| Parameter |
Value |
| Designation |
C/2017 C2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-01-21T14:49:52.703040Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:30Z |
| Obs used |
97 |
| NEO |
- |
| M1 |
12.400 |
| K1 |
13.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-03-11.0000000 |
| e |
0.97530974 |
| q (au) |
2.430997 |
| a (au) |
98.459722 |
| i (deg) |
118.583896 |
| Ω (om, deg) |
249.819140 |
| ω (w, deg) |
138.775813 |
| M (ma, deg) |
0.048809 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.786 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.786 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.999 |
| 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 |
00:05:30.96 |
-71:08:29.9 |
HIP 315 |
11.11 |
| 2026-09-20 12:00 |
00:05:14.55 |
-71:08:47.4 |
HIP 315 |
10.04 |
| 2026-09-21 00:00 |
00:04:58.13 |
-71:09:04.2 |
HIP 315 |
9.05 |
| 2026-09-21 12:00 |
00:04:41.71 |
-71:09:20.3 |
HIP 315 |
8.17 |
| 2026-09-22 00:00 |
00:04:25.27 |
-71:09:35.6 |
HIP 315 |
7.45 |
| 2026-09-22 12:00 |
00:04:08.84 |
-71:09:50.2 |
HIP 315 |
6.94 |
| 2026-09-23 00:00 |
00:03:52.40 |
-71:10:04.0 |
HIP 315 |
6.67 |
| 2026-09-23 12:00 |
00:03:35.96 |
-71:10:17.1 |
HIP 315 |
6.68 |
| 2026-09-24 00:00 |
00:03:19.52 |
-71:10:29.5 |
HIP 315 |
6.96 |
| 2026-09-24 12:00 |
00:03:03.08 |
-71:10:41.1 |
HIP 315 |
7.48 |
| 2026-09-25 00:00 |
00:02:46.64 |
-71:10:52.0 |
HIP 315 |
8.20 |
| 2026-09-25 12:00 |
00:02:30.22 |
-71:11:02.2 |
HIP 315 |
9.07 |
| 2026-09-26 00:00 |
00:02:13.79 |
-71:11:11.6 |
HIP 315 |
10.05 |
| 2026-09-26 12:00 |
00:01:57.38 |
-71:11:20.3 |
HIP 315 |
11.10 |
| 2026-09-27 00:00 |
00:01:40.98 |
-71:11:28.2 |
HIP 315 |
12.21 |
| 2026-09-27 12:00 |
00:01:24.59 |
-71:11:35.4 |
HIP 315 |
13.37 |
| 2026-09-28 00:00 |
00:01:08.21 |
-71:11:41.9 |
HIP 315 |
14.56 |
| 2026-09-28 12:00 |
00:00:51.85 |
-71:11:47.6 |
HIP 315 |
15.77 |
| 2026-09-29 00:00 |
00:00:35.50 |
-71:11:52.6 |
HIP 315 |
17.00 |
| 2026-09-29 12:00 |
00:00:19.17 |
-71:11:56.9 |
HIP 315 |
18.24 |
| 2026-09-30 00:00 |
00:00:02.86 |
-71:12:00.4 |
HIP 118021 |
18.47 |
| 2026-09-30 12:00 |
23:59:46.57 |
-71:12:03.2 |
HIP 118021 |
17.21 |
| 2026-10-01 00:00 |
23:59:30.31 |
-71:12:05.2 |
HIP 118021 |
15.97 |
| 2026-10-01 12:00 |
23:59:14.07 |
-71:12:06.5 |
HIP 118021 |
14.74 |
| 2026-10-02 00:00 |
23:58:57.85 |
-71:12:07.1 |
HIP 118021 |
13.54 |
| 2026-10-02 12:00 |
23:58:41.66 |
-71:12:06.9 |
HIP 118021 |
12.36 |
| 2026-10-03 00:00 |
23:58:25.51 |
-71:12:06.0 |
HIP 118021 |
11.23 |
| 2026-10-03 12:00 |
23:58:09.38 |
-71:12:04.4 |
HIP 118021 |
10.13 |
| 2026-10-04 00:00 |
23:57:53.28 |
-71:12:02.0 |
HIP 118021 |
9.11 |
| 2026-10-04 12:00 |
23:57:37.22 |
-71:11:58.9 |
HIP 118021 |
8.16 |
| 2026-10-05 00:00 |
23:57:21.19 |
-71:11:55.1 |
HIP 118021 |
7.34 |
| 2026-10-05 12:00 |
23:57:05.20 |
-71:11:50.5 |
HIP 118021 |
6.68 |
| 2026-10-06 00:00 |
23:56:49.25 |
-71:11:45.2 |
HIP 118021 |
6.23 |
| 2026-10-06 12:00 |
23:56:33.34 |
-71:11:39.2 |
HIP 118021 |
6.04 |
| 2026-10-07 00:00 |
23:56:17.47 |
-71:11:32.5 |
HIP 118021 |
6.13 |
| 2026-10-07 12:00 |
23:56:01.64 |
-71:11:25.0 |
HIP 118021 |
6.48 |
| 2026-10-08 00:00 |
23:55:45.86 |
-71:11:16.8 |
HIP 118021 |
7.07 |
| 2026-10-08 12:00 |
23:55:30.13 |
-71:11:07.8 |
HIP 118021 |
7.83 |
| 2026-10-09 00:00 |
23:55:14.44 |
-71:10:58.2 |
HIP 118021 |
8.71 |
| 2026-10-09 12:00 |
23:54:58.81 |
-71:10:47.8 |
HIP 118021 |
9.69 |
| 2026-10-10 00:00 |
23:54:43.22 |
-71:10:36.7 |
HIP 118021 |
10.73 |
| 2026-10-10 12:00 |
23:54:27.69 |
-71:10:24.9 |
HIP 118021 |
11.83 |
| 2026-10-11 00:00 |
23:54:12.22 |
-71:10:12.4 |
HIP 118021 |
12.95 |