| 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) |
| 2026-07-29 00:00 |
00:28:49.60 |
-69:37:59.0 |
HIP 2214 |
6.93 |
| 2026-07-29 12:00 |
00:28:41.52 |
-69:39:14.8 |
HIP 2214 |
7.61 |
| 2026-07-30 00:00 |
00:28:33.32 |
-69:40:30.3 |
HIP 2214 |
8.47 |
| 2026-07-30 12:00 |
00:28:25.00 |
-69:41:45.5 |
HIP 2214 |
9.47 |
| 2026-07-31 00:00 |
00:28:16.56 |
-69:43:00.5 |
HIP 2214 |
10.57 |
| 2026-07-31 12:00 |
00:28:08.00 |
-69:44:15.2 |
HIP 2214 |
11.74 |
| 2026-08-01 00:00 |
00:27:59.32 |
-69:45:29.5 |
HIP 2214 |
12.96 |
| 2026-08-01 12:00 |
00:27:50.53 |
-69:46:43.6 |
HIP 2214 |
14.22 |
| 2026-08-02 00:00 |
00:27:41.62 |
-69:47:57.4 |
HIP 2214 |
15.51 |
| 2026-08-02 12:00 |
00:27:32.59 |
-69:49:10.9 |
HIP 2214 |
16.82 |
| 2026-08-03 00:00 |
00:27:23.44 |
-69:50:24.0 |
HIP 2214 |
18.15 |
| 2026-08-03 12:00 |
00:27:14.17 |
-69:51:36.8 |
HIP 2214 |
19.50 |
| 2026-08-04 00:00 |
00:27:04.79 |
-69:52:49.3 |
HIP 2214 |
20.85 |
| 2026-08-04 12:00 |
00:26:55.29 |
-69:54:01.5 |
HIP 2137 |
20.90 |
| 2026-08-05 00:00 |
00:26:45.68 |
-69:55:13.3 |
HIP 2137 |
19.76 |
| 2026-08-05 12:00 |
00:26:35.95 |
-69:56:24.8 |
HIP 2137 |
18.67 |
| 2026-08-06 00:00 |
00:26:26.10 |
-69:57:35.9 |
HIP 2137 |
17.63 |
| 2026-08-06 12:00 |
00:26:16.14 |
-69:58:46.6 |
HIP 2137 |
16.67 |
| 2026-08-07 00:00 |
00:26:06.06 |
-69:59:57.0 |
HIP 2137 |
15.79 |
| 2026-08-07 12:00 |
00:25:55.87 |
-70:01:07.0 |
HIP 2137 |
15.01 |
| 2026-08-08 00:00 |
00:25:45.57 |
-70:02:16.6 |
HIP 2137 |
14.34 |
| 2026-08-08 12:00 |
00:25:35.15 |
-70:03:25.9 |
HIP 2137 |
13.80 |
| 2026-08-09 00:00 |
00:25:24.62 |
-70:04:34.7 |
HIP 2137 |
13.42 |
| 2026-08-09 12:00 |
00:25:13.98 |
-70:05:43.2 |
HIP 2137 |
13.19 |
| 2026-08-10 00:00 |
00:25:03.23 |
-70:06:51.2 |
HIP 2137 |
13.13 |
| 2026-08-10 12:00 |
00:24:52.36 |
-70:07:58.8 |
HIP 2137 |
13.24 |
| 2026-08-11 00:00 |
00:24:41.39 |
-70:09:06.0 |
HIP 2137 |
13.52 |
| 2026-08-11 12:00 |
00:24:30.30 |
-70:10:12.8 |
HIP 2137 |
13.95 |
| 2026-08-12 00:00 |
00:24:19.11 |
-70:11:19.2 |
HIP 2137 |
14.53 |
| 2026-08-12 12:00 |
00:24:07.81 |
-70:12:25.1 |
HIP 1909 |
14.22 |
| 2026-08-13 00:00 |
00:23:56.40 |
-70:13:30.6 |
HIP 1909 |
13.16 |
| 2026-08-13 12:00 |
00:23:44.88 |
-70:14:35.6 |
HIP 1909 |
12.19 |
| 2026-08-14 00:00 |
00:23:33.25 |
-70:15:40.1 |
HIP 1909 |
11.33 |
| 2026-08-14 12:00 |
00:23:21.53 |
-70:16:44.2 |
HIP 1909 |
10.61 |
| 2026-08-15 00:00 |
00:23:09.69 |
-70:17:47.8 |
HIP 1909 |
10.07 |
| 2026-08-15 12:00 |
00:22:57.75 |
-70:18:51.0 |
HIP 1909 |
9.72 |
| 2026-08-16 00:00 |
00:22:45.71 |
-70:19:53.7 |
HIP 1909 |
9.60 |
| 2026-08-16 12:00 |
00:22:33.57 |
-70:20:55.8 |
HIP 1909 |
9.70 |
| 2026-08-17 00:00 |
00:22:21.33 |
-70:21:57.5 |
HIP 1909 |
10.03 |
| 2026-08-17 12:00 |
00:22:08.98 |
-70:22:58.7 |
HIP 1909 |
10.56 |
| 2026-08-18 00:00 |
00:21:56.54 |
-70:23:59.4 |
HIP 1909 |
11.26 |
| 2026-08-18 12:00 |
00:21:44.00 |
-70:24:59.6 |
HIP 1909 |
12.10 |
| 2026-08-19 00:00 |
00:21:31.36 |
-70:25:59.3 |
HIP 1909 |
13.06 |