| 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) |
| 2026-07-29 00:00 |
20:54:41.78 |
-26:15:42.8 |
HIP 103148 |
10.88 |
| 2026-07-29 12:00 |
20:54:20.33 |
-26:17:19.5 |
HIP 103148 |
5.81 |
| 2026-07-30 00:00 |
20:53:58.80 |
-26:18:55.5 |
HIP 103148 |
0.72 |
| 2026-07-30 12:00 |
20:53:37.21 |
-26:20:30.7 |
HIP 103148 |
4.37 |
| 2026-07-31 00:00 |
20:53:15.54 |
-26:22:05.2 |
HIP 103148 |
9.47 |
| 2026-07-31 12:00 |
20:52:53.82 |
-26:23:39.0 |
HIP 103148 |
14.58 |
| 2026-08-01 00:00 |
20:52:32.03 |
-26:25:11.9 |
HIP 103148 |
19.70 |
| 2026-08-01 12:00 |
20:52:10.20 |
-26:26:44.0 |
HIP 102940 |
22.70 |
| 2026-08-02 00:00 |
20:51:48.31 |
-26:28:15.3 |
HIP 102940 |
19.40 |
| 2026-08-02 12:00 |
20:51:26.37 |
-26:29:45.7 |
HIP 102940 |
17.05 |
| 2026-08-03 00:00 |
20:51:04.40 |
-26:31:15.2 |
HIP 102940 |
16.06 |
| 2026-08-03 12:00 |
20:50:42.39 |
-26:32:43.9 |
HIP 102940 |
16.69 |
| 2026-08-04 00:00 |
20:50:20.35 |
-26:34:11.6 |
HIP 102940 |
18.77 |
| 2026-08-04 12:00 |
20:49:58.29 |
-26:35:38.4 |
HIP 102940 |
21.89 |
| 2026-08-05 00:00 |
20:49:36.20 |
-26:37:04.3 |
HIP 102940 |
25.68 |
| 2026-08-05 12:00 |
20:49:14.09 |
-26:38:29.2 |
HIP 102603 |
23.29 |
| 2026-08-06 00:00 |
20:48:51.97 |
-26:39:53.0 |
HIP 102603 |
19.20 |
| 2026-08-06 12:00 |
20:48:29.85 |
-26:41:15.9 |
HIP 102603 |
15.71 |
| 2026-08-07 00:00 |
20:48:07.72 |
-26:42:37.7 |
HIP 102603 |
13.32 |
| 2026-08-07 12:00 |
20:47:45.60 |
-26:43:58.5 |
HIP 102603 |
12.67 |
| 2026-08-08 00:00 |
20:47:23.49 |
-26:45:18.2 |
HIP 102603 |
13.98 |
| 2026-08-08 12:00 |
20:47:01.38 |
-26:46:36.9 |
HIP 102505 |
9.21 |
| 2026-08-09 00:00 |
20:46:39.30 |
-26:47:54.4 |
HIP 102505 |
4.78 |
| 2026-08-09 12:00 |
20:46:17.24 |
-26:49:10.8 |
HIP 102505 |
3.56 |
| 2026-08-10 00:00 |
20:45:55.20 |
-26:50:26.0 |
HIP 102505 |
7.36 |
| 2026-08-10 12:00 |
20:45:33.21 |
-26:51:40.1 |
HIP 102507 |
12.09 |
| 2026-08-11 00:00 |
20:45:11.25 |
-26:52:53.1 |
HIP 102507 |
17.00 |
| 2026-08-11 12:00 |
20:44:49.33 |
-26:54:04.8 |
HIP 102414 |
21.42 |
| 2026-08-12 00:00 |
20:44:27.46 |
-26:55:15.3 |
HIP 102414 |
22.06 |
| 2026-08-12 12:00 |
20:44:05.65 |
-26:56:24.6 |
HIP 102414 |
23.77 |
| 2026-08-13 00:00 |
20:43:43.90 |
-26:57:32.6 |
HIP 102414 |
26.33 |
| 2026-08-13 12:00 |
20:43:22.22 |
-26:58:39.4 |
HIP 102152 |
24.19 |
| 2026-08-14 00:00 |
20:43:00.60 |
-26:59:45.0 |
HIP 102152 |
19.76 |
| 2026-08-14 12:00 |
20:42:39.06 |
-27:00:49.2 |
HIP 102152 |
15.67 |
| 2026-08-15 00:00 |
20:42:17.60 |
-27:01:52.2 |
HIP 102152 |
12.22 |
| 2026-08-15 12:00 |
20:41:56.23 |
-27:02:53.8 |
HIP 102152 |
10.06 |
| 2026-08-16 00:00 |
20:41:34.95 |
-27:03:54.1 |
HIP 102152 |
10.05 |
| 2026-08-16 12:00 |
20:41:13.76 |
-27:04:53.1 |
HIP 102152 |
12.14 |
| 2026-08-17 00:00 |
20:40:52.68 |
-27:05:50.8 |
HIP 102152 |
15.48 |
| 2026-08-17 12:00 |
20:40:31.70 |
-27:06:47.1 |
HIP 102152 |
19.43 |
| 2026-08-18 00:00 |
20:40:10.83 |
-27:07:42.0 |
HIP 102152 |
23.65 |
| 2026-08-18 12:00 |
20:39:50.07 |
-27:08:35.6 |
HIP 102152 |
28.02 |
| 2026-08-19 00:00 |
20:39:29.44 |
-27:09:27.8 |
HIP 102030 |
29.60 |