| 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) |
| 2026-07-29 00:00 |
04:14:42.44 |
-09:55:09.9 |
HIP 19882 |
17.48 |
| 2026-07-29 12:00 |
04:14:44.47 |
-09:55:34.2 |
HIP 19882 |
16.94 |
| 2026-07-30 00:00 |
04:14:46.48 |
-09:55:58.8 |
HIP 19882 |
16.40 |
| 2026-07-30 12:00 |
04:14:48.45 |
-09:56:23.5 |
HIP 19882 |
15.88 |
| 2026-07-31 00:00 |
04:14:50.41 |
-09:56:48.4 |
HIP 19882 |
15.37 |
| 2026-07-31 12:00 |
04:14:52.33 |
-09:57:13.5 |
HIP 19882 |
14.88 |
| 2026-08-01 00:00 |
04:14:54.23 |
-09:57:38.8 |
HIP 19882 |
14.41 |
| 2026-08-01 12:00 |
04:14:56.10 |
-09:58:04.3 |
HIP 19882 |
13.96 |
| 2026-08-02 00:00 |
04:14:57.94 |
-09:58:29.9 |
HIP 19882 |
13.53 |
| 2026-08-02 12:00 |
04:14:59.76 |
-09:58:55.8 |
HIP 19882 |
13.12 |
| 2026-08-03 00:00 |
04:15:01.55 |
-09:59:21.7 |
HIP 19882 |
12.73 |
| 2026-08-03 12:00 |
04:15:03.31 |
-09:59:47.9 |
HIP 19882 |
12.37 |
| 2026-08-04 00:00 |
04:15:05.05 |
-10:00:14.3 |
HIP 19882 |
12.04 |
| 2026-08-04 12:00 |
04:15:06.76 |
-10:00:40.8 |
HIP 19882 |
11.74 |
| 2026-08-05 00:00 |
04:15:08.44 |
-10:01:07.4 |
HIP 19882 |
11.47 |
| 2026-08-05 12:00 |
04:15:10.09 |
-10:01:34.3 |
HIP 19882 |
11.23 |
| 2026-08-06 00:00 |
04:15:11.71 |
-10:02:01.3 |
HIP 19882 |
11.03 |
| 2026-08-06 12:00 |
04:15:13.31 |
-10:02:28.5 |
HIP 19882 |
10.87 |
| 2026-08-07 00:00 |
04:15:14.88 |
-10:02:55.8 |
HIP 19882 |
10.74 |
| 2026-08-07 12:00 |
04:15:16.42 |
-10:03:23.4 |
HIP 19882 |
10.66 |
| 2026-08-08 00:00 |
04:15:17.93 |
-10:03:51.0 |
HIP 19882 |
10.61 |
| 2026-08-08 12:00 |
04:15:19.42 |
-10:04:18.9 |
HIP 19882 |
10.61 |
| 2026-08-09 00:00 |
04:15:20.87 |
-10:04:46.9 |
HIP 19882 |
10.64 |
| 2026-08-09 12:00 |
04:15:22.30 |
-10:05:15.0 |
HIP 19882 |
10.71 |
| 2026-08-10 00:00 |
04:15:23.69 |
-10:05:43.3 |
HIP 19882 |
10.83 |
| 2026-08-10 12:00 |
04:15:25.06 |
-10:06:11.8 |
HIP 19882 |
10.97 |
| 2026-08-11 00:00 |
04:15:26.40 |
-10:06:40.4 |
HIP 19882 |
11.16 |
| 2026-08-11 12:00 |
04:15:27.71 |
-10:07:09.2 |
HIP 19882 |
11.37 |
| 2026-08-12 00:00 |
04:15:28.99 |
-10:07:38.1 |
HIP 19882 |
11.62 |
| 2026-08-12 12:00 |
04:15:30.24 |
-10:08:07.2 |
HIP 19882 |
11.89 |
| 2026-08-13 00:00 |
04:15:31.46 |
-10:08:36.4 |
HIP 19882 |
12.19 |
| 2026-08-13 12:00 |
04:15:32.65 |
-10:09:05.7 |
HIP 19882 |
12.52 |
| 2026-08-14 00:00 |
04:15:33.81 |
-10:09:35.2 |
HIP 19882 |
12.86 |
| 2026-08-14 12:00 |
04:15:34.94 |
-10:10:04.9 |
HIP 19882 |
13.23 |
| 2026-08-15 00:00 |
04:15:36.05 |
-10:10:34.7 |
HIP 19882 |
13.62 |
| 2026-08-15 12:00 |
04:15:37.12 |
-10:11:04.6 |
HIP 19882 |
14.02 |
| 2026-08-16 00:00 |
04:15:38.16 |
-10:11:34.6 |
HIP 19882 |
14.43 |
| 2026-08-16 12:00 |
04:15:39.17 |
-10:12:04.8 |
HIP 19882 |
14.86 |
| 2026-08-17 00:00 |
04:15:40.15 |
-10:12:35.1 |
HIP 19882 |
15.31 |
| 2026-08-17 12:00 |
04:15:41.10 |
-10:13:05.5 |
HIP 19938 |
15.67 |
| 2026-08-18 00:00 |
04:15:42.02 |
-10:13:36.1 |
HIP 19938 |
15.74 |
| 2026-08-18 12:00 |
04:15:42.91 |
-10:14:06.8 |
HIP 19938 |
15.84 |
| 2026-08-19 00:00 |
04:15:43.77 |
-10:14:37.6 |
HIP 19938 |
15.96 |