| Parameter |
Value |
| Designation |
C/2021 G1 (Leonard) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-07-22T06:47:31.761600Z |
| Orbit solution date (soln_date, UTC) |
2025-01-14T17:42:12Z |
| Obs used |
54 |
| NEO |
- |
| M1 |
13.700 |
| K1 |
10.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-04-11T07:50:24.892800Z |
| Discovery magnitude (MPC) |
21.72 G |
| Discovery observatory (MPC) |
G96 · Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-04-21.0000000 |
| e |
0.95490157 |
| q (au) |
3.423704 |
| a (au) |
75.916250 |
| i (deg) |
131.566251 |
| Ω (om, deg) |
270.695657 |
| ω (w, deg) |
107.498712 |
| M (ma, deg) |
359.862493 |
Magnitude
Scatter + Global Linear
$$
M_a = (19.995 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
19.995 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.800 |
| 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 |
03:56:37.00 |
-11:52:55.9 |
HIP 18339 |
23.66 |
| 2026-05-12 12:00 |
03:56:44.23 |
-11:52:42.9 |
HIP 18339 |
25.27 |
| 2026-05-13 00:00 |
03:56:51.48 |
-11:52:30.5 |
HIP 18339 |
26.90 |
| 2026-05-13 12:00 |
03:56:58.73 |
-11:52:18.5 |
HIP 18339 |
28.55 |
| 2026-05-14 00:00 |
03:57:05.99 |
-11:52:07.1 |
HIP 18339 |
30.21 |
| 2026-05-14 12:00 |
03:57:13.26 |
-11:51:56.2 |
HIP 18339 |
31.88 |
| 2026-05-15 00:00 |
03:57:20.54 |
-11:51:45.9 |
HIP 18339 |
33.56 |
| 2026-05-15 12:00 |
03:57:27.82 |
-11:51:36.1 |
HIP 18616 |
33.86 |
| 2026-05-16 00:00 |
03:57:35.11 |
-11:51:26.9 |
HIP 18616 |
32.60 |
| 2026-05-16 12:00 |
03:57:42.41 |
-11:51:18.2 |
HIP 18616 |
31.39 |
| 2026-05-17 00:00 |
03:57:49.71 |
-11:51:10.0 |
HIP 18616 |
30.24 |
| 2026-05-17 12:00 |
03:57:57.01 |
-11:51:02.4 |
HIP 18616 |
29.17 |
| 2026-05-18 00:00 |
03:58:04.32 |
-11:50:55.3 |
HIP 18616 |
28.18 |
| 2026-05-18 12:00 |
03:58:11.64 |
-11:50:48.8 |
HIP 18616 |
27.28 |
| 2026-05-19 00:00 |
03:58:18.95 |
-11:50:42.9 |
HIP 18616 |
26.48 |
| 2026-05-19 12:00 |
03:58:26.27 |
-11:50:37.5 |
HIP 18616 |
25.79 |
| 2026-05-20 00:00 |
03:58:33.59 |
-11:50:32.6 |
HIP 18616 |
25.22 |
| 2026-05-20 12:00 |
03:58:40.91 |
-11:50:28.3 |
HIP 18616 |
24.77 |
| 2026-05-21 00:00 |
03:58:48.23 |
-11:50:24.6 |
HIP 18616 |
24.46 |
| 2026-05-21 12:00 |
03:58:55.55 |
-11:50:21.4 |
HIP 18616 |
24.28 |
| 2026-05-22 00:00 |
03:59:02.87 |
-11:50:18.8 |
HIP 18616 |
24.24 |
| 2026-05-22 12:00 |
03:59:10.19 |
-11:50:16.7 |
HIP 18616 |
24.35 |
| 2026-05-23 00:00 |
03:59:17.51 |
-11:50:15.2 |
HIP 18616 |
24.60 |
| 2026-05-23 12:00 |
03:59:24.82 |
-11:50:14.3 |
HIP 18616 |
24.98 |
| 2026-05-24 00:00 |
03:59:32.14 |
-11:50:13.9 |
HIP 18616 |
25.49 |
| 2026-05-24 12:00 |
03:59:39.45 |
-11:50:14.1 |
HIP 18616 |
26.12 |
| 2026-05-25 00:00 |
03:59:46.75 |
-11:50:14.9 |
HIP 18616 |
26.86 |
| 2026-05-25 12:00 |
03:59:54.06 |
-11:50:16.2 |
HIP 18616 |
27.71 |
| 2026-05-26 00:00 |
04:00:01.36 |
-11:50:18.1 |
HIP 18616 |
28.65 |
| 2026-05-26 12:00 |
04:00:08.65 |
-11:50:20.5 |
HIP 18616 |
29.68 |
| 2026-05-27 00:00 |
04:00:15.94 |
-11:50:23.6 |
HIP 18616 |
30.78 |
| 2026-05-27 12:00 |
04:00:23.22 |
-11:50:27.1 |
HIP 18616 |
31.96 |
| 2026-05-28 00:00 |
04:00:30.50 |
-11:50:31.3 |
HIP 18616 |
33.19 |
| 2026-05-28 12:00 |
04:00:37.77 |
-11:50:36.0 |
HIP 18616 |
34.47 |
| 2026-05-29 00:00 |
04:00:45.04 |
-11:50:41.3 |
HIP 18616 |
35.81 |
| 2026-05-29 12:00 |
04:00:52.29 |
-11:50:47.2 |
HIP 18854 |
35.53 |
| 2026-05-30 00:00 |
04:00:59.54 |
-11:50:53.6 |
HIP 18854 |
34.43 |
| 2026-05-30 12:00 |
04:01:06.78 |
-11:51:00.6 |
HIP 18854 |
33.39 |
| 2026-05-31 00:00 |
04:01:14.01 |
-11:51:08.2 |
HIP 18854 |
32.42 |
| 2026-05-31 12:00 |
04:01:21.23 |
-11:51:16.3 |
HIP 18854 |
31.53 |
| 2026-06-01 00:00 |
04:01:28.44 |
-11:51:25.0 |
HIP 18854 |
30.73 |
| 2026-06-01 12:00 |
04:01:35.64 |
-11:51:34.3 |
HIP 18854 |
30.02 |
| 2026-06-02 00:00 |
04:01:42.83 |
-11:51:44.2 |
HIP 18854 |
29.41 |