| Parameter |
Value |
| Designation |
C/2018 DO4 (Lemmon) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2019-08-18T09:51:21.291840Z |
| Orbit solution date (soln_date, UTC) |
2022-06-28T08:33:35Z |
| Obs used |
660 |
| NEO |
- |
| M1 |
13.200 |
| K1 |
6.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2019-07-09.0000000 |
| e |
0.90695413 |
| q (au) |
2.405953 |
| a (au) |
25.857709 |
| i (deg) |
160.474821 |
| Ω (om, deg) |
251.132876 |
| ω (w, deg) |
175.974733 |
| M (ma, deg) |
359.697089 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.922 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.922 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.901 |
| 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 |
19:57:59.90 |
-33:32:44.3 |
HIP 98341 |
13.30 |
| 2026-03-26 12:00 |
19:58:01.97 |
-33:32:58.2 |
HIP 98341 |
13.10 |
| 2026-03-27 00:00 |
19:58:03.97 |
-33:33:12.5 |
HIP 98341 |
12.93 |
| 2026-03-27 12:00 |
19:58:05.90 |
-33:33:26.9 |
HIP 98341 |
12.79 |
| 2026-03-28 00:00 |
19:58:07.77 |
-33:33:41.7 |
HIP 98341 |
12.68 |
| 2026-03-28 12:00 |
19:58:09.56 |
-33:33:56.6 |
HIP 98341 |
12.60 |
| 2026-03-29 00:00 |
19:58:11.29 |
-33:34:11.9 |
HIP 98341 |
12.54 |
| 2026-03-29 12:00 |
19:58:12.96 |
-33:34:27.3 |
HIP 98341 |
12.51 |
| 2026-03-30 00:00 |
19:58:14.55 |
-33:34:43.1 |
HIP 98341 |
12.51 |
| 2026-03-30 12:00 |
19:58:16.07 |
-33:34:59.0 |
HIP 98341 |
12.54 |
| 2026-03-31 00:00 |
19:58:17.53 |
-33:35:15.2 |
HIP 98341 |
12.59 |
| 2026-03-31 12:00 |
19:58:18.92 |
-33:35:31.7 |
HIP 98341 |
12.66 |
| 2026-04-01 00:00 |
19:58:20.24 |
-33:35:48.4 |
HIP 98341 |
12.76 |
| 2026-04-01 12:00 |
19:58:21.49 |
-33:36:05.3 |
HIP 98341 |
12.88 |
| 2026-04-02 00:00 |
19:58:22.67 |
-33:36:22.5 |
HIP 98341 |
13.02 |
| 2026-04-02 12:00 |
19:58:23.78 |
-33:36:40.0 |
HIP 98341 |
13.18 |
| 2026-04-03 00:00 |
19:58:24.82 |
-33:36:57.6 |
HIP 98341 |
13.35 |
| 2026-04-03 12:00 |
19:58:25.79 |
-33:37:15.5 |
HIP 98341 |
13.55 |
| 2026-04-04 00:00 |
19:58:26.68 |
-33:37:33.7 |
HIP 98341 |
13.76 |
| 2026-04-04 12:00 |
19:58:27.51 |
-33:37:52.1 |
HIP 98341 |
13.98 |
| 2026-04-05 00:00 |
19:58:28.27 |
-33:38:10.7 |
HIP 98341 |
14.22 |
| 2026-04-05 12:00 |
19:58:28.96 |
-33:38:29.5 |
HIP 98341 |
14.47 |
| 2026-04-06 00:00 |
19:58:29.57 |
-33:38:48.6 |
HIP 98341 |
14.73 |
| 2026-04-06 12:00 |
19:58:30.12 |
-33:39:07.9 |
HIP 98341 |
15.00 |
| 2026-04-07 00:00 |
19:58:30.59 |
-33:39:27.5 |
HIP 98341 |
15.29 |
| 2026-04-07 12:00 |
19:58:30.99 |
-33:39:47.3 |
HIP 98341 |
15.58 |
| 2026-04-08 00:00 |
19:58:31.32 |
-33:40:07.3 |
HIP 98341 |
15.89 |
| 2026-04-08 12:00 |
19:58:31.57 |
-33:40:27.5 |
HIP 98341 |
16.20 |
| 2026-04-09 00:00 |
19:58:31.75 |
-33:40:48.0 |
HIP 98341 |
16.52 |
| 2026-04-09 12:00 |
19:58:31.86 |
-33:41:08.7 |
HIP 98341 |
16.85 |
| 2026-04-10 00:00 |
19:58:31.90 |
-33:41:29.6 |
HIP 98341 |
17.19 |
| 2026-04-10 12:00 |
19:58:31.87 |
-33:41:50.7 |
HIP 98341 |
17.53 |
| 2026-04-11 00:00 |
19:58:31.76 |
-33:42:12.1 |
HIP 98341 |
17.88 |
| 2026-04-11 12:00 |
19:58:31.57 |
-33:42:33.7 |
HIP 98341 |
18.24 |
| 2026-04-12 00:00 |
19:58:31.31 |
-33:42:55.5 |
HIP 98341 |
18.61 |
| 2026-04-12 12:00 |
19:58:30.98 |
-33:43:17.5 |
HIP 98341 |
18.98 |
| 2026-04-13 00:00 |
19:58:30.58 |
-33:43:39.8 |
HIP 98341 |
19.36 |
| 2026-04-13 12:00 |
19:58:30.10 |
-33:44:02.2 |
HIP 98341 |
19.75 |
| 2026-04-14 00:00 |
19:58:29.54 |
-33:44:24.9 |
HIP 98341 |
20.15 |
| 2026-04-14 12:00 |
19:58:28.91 |
-33:44:47.8 |
HIP 98341 |
20.55 |
| 2026-04-15 00:00 |
19:58:28.21 |
-33:45:10.9 |
HIP 98341 |
20.95 |
| 2026-04-15 12:00 |
19:58:27.43 |
-33:45:34.2 |
HIP 98341 |
21.37 |
| 2026-04-16 00:00 |
19:58:26.58 |
-33:45:57.7 |
HIP 98341 |
21.79 |