| Parameter |
Value |
| Designation |
357P/Hill |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2008-12-24T02:12:07.588800Z |
| Orbit solution date (soln_date, UTC) |
2026-09-04T08:42:17Z |
| Obs used |
298 |
| NEO |
- |
| M1 |
11.600 |
| K1 |
14.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2010-01-14.0000000 |
| e |
0.43552676 |
| q (au) |
2.511847 |
| a (au) |
4.449895 |
| i (deg) |
6.325939 |
| Ω (om, deg) |
44.673428 |
| ω (w, deg) |
1.300740 |
| M (ma, deg) |
40.519448 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.984 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.984 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.860 |
| k |
0.998 |
| 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 |
20:24:31.68 |
-27:15:55.0 |
HIP 100610 |
19.42 |
| 2026-09-20 12:00 |
20:24:26.34 |
-27:15:16.6 |
HIP 100610 |
19.73 |
| 2026-09-21 00:00 |
20:24:21.30 |
-27:14:36.9 |
HIP 100610 |
20.16 |
| 2026-09-21 12:00 |
20:24:16.58 |
-27:13:55.9 |
HIP 100610 |
20.68 |
| 2026-09-22 00:00 |
20:24:12.16 |
-27:13:13.7 |
HIP 100610 |
21.30 |
| 2026-09-22 12:00 |
20:24:08.06 |
-27:12:30.3 |
HIP 100610 |
21.98 |
| 2026-09-23 00:00 |
20:24:04.26 |
-27:11:45.7 |
HIP 100610 |
22.72 |
| 2026-09-23 12:00 |
20:24:00.77 |
-27:11:00.0 |
HIP 100610 |
23.51 |
| 2026-09-24 00:00 |
20:23:57.59 |
-27:10:12.9 |
HIP 100610 |
24.34 |
| 2026-09-24 12:00 |
20:23:54.73 |
-27:09:24.7 |
HIP 100610 |
25.19 |
| 2026-09-25 00:00 |
20:23:52.17 |
-27:08:35.3 |
HIP 100566 |
24.84 |
| 2026-09-25 12:00 |
20:23:49.93 |
-27:07:44.8 |
HIP 100566 |
23.93 |
| 2026-09-26 00:00 |
20:23:47.99 |
-27:06:53.1 |
HIP 100566 |
23.02 |
| 2026-09-26 12:00 |
20:23:46.37 |
-27:06:00.2 |
HIP 100566 |
22.09 |
| 2026-09-27 00:00 |
20:23:45.06 |
-27:05:06.2 |
HIP 100566 |
21.16 |
| 2026-09-27 12:00 |
20:23:44.05 |
-27:04:11.1 |
HIP 100566 |
20.23 |
| 2026-09-28 00:00 |
20:23:43.36 |
-27:03:14.8 |
HIP 100566 |
19.28 |
| 2026-09-28 12:00 |
20:23:42.98 |
-27:02:17.4 |
HIP 100566 |
18.32 |
| 2026-09-29 00:00 |
20:23:42.92 |
-27:01:18.8 |
HIP 100566 |
17.34 |
| 2026-09-29 12:00 |
20:23:43.16 |
-27:00:19.2 |
HIP 100566 |
16.37 |
| 2026-09-30 00:00 |
20:23:43.71 |
-26:59:18.4 |
HIP 100566 |
15.38 |
| 2026-09-30 12:00 |
20:23:44.58 |
-26:58:16.6 |
HIP 100566 |
14.39 |
| 2026-10-01 00:00 |
20:23:45.75 |
-26:57:13.6 |
HIP 100566 |
13.41 |
| 2026-10-01 12:00 |
20:23:47.24 |
-26:56:09.6 |
HIP 100566 |
12.45 |
| 2026-10-02 00:00 |
20:23:49.03 |
-26:55:04.4 |
HIP 100566 |
11.52 |
| 2026-10-02 12:00 |
20:23:51.14 |
-26:53:58.2 |
HIP 100566 |
10.63 |
| 2026-10-03 00:00 |
20:23:53.56 |
-26:52:51.0 |
HIP 100566 |
9.84 |
| 2026-10-03 12:00 |
20:23:56.29 |
-26:51:42.6 |
HIP 100566 |
9.16 |
| 2026-10-04 00:00 |
20:23:59.32 |
-26:50:33.2 |
HIP 100566 |
8.67 |
| 2026-10-04 12:00 |
20:24:02.67 |
-26:49:22.7 |
HIP 100566 |
8.40 |
| 2026-10-05 00:00 |
20:24:06.33 |
-26:48:11.2 |
HIP 100566 |
8.41 |
| 2026-10-05 12:00 |
20:24:10.29 |
-26:46:58.6 |
HIP 100566 |
8.72 |
| 2026-10-06 00:00 |
20:24:14.57 |
-26:45:45.0 |
HIP 100566 |
9.33 |
| 2026-10-06 12:00 |
20:24:19.15 |
-26:44:30.4 |
HIP 100566 |
10.22 |
| 2026-10-07 00:00 |
20:24:24.04 |
-26:43:14.7 |
HIP 100566 |
11.34 |
| 2026-10-07 12:00 |
20:24:29.24 |
-26:41:58.0 |
HIP 100566 |
12.65 |
| 2026-10-08 00:00 |
20:24:34.75 |
-26:40:40.2 |
HIP 100566 |
14.12 |
| 2026-10-08 12:00 |
20:24:40.56 |
-26:39:21.5 |
HIP 100566 |
15.73 |
| 2026-10-09 00:00 |
20:24:46.68 |
-26:38:01.7 |
HIP 100765 |
14.60 |
| 2026-10-09 12:00 |
20:24:53.11 |
-26:36:40.9 |
HIP 100765 |
12.84 |
| 2026-10-10 00:00 |
20:24:59.84 |
-26:35:19.2 |
HIP 100765 |
11.08 |
| 2026-10-10 12:00 |
20:25:06.87 |
-26:33:56.4 |
HIP 100765 |
9.35 |
| 2026-10-11 00:00 |
20:25:14.21 |
-26:32:32.6 |
HIP 100765 |
7.74 |