| Parameter |
Value |
| Designation |
C/2023 X1 (Leonard) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2023-10-18T02:08:14.887680Z |
| Orbit solution date (soln_date, UTC) |
2024-04-13T16:42:53Z |
| Obs used |
255 |
| NEO |
- |
| M1 |
17.400 |
| K1 |
7.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2023-12-04T10:33:40.492800Z |
| Discovery magnitude (MPC) |
17.38 G |
| Discovery observatory (MPC) |
703 · Catalina Sky Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2023-12-12.0000000 |
| e |
0.99415118 |
| q (au) |
0.950488 |
| a (au) |
162.509349 |
| i (deg) |
110.586652 |
| Ω (om, deg) |
137.010668 |
| ω (w, deg) |
321.470854 |
| M (ma, deg) |
0.026124 |
Magnitude
Scatter + Global Linear
$$
M_a = (16.820 + 3.580\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
16.820 |
| n |
3.580 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.951 |
| 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 |
| 2023-11-02 |
2025-08-30 |
-5.8104 |
+0.399 |
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 |
22:07:05.38 |
+55:31:04.3 |
HIP 109225 |
14.45 |
| 2026-03-26 12:00 |
22:07:20.82 |
+55:32:39.7 |
HIP 109225 |
12.33 |
| 2026-03-27 00:00 |
22:07:36.16 |
+55:34:15.9 |
HIP 109225 |
10.46 |
| 2026-03-27 12:00 |
22:07:51.41 |
+55:35:53.0 |
HIP 109225 |
9.00 |
| 2026-03-28 00:00 |
22:08:06.56 |
+55:37:30.9 |
HIP 109225 |
8.17 |
| 2026-03-28 12:00 |
22:08:21.62 |
+55:39:09.7 |
HIP 109225 |
8.16 |
| 2026-03-29 00:00 |
22:08:36.58 |
+55:40:49.2 |
HIP 109225 |
8.97 |
| 2026-03-29 12:00 |
22:08:51.43 |
+55:42:29.6 |
HIP 109225 |
10.41 |
| 2026-03-30 00:00 |
22:09:06.20 |
+55:44:10.7 |
HIP 109225 |
12.26 |
| 2026-03-30 12:00 |
22:09:20.86 |
+55:45:52.7 |
HIP 109225 |
14.35 |
| 2026-03-31 00:00 |
22:09:35.42 |
+55:47:35.4 |
HIP 109249 |
15.38 |
| 2026-03-31 12:00 |
22:09:49.88 |
+55:49:18.9 |
HIP 109307 |
15.64 |
| 2026-04-01 00:00 |
22:10:04.24 |
+55:51:03.2 |
HIP 109424 |
14.01 |
| 2026-04-01 12:00 |
22:10:18.50 |
+55:52:48.2 |
HIP 109424 |
12.28 |
| 2026-04-02 00:00 |
22:10:32.65 |
+55:54:34.0 |
HIP 109424 |
10.92 |
| 2026-04-02 12:00 |
22:10:46.70 |
+55:56:20.6 |
HIP 109424 |
10.07 |
| 2026-04-03 00:00 |
22:11:00.65 |
+55:58:07.9 |
HIP 109424 |
9.86 |
| 2026-04-03 12:00 |
22:11:14.49 |
+55:59:55.9 |
HIP 109424 |
10.32 |
| 2026-04-04 00:00 |
22:11:28.23 |
+56:01:44.7 |
HIP 109424 |
11.37 |
| 2026-04-04 12:00 |
22:11:41.86 |
+56:03:34.2 |
HIP 109424 |
12.86 |
| 2026-04-05 00:00 |
22:11:55.38 |
+56:05:24.4 |
HIP 109424 |
14.67 |
| 2026-04-05 12:00 |
22:12:08.80 |
+56:07:15.4 |
HIP 109424 |
16.67 |
| 2026-04-06 00:00 |
22:12:22.10 |
+56:09:07.0 |
HIP 109424 |
18.82 |
| 2026-04-06 12:00 |
22:12:35.30 |
+56:10:59.4 |
HIP 109424 |
21.06 |
| 2026-04-07 00:00 |
22:12:48.39 |
+56:12:52.4 |
HIP 109424 |
23.37 |
| 2026-04-07 12:00 |
22:13:01.36 |
+56:14:46.1 |
HIP 109424 |
25.73 |
| 2026-04-08 00:00 |
22:13:14.22 |
+56:16:40.5 |
HIP 109872 |
27.03 |
| 2026-04-08 12:00 |
22:13:26.97 |
+56:18:35.6 |
HIP 109872 |
27.61 |
| 2026-04-09 00:00 |
22:13:39.61 |
+56:20:31.3 |
HIP 109872 |
28.43 |
| 2026-04-09 12:00 |
22:13:52.13 |
+56:22:27.7 |
HIP 110021 |
28.78 |
| 2026-04-10 00:00 |
22:14:04.54 |
+56:24:24.8 |
HIP 110021 |
28.11 |
| 2026-04-10 12:00 |
22:14:16.83 |
+56:26:22.5 |
HIP 110021 |
27.70 |
| 2026-04-11 00:00 |
22:14:29.00 |
+56:28:20.8 |
HIP 110021 |
27.55 |
| 2026-04-11 12:00 |
22:14:41.06 |
+56:30:19.8 |
HIP 110021 |
27.66 |
| 2026-04-12 00:00 |
22:14:52.99 |
+56:32:19.3 |
HIP 110021 |
28.04 |
| 2026-04-12 12:00 |
22:15:04.81 |
+56:34:19.5 |
HIP 109857 |
28.29 |
| 2026-04-13 00:00 |
22:15:16.51 |
+56:36:20.3 |
HIP 109857 |
26.35 |
| 2026-04-13 12:00 |
22:15:28.08 |
+56:38:21.7 |
HIP 109857 |
24.51 |
| 2026-04-14 00:00 |
22:15:39.53 |
+56:40:23.7 |
HIP 109857 |
22.81 |
| 2026-04-14 12:00 |
22:15:50.86 |
+56:42:26.3 |
HIP 109857 |
21.26 |
| 2026-04-15 00:00 |
22:16:02.07 |
+56:44:29.5 |
HIP 109857 |
19.91 |
| 2026-04-15 12:00 |
22:16:13.15 |
+56:46:33.2 |
HIP 109857 |
18.79 |
| 2026-04-16 00:00 |
22:16:24.10 |
+56:48:37.4 |
HIP 109857 |
17.94 |