393P/Spacewatch-Hill
| 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) |
| 2026-02-03 00:00 |
14:47:22.97 |
-15:07:33.9 |
HIP 72417 |
16.22 |
| 2026-02-03 12:00 |
14:47:31.25 |
-15:08:47.9 |
HIP 72417 |
13.92 |
| 2026-02-04 00:00 |
14:47:39.36 |
-15:10:01.2 |
HIP 72417 |
11.67 |
| 2026-02-04 12:00 |
14:47:47.30 |
-15:11:13.8 |
HIP 72417 |
9.49 |
| 2026-02-05 00:00 |
14:47:55.07 |
-15:12:25.8 |
HIP 72417 |
7.41 |
| 2026-02-05 12:00 |
14:48:02.66 |
-15:13:37.1 |
HIP 72417 |
5.48 |
| 2026-02-06 00:00 |
14:48:10.08 |
-15:14:47.7 |
HIP 72417 |
3.88 |
| 2026-02-06 12:00 |
14:48:17.33 |
-15:15:57.6 |
HIP 72417 |
3.05 |
| 2026-02-07 00:00 |
14:48:24.40 |
-15:17:06.9 |
HIP 72417 |
3.52 |
| 2026-02-07 12:00 |
14:48:31.30 |
-15:18:15.5 |
HIP 72417 |
4.87 |
| 2026-02-08 00:00 |
14:48:38.02 |
-15:19:23.4 |
HIP 72417 |
6.54 |
| 2026-02-08 12:00 |
14:48:44.56 |
-15:20:30.6 |
HIP 72417 |
8.31 |
| 2026-02-09 00:00 |
14:48:50.93 |
-15:21:37.1 |
HIP 72417 |
10.11 |
| 2026-02-09 12:00 |
14:48:57.11 |
-15:22:42.9 |
HIP 72417 |
11.90 |
| 2026-02-10 00:00 |
14:49:03.12 |
-15:23:48.0 |
HIP 72417 |
13.66 |
| 2026-02-10 12:00 |
14:49:08.94 |
-15:24:52.5 |
HIP 72417 |
15.40 |
| 2026-02-11 00:00 |
14:49:14.58 |
-15:25:56.2 |
HIP 72417 |
17.11 |
| 2026-02-11 12:00 |
14:49:20.04 |
-15:26:59.3 |
HIP 72417 |
18.78 |
| 2026-02-12 00:00 |
14:49:25.32 |
-15:28:01.7 |
HIP 72417 |
20.41 |
| 2026-02-12 12:00 |
14:49:30.41 |
-15:29:03.3 |
HIP 72417 |
22.01 |
| 2026-02-13 00:00 |
14:49:35.32 |
-15:30:04.3 |
HIP 72417 |
23.56 |
| 2026-02-13 12:00 |
14:49:40.04 |
-15:31:04.5 |
HIP 72417 |
25.08 |
| 2026-02-14 00:00 |
14:49:44.57 |
-15:32:04.1 |
HIP 72417 |
26.56 |
| 2026-02-14 12:00 |
14:49:48.92 |
-15:33:02.9 |
HIP 72417 |
27.99 |
| 2026-02-15 00:00 |
14:49:53.07 |
-15:34:01.1 |
HIP 72603 |
28.29 |
| 2026-02-15 12:00 |
14:49:57.04 |
-15:34:58.5 |
HIP 72603 |
27.03 |
| 2026-02-16 00:00 |
14:50:00.82 |
-15:35:55.2 |
HIP 72603 |
25.81 |
| 2026-02-16 12:00 |
14:50:04.41 |
-15:36:51.2 |
HIP 72603 |
24.62 |
| 2026-02-17 00:00 |
14:50:07.81 |
-15:37:46.5 |
HIP 72603 |
23.47 |
| 2026-02-17 12:00 |
14:50:11.02 |
-15:38:41.1 |
HIP 72603 |
22.36 |
| 2026-02-18 00:00 |
14:50:14.04 |
-15:39:35.0 |
HIP 72603 |
21.28 |
| 2026-02-18 12:00 |
14:50:16.86 |
-15:40:28.1 |
HIP 72603 |
20.23 |
| 2026-02-19 00:00 |
14:50:19.49 |
-15:41:20.6 |
HIP 72603 |
19.21 |
| 2026-02-19 12:00 |
14:50:21.93 |
-15:42:12.3 |
HIP 72603 |
18.22 |
| 2026-02-20 00:00 |
14:50:24.17 |
-15:43:03.3 |
HIP 72603 |
17.27 |
| 2026-02-20 12:00 |
14:50:26.22 |
-15:43:53.6 |
HIP 72603 |
16.34 |
| 2026-02-21 00:00 |
14:50:28.08 |
-15:44:43.2 |
HIP 72603 |
15.43 |
| 2026-02-21 12:00 |
14:50:29.74 |
-15:45:32.1 |
HIP 72603 |
14.56 |
| 2026-02-22 00:00 |
14:50:31.20 |
-15:46:20.2 |
HIP 72603 |
13.70 |
| 2026-02-22 12:00 |
14:50:32.47 |
-15:47:07.6 |
HIP 72603 |
12.87 |
| 2026-02-23 00:00 |
14:50:33.55 |
-15:47:54.3 |
HIP 72603 |
12.06 |
| 2026-02-23 12:00 |
14:50:34.43 |
-15:48:40.3 |
HIP 72603 |
11.27 |
| 2026-02-24 00:00 |
14:50:35.11 |
-15:49:25.6 |
HIP 72603 |
10.50 |