C/2017 S2 (PANSTARRS)
| Parameter |
Value |
| Designation |
C/2017 S2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-08-29T08:08:37.178880Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:35Z |
| Obs used |
67 |
| NEO |
- |
| M1 |
7.700 |
| K1 |
19.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-10-10.0000000 |
| e |
0.82311096 |
| q (au) |
3.614508 |
| a (au) |
20.433760 |
| i (deg) |
12.683350 |
| Ω (om, deg) |
62.427792 |
| ω (w, deg) |
305.972876 |
| M (ma, deg) |
0.444537 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.505 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.505 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.753 |
| k |
0.800 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
10:19:49.87 |
+24:43:31.9 |
HIP 50516 |
11.18 |
| 2026-02-03 12:00 |
10:19:43.85 |
+24:44:11.2 |
HIP 50516 |
9.90 |
| 2026-02-04 00:00 |
10:19:37.81 |
+24:44:50.4 |
HIP 50516 |
8.68 |
| 2026-02-04 12:00 |
10:19:31.76 |
+24:45:29.5 |
HIP 50516 |
7.57 |
| 2026-02-05 00:00 |
10:19:25.68 |
+24:46:08.4 |
HIP 50516 |
6.61 |
| 2026-02-05 12:00 |
10:19:19.58 |
+24:46:47.2 |
HIP 50516 |
5.90 |
| 2026-02-06 00:00 |
10:19:13.46 |
+24:47:25.8 |
HIP 50516 |
5.52 |
| 2026-02-06 12:00 |
10:19:07.32 |
+24:48:04.3 |
HIP 50516 |
5.55 |
| 2026-02-07 00:00 |
10:19:01.16 |
+24:48:42.7 |
HIP 50516 |
5.99 |
| 2026-02-07 12:00 |
10:18:54.98 |
+24:49:20.9 |
HIP 50516 |
6.75 |
| 2026-02-08 00:00 |
10:18:48.79 |
+24:49:58.9 |
HIP 50516 |
7.75 |
| 2026-02-08 12:00 |
10:18:42.58 |
+24:50:36.8 |
HIP 50516 |
8.90 |
| 2026-02-09 00:00 |
10:18:36.35 |
+24:51:14.4 |
HIP 50516 |
10.15 |
| 2026-02-09 12:00 |
10:18:30.11 |
+24:51:52.0 |
HIP 50516 |
11.48 |
| 2026-02-10 00:00 |
10:18:23.85 |
+24:52:29.3 |
HIP 50516 |
12.86 |
| 2026-02-10 12:00 |
10:18:17.58 |
+24:53:06.4 |
HIP 50516 |
14.27 |
| 2026-02-11 00:00 |
10:18:11.30 |
+24:53:43.4 |
HIP 50516 |
15.71 |
| 2026-02-11 12:00 |
10:18:05.00 |
+24:54:20.2 |
HIP 50516 |
17.17 |
| 2026-02-12 00:00 |
10:17:58.70 |
+24:54:56.8 |
HIP 50516 |
18.64 |
| 2026-02-12 12:00 |
10:17:52.38 |
+24:55:33.2 |
HIP 50516 |
20.13 |
| 2026-02-13 00:00 |
10:17:46.04 |
+24:56:09.3 |
HIP 50516 |
21.62 |
| 2026-02-13 12:00 |
10:17:39.70 |
+24:56:45.3 |
HIP 50516 |
23.13 |
| 2026-02-14 00:00 |
10:17:33.35 |
+24:57:21.1 |
HIP 50321 |
24.45 |
| 2026-02-14 12:00 |
10:17:26.99 |
+24:57:56.6 |
HIP 50321 |
23.18 |
| 2026-02-15 00:00 |
10:17:20.63 |
+24:58:32.0 |
HIP 50321 |
21.95 |
| 2026-02-15 12:00 |
10:17:14.25 |
+24:59:07.1 |
HIP 50321 |
20.77 |
| 2026-02-16 00:00 |
10:17:07.87 |
+24:59:42.0 |
HIP 50321 |
19.64 |
| 2026-02-16 12:00 |
10:17:01.48 |
+25:00:16.7 |
HIP 50321 |
18.58 |
| 2026-02-17 00:00 |
10:16:55.09 |
+25:00:51.1 |
HIP 50321 |
17.60 |
| 2026-02-17 12:00 |
10:16:48.69 |
+25:01:25.3 |
HIP 50321 |
16.70 |
| 2026-02-18 00:00 |
10:16:42.29 |
+25:01:59.2 |
HIP 50321 |
15.92 |
| 2026-02-18 12:00 |
10:16:35.89 |
+25:02:32.9 |
HIP 50321 |
15.26 |
| 2026-02-19 00:00 |
10:16:29.48 |
+25:03:06.4 |
HIP 50321 |
14.73 |
| 2026-02-19 12:00 |
10:16:23.08 |
+25:03:39.6 |
HIP 50321 |
14.36 |
| 2026-02-20 00:00 |
10:16:16.67 |
+25:04:12.6 |
HIP 50321 |
14.16 |
| 2026-02-20 12:00 |
10:16:10.26 |
+25:04:45.3 |
HIP 50321 |
14.12 |
| 2026-02-21 00:00 |
10:16:03.85 |
+25:05:17.7 |
HIP 50321 |
14.26 |
| 2026-02-21 12:00 |
10:15:57.45 |
+25:05:49.9 |
HIP 50321 |
14.57 |
| 2026-02-22 00:00 |
10:15:51.04 |
+25:06:21.8 |
HIP 50321 |
15.03 |
| 2026-02-22 12:00 |
10:15:44.64 |
+25:06:53.4 |
HIP 50321 |
15.64 |
| 2026-02-23 00:00 |
10:15:38.24 |
+25:07:24.8 |
HIP 50321 |
16.37 |
| 2026-02-23 12:00 |
10:15:31.84 |
+25:07:55.9 |
HIP 50321 |
17.21 |
| 2026-02-24 00:00 |
10:15:25.45 |
+25:08:26.7 |
HIP 50321 |
18.14 |