C/2009 O4 (Hill)
| Parameter |
Value |
| Designation |
C/2009 O4 (Hill) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2010-01-01T06:37:51.360960Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:32Z |
| Obs used |
764 |
| NEO |
- |
| M1 |
4.900 |
| K1 |
21.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2009-09-03.0000000 |
| e |
1.00133631 |
| q (au) |
2.563789 |
| a (au) |
-1918.552115 |
| i (deg) |
95.823277 |
| Ω (om, deg) |
172.936518 |
| ω (w, deg) |
223.731941 |
| M (ma, deg) |
-0.001411 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.077 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.077 |
| n |
2.000 |
| gf |
0.998 |
| gb |
-0.622 |
| 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) |
| 2026-02-03 00:00 |
11:52:50.31 |
+13:36:34.8 |
HIP 57932 |
8.12 |
| 2026-02-03 12:00 |
11:52:47.90 |
+13:37:02.1 |
HIP 57932 |
7.74 |
| 2026-02-04 00:00 |
11:52:45.48 |
+13:37:29.4 |
HIP 57932 |
7.43 |
| 2026-02-04 12:00 |
11:52:43.03 |
+13:37:56.8 |
HIP 57932 |
7.17 |
| 2026-02-05 00:00 |
11:52:40.56 |
+13:38:24.2 |
HIP 57932 |
6.99 |
| 2026-02-05 12:00 |
11:52:38.07 |
+13:38:51.7 |
HIP 57932 |
6.90 |
| 2026-02-06 00:00 |
11:52:35.56 |
+13:39:19.2 |
HIP 57932 |
6.88 |
| 2026-02-06 12:00 |
11:52:33.02 |
+13:39:46.8 |
HIP 57932 |
6.96 |
| 2026-02-07 00:00 |
11:52:30.47 |
+13:40:14.5 |
HIP 57932 |
7.12 |
| 2026-02-07 12:00 |
11:52:27.90 |
+13:40:42.1 |
HIP 57932 |
7.36 |
| 2026-02-08 00:00 |
11:52:25.31 |
+13:41:09.8 |
HIP 57932 |
7.67 |
| 2026-02-08 12:00 |
11:52:22.70 |
+13:41:37.6 |
HIP 57932 |
8.06 |
| 2026-02-09 00:00 |
11:52:20.06 |
+13:42:05.4 |
HIP 57932 |
8.50 |
| 2026-02-09 12:00 |
11:52:17.41 |
+13:42:33.2 |
HIP 57932 |
9.00 |
| 2026-02-10 00:00 |
11:52:14.74 |
+13:43:01.0 |
HIP 57932 |
9.54 |
| 2026-02-10 12:00 |
11:52:12.05 |
+13:43:28.9 |
HIP 57932 |
10.12 |
| 2026-02-11 00:00 |
11:52:09.35 |
+13:43:56.8 |
HIP 57932 |
10.73 |
| 2026-02-11 12:00 |
11:52:06.62 |
+13:44:24.8 |
HIP 57932 |
11.37 |
| 2026-02-12 00:00 |
11:52:03.88 |
+13:44:52.7 |
HIP 57932 |
12.04 |
| 2026-02-12 12:00 |
11:52:01.12 |
+13:45:20.7 |
HIP 57932 |
12.72 |
| 2026-02-13 00:00 |
11:51:58.34 |
+13:45:48.7 |
HIP 57932 |
13.43 |
| 2026-02-13 12:00 |
11:51:55.54 |
+13:46:16.7 |
HIP 57932 |
14.15 |
| 2026-02-14 00:00 |
11:51:52.72 |
+13:46:44.8 |
HIP 57932 |
14.89 |
| 2026-02-14 12:00 |
11:51:49.89 |
+13:47:12.8 |
HIP 57932 |
15.64 |
| 2026-02-15 00:00 |
11:51:47.04 |
+13:47:40.9 |
HIP 57932 |
16.40 |
| 2026-02-15 12:00 |
11:51:44.18 |
+13:48:08.9 |
HIP 57932 |
17.17 |
| 2026-02-16 00:00 |
11:51:41.30 |
+13:48:37.0 |
HIP 57777 |
17.73 |
| 2026-02-16 12:00 |
11:51:38.40 |
+13:49:05.1 |
HIP 57777 |
17.64 |
| 2026-02-17 00:00 |
11:51:35.49 |
+13:49:33.2 |
HIP 57777 |
17.59 |
| 2026-02-17 12:00 |
11:51:32.56 |
+13:50:01.2 |
HIP 57777 |
17.58 |
| 2026-02-18 00:00 |
11:51:29.61 |
+13:50:29.3 |
HIP 57777 |
17.61 |
| 2026-02-18 12:00 |
11:51:26.65 |
+13:50:57.4 |
HIP 57777 |
17.67 |
| 2026-02-19 00:00 |
11:51:23.68 |
+13:51:25.5 |
HIP 57777 |
17.78 |
| 2026-02-19 12:00 |
11:51:20.69 |
+13:51:53.5 |
HIP 57777 |
17.92 |
| 2026-02-20 00:00 |
11:51:17.69 |
+13:52:21.6 |
HIP 57777 |
18.11 |
| 2026-02-20 12:00 |
11:51:14.67 |
+13:52:49.6 |
HIP 57777 |
18.33 |
| 2026-02-21 00:00 |
11:51:11.64 |
+13:53:17.6 |
HIP 57777 |
18.59 |
| 2026-02-21 12:00 |
11:51:08.60 |
+13:53:45.6 |
HIP 57777 |
18.88 |
| 2026-02-22 00:00 |
11:51:05.54 |
+13:54:13.6 |
HIP 57777 |
19.21 |
| 2026-02-22 12:00 |
11:51:02.47 |
+13:54:41.5 |
HIP 57777 |
19.57 |
| 2026-02-23 00:00 |
11:50:59.39 |
+13:55:09.5 |
HIP 57777 |
19.97 |
| 2026-02-23 12:00 |
11:50:56.30 |
+13:55:37.4 |
HIP 57777 |
20.39 |
| 2026-02-24 00:00 |
11:50:53.19 |
+13:56:05.3 |
HIP 57777 |
20.84 |