| 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 · University of Arizona 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
$$
M_a = (16.820 + 3.581\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
16.820 |
| n |
3.581 |
| gf |
0.997 |
| 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 |
-5.8110 |
+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) |
| 2026-07-29 00:00 |
21:53:30.49 |
+63:08:43.9 |
HIP 108033 |
7.19 |
| 2026-07-29 12:00 |
21:53:06.81 |
+63:08:57.6 |
HIP 107961 |
5.93 |
| 2026-07-30 00:00 |
21:52:43.06 |
+63:09:09.6 |
HIP 107961 |
3.97 |
| 2026-07-30 12:00 |
21:52:19.24 |
+63:09:20.0 |
HIP 107961 |
3.26 |
| 2026-07-31 00:00 |
21:51:55.35 |
+63:09:28.7 |
HIP 107961 |
4.47 |
| 2026-07-31 12:00 |
21:51:31.39 |
+63:09:35.8 |
HIP 107961 |
6.62 |
| 2026-08-01 00:00 |
21:51:07.37 |
+63:09:41.3 |
HIP 107961 |
9.06 |
| 2026-08-01 12:00 |
21:50:43.28 |
+63:09:45.1 |
HIP 107961 |
11.63 |
| 2026-08-02 00:00 |
21:50:19.14 |
+63:09:47.2 |
HIP 107961 |
14.25 |
| 2026-08-02 12:00 |
21:49:54.94 |
+63:09:47.7 |
HIP 107961 |
16.91 |
| 2026-08-03 00:00 |
21:49:30.68 |
+63:09:46.5 |
HIP 107961 |
19.59 |
| 2026-08-03 12:00 |
21:49:06.38 |
+63:09:43.7 |
HIP 107961 |
22.29 |
| 2026-08-04 00:00 |
21:48:42.02 |
+63:09:39.1 |
HIP 107961 |
24.99 |
| 2026-08-04 12:00 |
21:48:17.62 |
+63:09:32.9 |
HIP 107357 |
25.12 |
| 2026-08-05 00:00 |
21:47:53.18 |
+63:09:25.0 |
HIP 107357 |
22.50 |
| 2026-08-05 12:00 |
21:47:28.70 |
+63:09:15.4 |
HIP 107357 |
19.91 |
| 2026-08-06 00:00 |
21:47:04.18 |
+63:09:04.1 |
HIP 107357 |
17.37 |
| 2026-08-06 12:00 |
21:46:39.63 |
+63:08:51.1 |
HIP 107357 |
14.94 |
| 2026-08-07 00:00 |
21:46:15.05 |
+63:08:36.4 |
HIP 107357 |
12.65 |
| 2026-08-07 12:00 |
21:45:50.44 |
+63:08:20.0 |
HIP 107357 |
10.62 |
| 2026-08-08 00:00 |
21:45:25.80 |
+63:08:01.9 |
HIP 107357 |
9.03 |
| 2026-08-08 12:00 |
21:45:01.14 |
+63:07:42.1 |
HIP 107357 |
8.15 |
| 2026-08-09 00:00 |
21:44:36.46 |
+63:07:20.6 |
HIP 107357 |
8.20 |
| 2026-08-09 12:00 |
21:44:11.77 |
+63:06:57.3 |
HIP 107233 |
8.46 |
| 2026-08-10 00:00 |
21:43:47.06 |
+63:06:32.4 |
HIP 107233 |
6.38 |
| 2026-08-10 12:00 |
21:43:22.35 |
+63:06:05.7 |
HIP 107233 |
5.11 |
| 2026-08-11 00:00 |
21:42:57.63 |
+63:05:37.3 |
HIP 107233 |
5.27 |
| 2026-08-11 12:00 |
21:42:32.90 |
+63:05:07.2 |
HIP 107233 |
6.76 |
| 2026-08-12 00:00 |
21:42:08.17 |
+63:04:35.3 |
HIP 107233 |
8.96 |
| 2026-08-12 12:00 |
21:41:43.45 |
+63:04:01.8 |
HIP 107077 |
9.39 |
| 2026-08-13 00:00 |
21:41:18.73 |
+63:03:26.5 |
HIP 107077 |
8.30 |
| 2026-08-13 12:00 |
21:40:54.02 |
+63:02:49.5 |
HIP 107077 |
8.09 |
| 2026-08-14 00:00 |
21:40:29.32 |
+63:02:10.7 |
HIP 107077 |
8.85 |
| 2026-08-14 12:00 |
21:40:04.64 |
+63:01:30.3 |
HIP 107077 |
10.35 |
| 2026-08-15 00:00 |
21:39:39.98 |
+63:00:48.1 |
HIP 107077 |
12.35 |
| 2026-08-15 12:00 |
21:39:15.34 |
+63:00:04.2 |
HIP 107077 |
14.63 |
| 2026-08-16 00:00 |
21:38:50.72 |
+62:59:18.6 |
HIP 106738 |
16.86 |
| 2026-08-16 12:00 |
21:38:26.14 |
+62:58:31.3 |
HIP 106738 |
16.00 |
| 2026-08-17 00:00 |
21:38:01.58 |
+62:57:42.3 |
HIP 106738 |
15.66 |
| 2026-08-17 12:00 |
21:37:37.06 |
+62:56:51.5 |
HIP 106738 |
15.87 |
| 2026-08-18 00:00 |
21:37:12.57 |
+62:55:59.1 |
HIP 106738 |
16.63 |
| 2026-08-18 12:00 |
21:36:48.12 |
+62:55:05.0 |
HIP 106738 |
17.86 |
| 2026-08-19 00:00 |
21:36:23.72 |
+62:54:09.2 |
HIP 106738 |
19.48 |