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) |
|---|---|---|---|---|
| 2026-05-12 00:00 | 00:08:10.86 | +34:05:45.3 | HIP 725 | 19.17 |
| 2026-05-12 12:00 | 00:08:22.36 | +34:07:30.3 | HIP 725 | 16.47 |
| 2026-05-13 00:00 | 00:08:33.78 | +34:09:15.5 | HIP 725 | 13.88 |
| 2026-05-13 12:00 | 00:08:45.12 | +34:11:00.7 | HIP 725 | 11.46 |
| 2026-05-14 00:00 | 00:08:56.37 | +34:12:46.1 | HIP 725 | 9.33 |
| 2026-05-14 12:00 | 00:09:07.54 | +34:14:31.6 | HIP 725 | 7.73 |
| 2026-05-15 00:00 | 00:09:18.63 | +34:16:17.1 | HIP 725 | 7.01 |
| 2026-05-15 12:00 | 00:09:29.63 | +34:18:02.8 | HIP 725 | 7.41 |
| 2026-05-16 00:00 | 00:09:40.54 | +34:19:48.5 | HIP 725 | 8.77 |
| 2026-05-16 12:00 | 00:09:51.37 | +34:21:34.3 | HIP 725 | 10.71 |
| 2026-05-17 00:00 | 00:10:02.11 | +34:23:20.1 | HIP 725 | 12.98 |
| 2026-05-17 12:00 | 00:10:12.76 | +34:25:06.0 | HIP 725 | 15.41 |
| 2026-05-18 00:00 | 00:10:23.33 | +34:26:52.0 | HIP 725 | 17.94 |
| 2026-05-18 12:00 | 00:10:33.80 | +34:28:38.0 | HIP 725 | 20.52 |
| 2026-05-19 00:00 | 00:10:44.19 | +34:30:24.1 | HIP 725 | 23.13 |
| 2026-05-19 12:00 | 00:10:54.48 | +34:32:10.2 | HIP 725 | 25.76 |
| 2026-05-20 00:00 | 00:11:04.69 | +34:33:56.3 | HIP 725 | 28.39 |
| 2026-05-20 12:00 | 00:11:14.80 | +34:35:42.4 | HIP 725 | 31.03 |
| 2026-05-21 00:00 | 00:11:24.82 | +34:37:28.6 | HIP 725 | 33.67 |
| 2026-05-21 12:00 | 00:11:34.75 | +34:39:14.7 | HIP 725 | 36.30 |
| 2026-05-22 00:00 | 00:11:44.59 | +34:41:00.9 | HIP 725 | 38.92 |
| 2026-05-22 12:00 | 00:11:54.33 | +34:42:47.0 | HIP 1048 | 37.56 |
| 2026-05-23 00:00 | 00:12:03.98 | +34:44:33.2 | HIP 1048 | 35.19 |
| 2026-05-23 12:00 | 00:12:13.54 | +34:46:19.3 | HIP 1048 | 32.86 |
| 2026-05-24 00:00 | 00:12:23.00 | +34:48:05.4 | HIP 1048 | 30.60 |
| 2026-05-24 12:00 | 00:12:32.37 | +34:49:51.5 | HIP 1048 | 28.40 |
| 2026-05-25 00:00 | 00:12:41.64 | +34:51:37.6 | HIP 1048 | 26.29 |
| 2026-05-25 12:00 | 00:12:50.81 | +34:53:23.6 | HIP 1048 | 24.26 |
| 2026-05-26 00:00 | 00:12:59.89 | +34:55:09.5 | HIP 1048 | 22.36 |
| 2026-05-26 12:00 | 00:13:08.88 | +34:56:55.5 | HIP 1048 | 20.60 |
| 2026-05-27 00:00 | 00:13:17.76 | +34:58:41.3 | HIP 1048 | 19.01 |
| 2026-05-27 12:00 | 00:13:26.55 | +35:00:27.1 | HIP 1048 | 17.64 |
| 2026-05-28 00:00 | 00:13:35.24 | +35:02:12.9 | HIP 1048 | 16.54 |
| 2026-05-28 12:00 | 00:13:43.84 | +35:03:58.5 | HIP 1048 | 15.75 |
| 2026-05-29 00:00 | 00:13:52.33 | +35:05:44.1 | HIP 1048 | 15.32 |
| 2026-05-29 12:00 | 00:14:00.73 | +35:07:29.6 | HIP 1048 | 15.26 |
| 2026-05-30 00:00 | 00:14:09.02 | +35:09:15.0 | HIP 1048 | 15.58 |
| 2026-05-30 12:00 | 00:14:17.22 | +35:11:00.3 | HIP 1137 | 14.10 |
| 2026-05-31 00:00 | 00:14:25.31 | +35:12:45.6 | HIP 1137 | 12.57 |
| 2026-05-31 12:00 | 00:14:33.30 | +35:14:30.7 | HIP 1137 | 11.35 |
| 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 |