| Parameter |
Value |
| Designation |
C/2017 F1 (Lemmon) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-11-30T23:48:42.943680Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:32Z |
| Obs used |
89 |
| NEO |
- |
| M1 |
8.300 |
| K1 |
13.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-06-10.0000000 |
| e |
1.00410815 |
| q (au) |
4.499798 |
| a (au) |
-1095.333743 |
| i (deg) |
146.479803 |
| Ω (om, deg) |
158.739539 |
| ω (w, deg) |
64.812799 |
| M (ma, deg) |
-0.004731 |
Magnitude
Scatter + Global Linear
$$
M_a = (6.500 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
6.500 |
| n |
6.000 |
| gf |
0.999 |
| gb |
-0.663 |
| 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 |
22:29:48.54 |
-13:37:46.3 |
HIP 110978 |
11.58 |
| 2026-03-26 12:00 |
22:29:52.85 |
-13:37:32.6 |
HIP 110978 |
12.64 |
| 2026-03-27 00:00 |
22:29:57.14 |
-13:37:19.1 |
HIP 110978 |
13.69 |
| 2026-03-27 12:00 |
22:30:01.40 |
-13:37:05.7 |
HIP 110978 |
14.74 |
| 2026-03-28 00:00 |
22:30:05.64 |
-13:36:52.5 |
HIP 110978 |
15.79 |
| 2026-03-28 12:00 |
22:30:09.85 |
-13:36:39.6 |
HIP 110978 |
16.83 |
| 2026-03-29 00:00 |
22:30:14.04 |
-13:36:26.7 |
HIP 110978 |
17.86 |
| 2026-03-29 12:00 |
22:30:18.21 |
-13:36:14.1 |
HIP 110978 |
18.89 |
| 2026-03-30 00:00 |
22:30:22.35 |
-13:36:01.7 |
HIP 110978 |
19.91 |
| 2026-03-30 12:00 |
22:30:26.46 |
-13:35:49.5 |
HIP 110978 |
20.92 |
| 2026-03-31 00:00 |
22:30:30.55 |
-13:35:37.4 |
HIP 111194 |
20.59 |
| 2026-03-31 12:00 |
22:30:34.61 |
-13:35:25.5 |
HIP 111194 |
19.97 |
| 2026-04-01 00:00 |
22:30:38.65 |
-13:35:13.9 |
HIP 111194 |
19.39 |
| 2026-04-01 12:00 |
22:30:42.66 |
-13:35:02.4 |
HIP 111194 |
18.84 |
| 2026-04-02 00:00 |
22:30:46.64 |
-13:34:51.1 |
HIP 111194 |
18.33 |
| 2026-04-02 12:00 |
22:30:50.60 |
-13:34:40.0 |
HIP 111194 |
17.87 |
| 2026-04-03 00:00 |
22:30:54.53 |
-13:34:29.2 |
HIP 111194 |
17.44 |
| 2026-04-03 12:00 |
22:30:58.43 |
-13:34:18.5 |
HIP 111194 |
17.06 |
| 2026-04-04 00:00 |
22:31:02.31 |
-13:34:08.0 |
HIP 111234 |
16.40 |
| 2026-04-04 12:00 |
22:31:06.15 |
-13:33:57.7 |
HIP 111234 |
15.49 |
| 2026-04-05 00:00 |
22:31:09.97 |
-13:33:47.7 |
HIP 111234 |
14.59 |
| 2026-04-05 12:00 |
22:31:13.76 |
-13:33:37.8 |
HIP 111234 |
13.71 |
| 2026-04-06 00:00 |
22:31:17.52 |
-13:33:28.2 |
HIP 111234 |
12.83 |
| 2026-04-06 12:00 |
22:31:21.25 |
-13:33:18.7 |
HIP 111234 |
11.98 |
| 2026-04-07 00:00 |
22:31:24.95 |
-13:33:09.5 |
HIP 111234 |
11.14 |
| 2026-04-07 12:00 |
22:31:28.62 |
-13:33:00.5 |
HIP 111234 |
10.31 |
| 2026-04-08 00:00 |
22:31:32.27 |
-13:32:51.7 |
HIP 111234 |
9.51 |
| 2026-04-08 12:00 |
22:31:35.88 |
-13:32:43.1 |
HIP 111234 |
8.73 |
| 2026-04-09 00:00 |
22:31:39.46 |
-13:32:34.8 |
HIP 111234 |
7.98 |
| 2026-04-09 12:00 |
22:31:43.01 |
-13:32:26.6 |
HIP 111234 |
7.27 |
| 2026-04-10 00:00 |
22:31:46.53 |
-13:32:18.7 |
HIP 111234 |
6.59 |
| 2026-04-10 12:00 |
22:31:50.01 |
-13:32:11.0 |
HIP 111234 |
5.97 |
| 2026-04-11 00:00 |
22:31:53.47 |
-13:32:03.5 |
HIP 111234 |
5.42 |
| 2026-04-11 12:00 |
22:31:56.89 |
-13:31:56.3 |
HIP 111234 |
4.96 |
| 2026-04-12 00:00 |
22:32:00.28 |
-13:31:49.3 |
HIP 111234 |
4.60 |
| 2026-04-12 12:00 |
22:32:03.64 |
-13:31:42.5 |
HIP 111234 |
4.38 |
| 2026-04-13 00:00 |
22:32:06.97 |
-13:31:35.9 |
HIP 111234 |
4.30 |
| 2026-04-13 12:00 |
22:32:10.26 |
-13:31:29.6 |
HIP 111234 |
4.37 |
| 2026-04-14 00:00 |
22:32:13.52 |
-13:31:23.5 |
HIP 111234 |
4.57 |
| 2026-04-14 12:00 |
22:32:16.74 |
-13:31:17.6 |
HIP 111234 |
4.90 |
| 2026-04-15 00:00 |
22:32:19.93 |
-13:31:12.0 |
HIP 111234 |
5.31 |
| 2026-04-15 12:00 |
22:32:23.09 |
-13:31:06.6 |
HIP 111234 |
5.79 |
| 2026-04-16 00:00 |
22:32:26.21 |
-13:31:01.5 |
HIP 111234 |
6.33 |