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 | 0.998 |
| 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 | -24.0653 | +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) |
|---|---|---|---|---|
| 2026-09-20 00:00 | 23:21:22.24 | +11:49:45.9 | HIP 115373 | 24.04 |
| 2026-09-20 12:00 | 23:20:58.15 | +11:40:32.9 | HIP 115132 | 28.66 |
| 2026-09-21 00:00 | 23:20:34.10 | +11:31:16.0 | HIP 115132 | 20.12 |
| 2026-09-21 12:00 | 23:20:10.10 | +11:21:55.1 | HIP 115132 | 15.21 |
| 2026-09-22 00:00 | 23:19:46.16 | +11:12:30.4 | HIP 115132 | 17.42 |
| 2026-09-22 12:00 | 23:19:22.28 | +11:03:02.1 | HIP 115132 | 25.00 |
| 2026-09-23 00:00 | 23:18:58.48 | +10:53:30.2 | HIP 115132 | 34.61 |
| 2026-09-23 12:00 | 23:18:34.76 | +10:43:54.8 | HIP 114930 | 27.44 |
| 2026-09-24 00:00 | 23:18:11.13 | +10:34:16.0 | HIP 114930 | 20.53 |
| 2026-09-24 12:00 | 23:17:47.60 | +10:24:34.0 | HIP 114930 | 18.57 |
| 2026-09-25 00:00 | 23:17:24.18 | +10:14:48.9 | HIP 114930 | 22.94 |
| 2026-09-25 12:00 | 23:17:00.88 | +10:05:00.8 | HIP 115004 | 24.64 |
| 2026-09-26 00:00 | 23:16:37.70 | +09:55:09.8 | HIP 115004 | 19.08 |
| 2026-09-26 12:00 | 23:16:14.66 | +09:45:16.0 | HIP 115004 | 19.46 |
| 2026-09-27 00:00 | 23:15:51.76 | +09:35:19.5 | HIP 115004 | 25.55 |
| 2026-09-27 12:00 | 23:15:29.01 | +09:25:20.5 | HIP 115004 | 34.46 |
| 2026-09-28 00:00 | 23:15:06.42 | +09:15:19.1 | HIP 114784 | 27.95 |
| 2026-09-28 12:00 | 23:14:43.99 | +09:05:15.4 | HIP 114784 | 18.69 |
| 2026-09-29 00:00 | 23:14:21.73 | +08:55:09.6 | HIP 114784 | 13.41 |
| 2026-09-29 12:00 | 23:13:59.66 | +08:45:01.6 | HIP 114784 | 16.54 |
| 2026-09-30 00:00 | 23:13:37.78 | +08:34:51.8 | HIP 114608 | 24.33 |
| 2026-09-30 12:00 | 23:13:16.10 | +08:24:40.2 | HIP 114520 | 29.32 |
| 2026-10-01 00:00 | 23:12:54.62 | +08:14:26.9 | HIP 114671 | 23.60 |
| 2026-10-01 12:00 | 23:12:33.36 | +08:04:12.1 | HIP 114671 | 20.83 |
| 2026-10-02 00:00 | 23:12:12.31 | +07:53:55.8 | HIP 114671 | 23.95 |
| 2026-10-02 12:00 | 23:11:51.50 | +07:43:38.3 | HIP 114440 | 18.55 |
| 2026-10-03 00:00 | 23:11:30.92 | +07:33:19.7 | HIP 114440 | 18.38 |
| 2026-10-03 12:00 | 23:11:10.59 | +07:23:00.0 | HIP 114398 | 15.88 |
| 2026-10-04 00:00 | 23:10:50.51 | +07:12:39.5 | HIP 114398 | 14.16 |
| 2026-10-04 12:00 | 23:10:30.70 | +07:02:18.2 | HIP 114398 | 20.34 |
| 2026-10-05 00:00 | 23:10:11.15 | +06:51:56.3 | HIP 114294 | 26.75 |
| 2026-10-05 12:00 | 23:09:51.87 | +06:41:33.9 | HIP 114294 | 16.74 |
| 2026-10-06 00:00 | 23:09:32.88 | +06:31:11.2 | HIP 114294 | 10.35 |
| 2026-10-06 12:00 | 23:09:14.18 | +06:20:48.3 | HIP 114294 | 13.96 |
| 2026-10-07 00:00 | 23:08:55.78 | +06:10:25.3 | HIP 114294 | 23.27 |
| 2026-10-07 12:00 | 23:08:37.68 | +06:00:02.4 | HIP 114294 | 33.83 |
| 2026-10-08 00:00 | 23:08:19.90 | +05:49:39.7 | HIP 114288 | 30.37 |
| 2026-10-08 12:00 | 23:08:02.43 | +05:39:17.3 | HIP 114288 | 22.47 |
| 2026-10-09 00:00 | 23:07:45.30 | +05:28:55.4 | HIP 114288 | 18.38 |
| 2026-10-09 12:00 | 23:07:28.49 | +05:18:34.1 | HIP 114126 | 19.45 |
| 2026-10-10 00:00 | 23:07:12.03 | +05:08:13.5 | HIP 114126 | 8.78 |
| 2026-10-10 12:00 | 23:06:55.91 | +04:57:53.8 | HIP 114126 | 4.85 |
| 2026-10-11 00:00 | 23:06:40.14 | +04:47:35.0 | HIP 114069 | 10.06 |