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) |
|---|---|---|---|---|
| 2026-02-03 00:00 | 20:43:41.09 | +02:29:17.0 | HIP 102221 | 33.49 |
| 2026-02-03 12:00 | 20:44:22.12 | +02:31:09.4 | HIP 102479 | 27.94 |
| 2026-02-04 00:00 | 20:45:03.17 | +02:33:03.1 | HIP 102479 | 18.30 |
| 2026-02-04 12:00 | 20:45:44.22 | +02:34:57.9 | HIP 102479 | 10.30 |
| 2026-02-05 00:00 | 20:46:25.27 | +02:36:53.8 | HIP 102479 | 9.73 |
| 2026-02-05 12:00 | 20:47:06.33 | +02:38:51.0 | HIP 102546 | 13.29 |
| 2026-02-06 00:00 | 20:47:47.39 | +02:40:49.3 | HIP 102653 | 5.96 |
| 2026-02-06 12:00 | 20:48:28.46 | +02:42:48.7 | HIP 102653 | 4.68 |
| 2026-02-07 00:00 | 20:49:09.53 | +02:44:49.3 | HIP 102653 | 15.05 |
| 2026-02-07 12:00 | 20:49:50.60 | +02:46:51.1 | HIP 102832 | 20.92 |
| 2026-02-08 00:00 | 20:50:31.67 | +02:48:54.0 | HIP 102832 | 24.31 |
| 2026-02-08 12:00 | 20:51:12.75 | +02:50:58.1 | HIP 102832 | 31.04 |
| 2026-02-09 00:00 | 20:51:53.82 | +02:53:03.3 | HIP 103111 | 25.01 |
| 2026-02-09 12:00 | 20:52:34.90 | +02:55:09.6 | HIP 103111 | 14.60 |
| 2026-02-10 00:00 | 20:53:15.98 | +02:57:17.1 | HIP 103111 | 4.49 |
| 2026-02-10 12:00 | 20:53:57.06 | +02:59:25.7 | HIP 103111 | 6.81 |
| 2026-02-11 00:00 | 20:54:38.13 | +03:01:35.4 | HIP 103111 | 17.09 |
| 2026-02-11 12:00 | 20:55:19.21 | +03:03:46.2 | HIP 103313 | 21.26 |
| 2026-02-12 00:00 | 20:56:00.28 | +03:05:58.1 | HIP 103313 | 17.78 |
| 2026-02-12 12:00 | 20:56:41.35 | +03:08:11.2 | HIP 103313 | 19.99 |
| 2026-02-13 00:00 | 20:57:22.41 | +03:10:25.3 | HIP 103313 | 26.50 |
| 2026-02-13 12:00 | 20:58:03.48 | +03:12:40.5 | HIP 103577 | 26.19 |
| 2026-02-14 00:00 | 20:58:44.54 | +03:14:56.9 | HIP 103577 | 19.26 |
| 2026-02-14 12:00 | 20:59:25.59 | +03:17:14.3 | HIP 103577 | 16.59 |
| 2026-02-15 00:00 | 21:00:06.64 | +03:19:32.8 | HIP 103577 | 19.99 |
| 2026-02-15 12:00 | 21:00:47.68 | +03:21:52.3 | HIP 103577 | 27.28 |
| 2026-02-16 00:00 | 21:01:28.71 | +03:24:13.0 | HIP 103863 | 18.80 |
| 2026-02-16 12:00 | 21:02:09.74 | +03:26:34.6 | HIP 103863 | 9.97 |
| 2026-02-17 00:00 | 21:02:50.76 | +03:28:57.4 | HIP 103863 | 8.18 |
| 2026-02-17 12:00 | 21:03:31.77 | +03:31:21.2 | HIP 103924 | 3.61 |
| 2026-02-18 00:00 | 21:04:12.77 | +03:33:46.0 | HIP 104047 | 8.25 |
| 2026-02-18 12:00 | 21:04:53.76 | +03:36:11.9 | HIP 104047 | 4.69 |
| 2026-02-19 00:00 | 21:05:34.74 | +03:38:38.8 | HIP 104047 | 14.04 |
| 2026-02-19 12:00 | 21:06:15.71 | +03:41:06.7 | HIP 104202 | 9.27 |
| 2026-02-20 00:00 | 21:06:56.67 | +03:43:35.6 | HIP 104202 | 6.23 |
| 2026-02-20 12:00 | 21:07:37.62 | +03:46:05.6 | HIP 104202 | 14.58 |
| 2026-02-21 00:00 | 21:08:18.55 | +03:48:36.5 | HIP 104202 | 24.64 |
| 2026-02-21 12:00 | 21:08:59.47 | +03:51:08.5 | HIP 104442 | 19.57 |
| 2026-02-22 00:00 | 21:09:40.38 | +03:53:41.4 | HIP 104442 | 16.53 |
| 2026-02-22 12:00 | 21:10:21.27 | +03:56:15.3 | HIP 104577 | 10.49 |
| 2026-02-23 00:00 | 21:11:02.15 | +03:58:50.2 | HIP 104577 | 3.67 |
| 2026-02-23 12:00 | 21:11:43.01 | +04:01:26.1 | HIP 104577 | 11.76 |
| 2026-02-24 00:00 | 21:12:23.86 | +04:04:02.9 | HIP 104603 | 18.80 |