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 | 9.892 |
| 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 | +6.6905 | -5.821 |
| 2023-05-02 | 2024-02-14 | -0.5524 | -1.219 |
| 2024-02-14 | 2024-11-13 | +1.6113 | -0.826 |
| 2024-11-13 | 2025-12-27 | +6.1192 | -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) |
|---|---|---|---|---|
| 2026-03-26 00:00 | 23:45:19.09 | +31:42:24.9 | HIP 117161 | 1.99 |
| 2026-03-26 12:00 | 23:45:35.91 | +31:43:35.4 | HIP 117161 | 5.72 |
| 2026-03-27 00:00 | 23:45:52.70 | +31:44:46.5 | HIP 117161 | 9.47 |
| 2026-03-27 12:00 | 23:46:09.46 | +31:45:58.2 | HIP 117161 | 13.23 |
| 2026-03-28 00:00 | 23:46:26.18 | +31:47:10.5 | HIP 117161 | 16.98 |
| 2026-03-28 12:00 | 23:46:42.87 | +31:48:23.4 | HIP 117161 | 20.73 |
| 2026-03-29 00:00 | 23:46:59.53 | +31:49:36.9 | HIP 117448 | 24.39 |
| 2026-03-29 12:00 | 23:47:16.16 | +31:50:51.0 | HIP 117448 | 21.36 |
| 2026-03-30 00:00 | 23:47:32.75 | +31:52:05.6 | HIP 117448 | 18.61 |
| 2026-03-30 12:00 | 23:47:49.30 | +31:53:20.9 | HIP 117448 | 16.26 |
| 2026-03-31 00:00 | 23:48:05.82 | +31:54:36.7 | HIP 117458 | 13.61 |
| 2026-03-31 12:00 | 23:48:22.30 | +31:55:53.0 | HIP 117458 | 10.08 |
| 2026-04-01 00:00 | 23:48:38.75 | +31:57:10.0 | HIP 117458 | 6.75 |
| 2026-04-01 12:00 | 23:48:55.16 | +31:58:27.4 | HIP 117458 | 4.12 |
| 2026-04-02 00:00 | 23:49:11.53 | +31:59:45.4 | HIP 117458 | 3.99 |
| 2026-04-02 12:00 | 23:49:27.87 | +32:01:04.0 | HIP 117458 | 6.49 |
| 2026-04-03 00:00 | 23:49:44.16 | +32:02:23.1 | HIP 117458 | 9.78 |
| 2026-04-03 12:00 | 23:50:00.42 | +32:03:42.8 | HIP 117458 | 13.27 |
| 2026-04-04 00:00 | 23:50:16.63 | +32:05:02.9 | HIP 117458 | 16.84 |
| 2026-04-04 12:00 | 23:50:32.81 | +32:06:23.6 | HIP 117458 | 20.45 |
| 2026-04-05 00:00 | 23:50:48.95 | +32:07:44.8 | HIP 117458 | 24.07 |
| 2026-04-05 12:00 | 23:51:05.04 | +32:09:06.6 | HIP 117765 | 24.59 |
| 2026-04-06 00:00 | 23:51:21.10 | +32:10:28.8 | HIP 117765 | 21.65 |
| 2026-04-06 12:00 | 23:51:37.11 | +32:11:51.5 | HIP 117765 | 18.98 |
| 2026-04-07 00:00 | 23:51:53.08 | +32:13:14.8 | HIP 117765 | 16.70 |
| 2026-04-07 12:00 | 23:52:09.01 | +32:14:38.5 | HIP 117765 | 15.00 |
| 2026-04-08 00:00 | 23:52:24.89 | +32:16:02.7 | HIP 117784 | 12.90 |
| 2026-04-08 12:00 | 23:52:40.73 | +32:17:27.5 | HIP 117784 | 9.51 |
| 2026-04-09 00:00 | 23:52:56.52 | +32:18:52.7 | HIP 117784 | 6.41 |
| 2026-04-09 12:00 | 23:53:12.27 | +32:20:18.3 | HIP 117784 | 4.22 |
| 2026-04-10 00:00 | 23:53:27.97 | +32:21:44.5 | HIP 117784 | 4.54 |
| 2026-04-10 12:00 | 23:53:43.63 | +32:23:11.1 | HIP 117784 | 7.02 |
| 2026-04-11 00:00 | 23:53:59.23 | +32:24:38.1 | HIP 117784 | 10.19 |
| 2026-04-11 12:00 | 23:54:14.79 | +32:26:05.7 | HIP 117784 | 13.57 |
| 2026-04-12 00:00 | 23:54:30.31 | +32:27:33.6 | HIP 117784 | 17.02 |
| 2026-04-12 12:00 | 23:54:45.77 | +32:29:02.1 | HIP 117784 | 20.51 |
| 2026-04-13 00:00 | 23:55:01.19 | +32:30:30.9 | HIP 117938 | 23.45 |
| 2026-04-13 12:00 | 23:55:16.55 | +32:32:00.2 | HIP 117938 | 21.56 |
| 2026-04-14 00:00 | 23:55:31.86 | +32:33:30.0 | HIP 117938 | 20.12 |
| 2026-04-14 12:00 | 23:55:47.13 | +32:35:00.1 | HIP 117938 | 19.22 |
| 2026-04-15 00:00 | 23:56:02.34 | +32:36:30.7 | HIP 117938 | 18.95 |
| 2026-04-15 12:00 | 23:56:17.49 | +32:38:01.7 | HIP 117938 | 19.31 |
| 2026-04-16 00:00 | 23:56:32.60 | +32:39:33.1 | HIP 117938 | 20.28 |