| Parameter |
Value |
| Designation |
C/2008 FK75 (Lemmon-Siding Spring) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2010-09-29T05:04:17.762880Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:18Z |
| Obs used |
3622 |
| NEO |
- |
| M1 |
9.700 |
| K1 |
5.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2010-07-21.0000000 |
| e |
1.00270288 |
| q (au) |
4.510895 |
| a (au) |
-1668.924210 |
| i (deg) |
61.175512 |
| Ω (om, deg) |
218.266231 |
| ω (w, deg) |
80.415044 |
| M (ma, deg) |
-0.001015 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.961 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.961 |
| n |
2.000 |
| gf |
0.913 |
| gb |
-1.000 |
| k |
0.999 |
| δ90 |
1.000 |
| 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 |
04:06:00.64 |
-09:37:21.4 |
HIP 19226 |
20.21 |
| 2026-05-12 12:00 |
04:06:04.44 |
-09:37:10.3 |
HIP 19226 |
19.43 |
| 2026-05-13 00:00 |
04:06:08.25 |
-09:36:59.3 |
HIP 19226 |
18.67 |
| 2026-05-13 12:00 |
04:06:12.06 |
-09:36:48.6 |
HIP 19226 |
17.92 |
| 2026-05-14 00:00 |
04:06:15.88 |
-09:36:38.1 |
HIP 19226 |
17.19 |
| 2026-05-14 12:00 |
04:06:19.71 |
-09:36:27.8 |
HIP 19226 |
16.49 |
| 2026-05-15 00:00 |
04:06:23.54 |
-09:36:17.7 |
HIP 19226 |
15.80 |
| 2026-05-15 12:00 |
04:06:27.37 |
-09:36:07.8 |
HIP 19226 |
15.14 |
| 2026-05-16 00:00 |
04:06:31.21 |
-09:35:58.2 |
HIP 19226 |
14.51 |
| 2026-05-16 12:00 |
04:06:35.05 |
-09:35:48.7 |
HIP 19226 |
13.92 |
| 2026-05-17 00:00 |
04:06:38.90 |
-09:35:39.5 |
HIP 19226 |
13.37 |
| 2026-05-17 12:00 |
04:06:42.75 |
-09:35:30.6 |
HIP 19226 |
12.86 |
| 2026-05-18 00:00 |
04:06:46.60 |
-09:35:21.8 |
HIP 19226 |
12.40 |
| 2026-05-18 12:00 |
04:06:50.46 |
-09:35:13.3 |
HIP 19226 |
11.99 |
| 2026-05-19 00:00 |
04:06:54.32 |
-09:35:05.0 |
HIP 19226 |
11.65 |
| 2026-05-19 12:00 |
04:06:58.18 |
-09:34:56.9 |
HIP 19226 |
11.38 |
| 2026-05-20 00:00 |
04:07:02.04 |
-09:34:49.1 |
HIP 19226 |
11.17 |
| 2026-05-20 12:00 |
04:07:05.91 |
-09:34:41.4 |
HIP 19226 |
11.05 |
| 2026-05-21 00:00 |
04:07:09.78 |
-09:34:34.0 |
HIP 19226 |
11.00 |
| 2026-05-21 12:00 |
04:07:13.65 |
-09:34:26.9 |
HIP 19226 |
11.03 |
| 2026-05-22 00:00 |
04:07:17.52 |
-09:34:19.9 |
HIP 19226 |
11.14 |
| 2026-05-22 12:00 |
04:07:21.39 |
-09:34:13.2 |
HIP 19226 |
11.33 |
| 2026-05-23 00:00 |
04:07:25.27 |
-09:34:06.7 |
HIP 19226 |
11.60 |
| 2026-05-23 12:00 |
04:07:29.14 |
-09:34:00.5 |
HIP 19226 |
11.93 |
| 2026-05-24 00:00 |
04:07:33.01 |
-09:33:54.5 |
HIP 19226 |
12.32 |
| 2026-05-24 12:00 |
04:07:36.89 |
-09:33:48.7 |
HIP 19226 |
12.77 |
| 2026-05-25 00:00 |
04:07:40.76 |
-09:33:43.1 |
HIP 19226 |
13.27 |
| 2026-05-25 12:00 |
04:07:44.64 |
-09:33:37.8 |
HIP 19226 |
13.82 |
| 2026-05-26 00:00 |
04:07:48.51 |
-09:33:32.7 |
HIP 19226 |
14.40 |
| 2026-05-26 12:00 |
04:07:52.38 |
-09:33:27.8 |
HIP 19226 |
15.02 |
| 2026-05-27 00:00 |
04:07:56.26 |
-09:33:23.2 |
HIP 19226 |
15.67 |
| 2026-05-27 12:00 |
04:08:00.13 |
-09:33:18.8 |
HIP 19226 |
16.35 |
| 2026-05-28 00:00 |
04:08:04.00 |
-09:33:14.7 |
HIP 19226 |
17.05 |
| 2026-05-28 12:00 |
04:08:07.86 |
-09:33:10.7 |
HIP 19226 |
17.78 |
| 2026-05-29 00:00 |
04:08:11.73 |
-09:33:07.0 |
HIP 19226 |
18.52 |
| 2026-05-29 12:00 |
04:08:15.59 |
-09:33:03.6 |
HIP 19226 |
19.28 |
| 2026-05-30 00:00 |
04:08:19.46 |
-09:33:00.4 |
HIP 19226 |
20.05 |
| 2026-05-30 12:00 |
04:08:23.32 |
-09:32:57.4 |
HIP 19226 |
20.83 |
| 2026-05-31 00:00 |
04:08:27.17 |
-09:32:54.6 |
HIP 19226 |
21.63 |
| 2026-05-31 12:00 |
04:08:31.03 |
-09:32:52.1 |
HIP 19448 |
22.03 |
| 2026-06-01 00:00 |
04:08:34.88 |
-09:32:49.8 |
HIP 19448 |
21.17 |
| 2026-06-01 12:00 |
04:08:38.73 |
-09:32:47.8 |
HIP 19448 |
20.31 |
| 2026-06-02 00:00 |
04:08:42.57 |
-09:32:46.0 |
HIP 19448 |
19.46 |