| 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) |
| 2026-05-12 00:00 |
06:22:08.33 |
-67:35:42.7 |
HIP 30201 |
5.18 |
| 2026-05-12 12:00 |
06:22:20.83 |
-67:34:37.5 |
HIP 30201 |
6.33 |
| 2026-05-13 00:00 |
06:22:33.41 |
-67:33:32.9 |
HIP 30201 |
7.66 |
| 2026-05-13 12:00 |
06:22:46.07 |
-67:32:28.9 |
HIP 30201 |
9.09 |
| 2026-05-14 00:00 |
06:22:58.81 |
-67:31:25.6 |
HIP 30201 |
10.57 |
| 2026-05-14 12:00 |
06:23:11.64 |
-67:30:22.9 |
HIP 30201 |
12.10 |
| 2026-05-15 00:00 |
06:23:24.55 |
-67:29:20.8 |
HIP 30201 |
13.64 |
| 2026-05-15 12:00 |
06:23:37.55 |
-67:28:19.3 |
HIP 30201 |
15.21 |
| 2026-05-16 00:00 |
06:23:50.62 |
-67:27:18.4 |
HIP 30201 |
16.78 |
| 2026-05-16 12:00 |
06:24:03.77 |
-67:26:18.2 |
HIP 30201 |
18.37 |
| 2026-05-17 00:00 |
06:24:16.99 |
-67:25:18.7 |
HIP 30201 |
19.96 |
| 2026-05-17 12:00 |
06:24:30.30 |
-67:24:19.7 |
HIP 30201 |
21.56 |
| 2026-05-18 00:00 |
06:24:43.68 |
-67:23:21.4 |
HIP 30201 |
23.16 |
| 2026-05-18 12:00 |
06:24:57.13 |
-67:22:23.8 |
HIP 30366 |
24.36 |
| 2026-05-19 00:00 |
06:25:10.66 |
-67:21:26.8 |
HIP 30366 |
24.11 |
| 2026-05-19 12:00 |
06:25:24.26 |
-67:20:30.5 |
HIP 30366 |
23.98 |
| 2026-05-20 00:00 |
06:25:37.93 |
-67:19:34.8 |
HIP 30366 |
23.97 |
| 2026-05-20 12:00 |
06:25:51.67 |
-67:18:39.8 |
HIP 30366 |
24.09 |
| 2026-05-21 00:00 |
06:26:05.48 |
-67:17:45.5 |
HIP 30366 |
24.33 |
| 2026-05-21 12:00 |
06:26:19.36 |
-67:16:51.8 |
HIP 30366 |
24.68 |
| 2026-05-22 00:00 |
06:26:33.31 |
-67:15:58.8 |
HIP 30366 |
25.15 |
| 2026-05-22 12:00 |
06:26:47.32 |
-67:15:06.4 |
HIP 30366 |
25.72 |
| 2026-05-23 00:00 |
06:27:01.40 |
-67:14:14.7 |
HIP 30366 |
26.39 |
| 2026-05-23 12:00 |
06:27:15.54 |
-67:13:23.7 |
HIP 30366 |
27.16 |
| 2026-05-24 00:00 |
06:27:29.75 |
-67:12:33.4 |
HIP 30775 |
27.43 |
| 2026-05-24 12:00 |
06:27:44.02 |
-67:11:43.8 |
HIP 30775 |
26.50 |
| 2026-05-25 00:00 |
06:27:58.35 |
-67:10:54.8 |
HIP 30775 |
25.64 |
| 2026-05-25 12:00 |
06:28:12.74 |
-67:10:06.5 |
HIP 31057 |
24.27 |
| 2026-05-26 00:00 |
06:28:27.19 |
-67:09:18.9 |
HIP 31057 |
22.74 |
| 2026-05-26 12:00 |
06:28:41.70 |
-67:08:32.0 |
HIP 31057 |
21.23 |
| 2026-05-27 00:00 |
06:28:56.27 |
-67:07:45.8 |
HIP 31057 |
19.74 |
| 2026-05-27 12:00 |
06:29:10.89 |
-67:07:00.2 |
HIP 31057 |
18.27 |
| 2026-05-28 00:00 |
06:29:25.57 |
-67:06:15.4 |
HIP 31057 |
16.84 |
| 2026-05-28 12:00 |
06:29:40.31 |
-67:05:31.2 |
HIP 31057 |
15.45 |
| 2026-05-29 00:00 |
06:29:55.10 |
-67:04:47.7 |
HIP 31057 |
14.11 |
| 2026-05-29 12:00 |
06:30:09.94 |
-67:04:05.0 |
HIP 31057 |
12.85 |
| 2026-05-30 00:00 |
06:30:24.84 |
-67:03:22.9 |
HIP 31057 |
11.69 |
| 2026-05-30 12:00 |
06:30:39.79 |
-67:02:41.5 |
HIP 31057 |
10.65 |
| 2026-05-31 00:00 |
06:30:54.79 |
-67:02:00.9 |
HIP 31057 |
9.79 |
| 2026-05-31 12:00 |
06:31:09.84 |
-67:01:20.9 |
HIP 31057 |
9.14 |
| 2026-06-01 00:00 |
06:31:24.94 |
-67:00:41.6 |
HIP 31057 |
8.77 |
| 2026-06-01 12:00 |
06:31:40.09 |
-67:00:03.1 |
HIP 31057 |
8.69 |
| 2026-06-02 00:00 |
06:31:55.29 |
-66:59:25.2 |
HIP 31057 |
8.93 |