| 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) |
| 2026-03-26 00:00 |
02:00:38.14 |
-63:29:47.5 |
HIP 9393 |
5.36 |
| 2026-03-26 12:00 |
02:00:54.91 |
-63:28:15.8 |
HIP 9393 |
4.02 |
| 2026-03-27 00:00 |
02:01:11.74 |
-63:26:45.3 |
HIP 9393 |
3.91 |
| 2026-03-27 12:00 |
02:01:28.62 |
-63:25:15.8 |
HIP 9393 |
5.12 |
| 2026-03-28 00:00 |
02:01:45.56 |
-63:23:47.5 |
HIP 9393 |
6.99 |
| 2026-03-28 12:00 |
02:02:02.55 |
-63:22:20.3 |
HIP 9393 |
9.11 |
| 2026-03-29 00:00 |
02:02:19.59 |
-63:20:54.3 |
HIP 9393 |
11.35 |
| 2026-03-29 12:00 |
02:02:36.68 |
-63:19:29.3 |
HIP 9393 |
13.63 |
| 2026-03-30 00:00 |
02:02:53.82 |
-63:18:05.5 |
HIP 9393 |
15.95 |
| 2026-03-30 12:00 |
02:03:11.01 |
-63:16:42.9 |
HIP 9393 |
18.28 |
| 2026-03-31 00:00 |
02:03:28.24 |
-63:15:21.4 |
HIP 9393 |
20.62 |
| 2026-03-31 12:00 |
02:03:45.52 |
-63:14:01.0 |
HIP 9393 |
22.96 |
| 2026-04-01 00:00 |
02:04:02.85 |
-63:12:41.7 |
HIP 9393 |
25.30 |
| 2026-04-01 12:00 |
02:04:20.22 |
-63:11:23.7 |
HIP 9393 |
27.64 |
| 2026-04-02 00:00 |
02:04:37.63 |
-63:10:06.7 |
HIP 9784 |
29.85 |
| 2026-04-02 12:00 |
02:04:55.09 |
-63:08:50.9 |
HIP 9784 |
28.15 |
| 2026-04-03 00:00 |
02:05:12.59 |
-63:07:36.3 |
HIP 9784 |
26.56 |
| 2026-04-03 12:00 |
02:05:30.13 |
-63:06:22.8 |
HIP 9784 |
25.11 |
| 2026-04-04 00:00 |
02:05:47.71 |
-63:05:10.4 |
HIP 9784 |
23.81 |
| 2026-04-04 12:00 |
02:06:05.32 |
-63:03:59.3 |
HIP 9784 |
22.71 |
| 2026-04-05 00:00 |
02:06:22.98 |
-63:02:49.2 |
HIP 9784 |
21.82 |
| 2026-04-05 12:00 |
02:06:40.67 |
-63:01:40.4 |
HIP 9784 |
21.18 |
| 2026-04-06 00:00 |
02:06:58.40 |
-63:00:32.7 |
HIP 9784 |
20.79 |
| 2026-04-06 12:00 |
02:07:16.16 |
-62:59:26.2 |
HIP 9784 |
20.68 |
| 2026-04-07 00:00 |
02:07:33.96 |
-62:58:20.8 |
HIP 9784 |
20.84 |
| 2026-04-07 12:00 |
02:07:51.79 |
-62:57:16.7 |
HIP 9784 |
21.27 |
| 2026-04-08 00:00 |
02:08:09.65 |
-62:56:13.7 |
HIP 9784 |
21.96 |
| 2026-04-08 12:00 |
02:08:27.54 |
-62:55:11.9 |
HIP 9784 |
22.87 |
| 2026-04-09 00:00 |
02:08:45.47 |
-62:54:11.2 |
HIP 9784 |
23.98 |
| 2026-04-09 12:00 |
02:09:03.42 |
-62:53:11.8 |
HIP 9784 |
25.26 |
| 2026-04-10 00:00 |
02:09:21.40 |
-62:52:13.5 |
HIP 9784 |
26.69 |
| 2026-04-10 12:00 |
02:09:39.41 |
-62:51:16.5 |
HIP 9784 |
28.24 |
| 2026-04-11 00:00 |
02:09:57.45 |
-62:50:20.6 |
HIP 9784 |
29.90 |
| 2026-04-11 12:00 |
02:10:15.51 |
-62:49:25.9 |
HIP 9784 |
31.64 |
| 2026-04-12 00:00 |
02:10:33.60 |
-62:48:32.4 |
HIP 10100 |
32.88 |
| 2026-04-12 12:00 |
02:10:51.71 |
-62:47:40.1 |
HIP 10100 |
32.39 |
| 2026-04-13 00:00 |
02:11:09.84 |
-62:46:49.1 |
HIP 10100 |
32.07 |
| 2026-04-13 12:00 |
02:11:28.00 |
-62:45:59.2 |
HIP 10100 |
31.92 |
| 2026-04-14 00:00 |
02:11:46.17 |
-62:45:10.5 |
HIP 10100 |
31.95 |
| 2026-04-14 12:00 |
02:12:04.37 |
-62:44:23.1 |
HIP 10100 |
32.16 |
| 2026-04-15 00:00 |
02:12:22.59 |
-62:43:36.8 |
HIP 10100 |
32.55 |
| 2026-04-15 12:00 |
02:12:40.82 |
-62:42:51.8 |
HIP 10100 |
33.10 |
| 2026-04-16 00:00 |
02:12:59.07 |
-62:42:08.0 |
HIP 10692 |
32.18 |