| Parameter |
Value |
| Designation |
C/2009 UG89 (Lemmon) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2010-12-16T06:17:33.682560Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:37Z |
| Obs used |
966 |
| NEO |
- |
| M1 |
5.200 |
| K1 |
15.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2010-10-30.0000000 |
| e |
1.00795978 |
| q (au) |
3.931171 |
| a (au) |
-493.879168 |
| i (deg) |
130.099828 |
| Ω (om, deg) |
321.007061 |
| ω (w, deg) |
60.651338 |
| M (ma, deg) |
-0.004244 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.775 + 2.529\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.775 |
| n |
2.529 |
| gf |
0.926 |
| gb |
-1.000 |
| k |
0.994 |
| δ90 |
9.428 |
| 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) |
| 2026-09-25 00:00 |
08:33:59.63 |
+03:59:51.0 |
HIP 41886 |
30.02 |
| 2026-09-25 12:00 |
08:34:01.27 |
+03:59:29.8 |
HIP 41886 |
30.11 |
| 2026-09-26 00:00 |
08:34:02.89 |
+03:59:08.6 |
HIP 41886 |
30.20 |
| 2026-09-26 12:00 |
08:34:04.48 |
+03:58:47.4 |
HIP 42034 |
30.02 |
| 2026-09-27 00:00 |
08:34:06.05 |
+03:58:26.2 |
HIP 42034 |
29.66 |
| 2026-09-27 12:00 |
08:34:07.59 |
+03:58:05.0 |
HIP 42034 |
29.31 |
| 2026-09-28 00:00 |
08:34:09.11 |
+03:57:43.9 |
HIP 42034 |
28.97 |
| 2026-09-28 12:00 |
08:34:10.60 |
+03:57:22.8 |
HIP 42034 |
28.63 |
| 2026-09-29 00:00 |
08:34:12.07 |
+03:57:01.7 |
HIP 42034 |
28.29 |
| 2026-09-29 12:00 |
08:34:13.51 |
+03:56:40.7 |
HIP 42034 |
27.97 |
| 2026-09-30 00:00 |
08:34:14.93 |
+03:56:19.6 |
HIP 42034 |
27.64 |
| 2026-09-30 12:00 |
08:34:16.32 |
+03:55:58.7 |
HIP 42034 |
27.33 |
| 2026-10-01 00:00 |
08:34:17.69 |
+03:55:37.7 |
HIP 42034 |
27.01 |
| 2026-10-01 12:00 |
08:34:19.03 |
+03:55:16.8 |
HIP 42034 |
26.70 |
| 2026-10-02 00:00 |
08:34:20.34 |
+03:54:55.9 |
HIP 42034 |
26.40 |
| 2026-10-02 12:00 |
08:34:21.63 |
+03:54:35.0 |
HIP 42034 |
26.10 |
| 2026-10-03 00:00 |
08:34:22.89 |
+03:54:14.2 |
HIP 42034 |
25.81 |
| 2026-10-03 12:00 |
08:34:24.12 |
+03:53:53.4 |
HIP 42034 |
25.52 |
| 2026-10-04 00:00 |
08:34:25.33 |
+03:53:32.7 |
HIP 42034 |
25.24 |
| 2026-10-04 12:00 |
08:34:26.51 |
+03:53:12.0 |
HIP 42034 |
24.96 |
| 2026-10-05 00:00 |
08:34:27.67 |
+03:52:51.3 |
HIP 42034 |
24.68 |
| 2026-10-05 12:00 |
08:34:28.80 |
+03:52:30.7 |
HIP 42034 |
24.41 |
| 2026-10-06 00:00 |
08:34:29.90 |
+03:52:10.2 |
HIP 42034 |
24.15 |
| 2026-10-06 12:00 |
08:34:30.97 |
+03:51:49.6 |
HIP 42034 |
23.88 |
| 2026-10-07 00:00 |
08:34:32.01 |
+03:51:29.2 |
HIP 42034 |
23.63 |
| 2026-10-07 12:00 |
08:34:33.03 |
+03:51:08.8 |
HIP 42034 |
23.37 |
| 2026-10-08 00:00 |
08:34:34.02 |
+03:50:48.4 |
HIP 42034 |
23.12 |
| 2026-10-08 12:00 |
08:34:34.98 |
+03:50:28.1 |
HIP 42034 |
22.87 |
| 2026-10-09 00:00 |
08:34:35.91 |
+03:50:07.8 |
HIP 42034 |
22.63 |
| 2026-10-09 12:00 |
08:34:36.82 |
+03:49:47.6 |
HIP 42034 |
22.39 |
| 2026-10-10 00:00 |
08:34:37.70 |
+03:49:27.4 |
HIP 42034 |
22.15 |
| 2026-10-10 12:00 |
08:34:38.55 |
+03:49:07.3 |
HIP 42034 |
21.91 |
| 2026-10-11 00:00 |
08:34:39.37 |
+03:48:47.3 |
HIP 42034 |
21.68 |
| 2026-10-11 12:00 |
08:34:40.16 |
+03:48:27.3 |
HIP 42034 |
21.45 |
| 2026-10-12 00:00 |
08:34:40.92 |
+03:48:07.4 |
HIP 42034 |
21.23 |
| 2026-10-12 12:00 |
08:34:41.65 |
+03:47:47.6 |
HIP 42034 |
21.00 |
| 2026-10-13 00:00 |
08:34:42.36 |
+03:47:27.8 |
HIP 42034 |
20.78 |
| 2026-10-13 12:00 |
08:34:43.03 |
+03:47:08.1 |
HIP 42034 |
20.56 |
| 2026-10-14 00:00 |
08:34:43.68 |
+03:46:48.4 |
HIP 42034 |
20.34 |
| 2026-10-14 12:00 |
08:34:44.30 |
+03:46:28.9 |
HIP 42034 |
20.13 |
| 2026-10-15 00:00 |
08:34:44.88 |
+03:46:09.3 |
HIP 42034 |
19.91 |
| 2026-10-15 12:00 |
08:34:45.44 |
+03:45:49.9 |
HIP 42034 |
19.70 |
| 2026-10-16 00:00 |
08:34:45.97 |
+03:45:30.5 |
HIP 42034 |
19.49 |