| 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
$$
M_a = (14.078 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.078 |
| n |
2.000 |
| gf |
1.000 |
| 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) |
| 2026-07-29 00:00 |
11:43:53.43 |
+14:23:23.6 |
HIP 57320 |
20.37 |
| 2026-07-29 12:00 |
11:43:55.58 |
+14:23:05.9 |
HIP 57320 |
19.78 |
| 2026-07-30 00:00 |
11:43:57.74 |
+14:22:48.0 |
HIP 57320 |
19.18 |
| 2026-07-30 12:00 |
11:43:59.92 |
+14:22:30.1 |
HIP 57320 |
18.58 |
| 2026-07-31 00:00 |
11:44:02.12 |
+14:22:12.2 |
HIP 57320 |
17.97 |
| 2026-07-31 12:00 |
11:44:04.34 |
+14:21:54.2 |
HIP 57320 |
17.37 |
| 2026-08-01 00:00 |
11:44:06.58 |
+14:21:36.2 |
HIP 57320 |
16.75 |
| 2026-08-01 12:00 |
11:44:08.84 |
+14:21:18.0 |
HIP 57320 |
16.14 |
| 2026-08-02 00:00 |
11:44:11.12 |
+14:20:59.9 |
HIP 57320 |
15.51 |
| 2026-08-02 12:00 |
11:44:13.41 |
+14:20:41.7 |
HIP 57320 |
14.89 |
| 2026-08-03 00:00 |
11:44:15.72 |
+14:20:23.4 |
HIP 57320 |
14.26 |
| 2026-08-03 12:00 |
11:44:18.05 |
+14:20:05.2 |
HIP 57320 |
13.63 |
| 2026-08-04 00:00 |
11:44:20.40 |
+14:19:46.8 |
HIP 57320 |
12.99 |
| 2026-08-04 12:00 |
11:44:22.77 |
+14:19:28.4 |
HIP 57320 |
12.36 |
| 2026-08-05 00:00 |
11:44:25.15 |
+14:19:10.0 |
HIP 57320 |
11.71 |
| 2026-08-05 12:00 |
11:44:27.55 |
+14:18:51.5 |
HIP 57320 |
11.07 |
| 2026-08-06 00:00 |
11:44:29.97 |
+14:18:33.0 |
HIP 57320 |
10.42 |
| 2026-08-06 12:00 |
11:44:32.40 |
+14:18:14.5 |
HIP 57320 |
9.77 |
| 2026-08-07 00:00 |
11:44:34.86 |
+14:17:55.9 |
HIP 57320 |
9.12 |
| 2026-08-07 12:00 |
11:44:37.33 |
+14:17:37.3 |
HIP 57320 |
8.47 |
| 2026-08-08 00:00 |
11:44:39.81 |
+14:17:18.6 |
HIP 57320 |
7.81 |
| 2026-08-08 12:00 |
11:44:42.31 |
+14:17:00.0 |
HIP 57320 |
7.16 |
| 2026-08-09 00:00 |
11:44:44.83 |
+14:16:41.2 |
HIP 57320 |
6.51 |
| 2026-08-09 12:00 |
11:44:47.37 |
+14:16:22.5 |
HIP 57320 |
5.87 |
| 2026-08-10 00:00 |
11:44:49.92 |
+14:16:03.7 |
HIP 57320 |
5.23 |
| 2026-08-10 12:00 |
11:44:52.49 |
+14:15:44.9 |
HIP 57320 |
4.60 |
| 2026-08-11 00:00 |
11:44:55.07 |
+14:15:26.1 |
HIP 57320 |
3.99 |
| 2026-08-11 12:00 |
11:44:57.67 |
+14:15:07.3 |
HIP 57320 |
3.41 |
| 2026-08-12 00:00 |
11:45:00.28 |
+14:14:48.4 |
HIP 57320 |
2.89 |
| 2026-08-12 12:00 |
11:45:02.91 |
+14:14:29.5 |
HIP 57320 |
2.45 |
| 2026-08-13 00:00 |
11:45:05.55 |
+14:14:10.6 |
HIP 57320 |
2.16 |
| 2026-08-13 12:00 |
11:45:08.21 |
+14:13:51.7 |
HIP 57320 |
2.09 |
| 2026-08-14 00:00 |
11:45:10.88 |
+14:13:32.7 |
HIP 57320 |
2.26 |
| 2026-08-14 12:00 |
11:45:13.57 |
+14:13:13.8 |
HIP 57320 |
2.62 |
| 2026-08-15 00:00 |
11:45:16.27 |
+14:12:54.8 |
HIP 57320 |
3.11 |
| 2026-08-15 12:00 |
11:45:18.98 |
+14:12:35.9 |
HIP 57320 |
3.68 |
| 2026-08-16 00:00 |
11:45:21.71 |
+14:12:16.9 |
HIP 57320 |
4.31 |
| 2026-08-16 12:00 |
11:45:24.46 |
+14:11:57.9 |
HIP 57320 |
4.96 |
| 2026-08-17 00:00 |
11:45:27.21 |
+14:11:38.9 |
HIP 57320 |
5.64 |
| 2026-08-17 12:00 |
11:45:29.98 |
+14:11:19.9 |
HIP 57320 |
6.33 |
| 2026-08-18 00:00 |
11:45:32.76 |
+14:11:00.9 |
HIP 57320 |
7.04 |
| 2026-08-18 12:00 |
11:45:35.56 |
+14:10:41.9 |
HIP 57320 |
7.75 |
| 2026-08-19 00:00 |
11:45:38.37 |
+14:10:22.9 |
HIP 57320 |
8.48 |