| 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) |
| 2026-09-20 00:00 |
10:27:46.68 |
+22:36:16.3 |
HIP 51132 |
17.16 |
| 2026-09-20 12:00 |
10:27:53.30 |
+22:35:49.3 |
HIP 51132 |
18.22 |
| 2026-09-21 00:00 |
10:27:59.91 |
+22:35:22.5 |
HIP 51132 |
19.35 |
| 2026-09-21 12:00 |
10:28:06.50 |
+22:34:56.0 |
HIP 51132 |
20.53 |
| 2026-09-22 00:00 |
10:28:13.06 |
+22:34:29.7 |
HIP 51132 |
21.77 |
| 2026-09-22 12:00 |
10:28:19.61 |
+22:34:03.7 |
HIP 51132 |
23.04 |
| 2026-09-23 00:00 |
10:28:26.14 |
+22:33:38.0 |
HIP 51132 |
24.35 |
| 2026-09-23 12:00 |
10:28:32.64 |
+22:33:12.5 |
HIP 51132 |
25.68 |
| 2026-09-24 00:00 |
10:28:39.12 |
+22:32:47.2 |
HIP 51132 |
27.03 |
| 2026-09-24 12:00 |
10:28:45.59 |
+22:32:22.3 |
HIP 51132 |
28.40 |
| 2026-09-25 00:00 |
10:28:52.02 |
+22:31:57.6 |
HIP 51132 |
29.78 |
| 2026-09-25 12:00 |
10:28:58.44 |
+22:31:33.1 |
HIP 51132 |
31.18 |
| 2026-09-26 00:00 |
10:29:04.83 |
+22:31:08.9 |
HIP 51132 |
32.58 |
| 2026-09-26 12:00 |
10:29:11.20 |
+22:30:45.0 |
HIP 51509 |
32.18 |
| 2026-09-27 00:00 |
10:29:17.55 |
+22:30:21.4 |
HIP 51509 |
30.74 |
| 2026-09-27 12:00 |
10:29:23.87 |
+22:29:58.0 |
HIP 51509 |
29.31 |
| 2026-09-28 00:00 |
10:29:30.17 |
+22:29:34.9 |
HIP 51509 |
27.89 |
| 2026-09-28 12:00 |
10:29:36.45 |
+22:29:12.0 |
HIP 51509 |
26.49 |
| 2026-09-29 00:00 |
10:29:42.70 |
+22:28:49.5 |
HIP 51509 |
25.11 |
| 2026-09-29 12:00 |
10:29:48.92 |
+22:28:27.2 |
HIP 51509 |
23.76 |
| 2026-09-30 00:00 |
10:29:55.12 |
+22:28:05.2 |
HIP 51509 |
22.42 |
| 2026-09-30 12:00 |
10:30:01.30 |
+22:27:43.5 |
HIP 51509 |
21.12 |
| 2026-10-01 00:00 |
10:30:07.45 |
+22:27:22.0 |
HIP 51509 |
19.84 |
| 2026-10-01 12:00 |
10:30:13.57 |
+22:27:00.8 |
HIP 51509 |
18.60 |
| 2026-10-02 00:00 |
10:30:19.66 |
+22:26:39.9 |
HIP 51509 |
17.40 |
| 2026-10-02 12:00 |
10:30:25.73 |
+22:26:19.3 |
HIP 51509 |
16.25 |
| 2026-10-03 00:00 |
10:30:31.77 |
+22:25:59.0 |
HIP 51509 |
15.16 |
| 2026-10-03 12:00 |
10:30:37.78 |
+22:25:39.0 |
HIP 51509 |
14.13 |
| 2026-10-04 00:00 |
10:30:43.77 |
+22:25:19.2 |
HIP 51509 |
13.19 |
| 2026-10-04 12:00 |
10:30:49.72 |
+22:24:59.8 |
HIP 51509 |
12.35 |
| 2026-10-05 00:00 |
10:30:55.65 |
+22:24:40.6 |
HIP 51509 |
11.63 |
| 2026-10-05 12:00 |
10:31:01.54 |
+22:24:21.8 |
HIP 51509 |
11.04 |
| 2026-10-06 00:00 |
10:31:07.41 |
+22:24:03.2 |
HIP 51509 |
10.62 |
| 2026-10-06 12:00 |
10:31:13.25 |
+22:23:45.0 |
HIP 51509 |
10.36 |
| 2026-10-07 00:00 |
10:31:19.06 |
+22:23:27.0 |
HIP 51509 |
10.30 |
| 2026-10-07 12:00 |
10:31:24.83 |
+22:23:09.3 |
HIP 51509 |
10.42 |
| 2026-10-08 00:00 |
10:31:30.58 |
+22:22:52.0 |
HIP 51509 |
10.71 |
| 2026-10-08 12:00 |
10:31:36.29 |
+22:22:34.9 |
HIP 51509 |
11.17 |
| 2026-10-09 00:00 |
10:31:41.97 |
+22:22:18.2 |
HIP 51509 |
11.76 |
| 2026-10-09 12:00 |
10:31:47.62 |
+22:22:01.7 |
HIP 51509 |
12.47 |
| 2026-10-10 00:00 |
10:31:53.24 |
+22:21:45.6 |
HIP 51509 |
13.27 |
| 2026-10-10 12:00 |
10:31:58.83 |
+22:21:29.8 |
HIP 51509 |
14.15 |
| 2026-10-11 00:00 |
10:32:04.38 |
+22:21:14.3 |
HIP 51509 |
15.08 |