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) |
|---|---|---|---|---|
| 2026-03-26 00:00 | 13:37:04.18 | +66:34:03.5 | HIP 66520 | 6.52 |
| 2026-03-26 12:00 | 13:36:52.19 | +66:34:41.3 | HIP 66520 | 7.48 |
| 2026-03-27 00:00 | 13:36:40.16 | +66:35:18.4 | HIP 66520 | 8.55 |
| 2026-03-27 12:00 | 13:36:28.09 | +66:35:54.8 | HIP 66520 | 9.69 |
| 2026-03-28 00:00 | 13:36:15.97 | +66:36:30.5 | HIP 66520 | 10.88 |
| 2026-03-28 12:00 | 13:36:03.82 | +66:37:05.4 | HIP 66520 | 12.10 |
| 2026-03-29 00:00 | 13:35:51.62 | +66:37:39.7 | HIP 66520 | 13.35 |
| 2026-03-29 12:00 | 13:35:39.39 | +66:38:13.2 | HIP 66520 | 14.62 |
| 2026-03-30 00:00 | 13:35:27.12 | +66:38:46.0 | HIP 66520 | 15.89 |
| 2026-03-30 12:00 | 13:35:14.82 | +66:39:18.0 | HIP 66520 | 17.18 |
| 2026-03-31 00:00 | 13:35:02.48 | +66:39:49.4 | HIP 66520 | 18.48 |
| 2026-03-31 12:00 | 13:34:50.11 | +66:40:20.0 | HIP 66520 | 19.77 |
| 2026-04-01 00:00 | 13:34:37.70 | +66:40:49.8 | HIP 66520 | 21.08 |
| 2026-04-01 12:00 | 13:34:25.27 | +66:41:19.0 | HIP 66520 | 22.38 |
| 2026-04-02 00:00 | 13:34:12.80 | +66:41:47.4 | HIP 66520 | 23.69 |
| 2026-04-02 12:00 | 13:34:00.31 | +66:42:15.1 | HIP 66520 | 24.99 |
| 2026-04-03 00:00 | 13:33:47.79 | +66:42:42.0 | HIP 66520 | 26.30 |
| 2026-04-03 12:00 | 13:33:35.25 | +66:43:08.2 | HIP 66520 | 27.61 |
| 2026-04-04 00:00 | 13:33:22.68 | +66:43:33.6 | HIP 66422 | 28.52 |
| 2026-04-04 12:00 | 13:33:10.09 | +66:43:58.3 | HIP 66422 | 29.21 |
| 2026-04-05 00:00 | 13:32:57.48 | +66:44:22.3 | HIP 65773 | 29.32 |
| 2026-04-05 12:00 | 13:32:44.84 | +66:44:45.5 | HIP 65773 | 28.10 |
| 2026-04-06 00:00 | 13:32:32.19 | +66:45:08.0 | HIP 65773 | 26.91 |
| 2026-04-06 12:00 | 13:32:19.52 | +66:45:29.7 | HIP 65773 | 25.73 |
| 2026-04-07 00:00 | 13:32:06.83 | +66:45:50.7 | HIP 65773 | 24.57 |
| 2026-04-07 12:00 | 13:31:54.12 | +66:46:10.9 | HIP 65773 | 23.43 |
| 2026-04-08 00:00 | 13:31:41.41 | +66:46:30.3 | HIP 65773 | 22.32 |
| 2026-04-08 12:00 | 13:31:28.67 | +66:46:49.1 | HIP 65773 | 21.24 |
| 2026-04-09 00:00 | 13:31:15.93 | +66:47:07.0 | HIP 65773 | 20.19 |
| 2026-04-09 12:00 | 13:31:03.18 | +66:47:24.2 | HIP 65773 | 19.18 |
| 2026-04-10 00:00 | 13:30:50.41 | +66:47:40.7 | HIP 65773 | 18.21 |
| 2026-04-10 12:00 | 13:30:37.64 | +66:47:56.4 | HIP 65773 | 17.30 |
| 2026-04-11 00:00 | 13:30:24.86 | +66:48:11.3 | HIP 65773 | 16.44 |
| 2026-04-11 12:00 | 13:30:12.08 | +66:48:25.5 | HIP 65773 | 15.65 |
| 2026-04-12 00:00 | 13:29:59.29 | +66:48:38.9 | HIP 65773 | 14.94 |
| 2026-04-12 12:00 | 13:29:46.50 | +66:48:51.6 | HIP 65773 | 14.33 |
| 2026-04-13 00:00 | 13:29:33.71 | +66:49:03.5 | HIP 65773 | 13.81 |
| 2026-04-13 12:00 | 13:29:20.92 | +66:49:14.7 | HIP 65773 | 13.41 |
| 2026-04-14 00:00 | 13:29:08.13 | +66:49:25.0 | HIP 65773 | 13.13 |
| 2026-04-14 12:00 | 13:28:55.34 | +66:49:34.7 | HIP 65773 | 12.98 |
| 2026-04-15 00:00 | 13:28:42.56 | +66:49:43.5 | HIP 65773 | 12.97 |
| 2026-04-15 12:00 | 13:28:29.78 | +66:49:51.6 | HIP 65773 | 13.09 |
| 2026-04-16 00:00 | 13:28:17.01 | +66:49:59.0 | HIP 65773 | 13.34 |