C/2017 P2 (PANSTARRS)
| Parameter |
Value |
| Designation |
C/2017 P2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-12-06T13:31:41.891520Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:35Z |
| Obs used |
50 |
| NEO |
- |
| M1 |
9.300 |
| K1 |
23.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-09-13.0000000 |
| e |
0.99796653 |
| q (au) |
2.461777 |
| a (au) |
1210.625678 |
| i (deg) |
50.084856 |
| Ω (om, deg) |
165.546359 |
| ω (w, deg) |
132.238805 |
| M (ma, deg) |
359.998021 |
Magnitude
Scatter + Global Linear
$$
M_a = (16.551 + 5.128\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
16.551 |
| n |
5.128 |
| gf |
1.000 |
| gb |
-1.000 |
| 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 |
05:17:22.76 |
-28:17:56.5 |
HIP 24696 |
9.46 |
| 2026-02-03 12:00 |
05:17:19.54 |
-28:17:01.6 |
HIP 24696 |
9.20 |
| 2026-02-04 00:00 |
05:17:16.37 |
-28:16:06.4 |
HIP 24696 |
9.07 |
| 2026-02-04 12:00 |
05:17:13.26 |
-28:15:10.8 |
HIP 24696 |
9.08 |
| 2026-02-05 00:00 |
05:17:10.19 |
-28:14:14.8 |
HIP 24696 |
9.22 |
| 2026-02-05 12:00 |
05:17:07.18 |
-28:13:18.6 |
HIP 24696 |
9.49 |
| 2026-02-06 00:00 |
05:17:04.21 |
-28:12:22.0 |
HIP 24586 |
8.83 |
| 2026-02-06 12:00 |
05:17:01.30 |
-28:11:25.1 |
HIP 24586 |
7.84 |
| 2026-02-07 00:00 |
05:16:58.44 |
-28:10:27.8 |
HIP 24586 |
6.91 |
| 2026-02-07 12:00 |
05:16:55.63 |
-28:09:30.3 |
HIP 24586 |
6.07 |
| 2026-02-08 00:00 |
05:16:52.87 |
-28:08:32.4 |
HIP 24586 |
5.35 |
| 2026-02-08 12:00 |
05:16:50.17 |
-28:07:34.2 |
HIP 24586 |
4.81 |
| 2026-02-09 00:00 |
05:16:47.52 |
-28:06:35.7 |
HIP 24586 |
4.51 |
| 2026-02-09 12:00 |
05:16:44.92 |
-28:05:37.0 |
HIP 24586 |
4.50 |
| 2026-02-10 00:00 |
05:16:42.37 |
-28:04:37.9 |
HIP 24586 |
4.78 |
| 2026-02-10 12:00 |
05:16:39.88 |
-28:03:38.5 |
HIP 24586 |
5.30 |
| 2026-02-11 00:00 |
05:16:37.44 |
-28:02:38.9 |
HIP 24586 |
6.00 |
| 2026-02-11 12:00 |
05:16:35.05 |
-28:01:39.0 |
HIP 24586 |
6.83 |
| 2026-02-12 00:00 |
05:16:32.72 |
-28:00:38.8 |
HIP 24586 |
7.73 |
| 2026-02-12 12:00 |
05:16:30.44 |
-27:59:38.4 |
HIP 24586 |
8.70 |
| 2026-02-13 00:00 |
05:16:28.22 |
-27:58:37.7 |
HIP 24586 |
9.70 |
| 2026-02-13 12:00 |
05:16:26.05 |
-27:57:36.7 |
HIP 24586 |
10.73 |
| 2026-02-14 00:00 |
05:16:23.94 |
-27:56:35.5 |
HIP 24586 |
11.78 |
| 2026-02-14 12:00 |
05:16:21.88 |
-27:55:34.0 |
HIP 24586 |
12.85 |
| 2026-02-15 00:00 |
05:16:19.87 |
-27:54:32.3 |
HIP 24586 |
13.92 |
| 2026-02-15 12:00 |
05:16:17.92 |
-27:53:30.4 |
HIP 24586 |
15.01 |
| 2026-02-16 00:00 |
05:16:16.02 |
-27:52:28.2 |
HIP 24586 |
16.10 |
| 2026-02-16 12:00 |
05:16:14.18 |
-27:51:25.9 |
HIP 24586 |
17.19 |
| 2026-02-17 00:00 |
05:16:12.40 |
-27:50:23.3 |
HIP 24586 |
18.29 |
| 2026-02-17 12:00 |
05:16:10.67 |
-27:49:20.5 |
HIP 24586 |
19.39 |
| 2026-02-18 00:00 |
05:16:08.99 |
-27:48:17.4 |
HIP 24586 |
20.50 |
| 2026-02-18 12:00 |
05:16:07.38 |
-27:47:14.2 |
HIP 24586 |
21.60 |
| 2026-02-19 00:00 |
05:16:05.81 |
-27:46:10.8 |
HIP 24586 |
22.71 |
| 2026-02-19 12:00 |
05:16:04.31 |
-27:45:07.2 |
HIP 24586 |
23.82 |
| 2026-02-20 00:00 |
05:16:02.86 |
-27:44:03.4 |
HIP 24586 |
24.93 |
| 2026-02-20 12:00 |
05:16:01.46 |
-27:42:59.5 |
HIP 24586 |
26.03 |
| 2026-02-21 00:00 |
05:16:00.12 |
-27:41:55.3 |
HIP 24586 |
27.14 |
| 2026-02-21 12:00 |
05:15:58.84 |
-27:40:51.1 |
HIP 24586 |
28.25 |
| 2026-02-22 00:00 |
05:15:57.61 |
-27:39:46.6 |
HIP 24710 |
29.11 |
| 2026-02-22 12:00 |
05:15:56.44 |
-27:38:42.0 |
HIP 24710 |
29.00 |
| 2026-02-23 00:00 |
05:15:55.33 |
-27:37:37.2 |
HIP 24710 |
28.91 |
| 2026-02-23 12:00 |
05:15:54.27 |
-27:36:32.3 |
HIP 24644 |
28.29 |
| 2026-02-24 00:00 |
05:15:53.27 |
-27:35:27.3 |
HIP 24644 |
27.62 |