| Parameter |
Value |
| Designation |
C/2020 H4 (Leonard) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2020-08-29T06:41:40.873920Z |
| Orbit solution date (soln_date, UTC) |
2025-01-10T09:12:15Z |
| Obs used |
37 |
| NEO |
- |
| M1 |
16.600 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2020-04-21T11:20:52.512000Z |
| Discovery magnitude (MPC) |
19.50 G |
| Discovery observatory (MPC) |
G96 · Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2020-04-30.0000000 |
| e |
0.99234750 |
| q (au) |
0.937676 |
| a (au) |
122.531978 |
| i (deg) |
84.325459 |
| Ω (om, deg) |
307.763404 |
| ω (w, deg) |
116.826499 |
| M (ma, deg) |
359.911872 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.688 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.688 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.988 |
| 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 |
06:11:14.42 |
-69:52:12.8 |
HIP 29363 |
6.61 |
| 2026-03-26 12:00 |
06:11:14.47 |
-69:50:32.4 |
HIP 29363 |
4.95 |
| 2026-03-27 00:00 |
06:11:14.70 |
-69:48:52.1 |
HIP 29363 |
3.29 |
| 2026-03-27 12:00 |
06:11:15.11 |
-69:47:11.9 |
HIP 29363 |
1.66 |
| 2026-03-28 00:00 |
06:11:15.70 |
-69:45:31.8 |
HIP 29363 |
0.50 |
| 2026-03-28 12:00 |
06:11:16.46 |
-69:43:51.8 |
HIP 29363 |
1.81 |
| 2026-03-29 00:00 |
06:11:17.40 |
-69:42:11.9 |
HIP 29363 |
3.45 |
| 2026-03-29 12:00 |
06:11:18.52 |
-69:40:32.1 |
HIP 29363 |
5.10 |
| 2026-03-30 00:00 |
06:11:19.80 |
-69:38:52.5 |
HIP 29363 |
6.75 |
| 2026-03-30 12:00 |
06:11:21.26 |
-69:37:12.9 |
HIP 29363 |
8.41 |
| 2026-03-31 00:00 |
06:11:22.89 |
-69:35:33.6 |
HIP 29363 |
10.07 |
| 2026-03-31 12:00 |
06:11:24.68 |
-69:33:54.3 |
HIP 29363 |
11.72 |
| 2026-04-01 00:00 |
06:11:26.65 |
-69:32:15.2 |
HIP 29363 |
13.38 |
| 2026-04-01 12:00 |
06:11:28.79 |
-69:30:36.3 |
HIP 29363 |
15.03 |
| 2026-04-02 00:00 |
06:11:31.09 |
-69:28:57.6 |
HIP 29477 |
15.73 |
| 2026-04-02 12:00 |
06:11:33.56 |
-69:27:19.0 |
HIP 29477 |
14.14 |
| 2026-04-03 00:00 |
06:11:36.19 |
-69:25:40.6 |
HIP 29477 |
12.56 |
| 2026-04-03 12:00 |
06:11:38.99 |
-69:24:02.4 |
HIP 29477 |
10.99 |
| 2026-04-04 00:00 |
06:11:41.95 |
-69:22:24.3 |
HIP 29477 |
9.45 |
| 2026-04-04 12:00 |
06:11:45.07 |
-69:20:46.5 |
HIP 29477 |
7.95 |
| 2026-04-05 00:00 |
06:11:48.36 |
-69:19:08.9 |
HIP 29477 |
6.52 |
| 2026-04-05 12:00 |
06:11:51.80 |
-69:17:31.5 |
HIP 29477 |
5.21 |
| 2026-04-06 00:00 |
06:11:55.41 |
-69:15:54.4 |
HIP 29477 |
4.14 |
| 2026-04-06 12:00 |
06:11:59.17 |
-69:14:17.4 |
HIP 29477 |
3.53 |
| 2026-04-07 00:00 |
06:12:03.09 |
-69:12:40.7 |
HIP 29477 |
3.62 |
| 2026-04-07 12:00 |
06:12:07.17 |
-69:11:04.2 |
HIP 29477 |
4.37 |
| 2026-04-08 00:00 |
06:12:11.40 |
-69:09:28.0 |
HIP 29477 |
5.51 |
| 2026-04-08 12:00 |
06:12:15.79 |
-69:07:52.1 |
HIP 29477 |
6.86 |
| 2026-04-09 00:00 |
06:12:20.33 |
-69:06:16.3 |
HIP 29477 |
8.30 |
| 2026-04-09 12:00 |
06:12:25.02 |
-69:04:40.9 |
HIP 29477 |
9.80 |
| 2026-04-10 00:00 |
06:12:29.87 |
-69:03:05.8 |
HIP 29477 |
11.34 |
| 2026-04-10 12:00 |
06:12:34.86 |
-69:01:30.9 |
HIP 29477 |
12.90 |
| 2026-04-11 00:00 |
06:12:40.01 |
-68:59:56.3 |
HIP 29477 |
14.47 |
| 2026-04-11 12:00 |
06:12:45.30 |
-68:58:22.0 |
HIP 29477 |
16.05 |
| 2026-04-12 00:00 |
06:12:50.75 |
-68:56:48.0 |
HIP 29477 |
17.64 |
| 2026-04-12 12:00 |
06:12:56.34 |
-68:55:14.3 |
HIP 29477 |
19.23 |
| 2026-04-13 00:00 |
06:13:02.07 |
-68:53:40.9 |
HIP 29477 |
20.83 |
| 2026-04-13 12:00 |
06:13:07.95 |
-68:52:07.9 |
HIP 29477 |
22.43 |
| 2026-04-14 00:00 |
06:13:13.98 |
-68:50:35.2 |
HIP 29812 |
23.32 |
| 2026-04-14 12:00 |
06:13:20.15 |
-68:49:02.8 |
HIP 29812 |
23.86 |
| 2026-04-15 00:00 |
06:13:26.46 |
-68:47:30.7 |
HIP 29812 |
24.48 |
| 2026-04-15 12:00 |
06:13:32.91 |
-68:45:59.0 |
HIP 29812 |
25.18 |
| 2026-04-16 00:00 |
06:13:39.50 |
-68:44:27.7 |
HIP 29812 |
25.95 |