| Parameter |
Value |
| Designation |
C/2018 EF9 (Lemmon) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-05-23T03:04:52.170240Z |
| Orbit solution date (soln_date, UTC) |
2023-02-13T23:12:43Z |
| Obs used |
191 |
| NEO |
- |
| M1 |
8.600 |
| K1 |
45.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-04-18.0000000 |
| e |
0.99757417 |
| q (au) |
1.556633 |
| a (au) |
641.691299 |
| i (deg) |
84.694453 |
| Ω (om, deg) |
172.578066 |
| ω (w, deg) |
72.616575 |
| M (ma, deg) |
359.997870 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.870 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.870 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.997 |
| 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) |
| 2026-06-01 00:00 |
01:17:22.97 |
-36:20:03.7 |
HIP 6068 |
13.14 |
| 2026-06-01 12:00 |
01:17:27.42 |
-36:20:39.0 |
HIP 6068 |
12.22 |
| 2026-06-02 00:00 |
01:17:31.83 |
-36:21:14.9 |
HIP 6068 |
11.33 |
| 2026-06-02 12:00 |
01:17:36.20 |
-36:21:51.2 |
HIP 6068 |
10.46 |
| 2026-06-03 00:00 |
01:17:40.53 |
-36:22:27.9 |
HIP 6068 |
9.62 |
| 2026-06-03 12:00 |
01:17:44.83 |
-36:23:05.1 |
HIP 6068 |
8.83 |
| 2026-06-04 00:00 |
01:17:49.08 |
-36:23:42.7 |
HIP 6068 |
8.10 |
| 2026-06-04 12:00 |
01:17:53.30 |
-36:24:20.8 |
HIP 6068 |
7.43 |
| 2026-06-05 00:00 |
01:17:57.47 |
-36:24:59.4 |
HIP 6068 |
6.86 |
| 2026-06-05 12:00 |
01:18:01.61 |
-36:25:38.4 |
HIP 6068 |
6.40 |
| 2026-06-06 00:00 |
01:18:05.70 |
-36:26:17.8 |
HIP 6068 |
6.09 |
| 2026-06-06 12:00 |
01:18:09.76 |
-36:26:57.7 |
HIP 6068 |
5.93 |
| 2026-06-07 00:00 |
01:18:13.77 |
-36:27:38.1 |
HIP 6068 |
5.95 |
| 2026-06-07 12:00 |
01:18:17.75 |
-36:28:18.9 |
HIP 6068 |
6.14 |
| 2026-06-08 00:00 |
01:18:21.68 |
-36:29:00.1 |
HIP 6068 |
6.48 |
| 2026-06-08 12:00 |
01:18:25.57 |
-36:29:41.7 |
HIP 6068 |
6.95 |
| 2026-06-09 00:00 |
01:18:29.41 |
-36:30:23.8 |
HIP 6068 |
7.54 |
| 2026-06-09 12:00 |
01:18:33.22 |
-36:31:06.4 |
HIP 6068 |
8.20 |
| 2026-06-10 00:00 |
01:18:36.98 |
-36:31:49.4 |
HIP 6068 |
8.93 |
| 2026-06-10 12:00 |
01:18:40.70 |
-36:32:32.8 |
HIP 6068 |
9.70 |
| 2026-06-11 00:00 |
01:18:44.38 |
-36:33:16.6 |
HIP 6068 |
10.52 |
| 2026-06-11 12:00 |
01:18:48.01 |
-36:34:00.9 |
HIP 6068 |
11.36 |
| 2026-06-12 00:00 |
01:18:51.60 |
-36:34:45.5 |
HIP 6068 |
12.23 |
| 2026-06-12 12:00 |
01:18:55.15 |
-36:35:30.7 |
HIP 6068 |
13.11 |
| 2026-06-13 00:00 |
01:18:58.65 |
-36:36:16.2 |
HIP 6068 |
14.01 |
| 2026-06-13 12:00 |
01:19:02.10 |
-36:37:02.2 |
HIP 6068 |
14.92 |
| 2026-06-14 00:00 |
01:19:05.52 |
-36:37:48.5 |
HIP 6068 |
15.84 |
| 2026-06-14 12:00 |
01:19:08.88 |
-36:38:35.3 |
HIP 6068 |
16.77 |
| 2026-06-15 00:00 |
01:19:12.20 |
-36:39:22.5 |
HIP 6068 |
17.70 |
| 2026-06-15 12:00 |
01:19:15.48 |
-36:40:10.1 |
HIP 6068 |
18.64 |
| 2026-06-16 00:00 |
01:19:18.71 |
-36:40:58.2 |
HIP 6068 |
19.58 |
| 2026-06-16 12:00 |
01:19:21.89 |
-36:41:46.6 |
HIP 6068 |
20.53 |
| 2026-06-17 00:00 |
01:19:25.03 |
-36:42:35.4 |
HIP 6068 |
21.48 |
| 2026-06-17 12:00 |
01:19:28.12 |
-36:43:24.6 |
HIP 6068 |
22.43 |
| 2026-06-18 00:00 |
01:19:31.16 |
-36:44:14.2 |
HIP 6319 |
21.91 |
| 2026-06-18 12:00 |
01:19:34.16 |
-36:45:04.2 |
HIP 6319 |
21.00 |
| 2026-06-19 00:00 |
01:19:37.11 |
-36:45:54.6 |
HIP 6319 |
20.12 |
| 2026-06-19 12:00 |
01:19:40.01 |
-36:46:45.4 |
HIP 6319 |
19.25 |
| 2026-06-20 00:00 |
01:19:42.86 |
-36:47:36.6 |
HIP 6319 |
18.41 |
| 2026-06-20 12:00 |
01:19:45.67 |
-36:48:28.1 |
HIP 6319 |
17.60 |
| 2026-06-21 00:00 |
01:19:48.43 |
-36:49:20.1 |
HIP 6319 |
16.81 |
| 2026-06-21 12:00 |
01:19:51.14 |
-36:50:12.3 |
HIP 6319 |
16.06 |
| 2026-06-22 00:00 |
01:19:53.80 |
-36:51:05.0 |
HIP 6319 |
15.36 |