C/2017 C2 (PANSTARRS)
| 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) |
| 2026-02-03 00:00 |
23:54:41.92 |
-66:54:03.8 |
HIP 117783 |
17.73 |
| 2026-02-03 12:00 |
23:54:49.77 |
-66:53:06.1 |
HIP 117783 |
17.34 |
| 2026-02-04 00:00 |
23:54:57.68 |
-66:52:08.8 |
HIP 117783 |
17.04 |
| 2026-02-04 12:00 |
23:55:05.65 |
-66:51:11.8 |
HIP 117783 |
16.84 |
| 2026-02-05 00:00 |
23:55:13.69 |
-66:50:15.2 |
HIP 117783 |
16.73 |
| 2026-02-05 12:00 |
23:55:21.79 |
-66:49:19.0 |
HIP 117783 |
16.72 |
| 2026-02-06 00:00 |
23:55:29.95 |
-66:48:23.1 |
HIP 117783 |
16.82 |
| 2026-02-06 12:00 |
23:55:38.18 |
-66:47:27.7 |
HIP 117783 |
17.01 |
| 2026-02-07 00:00 |
23:55:46.46 |
-66:46:32.6 |
HIP 117783 |
17.29 |
| 2026-02-07 12:00 |
23:55:54.81 |
-66:45:38.0 |
HIP 117783 |
17.67 |
| 2026-02-08 00:00 |
23:56:03.21 |
-66:44:43.7 |
HIP 117783 |
18.13 |
| 2026-02-08 12:00 |
23:56:11.68 |
-66:43:49.9 |
HIP 117783 |
18.67 |
| 2026-02-09 00:00 |
23:56:20.20 |
-66:42:56.5 |
HIP 117783 |
19.28 |
| 2026-02-09 12:00 |
23:56:28.78 |
-66:42:03.4 |
HIP 117783 |
19.95 |
| 2026-02-10 00:00 |
23:56:37.42 |
-66:41:10.8 |
HIP 118144 |
20.56 |
| 2026-02-10 12:00 |
23:56:46.12 |
-66:40:18.6 |
HIP 118144 |
21.10 |
| 2026-02-11 00:00 |
23:56:54.87 |
-66:39:26.8 |
HIP 118144 |
21.68 |
| 2026-02-11 12:00 |
23:57:03.67 |
-66:38:35.5 |
HIP 55 |
21.35 |
| 2026-02-12 00:00 |
23:57:12.53 |
-66:37:44.6 |
HIP 55 |
20.60 |
| 2026-02-12 12:00 |
23:57:21.44 |
-66:36:54.1 |
HIP 55 |
19.89 |
| 2026-02-13 00:00 |
23:57:30.41 |
-66:36:04.0 |
HIP 55 |
19.22 |
| 2026-02-13 12:00 |
23:57:39.43 |
-66:35:14.4 |
HIP 55 |
18.60 |
| 2026-02-14 00:00 |
23:57:48.50 |
-66:34:25.2 |
HIP 55 |
18.04 |
| 2026-02-14 12:00 |
23:57:57.62 |
-66:33:36.5 |
HIP 55 |
17.53 |
| 2026-02-15 00:00 |
23:58:06.79 |
-66:32:48.2 |
HIP 55 |
17.08 |
| 2026-02-15 12:00 |
23:58:16.01 |
-66:32:00.4 |
HIP 55 |
16.70 |
| 2026-02-16 00:00 |
23:58:25.27 |
-66:31:13.0 |
HIP 55 |
16.39 |
| 2026-02-16 12:00 |
23:58:34.59 |
-66:30:26.1 |
HIP 55 |
16.16 |
| 2026-02-17 00:00 |
23:58:43.95 |
-66:29:39.6 |
HIP 55 |
16.01 |
| 2026-02-17 12:00 |
23:58:53.36 |
-66:28:53.6 |
HIP 55 |
15.94 |
| 2026-02-18 00:00 |
23:59:02.81 |
-66:28:08.1 |
HIP 55 |
15.95 |
| 2026-02-18 12:00 |
23:59:12.31 |
-66:27:23.0 |
HIP 55 |
16.04 |
| 2026-02-19 00:00 |
23:59:21.86 |
-66:26:38.4 |
HIP 55 |
16.22 |
| 2026-02-19 12:00 |
23:59:31.44 |
-66:25:54.3 |
HIP 55 |
16.46 |
| 2026-02-20 00:00 |
23:59:41.07 |
-66:25:10.7 |
HIP 55 |
16.79 |
| 2026-02-20 12:00 |
23:59:50.74 |
-66:24:27.6 |
HIP 55 |
17.18 |
| 2026-02-21 00:00 |
00:00:00.45 |
-66:23:44.9 |
HIP 55 |
17.64 |
| 2026-02-21 12:00 |
00:00:10.21 |
-66:23:02.7 |
HIP 55 |
18.15 |
| 2026-02-22 00:00 |
00:00:20.00 |
-66:22:21.1 |
HIP 55 |
18.72 |
| 2026-02-22 12:00 |
00:00:29.83 |
-66:21:39.9 |
HIP 55 |
19.34 |
| 2026-02-23 00:00 |
00:00:39.70 |
-66:20:59.2 |
HIP 55 |
20.00 |
| 2026-02-23 12:00 |
00:00:49.60 |
-66:20:19.0 |
HIP 55 |
20.70 |
| 2026-02-24 00:00 |
00:00:59.54 |
-66:19:39.3 |
HIP 55 |
21.44 |