C/2017 S3 (PANSTARRS)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2017 S3 (PANSTARRS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2018-08-15T22:45:39.003840Z |
| Orbit solution date (soln_date, UTC) | 2021-04-16T12:04:16Z |
| Obs used | 986 |
| NEO | - |
| M1 | 13.200 |
| K1 | 8.250 |
| PC | - |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2018-04-27.0000000 |
| e | 1.00007796 |
| q (au) | 0.208446 |
| a (au) | -2673.667700 |
| i (deg) | 99.038653 |
| Ω (om, deg) | 171.042492 |
| ω (w, deg) | 255.892231 |
| M (ma, deg) | -0.000791 |
Magnitude
Scatter + Global Linear
$$ M_a = (9.352 + 4.553\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 9.352 |
| n | 4.553 |
| gf | 0.800 |
| gb | -0.500 |
| k | 1.000 |
| δ90 | 1.000 |
| 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 |
|---|---|---|---|
| 2017-08-17 | 2018-06-23 | -3.2015 | +2.122 |
| 2018-06-23 | 2018-07-06 | +31.4848 | -3.170 |
| 2018-07-06 | 2018-07-15 | -12.2246 | +0.039 |
| 2018-07-15 | 2018-07-21 | +4.0302 | -0.473 |
| 2018-07-21 | 2018-08-03 | -20.0442 | -1.795 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-06-01 00:00 | 13:11:46.75 | +66:11:44.7 | HIP 64760 | 27.96 |
| 2026-06-01 12:00 | 13:11:39.34 | +66:10:52.4 | HIP 64760 | 28.56 |
| 2026-06-02 00:00 | 13:11:32.03 | +66:09:59.7 | HIP 64760 | 29.19 |
| 2026-06-02 12:00 | 13:11:24.82 | +66:09:06.5 | HIP 64760 | 29.83 |
| 2026-06-03 00:00 | 13:11:17.69 | +66:08:12.8 | HIP 64760 | 30.50 |
| 2026-06-03 12:00 | 13:11:10.66 | +66:07:18.8 | HIP 64760 | 31.19 |
| 2026-06-04 00:00 | 13:11:03.72 | +66:06:24.3 | HIP 64760 | 31.89 |
| 2026-06-04 12:00 | 13:10:56.88 | +66:05:29.3 | HIP 64294 | 31.49 |
| 2026-06-05 00:00 | 13:10:50.13 | +66:04:34.0 | HIP 64294 | 30.53 |
| 2026-06-05 12:00 | 13:10:43.48 | +66:03:38.2 | HIP 64294 | 29.58 |
| 2026-06-06 00:00 | 13:10:36.93 | +66:02:42.0 | HIP 64294 | 28.64 |
| 2026-06-06 12:00 | 13:10:30.47 | +66:01:45.4 | HIP 64294 | 27.71 |
| 2026-06-07 00:00 | 13:10:24.10 | +66:00:48.4 | HIP 64294 | 26.78 |
| 2026-06-07 12:00 | 13:10:17.83 | +65:59:51.0 | HIP 64294 | 25.87 |
| 2026-06-08 00:00 | 13:10:11.66 | +65:58:53.3 | HIP 64294 | 24.97 |
| 2026-06-08 12:00 | 13:10:05.58 | +65:57:55.1 | HIP 64294 | 24.09 |
| 2026-06-09 00:00 | 13:09:59.61 | +65:56:56.5 | HIP 64294 | 23.22 |
| 2026-06-09 12:00 | 13:09:53.73 | +65:55:57.6 | HIP 64294 | 22.36 |
| 2026-06-10 00:00 | 13:09:47.94 | +65:54:58.3 | HIP 64149 | 21.42 |
| 2026-06-10 12:00 | 13:09:42.26 | +65:53:58.6 | HIP 64149 | 20.31 |
| 2026-06-11 00:00 | 13:09:36.67 | +65:52:58.6 | HIP 64149 | 19.19 |
| 2026-06-11 12:00 | 13:09:31.19 | +65:51:58.2 | HIP 64149 | 18.08 |
| 2026-06-12 00:00 | 13:09:25.80 | +65:50:57.4 | HIP 64149 | 16.97 |
| 2026-06-12 12:00 | 13:09:20.51 | +65:49:56.3 | HIP 64149 | 15.86 |
| 2026-06-13 00:00 | 13:09:15.32 | +65:48:54.9 | HIP 64149 | 14.76 |
| 2026-06-13 12:00 | 13:09:10.23 | +65:47:53.1 | HIP 64149 | 13.66 |
| 2026-06-14 00:00 | 13:09:05.24 | +65:46:51.0 | HIP 64149 | 12.56 |
| 2026-06-14 12:00 | 13:09:00.35 | +65:45:48.6 | HIP 64149 | 11.48 |
| 2026-06-15 00:00 | 13:08:55.56 | +65:44:45.8 | HIP 64149 | 10.40 |
| 2026-06-15 12:00 | 13:08:50.87 | +65:43:42.7 | HIP 64149 | 9.34 |
| 2026-06-16 00:00 | 13:08:46.28 | +65:42:39.3 | HIP 64149 | 8.29 |
| 2026-06-16 12:00 | 13:08:41.79 | +65:41:35.7 | HIP 64149 | 7.28 |
| 2026-06-17 00:00 | 13:08:37.40 | +65:40:31.7 | HIP 64149 | 6.30 |
| 2026-06-17 12:00 | 13:08:33.11 | +65:39:27.4 | HIP 64149 | 5.40 |
| 2026-06-18 00:00 | 13:08:28.92 | +65:38:22.9 | HIP 64149 | 4.59 |
| 2026-06-18 12:00 | 13:08:24.84 | +65:37:18.0 | HIP 64149 | 3.96 |
| 2026-06-19 00:00 | 13:08:20.85 | +65:36:12.9 | HIP 64149 | 3.59 |
| 2026-06-19 12:00 | 13:08:16.97 | +65:35:07.5 | HIP 64149 | 3.57 |
| 2026-06-20 00:00 | 13:08:13.18 | +65:34:01.9 | HIP 64149 | 3.89 |
| 2026-06-20 12:00 | 13:08:09.50 | +65:32:56.0 | HIP 64149 | 4.50 |
| 2026-06-21 00:00 | 13:08:05.92 | +65:31:49.8 | HIP 64149 | 5.28 |
| 2026-06-21 12:00 | 13:08:02.44 | +65:30:43.5 | HIP 64149 | 6.19 |
| 2026-06-22 00:00 | 13:07:59.06 | +65:29:36.8 | HIP 64149 | 7.16 |