| 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) |
| 2026-03-26 00:00 |
21:04:05.31 |
-11:45:30.5 |
HIP 103801 |
30.94 |
| 2026-03-26 12:00 |
21:04:09.88 |
-11:45:00.3 |
HIP 103801 |
31.99 |
| 2026-03-27 00:00 |
21:04:14.42 |
-11:44:30.1 |
HIP 103801 |
33.05 |
| 2026-03-27 12:00 |
21:04:18.91 |
-11:44:00.1 |
HIP 103801 |
34.12 |
| 2026-03-28 00:00 |
21:04:23.37 |
-11:43:30.2 |
HIP 104186 |
34.03 |
| 2026-03-28 12:00 |
21:04:27.79 |
-11:43:00.4 |
HIP 104186 |
33.25 |
| 2026-03-29 00:00 |
21:04:32.17 |
-11:42:30.7 |
HIP 104186 |
32.51 |
| 2026-03-29 12:00 |
21:04:36.51 |
-11:42:01.1 |
HIP 104186 |
31.81 |
| 2026-03-30 00:00 |
21:04:40.81 |
-11:41:31.7 |
HIP 104186 |
31.13 |
| 2026-03-30 12:00 |
21:04:45.07 |
-11:41:02.4 |
HIP 104186 |
30.50 |
| 2026-03-31 00:00 |
21:04:49.29 |
-11:40:33.2 |
HIP 104186 |
29.90 |
| 2026-03-31 12:00 |
21:04:53.47 |
-11:40:04.1 |
HIP 104186 |
29.34 |
| 2026-04-01 00:00 |
21:04:57.62 |
-11:39:35.2 |
HIP 104186 |
28.82 |
| 2026-04-01 12:00 |
21:05:01.72 |
-11:39:06.4 |
HIP 104186 |
28.34 |
| 2026-04-02 00:00 |
21:05:05.78 |
-11:38:37.7 |
HIP 104186 |
27.91 |
| 2026-04-02 12:00 |
21:05:09.80 |
-11:38:09.1 |
HIP 104186 |
27.52 |
| 2026-04-03 00:00 |
21:05:13.78 |
-11:37:40.7 |
HIP 104186 |
27.17 |
| 2026-04-03 12:00 |
21:05:17.71 |
-11:37:12.4 |
HIP 104186 |
26.86 |
| 2026-04-04 00:00 |
21:05:21.61 |
-11:36:44.2 |
HIP 104186 |
26.60 |
| 2026-04-04 12:00 |
21:05:25.47 |
-11:36:16.2 |
HIP 104186 |
26.38 |
| 2026-04-05 00:00 |
21:05:29.28 |
-11:35:48.4 |
HIP 104186 |
26.21 |
| 2026-04-05 12:00 |
21:05:33.05 |
-11:35:20.6 |
HIP 104186 |
26.09 |
| 2026-04-06 00:00 |
21:05:36.78 |
-11:34:53.0 |
HIP 104186 |
26.00 |
| 2026-04-06 12:00 |
21:05:40.46 |
-11:34:25.6 |
HIP 104186 |
25.96 |
| 2026-04-07 00:00 |
21:05:44.10 |
-11:33:58.2 |
HIP 104186 |
25.96 |
| 2026-04-07 12:00 |
21:05:47.70 |
-11:33:31.1 |
HIP 104186 |
26.00 |
| 2026-04-08 00:00 |
21:05:51.26 |
-11:33:04.1 |
HIP 104186 |
26.08 |
| 2026-04-08 12:00 |
21:05:54.77 |
-11:32:37.2 |
HIP 104186 |
26.20 |
| 2026-04-09 00:00 |
21:05:58.24 |
-11:32:10.5 |
HIP 104186 |
26.36 |
| 2026-04-09 12:00 |
21:06:01.67 |
-11:31:43.9 |
HIP 104186 |
26.54 |
| 2026-04-10 00:00 |
21:06:05.05 |
-11:31:17.5 |
HIP 104186 |
26.76 |
| 2026-04-10 12:00 |
21:06:08.38 |
-11:30:51.2 |
HIP 104186 |
27.02 |
| 2026-04-11 00:00 |
21:06:11.67 |
-11:30:25.1 |
HIP 104186 |
27.29 |
| 2026-04-11 12:00 |
21:06:14.92 |
-11:29:59.2 |
HIP 104186 |
27.60 |
| 2026-04-12 00:00 |
21:06:18.12 |
-11:29:33.4 |
HIP 104186 |
27.93 |
| 2026-04-12 12:00 |
21:06:21.28 |
-11:29:07.7 |
HIP 104186 |
28.28 |
| 2026-04-13 00:00 |
21:06:24.39 |
-11:28:42.3 |
HIP 104186 |
28.66 |
| 2026-04-13 12:00 |
21:06:27.46 |
-11:28:17.0 |
HIP 104186 |
29.05 |
| 2026-04-14 00:00 |
21:06:30.48 |
-11:27:51.8 |
HIP 104186 |
29.46 |
| 2026-04-14 12:00 |
21:06:33.45 |
-11:27:26.9 |
HIP 104186 |
29.88 |
| 2026-04-15 00:00 |
21:06:36.38 |
-11:27:02.1 |
HIP 104186 |
30.32 |
| 2026-04-15 12:00 |
21:06:39.26 |
-11:26:37.4 |
HIP 104186 |
30.77 |
| 2026-04-16 00:00 |
21:06:42.09 |
-11:26:13.0 |
HIP 104186 |
31.24 |