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) |
|---|---|---|---|---|
| 2026-05-12 00:00 | 22:49:53.64 | +12:52:37.0 | HIP 112770 | 6.87 |
| 2026-05-12 12:00 | 22:50:26.87 | +12:56:23.3 | HIP 112770 | 8.46 |
| 2026-05-13 00:00 | 22:51:00.01 | +13:00:09.5 | HIP 112770 | 15.97 |
| 2026-05-13 12:00 | 22:51:33.05 | +13:03:55.4 | HIP 112770 | 24.41 |
| 2026-05-14 00:00 | 22:52:05.99 | +13:07:41.2 | HIP 112963 | 17.57 |
| 2026-05-14 12:00 | 22:52:38.84 | +13:11:26.8 | HIP 112963 | 12.02 |
| 2026-05-15 00:00 | 22:53:11.60 | +13:15:12.1 | HIP 112963 | 11.66 |
| 2026-05-15 12:00 | 22:53:44.26 | +13:18:57.3 | HIP 113119 | 16.23 |
| 2026-05-16 00:00 | 22:54:16.82 | +13:22:42.2 | HIP 113119 | 16.19 |
| 2026-05-16 12:00 | 22:54:49.28 | +13:26:26.8 | HIP 113119 | 20.35 |
| 2026-05-17 00:00 | 22:55:21.64 | +13:30:11.2 | HIP 113119 | 26.80 |
| 2026-05-17 12:00 | 22:55:53.89 | +13:33:55.4 | HIP 113270 | 20.90 |
| 2026-05-18 00:00 | 22:56:26.05 | +13:37:39.2 | HIP 113270 | 17.10 |
| 2026-05-18 12:00 | 22:56:58.10 | +13:41:22.8 | HIP 113398 | 14.88 |
| 2026-05-19 00:00 | 22:57:30.05 | +13:45:06.0 | HIP 113398 | 10.55 |
| 2026-05-19 12:00 | 22:58:01.90 | +13:48:49.0 | HIP 113398 | 12.20 |
| 2026-05-20 00:00 | 22:58:33.63 | +13:52:31.6 | HIP 113398 | 18.25 |
| 2026-05-20 12:00 | 22:59:05.27 | +13:56:13.8 | HIP 113550 | 12.31 |
| 2026-05-21 00:00 | 22:59:36.79 | +13:59:55.7 | HIP 113550 | 9.04 |
| 2026-05-21 12:00 | 23:00:08.21 | +14:03:37.3 | HIP 113581 | 4.47 |
| 2026-05-22 00:00 | 23:00:39.52 | +14:07:18.4 | HIP 113581 | 8.76 |
| 2026-05-22 12:00 | 23:01:10.71 | +14:10:59.2 | HIP 113581 | 16.59 |
| 2026-05-23 00:00 | 23:01:41.80 | +14:14:39.6 | HIP 113581 | 24.77 |
| 2026-05-23 12:00 | 23:02:12.78 | +14:18:19.6 | HIP 113707 | 25.73 |
| 2026-05-24 00:00 | 23:02:43.64 | +14:21:59.2 | HIP 113707 | 25.51 |
| 2026-05-24 12:00 | 23:03:14.40 | +14:25:38.3 | HIP 113707 | 27.87 |
| 2026-05-25 00:00 | 23:03:45.03 | +14:29:17.0 | HIP 114028 | 25.73 |
| 2026-05-25 12:00 | 23:04:15.56 | +14:32:55.3 | HIP 114028 | 19.15 |
| 2026-05-26 00:00 | 23:04:45.97 | +14:36:33.0 | HIP 114033 | 13.57 |
| 2026-05-26 12:00 | 23:05:16.26 | +14:40:10.4 | HIP 114033 | 5.43 |
| 2026-05-27 00:00 | 23:05:46.44 | +14:43:47.2 | HIP 114033 | 2.90 |
| 2026-05-27 12:00 | 23:06:16.49 | +14:47:23.6 | HIP 114033 | 10.92 |
| 2026-05-28 00:00 | 23:06:46.43 | +14:50:59.4 | HIP 114031 | 18.91 |
| 2026-05-28 12:00 | 23:07:16.25 | +14:54:34.8 | HIP 114031 | 25.11 |
| 2026-05-29 00:00 | 23:07:45.95 | +14:58:09.6 | HIP 114031 | 32.11 |
| 2026-05-29 12:00 | 23:08:15.53 | +15:01:43.9 | HIP 114300 | 32.28 |
| 2026-05-30 00:00 | 23:08:44.98 | +15:05:17.6 | HIP 114300 | 27.38 |
| 2026-05-30 12:00 | 23:09:14.31 | +15:08:50.8 | HIP 114300 | 24.17 |
| 2026-05-31 00:00 | 23:09:43.52 | +15:12:23.4 | HIP 114300 | 23.30 |
| 2026-05-31 12:00 | 23:10:12.60 | +15:15:55.4 | HIP 114300 | 25.01 |
| 2026-06-01 00:00 | 23:10:41.55 | +15:19:26.8 | HIP 114542 | 19.88 |
| 2026-06-01 12:00 | 23:11:10.37 | +15:22:57.7 | HIP 114542 | 13.56 |
| 2026-06-02 00:00 | 23:11:39.07 | +15:26:27.9 | HIP 114542 | 9.71 |