| 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) |
| 2026-05-12 00:00 |
21:22:46.92 |
-30:23:23.3 |
HIP 105598 |
10.52 |
| 2026-05-12 12:00 |
21:22:49.01 |
-30:23:56.7 |
HIP 105598 |
10.65 |
| 2026-05-13 00:00 |
21:22:50.98 |
-30:24:30.7 |
HIP 105598 |
10.85 |
| 2026-05-13 12:00 |
21:22:52.83 |
-30:25:05.2 |
HIP 105598 |
11.11 |
| 2026-05-14 00:00 |
21:22:54.56 |
-30:25:40.3 |
HIP 105598 |
11.43 |
| 2026-05-14 12:00 |
21:22:56.17 |
-30:26:15.8 |
HIP 105598 |
11.80 |
| 2026-05-15 00:00 |
21:22:57.66 |
-30:26:52.0 |
HIP 105598 |
12.21 |
| 2026-05-15 12:00 |
21:22:59.03 |
-30:27:28.6 |
HIP 105598 |
12.67 |
| 2026-05-16 00:00 |
21:23:00.27 |
-30:28:05.8 |
HIP 105598 |
13.16 |
| 2026-05-16 12:00 |
21:23:01.40 |
-30:28:43.5 |
HIP 105598 |
13.69 |
| 2026-05-17 00:00 |
21:23:02.40 |
-30:29:21.7 |
HIP 105598 |
14.24 |
| 2026-05-17 12:00 |
21:23:03.28 |
-30:30:00.4 |
HIP 105598 |
14.82 |
| 2026-05-18 00:00 |
21:23:04.04 |
-30:30:39.6 |
HIP 105598 |
15.41 |
| 2026-05-18 12:00 |
21:23:04.68 |
-30:31:19.4 |
HIP 105598 |
16.03 |
| 2026-05-19 00:00 |
21:23:05.19 |
-30:31:59.6 |
HIP 105598 |
16.67 |
| 2026-05-19 12:00 |
21:23:05.59 |
-30:32:40.4 |
HIP 105580 |
16.06 |
| 2026-05-20 00:00 |
21:23:05.85 |
-30:33:21.6 |
HIP 105580 |
15.37 |
| 2026-05-20 12:00 |
21:23:06.00 |
-30:34:03.4 |
HIP 105580 |
14.68 |
| 2026-05-21 00:00 |
21:23:06.02 |
-30:34:45.6 |
HIP 105580 |
13.97 |
| 2026-05-21 12:00 |
21:23:05.92 |
-30:35:28.3 |
HIP 105580 |
13.26 |
| 2026-05-22 00:00 |
21:23:05.70 |
-30:36:11.5 |
HIP 105580 |
12.54 |
| 2026-05-22 12:00 |
21:23:05.35 |
-30:36:55.2 |
HIP 105580 |
11.81 |
| 2026-05-23 00:00 |
21:23:04.89 |
-30:37:39.3 |
HIP 105580 |
11.08 |
| 2026-05-23 12:00 |
21:23:04.29 |
-30:38:23.9 |
HIP 105580 |
10.34 |
| 2026-05-24 00:00 |
21:23:03.58 |
-30:39:09.0 |
HIP 105580 |
9.60 |
| 2026-05-24 12:00 |
21:23:02.74 |
-30:39:54.6 |
HIP 105580 |
8.85 |
| 2026-05-25 00:00 |
21:23:01.78 |
-30:40:40.6 |
HIP 105580 |
8.11 |
| 2026-05-25 12:00 |
21:23:00.69 |
-30:41:27.0 |
HIP 105580 |
7.38 |
| 2026-05-26 00:00 |
21:22:59.48 |
-30:42:13.9 |
HIP 105580 |
6.66 |
| 2026-05-26 12:00 |
21:22:58.15 |
-30:43:01.3 |
HIP 105580 |
5.97 |
| 2026-05-27 00:00 |
21:22:56.69 |
-30:43:49.0 |
HIP 105580 |
5.32 |
| 2026-05-27 12:00 |
21:22:55.12 |
-30:44:37.3 |
HIP 105580 |
4.75 |
| 2026-05-28 00:00 |
21:22:53.41 |
-30:45:25.9 |
HIP 105580 |
4.30 |
| 2026-05-28 12:00 |
21:22:51.59 |
-30:46:15.0 |
HIP 105580 |
4.01 |
| 2026-05-29 00:00 |
21:22:49.64 |
-30:47:04.5 |
HIP 105580 |
3.93 |
| 2026-05-29 12:00 |
21:22:47.57 |
-30:47:54.4 |
HIP 105580 |
4.09 |
| 2026-05-30 00:00 |
21:22:45.37 |
-30:48:44.7 |
HIP 105580 |
4.48 |
| 2026-05-30 12:00 |
21:22:43.05 |
-30:49:35.4 |
HIP 105580 |
5.05 |
| 2026-05-31 00:00 |
21:22:40.61 |
-30:50:26.5 |
HIP 105580 |
5.76 |
| 2026-05-31 12:00 |
21:22:38.04 |
-30:51:18.1 |
HIP 105580 |
6.58 |
| 2026-06-01 00:00 |
21:22:35.35 |
-30:52:10.0 |
HIP 105580 |
7.47 |
| 2026-06-01 12:00 |
21:22:32.54 |
-30:53:02.3 |
HIP 105580 |
8.42 |
| 2026-06-02 00:00 |
21:22:29.60 |
-30:53:55.0 |
HIP 105580 |
9.42 |