| Parameter |
Value |
| Designation |
C/2017 U2 (Fuls) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-08-28T02:57:59.221440Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:37Z |
| Obs used |
59 |
| NEO |
- |
| M1 |
7.300 |
| K1 |
12.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-12-10.0000000 |
| e |
1.00001237 |
| q (au) |
6.700825 |
| a (au) |
-541554.498455 |
| i (deg) |
95.434086 |
| Ω (om, deg) |
149.710839 |
| ω (w, deg) |
147.727081 |
| M (ma, deg) |
0.000000 |
Magnitude
Scatter + Global Linear
$$
M_a = (3.858 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
3.858 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.502 |
| k |
1.000 |
| 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 |
04:18:19.87 |
-76:28:07.2 |
HIP 20755 |
30.07 |
| 2026-09-20 12:00 |
04:18:15.07 |
-76:29:27.0 |
HIP 20755 |
30.18 |
| 2026-09-21 00:00 |
04:18:10.05 |
-76:30:46.5 |
HIP 20755 |
30.36 |
| 2026-09-21 12:00 |
04:18:04.81 |
-76:32:05.6 |
HIP 20755 |
30.61 |
| 2026-09-22 00:00 |
04:17:59.36 |
-76:33:24.4 |
HIP 20110 |
30.06 |
| 2026-09-22 12:00 |
04:17:53.70 |
-76:34:42.9 |
HIP 20110 |
28.79 |
| 2026-09-23 00:00 |
04:17:47.82 |
-76:36:01.0 |
HIP 20110 |
27.53 |
| 2026-09-23 12:00 |
04:17:41.72 |
-76:37:18.8 |
HIP 20110 |
26.28 |
| 2026-09-24 00:00 |
04:17:35.41 |
-76:38:36.2 |
HIP 20110 |
25.05 |
| 2026-09-24 12:00 |
04:17:28.89 |
-76:39:53.2 |
HIP 20110 |
23.85 |
| 2026-09-25 00:00 |
04:17:22.14 |
-76:41:09.8 |
HIP 20110 |
22.66 |
| 2026-09-25 12:00 |
04:17:15.19 |
-76:42:26.1 |
HIP 20110 |
21.50 |
| 2026-09-26 00:00 |
04:17:08.02 |
-76:43:41.9 |
HIP 20110 |
20.38 |
| 2026-09-26 12:00 |
04:17:00.63 |
-76:44:57.4 |
HIP 20110 |
19.28 |
| 2026-09-27 00:00 |
04:16:53.03 |
-76:46:12.5 |
HIP 20110 |
18.23 |
| 2026-09-27 12:00 |
04:16:45.21 |
-76:47:27.1 |
HIP 20110 |
17.23 |
| 2026-09-28 00:00 |
04:16:37.18 |
-76:48:41.4 |
HIP 20110 |
16.28 |
| 2026-09-28 12:00 |
04:16:28.93 |
-76:49:55.2 |
HIP 20110 |
15.40 |
| 2026-09-29 00:00 |
04:16:20.46 |
-76:51:08.6 |
HIP 20110 |
14.59 |
| 2026-09-29 12:00 |
04:16:11.79 |
-76:52:21.5 |
HIP 20110 |
13.88 |
| 2026-09-30 00:00 |
04:16:02.90 |
-76:53:34.0 |
HIP 20110 |
13.27 |
| 2026-09-30 12:00 |
04:15:53.79 |
-76:54:46.1 |
HIP 20110 |
12.77 |
| 2026-10-01 00:00 |
04:15:44.47 |
-76:55:57.7 |
HIP 20110 |
12.41 |
| 2026-10-01 12:00 |
04:15:34.93 |
-76:57:08.8 |
HIP 20110 |
12.20 |
| 2026-10-02 00:00 |
04:15:25.18 |
-76:58:19.5 |
HIP 20110 |
12.13 |
| 2026-10-02 12:00 |
04:15:15.22 |
-76:59:29.7 |
HIP 20110 |
12.21 |
| 2026-10-03 00:00 |
04:15:05.05 |
-77:00:39.4 |
HIP 20110 |
12.44 |
| 2026-10-03 12:00 |
04:14:54.66 |
-77:01:48.6 |
HIP 20110 |
12.81 |
| 2026-10-04 00:00 |
04:14:44.06 |
-77:02:57.4 |
HIP 20110 |
13.30 |
| 2026-10-04 12:00 |
04:14:33.24 |
-77:04:05.6 |
HIP 20110 |
13.91 |
| 2026-10-05 00:00 |
04:14:22.22 |
-77:05:13.3 |
HIP 20110 |
14.62 |
| 2026-10-05 12:00 |
04:14:10.98 |
-77:06:20.5 |
HIP 20110 |
15.41 |
| 2026-10-06 00:00 |
04:13:59.53 |
-77:07:27.2 |
HIP 20110 |
16.27 |
| 2026-10-06 12:00 |
04:13:47.88 |
-77:08:33.3 |
HIP 19393 |
16.28 |
| 2026-10-07 00:00 |
04:13:36.01 |
-77:09:39.0 |
HIP 19393 |
16.06 |
| 2026-10-07 12:00 |
04:13:23.94 |
-77:10:44.0 |
HIP 19393 |
15.94 |
| 2026-10-08 00:00 |
04:13:11.66 |
-77:11:48.5 |
HIP 19393 |
15.90 |
| 2026-10-08 12:00 |
04:12:59.17 |
-77:12:52.5 |
HIP 19393 |
15.95 |
| 2026-10-09 00:00 |
04:12:46.48 |
-77:13:55.8 |
HIP 19393 |
16.09 |
| 2026-10-09 12:00 |
04:12:33.58 |
-77:14:58.7 |
HIP 19393 |
16.32 |
| 2026-10-10 00:00 |
04:12:20.48 |
-77:16:00.9 |
HIP 19393 |
16.62 |
| 2026-10-10 12:00 |
04:12:07.17 |
-77:17:02.5 |
HIP 19393 |
17.00 |
| 2026-10-11 00:00 |
04:11:53.67 |
-77:18:03.6 |
HIP 19393 |
17.45 |