| Parameter |
Value |
| Designation |
375P/Hill |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2018-12-20T18:39:30.548160Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:28:37Z |
| Obs used |
313 |
| NEO |
- |
| M1 |
16.700 |
| K1 |
6.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-07-29.0000000 |
| e |
0.66003940 |
| q (au) |
1.892519 |
| a (au) |
5.566878 |
| i (deg) |
17.369839 |
| Ω (om, deg) |
359.974029 |
| ω (w, deg) |
119.434290 |
| M (ma, deg) |
266.893415 |
Magnitude
Scatter + Global Linear
$$
M_a = (18.115 + 2.060\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
18.115 |
| n |
2.060 |
| gf |
1.000 |
| gb |
-0.603 |
| k |
0.800 |
| 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 |
20:44:20.83 |
-33:09:07.6 |
HIP 102365 |
20.17 |
| 2026-09-20 12:00 |
20:44:13.13 |
-33:08:43.4 |
HIP 102365 |
20.73 |
| 2026-09-21 00:00 |
20:44:05.54 |
-33:08:18.6 |
HIP 102365 |
21.42 |
| 2026-09-21 12:00 |
20:43:58.07 |
-33:07:53.2 |
HIP 102365 |
22.21 |
| 2026-09-22 00:00 |
20:43:50.72 |
-33:07:27.1 |
HIP 102200 |
21.29 |
| 2026-09-22 12:00 |
20:43:43.49 |
-33:07:00.3 |
HIP 102200 |
20.35 |
| 2026-09-23 00:00 |
20:43:36.37 |
-33:06:33.0 |
HIP 102200 |
19.51 |
| 2026-09-23 12:00 |
20:43:29.38 |
-33:06:05.0 |
HIP 102200 |
18.80 |
| 2026-09-24 00:00 |
20:43:22.51 |
-33:05:36.4 |
HIP 102200 |
18.20 |
| 2026-09-24 12:00 |
20:43:15.75 |
-33:05:07.1 |
HIP 102200 |
17.75 |
| 2026-09-25 00:00 |
20:43:09.12 |
-33:04:37.3 |
HIP 102200 |
17.42 |
| 2026-09-25 12:00 |
20:43:02.61 |
-33:04:06.8 |
HIP 102200 |
17.24 |
| 2026-09-26 00:00 |
20:42:56.22 |
-33:03:35.8 |
HIP 102200 |
17.20 |
| 2026-09-26 12:00 |
20:42:49.96 |
-33:03:04.1 |
HIP 102200 |
17.30 |
| 2026-09-27 00:00 |
20:42:43.81 |
-33:02:31.8 |
HIP 102200 |
17.52 |
| 2026-09-27 12:00 |
20:42:37.79 |
-33:01:59.0 |
HIP 102200 |
17.86 |
| 2026-09-28 00:00 |
20:42:31.90 |
-33:01:25.5 |
HIP 102200 |
18.31 |
| 2026-09-28 12:00 |
20:42:26.13 |
-33:00:51.5 |
HIP 102200 |
18.86 |
| 2026-09-29 00:00 |
20:42:20.48 |
-33:00:16.8 |
HIP 102200 |
19.49 |
| 2026-09-29 12:00 |
20:42:14.96 |
-32:59:41.6 |
HIP 102200 |
20.19 |
| 2026-09-30 00:00 |
20:42:09.56 |
-32:59:05.8 |
HIP 102200 |
20.96 |
| 2026-09-30 12:00 |
20:42:04.29 |
-32:58:29.4 |
HIP 102200 |
21.77 |
| 2026-10-01 00:00 |
20:41:59.15 |
-32:57:52.5 |
HIP 102021 |
20.74 |
| 2026-10-01 12:00 |
20:41:54.14 |
-32:57:15.0 |
HIP 102021 |
19.54 |
| 2026-10-02 00:00 |
20:41:49.25 |
-32:56:36.9 |
HIP 102021 |
18.37 |
| 2026-10-02 12:00 |
20:41:44.49 |
-32:55:58.3 |
HIP 102021 |
17.23 |
| 2026-10-03 00:00 |
20:41:39.85 |
-32:55:19.1 |
HIP 102021 |
16.11 |
| 2026-10-03 12:00 |
20:41:35.35 |
-32:54:39.3 |
HIP 102021 |
15.03 |
| 2026-10-04 00:00 |
20:41:30.97 |
-32:53:59.0 |
HIP 102021 |
13.99 |
| 2026-10-04 12:00 |
20:41:26.73 |
-32:53:18.2 |
HIP 102021 |
12.99 |
| 2026-10-05 00:00 |
20:41:22.61 |
-32:52:36.8 |
HIP 102021 |
12.03 |
| 2026-10-05 12:00 |
20:41:18.62 |
-32:51:54.9 |
HIP 102021 |
11.13 |
| 2026-10-06 00:00 |
20:41:14.77 |
-32:51:12.4 |
HIP 102021 |
10.29 |
| 2026-10-06 12:00 |
20:41:11.04 |
-32:50:29.4 |
HIP 102021 |
9.53 |
| 2026-10-07 00:00 |
20:41:07.45 |
-32:49:45.9 |
HIP 102021 |
8.86 |
| 2026-10-07 12:00 |
20:41:03.98 |
-32:49:01.9 |
HIP 102021 |
8.29 |
| 2026-10-08 00:00 |
20:41:00.65 |
-32:48:17.3 |
HIP 102021 |
7.85 |
| 2026-10-08 12:00 |
20:40:57.45 |
-32:47:32.2 |
HIP 102021 |
7.55 |
| 2026-10-09 00:00 |
20:40:54.38 |
-32:46:46.6 |
HIP 102021 |
7.41 |
| 2026-10-09 12:00 |
20:40:51.45 |
-32:46:00.5 |
HIP 102021 |
7.42 |
| 2026-10-10 00:00 |
20:40:48.65 |
-32:45:13.9 |
HIP 102021 |
7.59 |
| 2026-10-10 12:00 |
20:40:45.97 |
-32:44:26.8 |
HIP 102021 |
7.90 |
| 2026-10-11 00:00 |
20:40:43.44 |
-32:43:39.2 |
HIP 102021 |
8.33 |