| 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 · University of Arizona 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) |
| 2026-06-01 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 |
| 2026-06-02 12:00 |
04:01:50.01 |
-11:51:54.6 |
HIP 18854 |
28.91 |
| 2026-06-03 00:00 |
04:01:57.18 |
-11:52:05.7 |
HIP 18854 |
28.52 |
| 2026-06-03 12:00 |
04:02:04.34 |
-11:52:17.3 |
HIP 18854 |
28.24 |
| 2026-06-04 00:00 |
04:02:11.48 |
-11:52:29.4 |
HIP 18854 |
28.08 |
| 2026-06-04 12:00 |
04:02:18.61 |
-11:52:42.2 |
HIP 18854 |
28.04 |
| 2026-06-05 00:00 |
04:02:25.73 |
-11:52:55.5 |
HIP 18854 |
28.12 |
| 2026-06-05 12:00 |
04:02:32.83 |
-11:53:09.4 |
HIP 18854 |
28.32 |
| 2026-06-06 00:00 |
04:02:39.92 |
-11:53:23.9 |
HIP 18854 |
28.64 |
| 2026-06-06 12:00 |
04:02:47.00 |
-11:53:39.0 |
HIP 18854 |
29.07 |
| 2026-06-07 00:00 |
04:02:54.05 |
-11:53:54.7 |
HIP 18854 |
29.60 |
| 2026-06-07 12:00 |
04:03:01.10 |
-11:54:10.9 |
HIP 19053 |
28.86 |
| 2026-06-08 00:00 |
04:03:08.12 |
-11:54:27.8 |
HIP 19053 |
27.25 |
| 2026-06-08 12:00 |
04:03:15.14 |
-11:54:45.2 |
HIP 19053 |
25.66 |
| 2026-06-09 00:00 |
04:03:22.13 |
-11:55:03.2 |
HIP 19053 |
24.10 |
| 2026-06-09 12:00 |
04:03:29.10 |
-11:55:21.8 |
HIP 19053 |
22.58 |
| 2026-06-10 00:00 |
04:03:36.06 |
-11:55:41.0 |
HIP 19053 |
21.09 |
| 2026-06-10 12:00 |
04:03:43.00 |
-11:56:00.8 |
HIP 19053 |
19.66 |
| 2026-06-11 00:00 |
04:03:49.92 |
-11:56:21.1 |
HIP 19053 |
18.28 |
| 2026-06-11 12:00 |
04:03:56.82 |
-11:56:42.1 |
HIP 19053 |
16.98 |
| 2026-06-12 00:00 |
04:04:03.70 |
-11:57:03.6 |
HIP 19053 |
15.76 |
| 2026-06-12 12:00 |
04:04:10.56 |
-11:57:25.8 |
HIP 19053 |
14.66 |
| 2026-06-13 00:00 |
04:04:17.40 |
-11:57:48.5 |
HIP 19053 |
13.70 |
| 2026-06-13 12:00 |
04:04:24.21 |
-11:58:11.8 |
HIP 19053 |
12.91 |
| 2026-06-14 00:00 |
04:04:31.01 |
-11:58:35.7 |
HIP 19053 |
12.31 |
| 2026-06-14 12:00 |
04:04:37.78 |
-11:59:00.2 |
HIP 19053 |
11.95 |
| 2026-06-15 00:00 |
04:04:44.53 |
-11:59:25.3 |
HIP 19053 |
11.83 |
| 2026-06-15 12:00 |
04:04:51.25 |
-11:59:51.0 |
HIP 19053 |
11.97 |
| 2026-06-16 00:00 |
04:04:57.95 |
-12:00:17.3 |
HIP 19053 |
12.35 |
| 2026-06-16 12:00 |
04:05:04.63 |
-12:00:44.2 |
HIP 19053 |
12.96 |
| 2026-06-17 00:00 |
04:05:11.28 |
-12:01:11.7 |
HIP 19053 |
13.75 |
| 2026-06-17 12:00 |
04:05:17.90 |
-12:01:39.8 |
HIP 19053 |
14.71 |
| 2026-06-18 00:00 |
04:05:24.50 |
-12:02:08.5 |
HIP 19053 |
15.79 |
| 2026-06-18 12:00 |
04:05:31.07 |
-12:02:37.7 |
HIP 19053 |
16.98 |
| 2026-06-19 00:00 |
04:05:37.61 |
-12:03:07.6 |
HIP 19053 |
18.25 |
| 2026-06-19 12:00 |
04:05:44.13 |
-12:03:38.0 |
HIP 19053 |
19.58 |
| 2026-06-20 00:00 |
04:05:50.61 |
-12:04:09.1 |
HIP 19053 |
20.96 |
| 2026-06-20 12:00 |
04:05:57.07 |
-12:04:40.7 |
HIP 19053 |
22.39 |
| 2026-06-21 00:00 |
04:06:03.50 |
-12:05:12.9 |
HIP 19053 |
23.85 |
| 2026-06-21 12:00 |
04:06:09.90 |
-12:05:45.7 |
HIP 19053 |
25.34 |
| 2026-06-22 00:00 |
04:06:16.27 |
-12:06:19.1 |
HIP 19278 |
23.91 |