| 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 · University of Arizona 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) |
| 2026-09-20 00:00 |
07:23:12.36 |
-69:25:32.5 |
HIP 36138 |
20.23 |
| 2026-09-20 12:00 |
07:23:18.45 |
-69:27:14.1 |
HIP 36138 |
19.03 |
| 2026-09-21 00:00 |
07:23:24.40 |
-69:28:55.9 |
HIP 36138 |
17.93 |
| 2026-09-21 12:00 |
07:23:30.22 |
-69:30:38.0 |
HIP 36138 |
16.97 |
| 2026-09-22 00:00 |
07:23:35.90 |
-69:32:20.3 |
HIP 36138 |
16.15 |
| 2026-09-22 12:00 |
07:23:41.44 |
-69:34:02.9 |
HIP 36138 |
15.51 |
| 2026-09-23 00:00 |
07:23:46.83 |
-69:35:45.7 |
HIP 36138 |
15.06 |
| 2026-09-23 12:00 |
07:23:52.09 |
-69:37:28.8 |
HIP 36138 |
14.83 |
| 2026-09-24 00:00 |
07:23:57.21 |
-69:39:12.1 |
HIP 36138 |
14.83 |
| 2026-09-24 12:00 |
07:24:02.18 |
-69:40:55.7 |
HIP 36138 |
15.05 |
| 2026-09-25 00:00 |
07:24:07.02 |
-69:42:39.4 |
HIP 36138 |
15.49 |
| 2026-09-25 12:00 |
07:24:11.70 |
-69:44:23.4 |
HIP 36138 |
16.13 |
| 2026-09-26 00:00 |
07:24:16.25 |
-69:46:07.6 |
HIP 36138 |
16.94 |
| 2026-09-26 12:00 |
07:24:20.64 |
-69:47:52.0 |
HIP 36138 |
17.91 |
| 2026-09-27 00:00 |
07:24:24.89 |
-69:49:36.6 |
HIP 36138 |
19.00 |
| 2026-09-27 12:00 |
07:24:29.00 |
-69:51:21.4 |
HIP 36138 |
20.20 |
| 2026-09-28 00:00 |
07:24:32.95 |
-69:53:06.4 |
HIP 36138 |
21.50 |
| 2026-09-28 12:00 |
07:24:36.76 |
-69:54:51.5 |
HIP 36175 |
21.29 |
| 2026-09-29 00:00 |
07:24:40.41 |
-69:56:36.9 |
HIP 36175 |
19.69 |
| 2026-09-29 12:00 |
07:24:43.92 |
-69:58:22.4 |
HIP 36175 |
18.13 |
| 2026-09-30 00:00 |
07:24:47.27 |
-70:00:08.1 |
HIP 36175 |
16.63 |
| 2026-09-30 12:00 |
07:24:50.47 |
-70:01:53.9 |
HIP 36175 |
15.20 |
| 2026-10-01 00:00 |
07:24:53.51 |
-70:03:39.9 |
HIP 36175 |
13.85 |
| 2026-10-01 12:00 |
07:24:56.40 |
-70:05:26.0 |
HIP 36175 |
12.63 |
| 2026-10-02 00:00 |
07:24:59.14 |
-70:07:12.3 |
HIP 36175 |
11.57 |
| 2026-10-02 12:00 |
07:25:01.72 |
-70:08:58.7 |
HIP 36175 |
10.71 |
| 2026-10-03 00:00 |
07:25:04.14 |
-70:10:45.2 |
HIP 36175 |
10.11 |
| 2026-10-03 12:00 |
07:25:06.40 |
-70:12:31.9 |
HIP 36175 |
9.82 |
| 2026-10-04 00:00 |
07:25:08.50 |
-70:14:18.7 |
HIP 36175 |
9.87 |
| 2026-10-04 12:00 |
07:25:10.44 |
-70:16:05.6 |
HIP 35999 |
8.14 |
| 2026-10-05 00:00 |
07:25:12.22 |
-70:17:52.5 |
HIP 35999 |
6.36 |
| 2026-10-05 12:00 |
07:25:13.83 |
-70:19:39.6 |
HIP 35999 |
4.59 |
| 2026-10-06 00:00 |
07:25:15.29 |
-70:21:26.8 |
HIP 35999 |
2.83 |
| 2026-10-06 12:00 |
07:25:16.57 |
-70:23:14.0 |
HIP 35999 |
1.18 |
| 2026-10-07 00:00 |
07:25:17.69 |
-70:25:01.4 |
HIP 35999 |
1.07 |
| 2026-10-07 12:00 |
07:25:18.65 |
-70:26:48.7 |
HIP 35999 |
2.70 |
| 2026-10-08 00:00 |
07:25:19.44 |
-70:28:36.2 |
HIP 35999 |
4.46 |
| 2026-10-08 12:00 |
07:25:20.06 |
-70:30:23.7 |
HIP 35999 |
6.23 |
| 2026-10-09 00:00 |
07:25:20.50 |
-70:32:11.2 |
HIP 35999 |
8.01 |
| 2026-10-09 12:00 |
07:25:20.78 |
-70:33:58.8 |
HIP 35999 |
9.80 |
| 2026-10-10 00:00 |
07:25:20.89 |
-70:35:46.4 |
HIP 35809 |
11.38 |
| 2026-10-10 12:00 |
07:25:20.83 |
-70:37:34.0 |
HIP 35809 |
11.12 |
| 2026-10-11 00:00 |
07:25:20.59 |
-70:39:21.6 |
HIP 35882 |
10.12 |