| Parameter |
Value |
| Designation |
C/2009 U3 (Hill) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2010-03-20T06:06:49.440960Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:36Z |
| Obs used |
602 |
| NEO |
- |
| M1 |
15.400 |
| K1 |
6.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2010-01-01.0000000 |
| e |
0.99157651 |
| q (au) |
1.414425 |
| a (au) |
167.914294 |
| i (deg) |
51.260767 |
| Ω (om, deg) |
49.322883 |
| ω (w, deg) |
77.701400 |
| M (ma, deg) |
359.964553 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.668 + 5.160\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.668 |
| n |
5.160 |
| gf |
1.000 |
| gb |
-0.772 |
| k |
0.984 |
| δ90 |
9.994 |
| 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 |
| 2009-10-20 |
2009-11-16 |
-11.6949 |
+4.120 |
| 2009-11-16 |
2009-12-24 |
+7.8048 |
-2.355 |
| 2009-12-24 |
2010-01-26 |
-15.1111 |
+3.692 |
| 2010-01-26 |
2010-03-19 |
+34.3857 |
-6.645 |
| 2010-03-24 |
2010-05-14 |
+6.6096 |
-1.956 |
| 2010-05-14 |
2010-06-18 |
-14.3864 |
+3.611 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
18:15:46.05 |
-64:18:50.6 |
HIP 89200 |
30.37 |
| 2026-06-01 12:00 |
18:15:38.94 |
-64:19:06.7 |
HIP 89200 |
29.95 |
| 2026-06-02 00:00 |
18:15:31.80 |
-64:19:22.5 |
HIP 89200 |
29.56 |
| 2026-06-02 12:00 |
18:15:24.63 |
-64:19:38.0 |
HIP 89200 |
29.17 |
| 2026-06-03 00:00 |
18:15:17.44 |
-64:19:53.3 |
HIP 89200 |
28.80 |
| 2026-06-03 12:00 |
18:15:10.21 |
-64:20:08.2 |
HIP 89103 |
28.39 |
| 2026-06-04 00:00 |
18:15:02.96 |
-64:20:22.9 |
HIP 89103 |
27.57 |
| 2026-06-04 12:00 |
18:14:55.69 |
-64:20:37.3 |
HIP 89103 |
26.76 |
| 2026-06-05 00:00 |
18:14:48.39 |
-64:20:51.4 |
HIP 89103 |
25.94 |
| 2026-06-05 12:00 |
18:14:41.06 |
-64:21:05.1 |
HIP 89103 |
25.12 |
| 2026-06-06 00:00 |
18:14:33.71 |
-64:21:18.6 |
HIP 89103 |
24.30 |
| 2026-06-06 12:00 |
18:14:26.33 |
-64:21:31.8 |
HIP 89103 |
23.48 |
| 2026-06-07 00:00 |
18:14:18.94 |
-64:21:44.7 |
HIP 89103 |
22.66 |
| 2026-06-07 12:00 |
18:14:11.51 |
-64:21:57.3 |
HIP 89103 |
21.85 |
| 2026-06-08 00:00 |
18:14:04.07 |
-64:22:09.6 |
HIP 89103 |
21.03 |
| 2026-06-08 12:00 |
18:13:56.61 |
-64:22:21.6 |
HIP 89103 |
20.22 |
| 2026-06-09 00:00 |
18:13:49.12 |
-64:22:33.3 |
HIP 89103 |
19.40 |
| 2026-06-09 12:00 |
18:13:41.61 |
-64:22:44.6 |
HIP 89103 |
18.59 |
| 2026-06-10 00:00 |
18:13:34.09 |
-64:22:55.7 |
HIP 89103 |
17.78 |
| 2026-06-10 12:00 |
18:13:26.54 |
-64:23:06.5 |
HIP 89103 |
16.98 |
| 2026-06-11 00:00 |
18:13:18.98 |
-64:23:16.9 |
HIP 89103 |
16.17 |
| 2026-06-11 12:00 |
18:13:11.40 |
-64:23:27.1 |
HIP 89103 |
15.38 |
| 2026-06-12 00:00 |
18:13:03.80 |
-64:23:36.9 |
HIP 89103 |
14.58 |
| 2026-06-12 12:00 |
18:12:56.19 |
-64:23:46.5 |
HIP 89103 |
13.80 |
| 2026-06-13 00:00 |
18:12:48.56 |
-64:23:55.7 |
HIP 89103 |
13.02 |
| 2026-06-13 12:00 |
18:12:40.92 |
-64:24:04.6 |
HIP 89103 |
12.25 |
| 2026-06-14 00:00 |
18:12:33.26 |
-64:24:13.2 |
HIP 89103 |
11.49 |
| 2026-06-14 12:00 |
18:12:25.59 |
-64:24:21.5 |
HIP 89103 |
10.75 |
| 2026-06-15 00:00 |
18:12:17.90 |
-64:24:29.5 |
HIP 89103 |
10.03 |
| 2026-06-15 12:00 |
18:12:10.21 |
-64:24:37.1 |
HIP 89103 |
9.32 |
| 2026-06-16 00:00 |
18:12:02.50 |
-64:24:44.5 |
HIP 89103 |
8.65 |
| 2026-06-16 12:00 |
18:11:54.78 |
-64:24:51.5 |
HIP 89103 |
8.00 |
| 2026-06-17 00:00 |
18:11:47.06 |
-64:24:58.2 |
HIP 89103 |
7.41 |
| 2026-06-17 12:00 |
18:11:39.32 |
-64:25:04.6 |
HIP 89103 |
6.86 |
| 2026-06-18 00:00 |
18:11:31.58 |
-64:25:10.6 |
HIP 89103 |
6.39 |
| 2026-06-18 12:00 |
18:11:23.83 |
-64:25:16.4 |
HIP 89103 |
6.00 |
| 2026-06-19 00:00 |
18:11:16.07 |
-64:25:21.8 |
HIP 89103 |
5.72 |
| 2026-06-19 12:00 |
18:11:08.30 |
-64:25:27.0 |
HIP 89103 |
5.55 |
| 2026-06-20 00:00 |
18:11:00.53 |
-64:25:31.8 |
HIP 89103 |
5.51 |
| 2026-06-20 12:00 |
18:10:52.76 |
-64:25:36.2 |
HIP 89103 |
5.61 |
| 2026-06-21 00:00 |
18:10:44.98 |
-64:25:40.4 |
HIP 89103 |
5.83 |
| 2026-06-21 12:00 |
18:10:37.20 |
-64:25:44.2 |
HIP 89103 |
6.17 |
| 2026-06-22 00:00 |
18:10:29.41 |
-64:25:47.8 |
HIP 89103 |
6.60 |