| Parameter |
Value |
| Designation |
C/2010 G2 (Hill) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2011-09-02T01:12:35.795520Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:42Z |
| Obs used |
4103 |
| NEO |
- |
| M1 |
10.800 |
| K1 |
6.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2011-07-30.0000000 |
| e |
0.97940713 |
| q (au) |
1.980774 |
| a (au) |
96.187351 |
| i (deg) |
103.745283 |
| Ω (om, deg) |
246.781006 |
| ω (w, deg) |
137.425281 |
| M (ma, deg) |
359.964425 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.346 + 2.260\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.346 |
| n |
2.260 |
| gf |
0.993 |
| gb |
-0.971 |
| k |
1.000 |
| δ90 |
9.997 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2010-04-10 |
2010-08-28 |
+14.9148 |
-10.749 |
| 2010-08-28 |
2011-05-04 |
-7.9772 |
+3.754 |
| 2011-05-04 |
2011-09-02 |
+19.9398 |
-7.392 |
| 2011-09-02 |
2012-01-01 |
+7.3113 |
-2.940 |
| 2012-01-01 |
2013-03-06 |
+3.5605 |
-2.360 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
22:29:42.45 |
-87:52:10.6 |
HIP 110397 |
5.96 |
| 2026-09-20 12:00 |
22:28:08.50 |
-87:51:53.1 |
HIP 110397 |
5.11 |
| 2026-09-21 00:00 |
22:26:35.32 |
-87:51:34.7 |
HIP 110397 |
4.29 |
| 2026-09-21 12:00 |
22:25:02.95 |
-87:51:15.6 |
HIP 110397 |
3.51 |
| 2026-09-22 00:00 |
22:23:31.40 |
-87:50:55.7 |
HIP 110397 |
2.82 |
| 2026-09-22 12:00 |
22:22:00.70 |
-87:50:35.0 |
HIP 110397 |
2.29 |
| 2026-09-23 00:00 |
22:20:30.87 |
-87:50:13.5 |
HIP 110397 |
2.05 |
| 2026-09-23 12:00 |
22:19:01.94 |
-87:49:51.2 |
HIP 110397 |
2.19 |
| 2026-09-24 00:00 |
22:17:33.91 |
-87:49:28.2 |
HIP 110397 |
2.65 |
| 2026-09-24 12:00 |
22:16:06.82 |
-87:49:04.5 |
HIP 110397 |
3.31 |
| 2026-09-25 00:00 |
22:14:40.67 |
-87:48:40.0 |
HIP 110397 |
4.06 |
| 2026-09-25 12:00 |
22:13:15.50 |
-87:48:14.8 |
HIP 110397 |
4.86 |
| 2026-09-26 00:00 |
22:11:51.30 |
-87:47:48.9 |
HIP 110397 |
5.70 |
| 2026-09-26 12:00 |
22:10:28.10 |
-87:47:22.3 |
HIP 110397 |
6.55 |
| 2026-09-27 00:00 |
22:09:05.91 |
-87:46:55.0 |
HIP 110397 |
7.42 |
| 2026-09-27 12:00 |
22:07:44.75 |
-87:46:27.0 |
HIP 110397 |
8.29 |
| 2026-09-28 00:00 |
22:06:24.62 |
-87:45:58.3 |
HIP 110397 |
9.17 |
| 2026-09-28 12:00 |
22:05:05.55 |
-87:45:29.0 |
HIP 110397 |
10.06 |
| 2026-09-29 00:00 |
22:03:47.53 |
-87:44:58.9 |
HIP 110397 |
10.94 |
| 2026-09-29 12:00 |
22:02:30.57 |
-87:44:28.3 |
HIP 110397 |
11.83 |
| 2026-09-30 00:00 |
22:01:14.70 |
-87:43:57.0 |
HIP 110397 |
12.72 |
| 2026-09-30 12:00 |
21:59:59.91 |
-87:43:25.1 |
HIP 110397 |
13.61 |
| 2026-10-01 00:00 |
21:58:46.21 |
-87:42:52.5 |
HIP 110397 |
14.50 |
| 2026-10-01 12:00 |
21:57:33.61 |
-87:42:19.3 |
HIP 110397 |
15.39 |
| 2026-10-02 00:00 |
21:56:22.11 |
-87:41:45.6 |
HIP 110397 |
16.29 |
| 2026-10-02 12:00 |
21:55:11.72 |
-87:41:11.2 |
HIP 110397 |
17.18 |
| 2026-10-03 00:00 |
21:54:02.44 |
-87:40:36.3 |
HIP 110397 |
18.07 |
| 2026-10-03 12:00 |
21:52:54.28 |
-87:40:00.8 |
HIP 110397 |
18.96 |
| 2026-10-04 00:00 |
21:51:47.24 |
-87:39:24.7 |
HIP 110397 |
19.85 |
| 2026-10-04 12:00 |
21:50:41.33 |
-87:38:48.1 |
HIP 110397 |
20.75 |
| 2026-10-05 00:00 |
21:49:36.53 |
-87:38:10.9 |
HIP 110397 |
21.64 |
| 2026-10-05 12:00 |
21:48:32.86 |
-87:37:33.2 |
HIP 110397 |
22.53 |
| 2026-10-06 00:00 |
21:47:30.31 |
-87:36:55.0 |
HIP 110397 |
23.42 |
| 2026-10-06 12:00 |
21:46:28.89 |
-87:36:16.3 |
HIP 110397 |
24.31 |
| 2026-10-07 00:00 |
21:45:28.59 |
-87:35:37.1 |
HIP 110397 |
25.20 |
| 2026-10-07 12:00 |
21:44:29.41 |
-87:34:57.4 |
HIP 106463 |
24.83 |
| 2026-10-08 00:00 |
21:43:31.35 |
-87:34:17.1 |
HIP 106463 |
24.01 |
| 2026-10-08 12:00 |
21:42:34.40 |
-87:33:36.5 |
HIP 106463 |
23.18 |
| 2026-10-09 00:00 |
21:41:38.57 |
-87:32:55.3 |
HIP 106463 |
22.36 |
| 2026-10-09 12:00 |
21:40:43.85 |
-87:32:13.7 |
HIP 106463 |
21.54 |
| 2026-10-10 00:00 |
21:39:50.23 |
-87:31:31.7 |
HIP 106463 |
20.73 |
| 2026-10-10 12:00 |
21:38:57.72 |
-87:30:49.2 |
HIP 106463 |
19.92 |
| 2026-10-11 00:00 |
21:38:06.30 |
-87:30:06.3 |
HIP 106463 |
19.12 |