| 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 · University of Arizona 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 |
-0.998 |
| 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 |
+26.2283 |
-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) |
| 2026-09-20 00:00 |
02:31:07.82 |
-71:18:08.9 |
HIP 11598 |
21.27 |
| 2026-09-20 12:00 |
02:30:38.10 |
-71:19:52.0 |
HIP 11598 |
18.88 |
| 2026-09-21 00:00 |
02:30:08.13 |
-71:21:33.8 |
HIP 11598 |
16.68 |
| 2026-09-21 12:00 |
02:29:37.93 |
-71:23:14.2 |
HIP 11598 |
14.75 |
| 2026-09-22 00:00 |
02:29:07.48 |
-71:24:53.3 |
HIP 11598 |
13.23 |
| 2026-09-22 12:00 |
02:28:36.80 |
-71:26:30.9 |
HIP 11598 |
12.25 |
| 2026-09-23 00:00 |
02:28:05.88 |
-71:28:07.1 |
HIP 11598 |
11.95 |
| 2026-09-23 12:00 |
02:27:34.73 |
-71:29:41.9 |
HIP 11598 |
12.38 |
| 2026-09-24 00:00 |
02:27:03.36 |
-71:31:15.2 |
HIP 11598 |
13.48 |
| 2026-09-24 12:00 |
02:26:31.76 |
-71:32:47.1 |
HIP 11598 |
15.09 |
| 2026-09-25 00:00 |
02:25:59.93 |
-71:34:17.5 |
HIP 11598 |
17.07 |
| 2026-09-25 12:00 |
02:25:27.89 |
-71:35:46.4 |
HIP 11598 |
19.31 |
| 2026-09-26 00:00 |
02:24:55.63 |
-71:37:13.8 |
HIP 10941 |
18.97 |
| 2026-09-26 12:00 |
02:24:23.17 |
-71:38:39.8 |
HIP 10941 |
16.39 |
| 2026-09-27 00:00 |
02:23:50.49 |
-71:40:04.2 |
HIP 10941 |
13.94 |
| 2026-09-27 12:00 |
02:23:17.60 |
-71:41:27.1 |
HIP 10941 |
11.69 |
| 2026-09-28 00:00 |
02:22:44.52 |
-71:42:48.5 |
HIP 10941 |
9.80 |
| 2026-09-28 12:00 |
02:22:11.23 |
-71:44:08.3 |
HIP 10941 |
8.49 |
| 2026-09-29 00:00 |
02:21:37.75 |
-71:45:26.6 |
HIP 10941 |
8.06 |
| 2026-09-29 12:00 |
02:21:04.08 |
-71:46:43.3 |
HIP 10941 |
8.64 |
| 2026-09-30 00:00 |
02:20:30.22 |
-71:47:58.4 |
HIP 10941 |
10.06 |
| 2026-09-30 12:00 |
02:19:56.17 |
-71:49:12.0 |
HIP 10941 |
12.02 |
| 2026-10-01 00:00 |
02:19:21.95 |
-71:50:24.0 |
HIP 10941 |
14.30 |
| 2026-10-01 12:00 |
02:18:47.54 |
-71:51:34.3 |
HIP 10941 |
16.76 |
| 2026-10-02 00:00 |
02:18:12.97 |
-71:52:43.0 |
HIP 10941 |
19.35 |
| 2026-10-02 12:00 |
02:17:38.22 |
-71:53:50.2 |
HIP 10941 |
22.01 |
| 2026-10-03 00:00 |
02:17:03.31 |
-71:54:55.6 |
HIP 10941 |
24.73 |
| 2026-10-03 12:00 |
02:16:28.24 |
-71:55:59.5 |
HIP 10405 |
26.26 |
| 2026-10-04 00:00 |
02:15:53.02 |
-71:57:01.6 |
HIP 10405 |
26.18 |
| 2026-10-04 12:00 |
02:15:17.64 |
-71:58:02.2 |
HIP 10405 |
26.39 |
| 2026-10-05 00:00 |
02:14:42.11 |
-71:59:01.0 |
HIP 10405 |
26.91 |
| 2026-10-05 12:00 |
02:14:06.44 |
-71:59:58.1 |
HIP 10405 |
27.70 |
| 2026-10-06 00:00 |
02:13:30.63 |
-72:00:53.6 |
HIP 10405 |
28.74 |
| 2026-10-06 12:00 |
02:12:54.68 |
-72:01:47.4 |
HIP 10405 |
30.01 |
| 2026-10-07 00:00 |
02:12:18.61 |
-72:02:39.4 |
HIP 10105 |
29.05 |
| 2026-10-07 12:00 |
02:11:42.41 |
-72:03:29.8 |
HIP 10105 |
27.36 |
| 2026-10-08 00:00 |
02:11:06.09 |
-72:04:18.4 |
HIP 10105 |
25.90 |
| 2026-10-08 12:00 |
02:10:29.66 |
-72:05:05.3 |
HIP 10105 |
24.73 |
| 2026-10-09 00:00 |
02:09:53.11 |
-72:05:50.4 |
HIP 10105 |
23.87 |
| 2026-10-09 12:00 |
02:09:16.47 |
-72:06:33.8 |
HIP 10105 |
23.37 |
| 2026-10-10 00:00 |
02:08:39.72 |
-72:07:15.5 |
HIP 9684 |
21.65 |
| 2026-10-10 12:00 |
02:08:02.87 |
-72:07:55.4 |
HIP 9684 |
19.60 |
| 2026-10-11 00:00 |
02:07:25.94 |
-72:08:33.6 |
HIP 9684 |
17.76 |