| 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) |
| 2026-05-12 00:00 |
14:20:44.21 |
-15:38:40.0 |
HIP 69984 |
32.89 |
| 2026-05-12 12:00 |
14:20:27.54 |
-15:38:07.6 |
HIP 69984 |
29.92 |
| 2026-05-13 00:00 |
14:20:10.93 |
-15:37:35.3 |
HIP 69984 |
27.23 |
| 2026-05-13 12:00 |
14:19:54.39 |
-15:37:03.1 |
HIP 69984 |
24.92 |
| 2026-05-14 00:00 |
14:19:37.92 |
-15:36:31.1 |
HIP 69984 |
23.09 |
| 2026-05-14 12:00 |
14:19:21.53 |
-15:35:59.2 |
HIP 69984 |
21.86 |
| 2026-05-15 00:00 |
14:19:05.21 |
-15:35:27.4 |
HIP 69984 |
21.31 |
| 2026-05-15 12:00 |
14:18:48.98 |
-15:34:55.9 |
HIP 69984 |
21.49 |
| 2026-05-16 00:00 |
14:18:32.83 |
-15:34:24.5 |
HIP 69984 |
22.37 |
| 2026-05-16 12:00 |
14:18:16.76 |
-15:33:53.4 |
HIP 69984 |
23.86 |
| 2026-05-17 00:00 |
14:18:00.78 |
-15:33:22.5 |
HIP 69984 |
25.85 |
| 2026-05-17 12:00 |
14:17:44.90 |
-15:32:51.8 |
HIP 69984 |
28.23 |
| 2026-05-18 00:00 |
14:17:29.10 |
-15:32:21.3 |
HIP 69861 |
29.59 |
| 2026-05-18 12:00 |
14:17:13.41 |
-15:31:51.1 |
HIP 69861 |
30.92 |
| 2026-05-19 00:00 |
14:16:57.81 |
-15:31:21.2 |
HIP 69681 |
29.77 |
| 2026-05-19 12:00 |
14:16:42.31 |
-15:30:51.5 |
HIP 69681 |
27.44 |
| 2026-05-20 00:00 |
14:16:26.92 |
-15:30:22.2 |
HIP 69681 |
25.46 |
| 2026-05-20 12:00 |
14:16:11.63 |
-15:29:53.1 |
HIP 69681 |
23.92 |
| 2026-05-21 00:00 |
14:15:56.45 |
-15:29:24.4 |
HIP 69681 |
22.90 |
| 2026-05-21 12:00 |
14:15:41.38 |
-15:28:55.9 |
HIP 69562 |
20.70 |
| 2026-05-22 00:00 |
14:15:26.42 |
-15:28:27.8 |
HIP 69562 |
17.20 |
| 2026-05-22 12:00 |
14:15:11.58 |
-15:28:00.1 |
HIP 69562 |
13.79 |
| 2026-05-23 00:00 |
14:14:56.86 |
-15:27:32.7 |
HIP 69562 |
10.55 |
| 2026-05-23 12:00 |
14:14:42.25 |
-15:27:05.7 |
HIP 69562 |
7.63 |
| 2026-05-24 00:00 |
14:14:27.77 |
-15:26:39.1 |
HIP 69562 |
5.53 |
| 2026-05-24 12:00 |
14:14:13.40 |
-15:26:12.8 |
HIP 69562 |
5.25 |
| 2026-05-25 00:00 |
14:13:59.17 |
-15:25:47.0 |
HIP 69562 |
6.98 |
| 2026-05-25 12:00 |
14:13:45.05 |
-15:25:21.6 |
HIP 69562 |
9.66 |
| 2026-05-26 00:00 |
14:13:31.07 |
-15:24:56.5 |
HIP 69562 |
12.67 |
| 2026-05-26 12:00 |
14:13:17.22 |
-15:24:32.0 |
HIP 69455 |
12.99 |
| 2026-05-27 00:00 |
14:13:03.50 |
-15:24:07.8 |
HIP 69455 |
13.53 |
| 2026-05-27 12:00 |
14:12:49.91 |
-15:23:44.1 |
HIP 69455 |
14.79 |
| 2026-05-28 00:00 |
14:12:36.46 |
-15:23:20.8 |
HIP 69455 |
16.60 |
| 2026-05-28 12:00 |
14:12:23.15 |
-15:22:58.1 |
HIP 69455 |
18.78 |
| 2026-05-29 00:00 |
14:12:09.97 |
-15:22:35.7 |
HIP 69312 |
16.85 |
| 2026-05-29 12:00 |
14:11:56.93 |
-15:22:13.9 |
HIP 69312 |
14.19 |
| 2026-05-30 00:00 |
14:11:44.04 |
-15:21:52.6 |
HIP 69312 |
11.80 |
| 2026-05-30 12:00 |
14:11:31.29 |
-15:21:31.7 |
HIP 69312 |
9.87 |
| 2026-05-31 00:00 |
14:11:18.69 |
-15:21:11.4 |
HIP 69312 |
8.65 |
| 2026-05-31 12:00 |
14:11:06.23 |
-15:20:51.6 |
HIP 69312 |
8.43 |
| 2026-06-01 00:00 |
14:10:53.92 |
-15:20:32.3 |
HIP 69273 |
8.89 |
| 2026-06-01 12:00 |
14:10:41.76 |
-15:20:13.6 |
HIP 69273 |
8.93 |
| 2026-06-02 00:00 |
14:10:29.75 |
-15:19:55.4 |
HIP 69273 |
9.88 |