| 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 |
0.995 |
| 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) |
| 2026-03-26 00:00 |
11:47:35.15 |
+14:21:52.7 |
HIP 57606 |
16.15 |
| 2026-03-26 12:00 |
11:47:31.83 |
+14:22:15.3 |
HIP 57606 |
17.03 |
| 2026-03-27 00:00 |
11:47:28.51 |
+14:22:37.7 |
HIP 57606 |
17.91 |
| 2026-03-27 12:00 |
11:47:25.21 |
+14:23:00.0 |
HIP 57606 |
18.78 |
| 2026-03-28 00:00 |
11:47:21.90 |
+14:23:22.0 |
HIP 57606 |
19.66 |
| 2026-03-28 12:00 |
11:47:18.61 |
+14:23:44.0 |
HIP 57606 |
20.53 |
| 2026-03-29 00:00 |
11:47:15.32 |
+14:24:05.8 |
HIP 57428 |
20.85 |
| 2026-03-29 12:00 |
11:47:12.04 |
+14:24:27.5 |
HIP 57428 |
20.68 |
| 2026-03-30 00:00 |
11:47:08.76 |
+14:24:49.0 |
HIP 57428 |
20.54 |
| 2026-03-30 12:00 |
11:47:05.49 |
+14:25:10.4 |
HIP 57428 |
20.44 |
| 2026-03-31 00:00 |
11:47:02.23 |
+14:25:31.6 |
HIP 57428 |
20.37 |
| 2026-03-31 12:00 |
11:46:58.98 |
+14:25:52.7 |
HIP 57428 |
20.34 |
| 2026-04-01 00:00 |
11:46:55.73 |
+14:26:13.6 |
HIP 57428 |
20.34 |
| 2026-04-01 12:00 |
11:46:52.49 |
+14:26:34.4 |
HIP 57428 |
20.38 |
| 2026-04-02 00:00 |
11:46:49.26 |
+14:26:55.0 |
HIP 57428 |
20.45 |
| 2026-04-02 12:00 |
11:46:46.04 |
+14:27:15.4 |
HIP 57428 |
20.56 |
| 2026-04-03 00:00 |
11:46:42.83 |
+14:27:35.7 |
HIP 57428 |
20.69 |
| 2026-04-03 12:00 |
11:46:39.63 |
+14:27:55.9 |
HIP 57428 |
20.86 |
| 2026-04-04 00:00 |
11:46:36.43 |
+14:28:15.8 |
HIP 57428 |
21.06 |
| 2026-04-04 12:00 |
11:46:33.25 |
+14:28:35.6 |
HIP 57428 |
21.29 |
| 2026-04-05 00:00 |
11:46:30.07 |
+14:28:55.3 |
HIP 57428 |
21.54 |
| 2026-04-05 12:00 |
11:46:26.91 |
+14:29:14.8 |
HIP 57428 |
21.82 |
| 2026-04-06 00:00 |
11:46:23.76 |
+14:29:34.1 |
HIP 57428 |
22.13 |
| 2026-04-06 12:00 |
11:46:20.61 |
+14:29:53.2 |
HIP 57320 |
21.88 |
| 2026-04-07 00:00 |
11:46:17.48 |
+14:30:12.2 |
HIP 57320 |
21.52 |
| 2026-04-07 12:00 |
11:46:14.36 |
+14:30:31.0 |
HIP 57320 |
21.18 |
| 2026-04-08 00:00 |
11:46:11.25 |
+14:30:49.7 |
HIP 57320 |
20.87 |
| 2026-04-08 12:00 |
11:46:08.15 |
+14:31:08.2 |
HIP 57320 |
20.58 |
| 2026-04-09 00:00 |
11:46:05.07 |
+14:31:26.5 |
HIP 57320 |
20.33 |
| 2026-04-09 12:00 |
11:46:01.99 |
+14:31:44.6 |
HIP 57320 |
20.10 |
| 2026-04-10 00:00 |
11:45:58.93 |
+14:32:02.5 |
HIP 57320 |
19.90 |
| 2026-04-10 12:00 |
11:45:55.88 |
+14:32:20.3 |
HIP 57320 |
19.73 |
| 2026-04-11 00:00 |
11:45:52.84 |
+14:32:37.9 |
HIP 57320 |
19.59 |
| 2026-04-11 12:00 |
11:45:49.82 |
+14:32:55.4 |
HIP 57320 |
19.48 |
| 2026-04-12 00:00 |
11:45:46.81 |
+14:33:12.6 |
HIP 57320 |
19.40 |
| 2026-04-12 12:00 |
11:45:43.81 |
+14:33:29.7 |
HIP 57320 |
19.35 |
| 2026-04-13 00:00 |
11:45:40.83 |
+14:33:46.6 |
HIP 57320 |
19.33 |
| 2026-04-13 12:00 |
11:45:37.86 |
+14:34:03.3 |
HIP 57320 |
19.34 |
| 2026-04-14 00:00 |
11:45:34.90 |
+14:34:19.8 |
HIP 57320 |
19.38 |
| 2026-04-14 12:00 |
11:45:31.96 |
+14:34:36.1 |
HIP 57320 |
19.45 |
| 2026-04-15 00:00 |
11:45:29.04 |
+14:34:52.3 |
HIP 57320 |
19.54 |
| 2026-04-15 12:00 |
11:45:26.12 |
+14:35:08.3 |
HIP 57320 |
19.66 |
| 2026-04-16 00:00 |
11:45:23.23 |
+14:35:24.0 |
HIP 57320 |
19.81 |