C/2017 U4 (PANSTARRS)
| 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 |
0.992 |
| gb |
-1.000 |
| k |
1.000 |
| δ90 |
9.972 |
| 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 |
23:59:58.30 |
-21:54:31.0 |
HIP 118164 |
25.51 |
| 2026-02-03 12:00 |
00:00:01.55 |
-21:53:49.4 |
HIP 118164 |
26.26 |
| 2026-02-04 00:00 |
00:00:04.85 |
-21:53:07.9 |
HIP 118164 |
27.04 |
| 2026-02-04 12:00 |
00:00:08.18 |
-21:52:26.3 |
HIP 118164 |
27.85 |
| 2026-02-05 00:00 |
00:00:11.55 |
-21:51:44.8 |
HIP 118164 |
28.68 |
| 2026-02-05 12:00 |
00:00:14.96 |
-21:51:03.4 |
HIP 118164 |
29.53 |
| 2026-02-06 00:00 |
00:00:18.40 |
-21:50:22.0 |
HIP 97 |
29.12 |
| 2026-02-06 12:00 |
00:00:21.89 |
-21:49:40.6 |
HIP 97 |
28.15 |
| 2026-02-07 00:00 |
00:00:25.40 |
-21:48:59.2 |
HIP 97 |
27.18 |
| 2026-02-07 12:00 |
00:00:28.96 |
-21:48:17.9 |
HIP 97 |
26.21 |
| 2026-02-08 00:00 |
00:00:32.55 |
-21:47:36.7 |
HIP 97 |
25.26 |
| 2026-02-08 12:00 |
00:00:36.17 |
-21:46:55.5 |
HIP 97 |
24.31 |
| 2026-02-09 00:00 |
00:00:39.83 |
-21:46:14.4 |
HIP 97 |
23.37 |
| 2026-02-09 12:00 |
00:00:43.53 |
-21:45:33.3 |
HIP 97 |
22.44 |
| 2026-02-10 00:00 |
00:00:47.26 |
-21:44:52.3 |
HIP 97 |
21.53 |
| 2026-02-10 12:00 |
00:00:51.02 |
-21:44:11.4 |
HIP 97 |
20.64 |
| 2026-02-11 00:00 |
00:00:54.82 |
-21:43:30.5 |
HIP 97 |
19.76 |
| 2026-02-11 12:00 |
00:00:58.65 |
-21:42:49.8 |
HIP 97 |
18.92 |
| 2026-02-12 00:00 |
00:01:02.51 |
-21:42:09.1 |
HIP 97 |
18.10 |
| 2026-02-12 12:00 |
00:01:06.40 |
-21:41:28.4 |
HIP 97 |
17.32 |
| 2026-02-13 00:00 |
00:01:10.33 |
-21:40:47.9 |
HIP 97 |
16.58 |
| 2026-02-13 12:00 |
00:01:14.28 |
-21:40:07.5 |
HIP 97 |
15.88 |
| 2026-02-14 00:00 |
00:01:18.27 |
-21:39:27.1 |
HIP 97 |
15.25 |
| 2026-02-14 12:00 |
00:01:22.29 |
-21:38:46.9 |
HIP 97 |
14.67 |
| 2026-02-15 00:00 |
00:01:26.34 |
-21:38:06.7 |
HIP 97 |
14.17 |
| 2026-02-15 12:00 |
00:01:30.42 |
-21:37:26.7 |
HIP 97 |
13.76 |
| 2026-02-16 00:00 |
00:01:34.52 |
-21:36:46.8 |
HIP 97 |
13.43 |
| 2026-02-16 12:00 |
00:01:38.66 |
-21:36:06.9 |
HIP 97 |
13.21 |
| 2026-02-17 00:00 |
00:01:42.83 |
-21:35:27.2 |
HIP 97 |
13.09 |
| 2026-02-17 12:00 |
00:01:47.02 |
-21:34:47.6 |
HIP 97 |
13.08 |
| 2026-02-18 00:00 |
00:01:51.24 |
-21:34:08.2 |
HIP 97 |
13.19 |
| 2026-02-18 12:00 |
00:01:55.49 |
-21:33:28.8 |
HIP 97 |
13.40 |
| 2026-02-19 00:00 |
00:01:59.76 |
-21:32:49.6 |
HIP 97 |
13.72 |
| 2026-02-19 12:00 |
00:02:04.06 |
-21:32:10.5 |
HIP 97 |
14.14 |
| 2026-02-20 00:00 |
00:02:08.38 |
-21:31:31.6 |
HIP 97 |
14.65 |
| 2026-02-20 12:00 |
00:02:12.74 |
-21:30:52.8 |
HIP 97 |
15.24 |
| 2026-02-21 00:00 |
00:02:17.11 |
-21:30:14.1 |
HIP 97 |
15.91 |
| 2026-02-21 12:00 |
00:02:21.51 |
-21:29:35.6 |
HIP 97 |
16.65 |
| 2026-02-22 00:00 |
00:02:25.93 |
-21:28:57.3 |
HIP 97 |
17.44 |
| 2026-02-22 12:00 |
00:02:30.38 |
-21:28:19.1 |
HIP 97 |
18.29 |
| 2026-02-23 00:00 |
00:02:34.85 |
-21:27:41.0 |
HIP 97 |
19.18 |
| 2026-02-23 12:00 |
00:02:39.34 |
-21:27:03.1 |
HIP 97 |
20.11 |
| 2026-02-24 00:00 |
00:02:43.86 |
-21:26:25.4 |
HIP 97 |
21.08 |