| Parameter |
Value |
| Designation |
C/2007 S2 (Lemmon) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2008-09-14T20:38:31.534080Z |
| Orbit solution date (soln_date, UTC) |
2024-04-13T16:42:27Z |
| Obs used |
423 |
| NEO |
- |
| M1 |
10.500 |
| K1 |
6.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2008-07-02.0000000 |
| e |
0.55701356 |
| q (au) |
5.557956 |
| a (au) |
12.546561 |
| i (deg) |
16.862815 |
| Ω (om, deg) |
296.252831 |
| ω (w, deg) |
210.466010 |
| M (ma, deg) |
358.339773 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.208 + 2.571\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.208 |
| n |
2.571 |
| gf |
1.000 |
| gb |
-0.969 |
| 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) |
| 2026-09-20 00:00 |
20:51:07.95 |
-11:52:41.9 |
HIP 102994 |
29.33 |
| 2026-09-20 12:00 |
20:51:04.54 |
-11:52:58.6 |
HIP 102994 |
29.95 |
| 2026-09-21 00:00 |
20:51:01.18 |
-11:53:15.2 |
HIP 102994 |
30.58 |
| 2026-09-21 12:00 |
20:50:57.86 |
-11:53:31.7 |
HIP 102994 |
31.22 |
| 2026-09-22 00:00 |
20:50:54.58 |
-11:53:48.1 |
HIP 102994 |
31.85 |
| 2026-09-22 12:00 |
20:50:51.34 |
-11:54:04.3 |
HIP 102994 |
32.49 |
| 2026-09-23 00:00 |
20:50:48.15 |
-11:54:20.4 |
HIP 102994 |
33.14 |
| 2026-09-23 12:00 |
20:50:45.00 |
-11:54:36.4 |
HIP 102785 |
33.60 |
| 2026-09-24 00:00 |
20:50:41.89 |
-11:54:52.3 |
HIP 102785 |
33.38 |
| 2026-09-24 12:00 |
20:50:38.83 |
-11:55:08.0 |
HIP 102785 |
33.18 |
| 2026-09-25 00:00 |
20:50:35.81 |
-11:55:23.6 |
HIP 102785 |
33.00 |
| 2026-09-25 12:00 |
20:50:32.84 |
-11:55:39.0 |
HIP 102785 |
32.85 |
| 2026-09-26 00:00 |
20:50:29.91 |
-11:55:54.3 |
HIP 102785 |
32.72 |
| 2026-09-26 12:00 |
20:50:27.02 |
-11:56:09.5 |
HIP 102785 |
32.60 |
| 2026-09-27 00:00 |
20:50:24.18 |
-11:56:24.6 |
HIP 102785 |
32.51 |
| 2026-09-27 12:00 |
20:50:21.39 |
-11:56:39.4 |
HIP 102785 |
32.44 |
| 2026-09-28 00:00 |
20:50:18.64 |
-11:56:54.2 |
HIP 102785 |
32.38 |
| 2026-09-28 12:00 |
20:50:15.94 |
-11:57:08.8 |
HIP 102785 |
32.34 |
| 2026-09-29 00:00 |
20:50:13.28 |
-11:57:23.3 |
HIP 102785 |
32.32 |
| 2026-09-29 12:00 |
20:50:10.67 |
-11:57:37.6 |
HIP 102785 |
32.32 |
| 2026-09-30 00:00 |
20:50:08.11 |
-11:57:51.8 |
HIP 102785 |
32.33 |
| 2026-09-30 12:00 |
20:50:05.59 |
-11:58:05.8 |
HIP 102785 |
32.36 |
| 2026-10-01 00:00 |
20:50:03.12 |
-11:58:19.7 |
HIP 102785 |
32.40 |
| 2026-10-01 12:00 |
20:50:00.70 |
-11:58:33.4 |
HIP 102785 |
32.45 |
| 2026-10-02 00:00 |
20:49:58.33 |
-11:58:47.0 |
HIP 102785 |
32.52 |
| 2026-10-02 12:00 |
20:49:56.00 |
-11:59:00.4 |
HIP 102785 |
32.60 |
| 2026-10-03 00:00 |
20:49:53.72 |
-11:59:13.6 |
HIP 102785 |
32.69 |
| 2026-10-03 12:00 |
20:49:51.49 |
-11:59:26.7 |
HIP 102785 |
32.79 |
| 2026-10-04 00:00 |
20:49:49.31 |
-11:59:39.7 |
HIP 102785 |
32.90 |
| 2026-10-04 12:00 |
20:49:47.18 |
-11:59:52.4 |
HIP 102785 |
33.02 |
| 2026-10-05 00:00 |
20:49:45.09 |
-12:00:05.0 |
HIP 102785 |
33.15 |
| 2026-10-05 12:00 |
20:49:43.06 |
-12:00:17.5 |
HIP 102785 |
33.29 |
| 2026-10-06 00:00 |
20:49:41.08 |
-12:00:29.8 |
HIP 102785 |
33.43 |
| 2026-10-06 12:00 |
20:49:39.14 |
-12:00:41.9 |
HIP 102664 |
33.56 |
| 2026-10-07 00:00 |
20:49:37.25 |
-12:00:53.8 |
HIP 102664 |
33.12 |
| 2026-10-07 12:00 |
20:49:35.42 |
-12:01:05.6 |
HIP 102664 |
32.70 |
| 2026-10-08 00:00 |
20:49:33.63 |
-12:01:17.2 |
HIP 102664 |
32.28 |
| 2026-10-08 12:00 |
20:49:31.90 |
-12:01:28.6 |
HIP 102664 |
31.88 |
| 2026-10-09 00:00 |
20:49:30.21 |
-12:01:39.9 |
HIP 102664 |
31.48 |
| 2026-10-09 12:00 |
20:49:28.58 |
-12:01:50.9 |
HIP 102664 |
31.10 |
| 2026-10-10 00:00 |
20:49:27.00 |
-12:02:01.8 |
HIP 102664 |
30.73 |
| 2026-10-10 12:00 |
20:49:25.47 |
-12:02:12.6 |
HIP 102664 |
30.37 |
| 2026-10-11 00:00 |
20:49:23.99 |
-12:02:23.1 |
HIP 102664 |
30.02 |