| 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) |
| 2026-09-20 00:00 |
19:20:17.09 |
-35:03:30.3 |
HIP 95149 |
15.54 |
| 2026-09-20 12:00 |
19:20:13.05 |
-35:03:10.7 |
HIP 95149 |
16.24 |
| 2026-09-21 00:00 |
19:20:09.07 |
-35:02:50.8 |
HIP 95149 |
16.95 |
| 2026-09-21 12:00 |
19:20:05.18 |
-35:02:30.9 |
HIP 95149 |
17.66 |
| 2026-09-22 00:00 |
19:20:01.36 |
-35:02:10.7 |
HIP 95149 |
18.37 |
| 2026-09-22 12:00 |
19:19:57.61 |
-35:01:50.4 |
HIP 94891 |
19.04 |
| 2026-09-23 00:00 |
19:19:53.94 |
-35:01:30.0 |
HIP 94891 |
18.59 |
| 2026-09-23 12:00 |
19:19:50.34 |
-35:01:09.3 |
HIP 94891 |
18.18 |
| 2026-09-24 00:00 |
19:19:46.82 |
-35:00:48.5 |
HIP 94891 |
17.81 |
| 2026-09-24 12:00 |
19:19:43.37 |
-35:00:27.6 |
HIP 94891 |
17.48 |
| 2026-09-25 00:00 |
19:19:40.00 |
-35:00:06.5 |
HIP 94891 |
17.20 |
| 2026-09-25 12:00 |
19:19:36.70 |
-34:59:45.2 |
HIP 94891 |
16.96 |
| 2026-09-26 00:00 |
19:19:33.48 |
-34:59:23.8 |
HIP 94891 |
16.76 |
| 2026-09-26 12:00 |
19:19:30.34 |
-34:59:02.3 |
HIP 94891 |
16.61 |
| 2026-09-27 00:00 |
19:19:27.27 |
-34:58:40.6 |
HIP 94891 |
16.50 |
| 2026-09-27 12:00 |
19:19:24.27 |
-34:58:18.7 |
HIP 94891 |
16.43 |
| 2026-09-28 00:00 |
19:19:21.35 |
-34:57:56.7 |
HIP 94891 |
16.40 |
| 2026-09-28 12:00 |
19:19:18.50 |
-34:57:34.6 |
HIP 94891 |
16.41 |
| 2026-09-29 00:00 |
19:19:15.73 |
-34:57:12.3 |
HIP 94891 |
16.46 |
| 2026-09-29 12:00 |
19:19:13.04 |
-34:56:49.9 |
HIP 94891 |
16.55 |
| 2026-09-30 00:00 |
19:19:10.42 |
-34:56:27.4 |
HIP 94891 |
16.67 |
| 2026-09-30 12:00 |
19:19:07.87 |
-34:56:04.7 |
HIP 94891 |
16.82 |
| 2026-10-01 00:00 |
19:19:05.41 |
-34:55:41.9 |
HIP 94891 |
17.00 |
| 2026-10-01 12:00 |
19:19:03.01 |
-34:55:19.0 |
HIP 94891 |
17.21 |
| 2026-10-02 00:00 |
19:19:00.69 |
-34:54:55.9 |
HIP 94891 |
17.45 |
| 2026-10-02 12:00 |
19:18:58.45 |
-34:54:32.7 |
HIP 94891 |
17.71 |
| 2026-10-03 00:00 |
19:18:56.28 |
-34:54:09.4 |
HIP 94891 |
17.99 |
| 2026-10-03 12:00 |
19:18:54.19 |
-34:53:46.0 |
HIP 94891 |
18.29 |
| 2026-10-04 00:00 |
19:18:52.18 |
-34:53:22.4 |
HIP 94891 |
18.61 |
| 2026-10-04 12:00 |
19:18:50.24 |
-34:52:58.8 |
HIP 94891 |
18.94 |
| 2026-10-05 00:00 |
19:18:48.37 |
-34:52:35.0 |
HIP 94891 |
19.29 |
| 2026-10-05 12:00 |
19:18:46.58 |
-34:52:11.1 |
HIP 94891 |
19.65 |
| 2026-10-06 00:00 |
19:18:44.87 |
-34:51:47.1 |
HIP 94891 |
20.02 |
| 2026-10-06 12:00 |
19:18:43.23 |
-34:51:22.9 |
HIP 94891 |
20.40 |
| 2026-10-07 00:00 |
19:18:41.66 |
-34:50:58.7 |
HIP 94891 |
20.79 |
| 2026-10-07 12:00 |
19:18:40.18 |
-34:50:34.4 |
HIP 94891 |
21.19 |
| 2026-10-08 00:00 |
19:18:38.76 |
-34:50:09.9 |
HIP 94844 |
20.95 |
| 2026-10-08 12:00 |
19:18:37.43 |
-34:49:45.4 |
HIP 94844 |
20.47 |
| 2026-10-09 00:00 |
19:18:36.16 |
-34:49:20.7 |
HIP 94844 |
19.99 |
| 2026-10-09 12:00 |
19:18:34.98 |
-34:48:56.0 |
HIP 94844 |
19.51 |
| 2026-10-10 00:00 |
19:18:33.87 |
-34:48:31.1 |
HIP 94844 |
19.04 |
| 2026-10-10 12:00 |
19:18:32.83 |
-34:48:06.2 |
HIP 94844 |
18.57 |
| 2026-10-11 00:00 |
19:18:31.87 |
-34:47:41.2 |
HIP 94844 |
18.11 |