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) |
|---|---|---|---|---|
| 2026-07-29 00:00 | 23:45:26.81 | +19:37:51.9 | HIP 117214 | 9.21 |
| 2026-07-29 12:00 | 23:45:29.69 | +19:37:48.8 | HIP 117214 | 8.61 |
| 2026-07-30 00:00 | 23:45:32.24 | +19:37:41.9 | HIP 117214 | 8.05 |
| 2026-07-30 12:00 | 23:45:34.46 | +19:37:31.4 | HIP 117214 | 7.53 |
| 2026-07-31 00:00 | 23:45:36.35 | +19:37:17.1 | HIP 117214 | 7.03 |
| 2026-07-31 12:00 | 23:45:37.90 | +19:36:58.9 | HIP 117214 | 6.56 |
| 2026-08-01 00:00 | 23:45:39.12 | +19:36:37.0 | HIP 117214 | 6.11 |
| 2026-08-01 12:00 | 23:45:40.00 | +19:36:11.1 | HIP 117214 | 5.69 |
| 2026-08-02 00:00 | 23:45:40.54 | +19:35:41.3 | HIP 117214 | 5.31 |
| 2026-08-02 12:00 | 23:45:40.74 | +19:35:07.5 | HIP 117214 | 5.00 |
| 2026-08-03 00:00 | 23:45:40.59 | +19:34:29.7 | HIP 117214 | 4.79 |
| 2026-08-03 12:00 | 23:45:40.11 | +19:33:47.8 | HIP 117214 | 4.73 |
| 2026-08-04 00:00 | 23:45:39.28 | +19:33:01.7 | HIP 117214 | 4.85 |
| 2026-08-04 12:00 | 23:45:38.10 | +19:32:11.5 | HIP 117214 | 5.18 |
| 2026-08-05 00:00 | 23:45:36.57 | +19:31:17.1 | HIP 117214 | 5.73 |
| 2026-08-05 12:00 | 23:45:34.70 | +19:30:18.3 | HIP 117214 | 6.49 |
| 2026-08-06 00:00 | 23:45:32.47 | +19:29:15.3 | HIP 117214 | 7.43 |
| 2026-08-06 12:00 | 23:45:29.90 | +19:28:07.9 | HIP 117214 | 8.54 |
| 2026-08-07 00:00 | 23:45:26.97 | +19:26:56.1 | HIP 117214 | 9.81 |
| 2026-08-07 12:00 | 23:45:23.69 | +19:25:39.8 | HIP 117214 | 11.21 |
| 2026-08-08 00:00 | 23:45:20.05 | +19:24:18.9 | HIP 117214 | 12.75 |
| 2026-08-08 12:00 | 23:45:16.06 | +19:22:53.5 | HIP 117214 | 14.41 |
| 2026-08-09 00:00 | 23:45:11.72 | +19:21:23.5 | HIP 117214 | 16.19 |
| 2026-08-09 12:00 | 23:45:07.02 | +19:19:48.8 | HIP 117214 | 18.10 |
| 2026-08-10 00:00 | 23:45:01.96 | +19:18:09.5 | HIP 117214 | 20.12 |
| 2026-08-10 12:00 | 23:44:56.55 | +19:16:25.3 | HIP 117042 | 21.16 |
| 2026-08-11 00:00 | 23:44:50.78 | +19:14:36.3 | HIP 117042 | 19.21 |
| 2026-08-11 12:00 | 23:44:44.66 | +19:12:42.5 | HIP 117042 | 17.23 |
| 2026-08-12 00:00 | 23:44:38.18 | +19:10:43.8 | HIP 117042 | 15.27 |
| 2026-08-12 12:00 | 23:44:31.34 | +19:08:40.2 | HIP 117042 | 13.40 |
| 2026-08-13 00:00 | 23:44:24.15 | +19:06:31.5 | HIP 117042 | 11.75 |
| 2026-08-13 12:00 | 23:44:16.61 | +19:04:17.9 | HIP 117042 | 10.50 |
| 2026-08-14 00:00 | 23:44:08.71 | +19:01:59.1 | HIP 117042 | 9.91 |
| 2026-08-14 12:00 | 23:44:00.46 | +18:59:35.3 | HIP 117042 | 10.22 |
| 2026-08-15 00:00 | 23:43:51.86 | +18:57:06.2 | HIP 117042 | 11.43 |
| 2026-08-15 12:00 | 23:43:42.91 | +18:54:32.0 | HIP 117042 | 13.40 |
| 2026-08-16 00:00 | 23:43:33.61 | +18:51:52.6 | HIP 117042 | 15.92 |
| 2026-08-16 12:00 | 23:43:23.96 | +18:49:07.9 | HIP 116961 | 15.45 |
| 2026-08-17 00:00 | 23:43:13.96 | +18:46:17.9 | HIP 116961 | 11.90 |
| 2026-08-17 12:00 | 23:43:03.62 | +18:43:22.5 | HIP 116961 | 8.36 |
| 2026-08-18 00:00 | 23:42:52.94 | +18:40:21.8 | HIP 116961 | 5.13 |
| 2026-08-18 12:00 | 23:42:41.92 | +18:37:15.6 | HIP 116961 | 3.71 |
| 2026-08-19 00:00 | 23:42:30.55 | +18:34:04.0 | HIP 116961 | 5.93 |