| 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
$$
M_a = (10.330 + 2.265\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.330 |
| n |
2.265 |
| gf |
1.000 |
| gb |
-0.998 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2010-04-10 |
2010-08-28 |
+14.8129 |
-10.677 |
| 2010-08-28 |
2011-05-04 |
-8.0013 |
+3.774 |
| 2011-05-04 |
2011-09-02 |
+19.9294 |
-7.377 |
| 2011-09-02 |
2012-01-01 |
+7.1177 |
-2.882 |
| 2012-01-01 |
2013-03-06 |
+3.5813 |
-2.363 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
00:30:00.91 |
-84:46:53.0 |
HIP 1074 |
25.69 |
| 2026-05-12 12:00 |
00:30:27.35 |
-84:47:33.8 |
HIP 1074 |
25.86 |
| 2026-05-13 00:00 |
00:30:53.68 |
-84:48:14.8 |
HIP 1074 |
26.05 |
| 2026-05-13 12:00 |
00:31:19.90 |
-84:48:56.1 |
HIP 3899 |
26.03 |
| 2026-05-14 00:00 |
00:31:46.01 |
-84:49:37.8 |
HIP 3899 |
25.26 |
| 2026-05-14 12:00 |
00:32:11.99 |
-84:50:19.7 |
HIP 3899 |
24.50 |
| 2026-05-15 00:00 |
00:32:37.86 |
-84:51:01.9 |
HIP 3899 |
23.75 |
| 2026-05-15 12:00 |
00:33:03.61 |
-84:51:44.4 |
HIP 3899 |
23.02 |
| 2026-05-16 00:00 |
00:33:29.24 |
-84:52:27.2 |
HIP 3899 |
22.31 |
| 2026-05-16 12:00 |
00:33:54.75 |
-84:53:10.3 |
HIP 3899 |
21.62 |
| 2026-05-17 00:00 |
00:34:20.13 |
-84:53:53.7 |
HIP 3899 |
20.95 |
| 2026-05-17 12:00 |
00:34:45.39 |
-84:54:37.3 |
HIP 3899 |
20.30 |
| 2026-05-18 00:00 |
00:35:10.51 |
-84:55:21.3 |
HIP 3899 |
19.68 |
| 2026-05-18 12:00 |
00:35:35.51 |
-84:56:05.5 |
HIP 3899 |
19.09 |
| 2026-05-19 00:00 |
00:36:00.37 |
-84:56:50.0 |
HIP 2928 |
18.38 |
| 2026-05-19 12:00 |
00:36:25.11 |
-84:57:34.8 |
HIP 2928 |
17.60 |
| 2026-05-20 00:00 |
00:36:49.70 |
-84:58:19.8 |
HIP 2928 |
16.83 |
| 2026-05-20 12:00 |
00:37:14.16 |
-84:59:05.1 |
HIP 2928 |
16.07 |
| 2026-05-21 00:00 |
00:37:38.48 |
-84:59:50.7 |
HIP 2928 |
15.32 |
| 2026-05-21 12:00 |
00:38:02.65 |
-85:00:36.6 |
HIP 2928 |
14.59 |
| 2026-05-22 00:00 |
00:38:26.69 |
-85:01:22.7 |
HIP 2928 |
13.87 |
| 2026-05-22 12:00 |
00:38:50.58 |
-85:02:09.1 |
HIP 2928 |
13.18 |
| 2026-05-23 00:00 |
00:39:14.32 |
-85:02:55.7 |
HIP 2928 |
12.51 |
| 2026-05-23 12:00 |
00:39:37.92 |
-85:03:42.6 |
HIP 2928 |
11.87 |
| 2026-05-24 00:00 |
00:40:01.37 |
-85:04:29.8 |
HIP 2928 |
11.26 |
| 2026-05-24 12:00 |
00:40:24.67 |
-85:05:17.2 |
HIP 2928 |
10.69 |
| 2026-05-25 00:00 |
00:40:47.81 |
-85:06:04.9 |
HIP 2928 |
10.17 |
| 2026-05-25 12:00 |
00:41:10.80 |
-85:06:52.8 |
HIP 2928 |
9.71 |
| 2026-05-26 00:00 |
00:41:33.63 |
-85:07:40.9 |
HIP 2928 |
9.31 |
| 2026-05-26 12:00 |
00:41:56.30 |
-85:08:29.3 |
HIP 2928 |
8.98 |
| 2026-05-27 00:00 |
00:42:18.82 |
-85:09:18.0 |
HIP 2928 |
8.73 |
| 2026-05-27 12:00 |
00:42:41.17 |
-85:10:06.9 |
HIP 2928 |
8.57 |
| 2026-05-28 00:00 |
00:43:03.36 |
-85:10:56.0 |
HIP 2928 |
8.51 |
| 2026-05-28 12:00 |
00:43:25.38 |
-85:11:45.4 |
HIP 2928 |
8.54 |
| 2026-05-29 00:00 |
00:43:47.23 |
-85:12:35.0 |
HIP 2928 |
8.67 |
| 2026-05-29 12:00 |
00:44:08.91 |
-85:13:24.8 |
HIP 2928 |
8.89 |
| 2026-05-30 00:00 |
00:44:30.42 |
-85:14:14.9 |
HIP 2928 |
9.20 |
| 2026-05-30 12:00 |
00:44:51.76 |
-85:15:05.2 |
HIP 2928 |
9.58 |
| 2026-05-31 00:00 |
00:45:12.91 |
-85:15:55.7 |
HIP 2928 |
10.03 |
| 2026-05-31 12:00 |
00:45:33.89 |
-85:16:46.5 |
HIP 2928 |
10.55 |
| 2026-06-01 00:00 |
00:45:54.69 |
-85:17:37.4 |
HIP 2928 |
11.11 |
| 2026-06-01 12:00 |
00:46:15.30 |
-85:18:28.6 |
HIP 3053 |
11.04 |
| 2026-06-02 00:00 |
00:46:35.73 |
-85:19:20.0 |
HIP 3053 |
10.92 |