| Parameter |
Value |
| Designation |
C/2023 A1 (Leonard) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2023-03-18T17:25:38.349120Z |
| Orbit solution date (soln_date, UTC) |
2024-04-13T16:42:45Z |
| Obs used |
453 |
| NEO |
- |
| M1 |
6.300 |
| K1 |
37.000 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2023-01-09T12:59:03.782400Z |
| Discovery magnitude (MPC) |
18.94 G |
| Discovery observatory (MPC) |
G96 · Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2023-03-06.0000000 |
| e |
0.99200431 |
| q (au) |
1.834725 |
| a (au) |
229.464077 |
| i (deg) |
94.743121 |
| Ω (om, deg) |
318.307926 |
| ω (w, deg) |
159.249397 |
| M (ma, deg) |
359.996391 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.463 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.463 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.502 |
| k |
1.000 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2022-12-15 |
2023-03-18 |
+26.2284 |
-7.251 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
02:28:46.93 |
-62:32:24.4 |
HIP 11701 |
15.27 |
| 2026-05-12 12:00 |
02:29:04.71 |
-62:32:45.7 |
HIP 11701 |
13.20 |
| 2026-05-13 00:00 |
02:29:22.46 |
-62:33:08.4 |
HIP 11701 |
11.12 |
| 2026-05-13 12:00 |
02:29:40.18 |
-62:33:32.2 |
HIP 11701 |
9.04 |
| 2026-05-14 00:00 |
02:29:57.87 |
-62:33:57.3 |
HIP 11701 |
6.97 |
| 2026-05-14 12:00 |
02:30:15.52 |
-62:34:23.6 |
HIP 11701 |
4.89 |
| 2026-05-15 00:00 |
02:30:33.13 |
-62:34:51.1 |
HIP 11701 |
2.82 |
| 2026-05-15 12:00 |
02:30:50.70 |
-62:35:19.8 |
HIP 11701 |
0.78 |
| 2026-05-16 00:00 |
02:31:08.24 |
-62:35:49.8 |
HIP 11701 |
1.38 |
| 2026-05-16 12:00 |
02:31:25.74 |
-62:36:21.0 |
HIP 11701 |
3.44 |
| 2026-05-17 00:00 |
02:31:43.19 |
-62:36:53.4 |
HIP 11701 |
5.51 |
| 2026-05-17 12:00 |
02:32:00.60 |
-62:37:27.1 |
HIP 11701 |
7.59 |
| 2026-05-18 00:00 |
02:32:17.97 |
-62:38:02.0 |
HIP 11900 |
9.14 |
| 2026-05-18 12:00 |
02:32:35.30 |
-62:38:38.0 |
HIP 11900 |
7.53 |
| 2026-05-19 00:00 |
02:32:52.58 |
-62:39:15.3 |
HIP 11900 |
6.21 |
| 2026-05-19 12:00 |
02:33:09.81 |
-62:39:53.9 |
HIP 11900 |
5.43 |
| 2026-05-20 00:00 |
02:33:26.99 |
-62:40:33.6 |
HIP 11900 |
5.41 |
| 2026-05-20 12:00 |
02:33:44.13 |
-62:41:14.5 |
HIP 11900 |
6.16 |
| 2026-05-21 00:00 |
02:34:01.22 |
-62:41:56.6 |
HIP 11900 |
7.45 |
| 2026-05-21 12:00 |
02:34:18.26 |
-62:42:40.0 |
HIP 11900 |
9.06 |
| 2026-05-22 00:00 |
02:34:35.24 |
-62:43:24.5 |
HIP 11900 |
10.84 |
| 2026-05-22 12:00 |
02:34:52.17 |
-62:44:10.2 |
HIP 11900 |
12.72 |
| 2026-05-23 00:00 |
02:35:09.05 |
-62:44:57.2 |
HIP 11900 |
14.67 |
| 2026-05-23 12:00 |
02:35:25.88 |
-62:45:45.3 |
HIP 11900 |
16.66 |
| 2026-05-24 00:00 |
02:35:42.65 |
-62:46:34.6 |
HIP 11900 |
18.67 |
| 2026-05-24 12:00 |
02:35:59.36 |
-62:47:25.1 |
HIP 11900 |
20.71 |
| 2026-05-25 00:00 |
02:36:16.01 |
-62:48:16.7 |
HIP 11900 |
22.76 |
| 2026-05-25 12:00 |
02:36:32.61 |
-62:49:09.6 |
HIP 12404 |
23.17 |
| 2026-05-26 00:00 |
02:36:49.15 |
-62:50:03.6 |
HIP 12404 |
21.70 |
| 2026-05-26 12:00 |
02:37:05.63 |
-62:50:58.8 |
HIP 12404 |
20.37 |
| 2026-05-27 00:00 |
02:37:22.05 |
-62:51:55.1 |
HIP 12404 |
19.19 |
| 2026-05-27 12:00 |
02:37:38.40 |
-62:52:52.6 |
HIP 12404 |
18.19 |
| 2026-05-28 00:00 |
02:37:54.70 |
-62:53:51.3 |
HIP 12404 |
17.41 |
| 2026-05-28 12:00 |
02:38:10.93 |
-62:54:51.1 |
HIP 12404 |
16.89 |
| 2026-05-29 00:00 |
02:38:27.10 |
-62:55:52.1 |
HIP 12404 |
16.63 |
| 2026-05-29 12:00 |
02:38:43.20 |
-62:56:54.3 |
HIP 12404 |
16.66 |
| 2026-05-30 00:00 |
02:38:59.23 |
-62:57:57.5 |
HIP 12404 |
16.98 |
| 2026-05-30 12:00 |
02:39:15.20 |
-62:59:02.0 |
HIP 12404 |
17.57 |
| 2026-05-31 00:00 |
02:39:31.10 |
-63:00:07.6 |
HIP 12404 |
18.41 |
| 2026-05-31 12:00 |
02:39:46.93 |
-63:01:14.3 |
HIP 12404 |
19.46 |
| 2026-06-01 00:00 |
02:40:02.69 |
-63:02:22.1 |
HIP 12404 |
20.69 |
| 2026-06-01 12:00 |
02:40:18.38 |
-63:03:31.1 |
HIP 12404 |
22.08 |
| 2026-06-02 00:00 |
02:40:34.00 |
-63:04:41.3 |
HIP 12726 |
22.70 |