| Parameter |
Value |
| Designation |
357P/Hill |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2008-12-24T01:09:27.063360Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:28:34Z |
| Obs used |
293 |
| NEO |
- |
| M1 |
5.100 |
| K1 |
29.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2009-12-05.0000000 |
| e |
0.43548563 |
| q (au) |
2.511840 |
| a (au) |
4.449560 |
| i (deg) |
6.325985 |
| Ω (om, deg) |
44.675030 |
| ω (w, deg) |
1.288453 |
| M (ma, deg) |
36.328214 |
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) |
| 2026-06-01 00:00 |
21:14:27.43 |
-23:26:01.8 |
HIP 104864 |
33.37 |
| 2026-06-01 12:00 |
21:14:31.22 |
-23:26:44.5 |
HIP 104864 |
34.06 |
| 2026-06-02 00:00 |
21:14:34.76 |
-23:27:28.3 |
HIP 104864 |
34.79 |
| 2026-06-02 12:00 |
21:14:38.07 |
-23:28:13.2 |
HIP 104864 |
35.56 |
| 2026-06-03 00:00 |
21:14:41.12 |
-23:28:59.1 |
HIP 104864 |
36.35 |
| 2026-06-03 12:00 |
21:14:43.94 |
-23:29:46.2 |
HIP 104864 |
37.17 |
| 2026-06-04 00:00 |
21:14:46.50 |
-23:30:34.4 |
HIP 104864 |
38.02 |
| 2026-06-04 12:00 |
21:14:48.82 |
-23:31:23.6 |
HIP 104864 |
38.88 |
| 2026-06-05 00:00 |
21:14:50.89 |
-23:32:14.0 |
HIP 104827 |
38.75 |
| 2026-06-05 12:00 |
21:14:52.71 |
-23:33:05.4 |
HIP 104827 |
38.02 |
| 2026-06-06 00:00 |
21:14:54.28 |
-23:33:57.9 |
HIP 104827 |
37.26 |
| 2026-06-06 12:00 |
21:14:55.59 |
-23:34:51.6 |
HIP 104827 |
36.48 |
| 2026-06-07 00:00 |
21:14:56.66 |
-23:35:46.3 |
HIP 104827 |
35.67 |
| 2026-06-07 12:00 |
21:14:57.47 |
-23:36:42.1 |
HIP 104827 |
34.83 |
| 2026-06-08 00:00 |
21:14:58.03 |
-23:37:39.0 |
HIP 104827 |
33.97 |
| 2026-06-08 12:00 |
21:14:58.34 |
-23:38:36.9 |
HIP 104827 |
33.07 |
| 2026-06-09 00:00 |
21:14:58.38 |
-23:39:36.0 |
HIP 104827 |
32.14 |
| 2026-06-09 12:00 |
21:14:58.18 |
-23:40:36.1 |
HIP 104827 |
31.18 |
| 2026-06-10 00:00 |
21:14:57.71 |
-23:41:37.3 |
HIP 104827 |
30.19 |
| 2026-06-10 12:00 |
21:14:56.99 |
-23:42:39.5 |
HIP 104827 |
29.16 |
| 2026-06-11 00:00 |
21:14:56.01 |
-23:43:42.8 |
HIP 104827 |
28.09 |
| 2026-06-11 12:00 |
21:14:54.77 |
-23:44:47.2 |
HIP 104827 |
26.99 |
| 2026-06-12 00:00 |
21:14:53.28 |
-23:45:52.7 |
HIP 104827 |
25.85 |
| 2026-06-12 12:00 |
21:14:51.52 |
-23:46:59.1 |
HIP 104827 |
24.67 |
| 2026-06-13 00:00 |
21:14:49.50 |
-23:48:06.7 |
HIP 104827 |
23.45 |
| 2026-06-13 12:00 |
21:14:47.22 |
-23:49:15.2 |
HIP 104827 |
22.20 |
| 2026-06-14 00:00 |
21:14:44.68 |
-23:50:24.8 |
HIP 104827 |
20.91 |
| 2026-06-14 12:00 |
21:14:41.88 |
-23:51:35.4 |
HIP 104827 |
19.58 |
| 2026-06-15 00:00 |
21:14:38.82 |
-23:52:47.0 |
HIP 104827 |
18.22 |
| 2026-06-15 12:00 |
21:14:35.49 |
-23:53:59.7 |
HIP 104827 |
16.83 |
| 2026-06-16 00:00 |
21:14:31.91 |
-23:55:13.3 |
HIP 104827 |
15.41 |
| 2026-06-16 12:00 |
21:14:28.06 |
-23:56:27.9 |
HIP 104827 |
13.97 |
| 2026-06-17 00:00 |
21:14:23.95 |
-23:57:43.5 |
HIP 104827 |
12.52 |
| 2026-06-17 12:00 |
21:14:19.58 |
-23:59:00.1 |
HIP 104827 |
11.09 |
| 2026-06-18 00:00 |
21:14:14.95 |
-24:00:17.6 |
HIP 104827 |
9.68 |
| 2026-06-18 12:00 |
21:14:10.05 |
-24:01:36.0 |
HIP 104827 |
8.37 |
| 2026-06-19 00:00 |
21:14:04.90 |
-24:02:55.4 |
HIP 104827 |
7.22 |
| 2026-06-19 12:00 |
21:13:59.49 |
-24:04:15.7 |
HIP 104827 |
6.38 |
| 2026-06-20 00:00 |
21:13:53.81 |
-24:05:36.9 |
HIP 104827 |
6.02 |
| 2026-06-20 12:00 |
21:13:47.88 |
-24:06:59.1 |
HIP 104827 |
6.28 |
| 2026-06-21 00:00 |
21:13:41.69 |
-24:08:22.1 |
HIP 104827 |
7.12 |
| 2026-06-21 12:00 |
21:13:35.23 |
-24:09:46.0 |
HIP 104827 |
8.41 |
| 2026-06-22 00:00 |
21:13:28.52 |
-24:11:10.7 |
HIP 104827 |
10.02 |