| Parameter |
Value |
| Designation |
C/2017 U4 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-09-25T16:38:00.893760Z |
| Orbit solution date (soln_date, UTC) |
2023-02-13T23:12:42Z |
| Obs used |
85 |
| NEO |
- |
| M1 |
7.100 |
| K1 |
10.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-01-03.0000000 |
| e |
1.00304382 |
| q (au) |
7.724158 |
| a (au) |
-2537.649728 |
| i (deg) |
158.225721 |
| Ω (om, deg) |
245.952559 |
| ω (w, deg) |
159.177100 |
| M (ma, deg) |
-0.002049 |
Magnitude
Scatter + Global Linear
$$
M_a = (2.306 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
2.306 |
| n |
6.000 |
| gf |
0.993 |
| gb |
-1.000 |
| k |
1.000 |
| δ90 |
9.974 |
| 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 |
23:59:17.68 |
-24:38:37.7 |
HIP 118302 |
5.93 |
| 2026-09-20 12:00 |
23:59:09.23 |
-24:39:27.7 |
HIP 118302 |
7.89 |
| 2026-09-21 00:00 |
23:59:00.78 |
-24:40:17.4 |
HIP 118302 |
9.90 |
| 2026-09-21 12:00 |
23:58:52.32 |
-24:41:06.7 |
HIP 118302 |
11.93 |
| 2026-09-22 00:00 |
23:58:43.87 |
-24:41:55.6 |
HIP 118302 |
13.98 |
| 2026-09-22 12:00 |
23:58:35.42 |
-24:42:44.0 |
HIP 118302 |
16.04 |
| 2026-09-23 00:00 |
23:58:26.97 |
-24:43:32.0 |
HIP 118302 |
18.10 |
| 2026-09-23 12:00 |
23:58:18.52 |
-24:44:19.6 |
HIP 118302 |
20.16 |
| 2026-09-24 00:00 |
23:58:10.08 |
-24:45:06.8 |
HIP 118302 |
22.22 |
| 2026-09-24 12:00 |
23:58:01.64 |
-24:45:53.6 |
HIP 118029 |
20.88 |
| 2026-09-25 00:00 |
23:57:53.20 |
-24:46:39.9 |
HIP 118029 |
19.06 |
| 2026-09-25 12:00 |
23:57:44.77 |
-24:47:25.8 |
HIP 118029 |
17.28 |
| 2026-09-26 00:00 |
23:57:36.34 |
-24:48:11.3 |
HIP 118029 |
15.58 |
| 2026-09-26 12:00 |
23:57:27.92 |
-24:48:56.3 |
HIP 118029 |
13.97 |
| 2026-09-27 00:00 |
23:57:19.50 |
-24:49:40.9 |
HIP 118029 |
12.50 |
| 2026-09-27 12:00 |
23:57:11.09 |
-24:50:25.0 |
HIP 118029 |
11.20 |
| 2026-09-28 00:00 |
23:57:02.69 |
-24:51:08.7 |
HIP 118029 |
10.15 |
| 2026-09-28 12:00 |
23:56:54.30 |
-24:51:51.9 |
HIP 118029 |
9.42 |
| 2026-09-29 00:00 |
23:56:45.92 |
-24:52:34.7 |
HIP 118029 |
9.10 |
| 2026-09-29 12:00 |
23:56:37.54 |
-24:53:17.1 |
HIP 118029 |
9.21 |
| 2026-09-30 00:00 |
23:56:29.18 |
-24:53:59.0 |
HIP 118029 |
9.75 |
| 2026-09-30 12:00 |
23:56:20.82 |
-24:54:40.4 |
HIP 118029 |
10.64 |
| 2026-10-01 00:00 |
23:56:12.48 |
-24:55:21.4 |
HIP 118029 |
11.81 |
| 2026-10-01 12:00 |
23:56:04.15 |
-24:56:01.9 |
HIP 118029 |
13.17 |
| 2026-10-02 00:00 |
23:55:55.83 |
-24:56:41.9 |
HIP 118029 |
14.67 |
| 2026-10-02 12:00 |
23:55:47.53 |
-24:57:21.5 |
HIP 118029 |
16.27 |
| 2026-10-03 00:00 |
23:55:39.24 |
-24:58:00.6 |
HIP 118029 |
17.95 |
| 2026-10-03 12:00 |
23:55:30.96 |
-24:58:39.3 |
HIP 118029 |
19.67 |
| 2026-10-04 00:00 |
23:55:22.70 |
-24:59:17.4 |
HIP 118000 |
21.15 |
| 2026-10-04 12:00 |
23:55:14.45 |
-24:59:55.1 |
HIP 118000 |
21.57 |
| 2026-10-05 00:00 |
23:55:06.22 |
-25:00:32.3 |
HIP 118000 |
22.16 |
| 2026-10-05 12:00 |
23:54:58.00 |
-25:01:09.0 |
HIP 118000 |
22.91 |
| 2026-10-06 00:00 |
23:54:49.81 |
-25:01:45.3 |
HIP 118000 |
23.79 |
| 2026-10-06 12:00 |
23:54:41.63 |
-25:02:21.0 |
HIP 118000 |
24.80 |
| 2026-10-07 00:00 |
23:54:33.47 |
-25:02:56.3 |
HIP 117737 |
25.79 |
| 2026-10-07 12:00 |
23:54:25.33 |
-25:03:31.1 |
HIP 117737 |
24.07 |
| 2026-10-08 00:00 |
23:54:17.21 |
-25:04:05.3 |
HIP 117737 |
22.38 |
| 2026-10-08 12:00 |
23:54:09.11 |
-25:04:39.1 |
HIP 117737 |
20.74 |
| 2026-10-09 00:00 |
23:54:01.03 |
-25:05:12.4 |
HIP 117737 |
19.15 |
| 2026-10-09 12:00 |
23:53:52.98 |
-25:05:45.2 |
HIP 117737 |
17.63 |
| 2026-10-10 00:00 |
23:53:44.94 |
-25:06:17.5 |
HIP 117737 |
16.19 |
| 2026-10-10 12:00 |
23:53:36.93 |
-25:06:49.3 |
HIP 117737 |
14.85 |
| 2026-10-11 00:00 |
23:53:28.94 |
-25:07:20.5 |
HIP 117737 |
13.65 |