| 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) |
| 2026-05-12 00:00 |
22:22:39.66 |
+58:45:26.6 |
HIP 110459 |
9.55 |
| 2026-05-12 12:00 |
22:22:42.78 |
+58:47:47.7 |
HIP 110459 |
11.93 |
| 2026-05-13 00:00 |
22:22:45.73 |
+58:50:08.9 |
HIP 110459 |
14.32 |
| 2026-05-13 12:00 |
22:22:48.51 |
+58:52:30.2 |
HIP 110459 |
16.70 |
| 2026-05-14 00:00 |
22:22:51.12 |
+58:54:51.5 |
HIP 110459 |
19.08 |
| 2026-05-14 12:00 |
22:22:53.55 |
+58:57:12.9 |
HIP 110459 |
21.45 |
| 2026-05-15 00:00 |
22:22:55.81 |
+58:59:34.3 |
HIP 110459 |
23.82 |
| 2026-05-15 12:00 |
22:22:57.90 |
+59:01:55.7 |
HIP 110459 |
26.19 |
| 2026-05-16 00:00 |
22:22:59.82 |
+59:04:17.1 |
HIP 110730 |
25.70 |
| 2026-05-16 12:00 |
22:23:01.55 |
+59:06:38.6 |
HIP 110730 |
24.61 |
| 2026-05-17 00:00 |
22:23:03.11 |
+59:09:00.0 |
HIP 110730 |
23.72 |
| 2026-05-17 12:00 |
22:23:04.50 |
+59:11:21.4 |
HIP 110730 |
23.06 |
| 2026-05-18 00:00 |
22:23:05.70 |
+59:13:42.7 |
HIP 110730 |
22.66 |
| 2026-05-18 12:00 |
22:23:06.73 |
+59:16:04.0 |
HIP 110730 |
22.52 |
| 2026-05-19 00:00 |
22:23:07.58 |
+59:18:25.3 |
HIP 110730 |
22.66 |
| 2026-05-19 12:00 |
22:23:08.25 |
+59:20:46.4 |
HIP 110730 |
23.05 |
| 2026-05-20 00:00 |
22:23:08.74 |
+59:23:07.5 |
HIP 110730 |
23.70 |
| 2026-05-20 12:00 |
22:23:09.04 |
+59:25:28.5 |
HIP 110730 |
24.57 |
| 2026-05-21 00:00 |
22:23:09.17 |
+59:27:49.4 |
HIP 110730 |
25.65 |
| 2026-05-21 12:00 |
22:23:09.11 |
+59:30:10.2 |
HIP 110730 |
26.91 |
| 2026-05-22 00:00 |
22:23:08.87 |
+59:32:30.8 |
HIP 110438 |
27.55 |
| 2026-05-22 12:00 |
22:23:08.45 |
+59:34:51.3 |
HIP 110438 |
25.28 |
| 2026-05-23 00:00 |
22:23:07.84 |
+59:37:11.7 |
HIP 110438 |
23.02 |
| 2026-05-23 12:00 |
22:23:07.05 |
+59:39:31.9 |
HIP 110438 |
20.78 |
| 2026-05-24 00:00 |
22:23:06.07 |
+59:41:51.9 |
HIP 110438 |
18.55 |
| 2026-05-24 12:00 |
22:23:04.91 |
+59:44:11.7 |
HIP 110438 |
16.35 |
| 2026-05-25 00:00 |
22:23:03.57 |
+59:46:31.4 |
HIP 110438 |
14.18 |
| 2026-05-25 12:00 |
22:23:02.03 |
+59:48:50.8 |
HIP 110438 |
12.07 |
| 2026-05-26 00:00 |
22:23:00.31 |
+59:51:10.0 |
HIP 110438 |
10.04 |
| 2026-05-26 12:00 |
22:22:58.40 |
+59:53:29.0 |
HIP 110438 |
8.15 |
| 2026-05-27 00:00 |
22:22:56.31 |
+59:55:47.8 |
HIP 110438 |
6.55 |
| 2026-05-27 12:00 |
22:22:54.02 |
+59:58:06.3 |
HIP 110438 |
5.46 |
| 2026-05-28 00:00 |
22:22:51.55 |
+60:00:24.6 |
HIP 110438 |
5.24 |
| 2026-05-28 12:00 |
22:22:48.89 |
+60:02:42.6 |
HIP 110438 |
5.96 |
| 2026-05-29 00:00 |
22:22:46.04 |
+60:05:00.3 |
HIP 110438 |
7.36 |
| 2026-05-29 12:00 |
22:22:43.00 |
+60:07:17.7 |
HIP 110438 |
9.13 |
| 2026-05-30 00:00 |
22:22:39.77 |
+60:09:34.9 |
HIP 110438 |
11.09 |
| 2026-05-30 12:00 |
22:22:36.34 |
+60:11:51.7 |
HIP 110438 |
13.16 |
| 2026-05-31 00:00 |
22:22:32.73 |
+60:14:08.2 |
HIP 110438 |
15.30 |
| 2026-05-31 12:00 |
22:22:28.92 |
+60:16:24.4 |
HIP 110320 |
17.23 |
| 2026-06-01 00:00 |
22:22:24.92 |
+60:18:40.2 |
HIP 110320 |
18.37 |
| 2026-06-01 12:00 |
22:22:20.73 |
+60:20:55.7 |
HIP 110320 |
19.70 |
| 2026-06-02 00:00 |
22:22:16.34 |
+60:23:10.8 |
HIP 110320 |
21.18 |