| Parameter |
Value |
| Designation |
C/2012 E1 (Hill) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2011-07-04T01:06:25.787520Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:04Z |
| Obs used |
98 |
| NEO |
- |
| M1 |
6.900 |
| K1 |
9.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2012-04-26.0000000 |
| e |
0.99801285 |
| q (au) |
7.502904 |
| a (au) |
3775.710106 |
| i (deg) |
122.542018 |
| Ω (om, deg) |
286.319642 |
| ω (w, deg) |
48.887314 |
| M (ma, deg) |
0.001262 |
Magnitude
Scatter + Global Linear
$$
M_a = (1.132 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
1.132 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.500 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
07:49:45.96 |
+31:25:21.2 |
HIP 38317 |
19.54 |
| 2026-07-29 12:00 |
07:49:49.98 |
+31:25:07.0 |
HIP 38317 |
19.00 |
| 2026-07-30 00:00 |
07:49:53.98 |
+31:24:52.8 |
HIP 38317 |
18.49 |
| 2026-07-30 12:00 |
07:49:57.98 |
+31:24:38.8 |
HIP 38317 |
18.00 |
| 2026-07-31 00:00 |
07:50:01.97 |
+31:24:24.8 |
HIP 38317 |
17.55 |
| 2026-07-31 12:00 |
07:50:05.96 |
+31:24:10.9 |
HIP 38317 |
17.13 |
| 2026-08-01 00:00 |
07:50:09.93 |
+31:23:57.2 |
HIP 38317 |
16.74 |
| 2026-08-01 12:00 |
07:50:13.90 |
+31:23:43.5 |
HIP 38317 |
16.40 |
| 2026-08-02 00:00 |
07:50:17.85 |
+31:23:29.9 |
HIP 38317 |
16.09 |
| 2026-08-02 12:00 |
07:50:21.80 |
+31:23:16.5 |
HIP 38317 |
15.83 |
| 2026-08-03 00:00 |
07:50:25.74 |
+31:23:03.1 |
HIP 38317 |
15.60 |
| 2026-08-03 12:00 |
07:50:29.67 |
+31:22:49.9 |
HIP 38317 |
15.43 |
| 2026-08-04 00:00 |
07:50:33.59 |
+31:22:36.7 |
HIP 38317 |
15.30 |
| 2026-08-04 12:00 |
07:50:37.50 |
+31:22:23.7 |
HIP 38317 |
15.21 |
| 2026-08-05 00:00 |
07:50:41.39 |
+31:22:10.7 |
HIP 38317 |
15.18 |
| 2026-08-05 12:00 |
07:50:45.28 |
+31:21:57.9 |
HIP 38317 |
15.19 |
| 2026-08-06 00:00 |
07:50:49.16 |
+31:21:45.1 |
HIP 38317 |
15.25 |
| 2026-08-06 12:00 |
07:50:53.02 |
+31:21:32.5 |
HIP 38317 |
15.35 |
| 2026-08-07 00:00 |
07:50:56.87 |
+31:21:19.9 |
HIP 38317 |
15.50 |
| 2026-08-07 12:00 |
07:51:00.71 |
+31:21:07.5 |
HIP 38317 |
15.69 |
| 2026-08-08 00:00 |
07:51:04.54 |
+31:20:55.2 |
HIP 38317 |
15.92 |
| 2026-08-08 12:00 |
07:51:08.36 |
+31:20:43.0 |
HIP 38317 |
16.20 |
| 2026-08-09 00:00 |
07:51:12.16 |
+31:20:30.9 |
HIP 38329 |
16.50 |
| 2026-08-09 12:00 |
07:51:15.95 |
+31:20:18.9 |
HIP 38329 |
16.78 |
| 2026-08-10 00:00 |
07:51:19.73 |
+31:20:07.0 |
HIP 38456 |
16.98 |
| 2026-08-10 12:00 |
07:51:23.49 |
+31:19:55.2 |
HIP 38456 |
16.21 |
| 2026-08-11 00:00 |
07:51:27.24 |
+31:19:43.6 |
HIP 38456 |
15.45 |
| 2026-08-11 12:00 |
07:51:30.97 |
+31:19:32.0 |
HIP 38456 |
14.69 |
| 2026-08-12 00:00 |
07:51:34.69 |
+31:19:20.6 |
HIP 38456 |
13.95 |
| 2026-08-12 12:00 |
07:51:38.40 |
+31:19:09.2 |
HIP 38456 |
13.21 |
| 2026-08-13 00:00 |
07:51:42.09 |
+31:18:58.0 |
HIP 38456 |
12.49 |
| 2026-08-13 12:00 |
07:51:45.76 |
+31:18:46.9 |
HIP 38456 |
11.78 |
| 2026-08-14 00:00 |
07:51:49.42 |
+31:18:35.9 |
HIP 38456 |
11.09 |
| 2026-08-14 12:00 |
07:51:53.06 |
+31:18:25.0 |
HIP 38456 |
10.42 |
| 2026-08-15 00:00 |
07:51:56.68 |
+31:18:14.3 |
HIP 38456 |
9.77 |
| 2026-08-15 12:00 |
07:52:00.29 |
+31:18:03.6 |
HIP 38456 |
9.14 |
| 2026-08-16 00:00 |
07:52:03.88 |
+31:17:53.1 |
HIP 38456 |
8.54 |
| 2026-08-16 12:00 |
07:52:07.46 |
+31:17:42.6 |
HIP 38456 |
7.98 |
| 2026-08-17 00:00 |
07:52:11.01 |
+31:17:32.3 |
HIP 38456 |
7.46 |
| 2026-08-17 12:00 |
07:52:14.55 |
+31:17:22.2 |
HIP 38456 |
6.99 |
| 2026-08-18 00:00 |
07:52:18.07 |
+31:17:12.1 |
HIP 38456 |
6.57 |
| 2026-08-18 12:00 |
07:52:21.57 |
+31:17:02.1 |
HIP 38456 |
6.23 |
| 2026-08-19 00:00 |
07:52:25.06 |
+31:16:52.3 |
HIP 38456 |
5.96 |