| 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) |
| 2026-05-12 00:00 |
21:08:02.05 |
-11:09:27.4 |
HIP 104405 |
25.72 |
| 2026-05-12 12:00 |
21:08:02.26 |
-11:09:13.6 |
HIP 104405 |
25.50 |
| 2026-05-13 00:00 |
21:08:02.41 |
-11:09:00.1 |
HIP 104405 |
25.30 |
| 2026-05-13 12:00 |
21:08:02.51 |
-11:08:46.8 |
HIP 104405 |
25.11 |
| 2026-05-14 00:00 |
21:08:02.56 |
-11:08:33.7 |
HIP 104405 |
24.93 |
| 2026-05-14 12:00 |
21:08:02.55 |
-11:08:20.9 |
HIP 104405 |
24.75 |
| 2026-05-15 00:00 |
21:08:02.50 |
-11:08:08.2 |
HIP 104405 |
24.59 |
| 2026-05-15 12:00 |
21:08:02.39 |
-11:07:55.9 |
HIP 104405 |
24.45 |
| 2026-05-16 00:00 |
21:08:02.23 |
-11:07:43.7 |
HIP 104405 |
24.31 |
| 2026-05-16 12:00 |
21:08:02.02 |
-11:07:31.8 |
HIP 104405 |
24.19 |
| 2026-05-17 00:00 |
21:08:01.76 |
-11:07:20.1 |
HIP 104405 |
24.07 |
| 2026-05-17 12:00 |
21:08:01.45 |
-11:07:08.6 |
HIP 104405 |
23.97 |
| 2026-05-18 00:00 |
21:08:01.09 |
-11:06:57.4 |
HIP 104405 |
23.89 |
| 2026-05-18 12:00 |
21:08:00.67 |
-11:06:46.4 |
HIP 104405 |
23.81 |
| 2026-05-19 00:00 |
21:08:00.20 |
-11:06:35.7 |
HIP 104405 |
23.75 |
| 2026-05-19 12:00 |
21:07:59.69 |
-11:06:25.2 |
HIP 104405 |
23.70 |
| 2026-05-20 00:00 |
21:07:59.12 |
-11:06:14.9 |
HIP 104405 |
23.66 |
| 2026-05-20 12:00 |
21:07:58.50 |
-11:06:04.8 |
HIP 104405 |
23.64 |
| 2026-05-21 00:00 |
21:07:57.83 |
-11:05:55.0 |
HIP 104405 |
23.63 |
| 2026-05-21 12:00 |
21:07:57.11 |
-11:05:45.4 |
HIP 104405 |
23.63 |
| 2026-05-22 00:00 |
21:07:56.33 |
-11:05:36.1 |
HIP 104405 |
23.65 |
| 2026-05-22 12:00 |
21:07:55.51 |
-11:05:27.0 |
HIP 104405 |
23.68 |
| 2026-05-23 00:00 |
21:07:54.64 |
-11:05:18.1 |
HIP 104405 |
23.73 |
| 2026-05-23 12:00 |
21:07:53.71 |
-11:05:09.5 |
HIP 104405 |
23.79 |
| 2026-05-24 00:00 |
21:07:52.74 |
-11:05:01.1 |
HIP 104405 |
23.87 |
| 2026-05-24 12:00 |
21:07:51.71 |
-11:04:52.9 |
HIP 104405 |
23.96 |
| 2026-05-25 00:00 |
21:07:50.64 |
-11:04:45.0 |
HIP 104405 |
24.06 |
| 2026-05-25 12:00 |
21:07:49.52 |
-11:04:37.3 |
HIP 104405 |
24.18 |
| 2026-05-26 00:00 |
21:07:48.34 |
-11:04:29.9 |
HIP 104405 |
24.32 |
| 2026-05-26 12:00 |
21:07:47.12 |
-11:04:22.7 |
HIP 104405 |
24.47 |
| 2026-05-27 00:00 |
21:07:45.84 |
-11:04:15.7 |
HIP 104405 |
24.63 |
| 2026-05-27 12:00 |
21:07:44.52 |
-11:04:09.0 |
HIP 104405 |
24.81 |
| 2026-05-28 00:00 |
21:07:43.15 |
-11:04:02.5 |
HIP 104405 |
25.01 |
| 2026-05-28 12:00 |
21:07:41.73 |
-11:03:56.2 |
HIP 104405 |
25.22 |
| 2026-05-29 00:00 |
21:07:40.26 |
-11:03:50.2 |
HIP 104405 |
25.44 |
| 2026-05-29 12:00 |
21:07:38.74 |
-11:03:44.4 |
HIP 104405 |
25.69 |
| 2026-05-30 00:00 |
21:07:37.17 |
-11:03:38.8 |
HIP 104405 |
25.94 |
| 2026-05-30 12:00 |
21:07:35.55 |
-11:03:33.5 |
HIP 104405 |
26.22 |
| 2026-05-31 00:00 |
21:07:33.88 |
-11:03:28.4 |
HIP 104405 |
26.51 |
| 2026-05-31 12:00 |
21:07:32.17 |
-11:03:23.6 |
HIP 104405 |
26.81 |
| 2026-06-01 00:00 |
21:07:30.41 |
-11:03:19.0 |
HIP 104405 |
27.13 |
| 2026-06-01 12:00 |
21:07:28.60 |
-11:03:14.6 |
HIP 104405 |
27.47 |
| 2026-06-02 00:00 |
21:07:26.74 |
-11:03:10.5 |
HIP 104405 |
27.82 |