C/2020 H4 (Leonard)
| 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) |
| 2026-02-03 00:00 |
06:28:32.83 |
-72:22:04.2 |
HIP 30582 |
23.52 |
| 2026-02-03 12:00 |
06:28:12.66 |
-72:21:04.4 |
HIP 30582 |
21.85 |
| 2026-02-04 00:00 |
06:27:52.67 |
-72:20:03.7 |
HIP 30582 |
20.20 |
| 2026-02-04 12:00 |
06:27:32.85 |
-72:19:02.2 |
HIP 30582 |
18.57 |
| 2026-02-05 00:00 |
06:27:13.20 |
-72:17:59.8 |
HIP 30582 |
16.97 |
| 2026-02-05 12:00 |
06:26:53.73 |
-72:16:56.6 |
HIP 30582 |
15.42 |
| 2026-02-06 00:00 |
06:26:34.43 |
-72:15:52.5 |
HIP 30582 |
13.92 |
| 2026-02-06 12:00 |
06:26:15.32 |
-72:14:47.6 |
HIP 30582 |
12.50 |
| 2026-02-07 00:00 |
06:25:56.38 |
-72:13:41.9 |
HIP 30582 |
11.18 |
| 2026-02-07 12:00 |
06:25:37.63 |
-72:12:35.4 |
HIP 30582 |
10.01 |
| 2026-02-08 00:00 |
06:25:19.06 |
-72:11:28.0 |
HIP 30582 |
9.03 |
| 2026-02-08 12:00 |
06:25:00.67 |
-72:10:19.9 |
HIP 30582 |
8.33 |
| 2026-02-09 00:00 |
06:24:42.48 |
-72:09:11.0 |
HIP 30582 |
7.96 |
| 2026-02-09 12:00 |
06:24:24.46 |
-72:08:01.3 |
HIP 30582 |
7.98 |
| 2026-02-10 00:00 |
06:24:06.64 |
-72:06:50.8 |
HIP 30582 |
8.38 |
| 2026-02-10 12:00 |
06:23:49.01 |
-72:05:39.5 |
HIP 30582 |
9.11 |
| 2026-02-11 00:00 |
06:23:31.56 |
-72:04:27.6 |
HIP 30582 |
10.09 |
| 2026-02-11 12:00 |
06:23:14.32 |
-72:03:14.8 |
HIP 30582 |
11.27 |
| 2026-02-12 00:00 |
06:22:57.26 |
-72:02:01.3 |
HIP 30582 |
12.59 |
| 2026-02-12 12:00 |
06:22:40.40 |
-72:00:47.1 |
HIP 30582 |
14.00 |
| 2026-02-13 00:00 |
06:22:23.73 |
-71:59:32.2 |
HIP 30582 |
15.48 |
| 2026-02-13 12:00 |
06:22:07.27 |
-71:58:16.6 |
HIP 30582 |
17.01 |
| 2026-02-14 00:00 |
06:21:51.00 |
-71:57:00.3 |
HIP 29964 |
16.67 |
| 2026-02-14 12:00 |
06:21:34.92 |
-71:55:43.3 |
HIP 29964 |
16.03 |
| 2026-02-15 00:00 |
06:21:19.05 |
-71:54:25.6 |
HIP 29964 |
15.59 |
| 2026-02-15 12:00 |
06:21:03.38 |
-71:53:07.2 |
HIP 29964 |
15.36 |
| 2026-02-16 00:00 |
06:20:47.92 |
-71:51:48.2 |
HIP 29964 |
15.36 |
| 2026-02-16 12:00 |
06:20:32.65 |
-71:50:28.6 |
HIP 29964 |
15.57 |
| 2026-02-17 00:00 |
06:20:17.59 |
-71:49:08.3 |
HIP 29964 |
16.00 |
| 2026-02-17 12:00 |
06:20:02.73 |
-71:47:47.4 |
HIP 29964 |
16.62 |
| 2026-02-18 00:00 |
06:19:48.08 |
-71:46:25.8 |
HIP 29964 |
17.41 |
| 2026-02-18 12:00 |
06:19:33.63 |
-71:45:03.7 |
HIP 29964 |
18.36 |
| 2026-02-19 00:00 |
06:19:19.39 |
-71:43:40.9 |
HIP 29964 |
19.43 |
| 2026-02-19 12:00 |
06:19:05.35 |
-71:42:17.6 |
HIP 29673 |
18.78 |
| 2026-02-20 00:00 |
06:18:51.53 |
-71:40:53.6 |
HIP 29673 |
17.75 |
| 2026-02-20 12:00 |
06:18:37.91 |
-71:39:29.2 |
HIP 29673 |
16.86 |
| 2026-02-21 00:00 |
06:18:24.50 |
-71:38:04.1 |
HIP 29673 |
16.13 |
| 2026-02-21 12:00 |
06:18:11.30 |
-71:36:38.6 |
HIP 29673 |
15.59 |
| 2026-02-22 00:00 |
06:17:58.30 |
-71:35:12.4 |
HIP 29660 |
15.05 |
| 2026-02-22 12:00 |
06:17:45.52 |
-71:33:45.8 |
HIP 29660 |
14.58 |
| 2026-02-23 00:00 |
06:17:32.95 |
-71:32:18.6 |
HIP 29660 |
14.34 |
| 2026-02-23 12:00 |
06:17:20.58 |
-71:30:51.0 |
HIP 29660 |
14.32 |
| 2026-02-24 00:00 |
06:17:08.43 |
-71:29:22.8 |
HIP 29660 |
14.53 |