P/2017 S8 (PANSTARRS)
Metadata
| Parameter | Value |
|---|---|
| Designation | P/2017 S8 (PANSTARRS) |
| Type | P |
| Perihelion (tp_cal, UTC) | 2018-01-28T15:29:27.191040Z |
| Orbit solution date (soln_date, UTC) | 2022-07-31T01:43:24Z |
| Obs used | 178 |
| NEO | - |
| M1 | 18.100 |
| K1 | 4.500 |
| PC | - |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2017-10-19.0000000 |
| e | 0.39352874 |
| q (au) | 1.682991 |
| a (au) | 2.775056 |
| i (deg) | 29.851080 |
| Ω (om, deg) | 191.802254 |
| ω (w, deg) | 254.566958 |
| M (ma, deg) | 338.328723 |
Magnitude
Scatter + Global Linear
$$ M_a = (20.000 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 20.000 |
| n | 2.000 |
| gf | 1.000 |
| gb | -0.852 |
| k | 0.909 |
| δ90 | 10.000 |
| 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 |
|---|---|---|---|
| 2017-09-25 | 2018-01-22 | -24.0654 | +6.668 |
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 | 21:52:32.06 | +07:06:32.5 | HIP 108046 | 23.04 |
| 2026-03-26 12:00 | 21:53:11.21 | +07:09:56.8 | HIP 108090 | 21.43 |
| 2026-03-27 00:00 | 21:53:50.32 | +07:13:21.6 | HIP 108090 | 21.55 |
| 2026-03-27 12:00 | 21:54:29.39 | +07:16:47.0 | HIP 108239 | 17.59 |
| 2026-03-28 00:00 | 21:55:08.42 | +07:20:13.0 | HIP 108239 | 9.29 |
| 2026-03-28 12:00 | 21:55:47.40 | +07:23:39.5 | HIP 108239 | 8.62 |
| 2026-03-29 00:00 | 21:56:26.34 | +07:27:06.6 | HIP 108286 | 6.42 |
| 2026-03-29 12:00 | 21:57:05.24 | +07:30:34.2 | HIP 108286 | 11.86 |
| 2026-03-30 00:00 | 21:57:44.10 | +07:34:02.3 | HIP 108286 | 21.20 |
| 2026-03-30 12:00 | 21:58:22.91 | +07:37:30.9 | HIP 108286 | 31.10 |
| 2026-03-31 00:00 | 21:59:01.68 | +07:41:00.1 | HIP 108663 | 28.90 |
| 2026-03-31 12:00 | 21:59:40.41 | +07:44:29.8 | HIP 108663 | 18.69 |
| 2026-04-01 00:00 | 22:00:19.09 | +07:48:00.0 | HIP 108663 | 8.49 |
| 2026-04-01 12:00 | 22:00:57.72 | +07:51:30.6 | HIP 108663 | 1.72 |
| 2026-04-02 00:00 | 22:01:36.31 | +07:55:01.8 | HIP 108663 | 11.89 |
| 2026-04-02 12:00 | 22:02:14.86 | +07:58:33.5 | HIP 108663 | 22.07 |
| 2026-04-03 00:00 | 22:02:53.36 | +08:02:05.7 | HIP 108820 | 17.74 |
| 2026-04-03 12:00 | 22:03:31.81 | +08:05:38.3 | HIP 108820 | 18.24 |
| 2026-04-04 00:00 | 22:04:10.22 | +08:09:11.4 | HIP 108820 | 23.57 |
| 2026-04-04 12:00 | 22:04:48.58 | +08:12:45.0 | HIP 109095 | 16.97 |
| 2026-04-05 00:00 | 22:05:26.89 | +08:16:19.0 | HIP 109095 | 8.13 |
| 2026-04-05 12:00 | 22:06:05.16 | +08:19:53.5 | HIP 109095 | 7.04 |
| 2026-04-06 00:00 | 22:06:43.38 | +08:23:28.5 | HIP 109095 | 15.42 |
| 2026-04-06 12:00 | 22:07:21.55 | +08:27:03.8 | HIP 109095 | 25.10 |
| 2026-04-07 00:00 | 22:07:59.67 | +08:30:39.7 | HIP 109314 | 25.85 |
| 2026-04-07 12:00 | 22:08:37.74 | +08:34:15.9 | HIP 109314 | 19.66 |
| 2026-04-08 00:00 | 22:09:15.76 | +08:37:52.6 | HIP 109314 | 17.54 |
| 2026-04-08 12:00 | 22:09:53.73 | +08:41:29.7 | HIP 109314 | 20.76 |
| 2026-04-09 00:00 | 22:10:31.65 | +08:45:07.1 | HIP 109314 | 27.48 |
| 2026-04-09 12:00 | 22:11:09.52 | +08:48:45.0 | HIP 109598 | 17.83 |
| 2026-04-10 00:00 | 22:11:47.34 | +08:52:23.3 | HIP 109598 | 8.88 |
| 2026-04-10 12:00 | 22:12:25.10 | +08:56:02.0 | HIP 109598 | 6.37 |
| 2026-04-11 00:00 | 22:13:02.82 | +08:59:41.1 | HIP 109598 | 14.22 |
| 2026-04-11 12:00 | 22:13:40.47 | +09:03:20.5 | HIP 109825 | 20.07 |
| 2026-04-12 00:00 | 22:14:18.08 | +09:07:00.3 | HIP 109825 | 18.30 |
| 2026-04-12 12:00 | 22:14:55.63 | +09:10:40.4 | HIP 109825 | 21.59 |
| 2026-04-13 00:00 | 22:15:33.12 | +09:14:21.0 | HIP 109765 | 27.38 |
| 2026-04-13 12:00 | 22:16:10.56 | +09:18:01.8 | HIP 109765 | 34.22 |
| 2026-04-14 00:00 | 22:16:47.94 | +09:21:43.0 | HIP 109854 | 39.34 |
| 2026-04-14 12:00 | 22:17:25.27 | +09:25:24.5 | HIP 110120 | 31.91 |
| 2026-04-15 00:00 | 22:18:02.53 | +09:29:06.3 | HIP 110120 | 25.21 |
| 2026-04-15 12:00 | 22:18:39.74 | +09:32:48.4 | HIP 110120 | 21.18 |
| 2026-04-16 00:00 | 22:19:16.89 | +09:36:30.8 | HIP 110120 | 21.37 |