18:13.77 | +36:17:09.6 | HIP 1403 | 17.86 |
| 2026-06-19 12:00 | 00:18:17.58 | +36:18:46.0 | HIP 1403 | 16.84 |
| 2026-06-20 00:00 | 00:18:21.27 | +36:20:22.0 | HIP 1403 | 15.95 |
| 2026-06-20 12:00 | 00:18:24.84 | +36:21:57.6 | HIP 1403 | 15.20 |
| 2026-06-21 00:00 | 00:18:28.29 | +36:23:32.9 | HIP 1403 | 14.60 |
| 2026-06-21 12:00 | 00:18:31.62 | +36:25:07.7 | HIP 1403 | 14.18 |
| 2026-06-22 00:00 | 00:18:34.84 | +36:26:42.2 | HIP 1403 | 13.94 |