| 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) |
| 2026-05-12 00:00 |
21:08:47.41 |
-23:12:18.0 |
HIP 104229 |
24.09 |
| 2026-05-12 12:00 |
21:09:00.14 |
-23:12:18.2 |
HIP 104549 |
23.94 |
| 2026-05-13 00:00 |
21:09:12.67 |
-23:12:19.4 |
HIP 104549 |
21.17 |
| 2026-05-13 12:00 |
21:09:24.99 |
-23:12:21.6 |
HIP 104549 |
18.48 |
| 2026-05-14 00:00 |
21:09:37.11 |
-23:12:24.9 |
HIP 104549 |
15.87 |
| 2026-05-14 12:00 |
21:09:49.02 |
-23:12:29.1 |
HIP 104549 |
13.37 |
| 2026-05-15 00:00 |
21:10:00.72 |
-23:12:34.4 |
HIP 104549 |
11.01 |
| 2026-05-15 12:00 |
21:10:12.21 |
-23:12:40.6 |
HIP 104549 |
8.86 |
| 2026-05-16 00:00 |
21:10:23.49 |
-23:12:47.9 |
HIP 104549 |
7.07 |
| 2026-05-16 12:00 |
21:10:34.56 |
-23:12:56.3 |
HIP 104549 |
5.90 |
| 2026-05-17 00:00 |
21:10:45.42 |
-23:13:05.6 |
HIP 104549 |
5.69 |
| 2026-05-17 12:00 |
21:10:56.07 |
-23:13:16.0 |
HIP 104549 |
6.47 |
| 2026-05-18 00:00 |
21:11:06.50 |
-23:13:27.5 |
HIP 104549 |
7.91 |
| 2026-05-18 12:00 |
21:11:16.71 |
-23:13:40.0 |
HIP 104619 |
7.99 |
| 2026-05-19 00:00 |
21:11:26.71 |
-23:13:53.5 |
HIP 104619 |
7.33 |
| 2026-05-19 12:00 |
21:11:36.48 |
-23:14:08.1 |
HIP 104619 |
7.39 |
| 2026-05-20 00:00 |
21:11:46.04 |
-23:14:23.8 |
HIP 104619 |
8.10 |
| 2026-05-20 12:00 |
21:11:55.38 |
-23:14:40.5 |
HIP 104619 |
9.29 |
| 2026-05-21 00:00 |
21:12:04.50 |
-23:14:58.3 |
HIP 104619 |
10.76 |
| 2026-05-21 12:00 |
21:12:13.40 |
-23:15:17.1 |
HIP 104619 |
12.40 |
| 2026-05-22 00:00 |
21:12:22.07 |
-23:15:37.0 |
HIP 104619 |
14.12 |
| 2026-05-22 12:00 |
21:12:30.52 |
-23:15:58.0 |
HIP 104619 |
15.88 |
| 2026-05-23 00:00 |
21:12:38.75 |
-23:16:20.0 |
HIP 104619 |
17.65 |
| 2026-05-23 12:00 |
21:12:46.75 |
-23:16:43.1 |
HIP 104619 |
19.41 |
| 2026-05-24 00:00 |
21:12:54.53 |
-23:17:07.3 |
HIP 104619 |
21.16 |
| 2026-05-24 12:00 |
21:13:02.08 |
-23:17:32.6 |
HIP 104619 |
22.89 |
| 2026-05-25 00:00 |
21:13:09.40 |
-23:17:58.9 |
HIP 104619 |
24.58 |
| 2026-05-25 12:00 |
21:13:16.49 |
-23:18:26.4 |
HIP 104619 |
26.24 |
| 2026-05-26 00:00 |
21:13:23.35 |
-23:18:54.9 |
HIP 104619 |
27.86 |
| 2026-05-26 12:00 |
21:13:29.98 |
-23:19:24.5 |
HIP 104619 |
29.45 |
| 2026-05-27 00:00 |
21:13:36.38 |
-23:19:55.1 |
HIP 104864 |
30.16 |
| 2026-05-27 12:00 |
21:13:42.55 |
-23:20:26.9 |
HIP 104864 |
30.07 |
| 2026-05-28 00:00 |
21:13:48.48 |
-23:20:59.7 |
HIP 104864 |
30.09 |
| 2026-05-28 12:00 |
21:13:54.18 |
-23:21:33.7 |
HIP 104864 |
30.21 |
| 2026-05-29 00:00 |
21:13:59.64 |
-23:22:08.7 |
HIP 104864 |
30.43 |
| 2026-05-29 12:00 |
21:14:04.87 |
-23:22:44.8 |
HIP 104864 |
30.74 |
| 2026-05-30 00:00 |
21:14:09.86 |
-23:23:22.0 |
HIP 104864 |
31.13 |
| 2026-05-30 12:00 |
21:14:14.61 |
-23:24:00.3 |
HIP 104864 |
31.60 |
| 2026-05-31 00:00 |
21:14:19.12 |
-23:24:39.7 |
HIP 104864 |
32.13 |
| 2026-05-31 12:00 |
21:14:23.40 |
-23:25:20.2 |
HIP 104864 |
32.72 |
| 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 |