| Parameter |
Value |
| Designation |
393P/Spacewatch-Hill |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2009-05-26T09:40:17.238720Z |
| Orbit solution date (soln_date, UTC) |
2024-02-20T23:48:44Z |
| Obs used |
140 |
| NEO |
- |
| M1 |
7.600 |
| K1 |
16.750 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2019-09-24T06:56:17.376000Z |
| Discovery magnitude (MPC) |
21.50 r |
| Discovery observatory (MPC) |
807 · Cerro Tololo Observatory, La Serena |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2011-12-17.0000000 |
| e |
0.11963494 |
| q (au) |
4.202481 |
| a (au) |
4.773566 |
| i (deg) |
16.807080 |
| Ω (om, deg) |
36.411015 |
| ω (w, deg) |
328.592400 |
| M (ma, deg) |
88.321023 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.412 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.412 |
| n |
2.000 |
| gf |
0.999 |
| gb |
-0.503 |
| k |
1.000 |
| 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) |
| 2026-03-26 00:00 |
14:45:18.54 |
-16:12:36.5 |
HIP 72292 |
29.49 |
| 2026-03-26 12:00 |
14:45:07.57 |
-16:12:37.9 |
HIP 72292 |
31.73 |
| 2026-03-27 00:00 |
14:44:56.44 |
-16:12:38.6 |
HIP 72161 |
33.35 |
| 2026-03-27 12:00 |
14:44:45.15 |
-16:12:38.7 |
HIP 72161 |
34.21 |
| 2026-03-28 00:00 |
14:44:33.70 |
-16:12:38.1 |
HIP 72161 |
35.29 |
| 2026-03-28 12:00 |
14:44:22.08 |
-16:12:36.8 |
HIP 72161 |
36.57 |
| 2026-03-29 00:00 |
14:44:10.30 |
-16:12:34.9 |
HIP 72161 |
38.04 |
| 2026-03-29 12:00 |
14:43:58.37 |
-16:12:32.3 |
HIP 72161 |
39.69 |
| 2026-03-30 00:00 |
14:43:46.28 |
-16:12:29.0 |
HIP 72068 |
41.30 |
| 2026-03-30 12:00 |
14:43:34.03 |
-16:12:25.1 |
HIP 72068 |
42.18 |
| 2026-03-31 00:00 |
14:43:21.64 |
-16:12:20.6 |
HIP 71743 |
40.92 |
| 2026-03-31 12:00 |
14:43:09.09 |
-16:12:15.4 |
HIP 71743 |
37.91 |
| 2026-04-01 00:00 |
14:42:56.39 |
-16:12:09.6 |
HIP 71743 |
34.86 |
| 2026-04-01 12:00 |
14:42:43.54 |
-16:12:03.2 |
HIP 71743 |
31.78 |
| 2026-04-02 00:00 |
14:42:30.55 |
-16:11:56.1 |
HIP 71743 |
28.66 |
| 2026-04-02 12:00 |
14:42:17.41 |
-16:11:48.4 |
HIP 71743 |
25.52 |
| 2026-04-03 00:00 |
14:42:04.13 |
-16:11:40.0 |
HIP 71743 |
22.33 |
| 2026-04-03 12:00 |
14:41:50.71 |
-16:11:31.1 |
HIP 71743 |
19.12 |
| 2026-04-04 00:00 |
14:41:37.15 |
-16:11:21.5 |
HIP 71743 |
15.88 |
| 2026-04-04 12:00 |
14:41:23.45 |
-16:11:11.4 |
HIP 71743 |
12.62 |
| 2026-04-05 00:00 |
14:41:09.62 |
-16:11:00.6 |
HIP 71743 |
9.36 |
| 2026-04-05 12:00 |
14:40:55.65 |
-16:10:49.2 |
HIP 71743 |
6.13 |
| 2026-04-06 00:00 |
14:40:41.56 |
-16:10:37.3 |
HIP 71743 |
3.15 |
| 2026-04-06 12:00 |
14:40:27.33 |
-16:10:24.7 |
HIP 71743 |
2.33 |
| 2026-04-07 00:00 |
14:40:12.98 |
-16:10:11.6 |
HIP 71713 |
2.19 |
| 2026-04-07 12:00 |
14:39:58.50 |
-16:09:57.8 |
HIP 71713 |
3.21 |
| 2026-04-08 00:00 |
14:39:43.90 |
-16:09:43.5 |
HIP 71713 |
6.36 |
| 2026-04-08 12:00 |
14:39:29.17 |
-16:09:28.7 |
HIP 71713 |
9.79 |
| 2026-04-09 00:00 |
14:39:14.33 |
-16:09:13.2 |
HIP 71713 |
13.31 |
| 2026-04-09 12:00 |
14:38:59.37 |
-16:08:57.3 |
HIP 71713 |
16.89 |
| 2026-04-10 00:00 |
14:38:44.30 |
-16:08:40.7 |
HIP 71713 |
20.50 |
| 2026-04-10 12:00 |
14:38:29.11 |
-16:08:23.6 |
HIP 71713 |
24.14 |
| 2026-04-11 00:00 |
14:38:13.82 |
-16:08:06.0 |
HIP 71515 |
26.22 |
| 2026-04-11 12:00 |
14:37:58.41 |
-16:07:47.9 |
HIP 71515 |
25.38 |
| 2026-04-12 00:00 |
14:37:42.90 |
-16:07:29.2 |
HIP 71515 |
25.06 |
| 2026-04-12 12:00 |
14:37:27.29 |
-16:07:10.0 |
HIP 71515 |
25.31 |
| 2026-04-13 00:00 |
14:37:11.58 |
-16:06:50.3 |
HIP 71515 |
26.12 |
| 2026-04-13 12:00 |
14:36:55.77 |
-16:06:30.1 |
HIP 71515 |
27.44 |
| 2026-04-14 00:00 |
14:36:39.87 |
-16:06:09.4 |
HIP 71515 |
29.22 |
| 2026-04-14 12:00 |
14:36:23.87 |
-16:05:48.2 |
HIP 71515 |
31.39 |
| 2026-04-15 00:00 |
14:36:07.79 |
-16:05:26.6 |
HIP 71515 |
33.88 |
| 2026-04-15 12:00 |
14:35:51.61 |
-16:05:04.4 |
HIP 71515 |
36.63 |
| 2026-04-16 00:00 |
14:35:35.35 |
-16:04:41.8 |
HIP 71220 |
33.83 |