| 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 |
1.000 |
| gb |
-0.501 |
| 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) |
| 2026-07-29 00:00 |
14:07:07.63 |
-16:06:25.2 |
HIP 68970 |
5.23 |
| 2026-07-29 12:00 |
14:07:16.19 |
-16:07:35.7 |
HIP 68970 |
3.87 |
| 2026-07-30 00:00 |
14:07:24.91 |
-16:08:46.8 |
HIP 68970 |
3.75 |
| 2026-07-30 12:00 |
14:07:33.79 |
-16:09:58.7 |
HIP 68970 |
5.00 |
| 2026-07-31 00:00 |
14:07:42.84 |
-16:11:11.4 |
HIP 68970 |
6.96 |
| 2026-07-31 12:00 |
14:07:52.04 |
-16:12:24.8 |
HIP 68970 |
9.22 |
| 2026-08-01 00:00 |
14:08:01.41 |
-16:13:38.9 |
HIP 68970 |
11.63 |
| 2026-08-01 12:00 |
14:08:10.94 |
-16:14:53.7 |
HIP 68970 |
14.13 |
| 2026-08-02 00:00 |
14:08:20.62 |
-16:16:09.2 |
HIP 68970 |
16.71 |
| 2026-08-02 12:00 |
14:08:30.47 |
-16:17:25.5 |
HIP 69073 |
17.06 |
| 2026-08-03 00:00 |
14:08:40.47 |
-16:18:42.5 |
HIP 69073 |
16.30 |
| 2026-08-03 12:00 |
14:08:50.63 |
-16:20:00.2 |
HIP 69073 |
15.97 |
| 2026-08-04 00:00 |
14:09:00.95 |
-16:21:18.5 |
HIP 69073 |
16.13 |
| 2026-08-04 12:00 |
14:09:11.42 |
-16:22:37.6 |
HIP 69073 |
16.78 |
| 2026-08-05 00:00 |
14:09:22.05 |
-16:23:57.4 |
HIP 69073 |
17.89 |
| 2026-08-05 12:00 |
14:09:32.83 |
-16:25:17.9 |
HIP 69073 |
19.39 |
| 2026-08-06 00:00 |
14:09:43.77 |
-16:26:39.1 |
HIP 69269 |
18.13 |
| 2026-08-06 12:00 |
14:09:54.86 |
-16:28:01.0 |
HIP 69269 |
16.61 |
| 2026-08-07 00:00 |
14:10:06.11 |
-16:29:23.6 |
HIP 69269 |
15.50 |
| 2026-08-07 12:00 |
14:10:17.50 |
-16:30:46.9 |
HIP 69269 |
14.93 |
| 2026-08-08 00:00 |
14:10:29.05 |
-16:32:10.8 |
HIP 69269 |
14.97 |
| 2026-08-08 12:00 |
14:10:40.76 |
-16:33:35.4 |
HIP 69269 |
15.65 |
| 2026-08-09 00:00 |
14:10:52.61 |
-16:35:00.7 |
HIP 69269 |
16.90 |
| 2026-08-09 12:00 |
14:11:04.61 |
-16:36:26.7 |
HIP 69269 |
18.64 |
| 2026-08-10 00:00 |
14:11:16.76 |
-16:37:53.3 |
HIP 69269 |
20.75 |
| 2026-08-10 12:00 |
14:11:29.07 |
-16:39:20.6 |
HIP 69423 |
21.17 |
| 2026-08-11 00:00 |
14:11:41.52 |
-16:40:48.6 |
HIP 69423 |
17.88 |
| 2026-08-11 12:00 |
14:11:54.11 |
-16:42:17.2 |
HIP 69423 |
14.57 |
| 2026-08-12 00:00 |
14:12:06.86 |
-16:43:46.5 |
HIP 69423 |
11.25 |
| 2026-08-12 12:00 |
14:12:19.75 |
-16:45:16.4 |
HIP 69423 |
7.95 |
| 2026-08-13 00:00 |
14:12:32.79 |
-16:46:47.0 |
HIP 69423 |
4.81 |
| 2026-08-13 12:00 |
14:12:45.97 |
-16:48:18.2 |
HIP 69423 |
2.66 |
| 2026-08-14 00:00 |
14:12:59.30 |
-16:49:50.0 |
HIP 69423 |
3.97 |
| 2026-08-14 12:00 |
14:13:12.77 |
-16:51:22.5 |
HIP 69423 |
7.06 |
| 2026-08-15 00:00 |
14:13:26.38 |
-16:52:55.6 |
HIP 69423 |
10.50 |
| 2026-08-15 12:00 |
14:13:40.13 |
-16:54:29.3 |
HIP 69423 |
14.05 |
| 2026-08-16 00:00 |
14:13:54.03 |
-16:56:03.7 |
HIP 69423 |
17.68 |
| 2026-08-16 12:00 |
14:14:08.06 |
-16:57:38.6 |
HIP 69423 |
21.35 |
| 2026-08-17 00:00 |
14:14:22.23 |
-16:59:14.1 |
HIP 69423 |
25.07 |
| 2026-08-17 12:00 |
14:14:36.55 |
-17:00:50.3 |
HIP 69548 |
27.62 |
| 2026-08-18 00:00 |
14:14:51.00 |
-17:02:27.0 |
HIP 69548 |
27.04 |
| 2026-08-18 12:00 |
14:15:05.58 |
-17:04:04.4 |
HIP 69548 |
27.00 |
| 2026-08-19 00:00 |
14:15:20.30 |
-17:05:42.3 |
HIP 69548 |
27.52 |