| 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) |
| 2026-06-01 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 |
| 2026-06-02 12:00 |
22:22:11.76 |
+60:25:25.5 |
HIP 110320 |
22.79 |
| 2026-06-03 00:00 |
22:22:06.99 |
+60:27:39.9 |
HIP 110320 |
24.49 |
| 2026-06-03 12:00 |
22:22:02.02 |
+60:29:53.8 |
HIP 110320 |
26.27 |
| 2026-06-04 00:00 |
22:21:56.86 |
+60:32:07.4 |
HIP 110320 |
28.12 |
| 2026-06-04 12:00 |
22:21:51.50 |
+60:34:20.5 |
HIP 110216 |
28.13 |
| 2026-06-05 00:00 |
22:21:45.94 |
+60:36:33.2 |
HIP 110216 |
25.96 |
| 2026-06-05 12:00 |
22:21:40.19 |
+60:38:45.4 |
HIP 110216 |
23.80 |
| 2026-06-06 00:00 |
22:21:34.24 |
+60:40:57.2 |
HIP 110216 |
21.67 |
| 2026-06-06 12:00 |
22:21:28.10 |
+60:43:08.6 |
HIP 110216 |
19.58 |
| 2026-06-07 00:00 |
22:21:21.75 |
+60:45:19.4 |
HIP 110216 |
17.52 |
| 2026-06-07 12:00 |
22:21:15.21 |
+60:47:29.8 |
HIP 110216 |
15.53 |
| 2026-06-08 00:00 |
22:21:08.47 |
+60:49:39.6 |
HIP 110216 |
13.62 |
| 2026-06-08 12:00 |
22:21:01.53 |
+60:51:49.0 |
HIP 110216 |
11.84 |
| 2026-06-09 00:00 |
22:20:54.40 |
+60:53:57.8 |
HIP 110216 |
10.26 |
| 2026-06-09 12:00 |
22:20:47.06 |
+60:56:06.1 |
HIP 110216 |
8.98 |
| 2026-06-10 00:00 |
22:20:39.53 |
+60:58:13.8 |
HIP 110216 |
8.14 |
| 2026-06-10 12:00 |
22:20:31.79 |
+61:00:20.9 |
HIP 110216 |
7.90 |
| 2026-06-11 00:00 |
22:20:23.85 |
+61:02:27.5 |
HIP 110216 |
8.30 |
| 2026-06-11 12:00 |
22:20:15.72 |
+61:04:33.5 |
HIP 110216 |
9.26 |
| 2026-06-12 00:00 |
22:20:07.38 |
+61:06:38.9 |
HIP 110216 |
10.63 |
| 2026-06-12 12:00 |
22:19:58.85 |
+61:08:43.7 |
HIP 110216 |
12.27 |
| 2026-06-13 00:00 |
22:19:50.11 |
+61:10:47.8 |
HIP 110094 |
12.81 |
| 2026-06-13 12:00 |
22:19:41.17 |
+61:12:51.3 |
HIP 110094 |
12.40 |
| 2026-06-14 00:00 |
22:19:32.03 |
+61:14:54.1 |
HIP 110094 |
12.39 |
| 2026-06-14 12:00 |
22:19:22.69 |
+61:16:56.3 |
HIP 110094 |
12.79 |
| 2026-06-15 00:00 |
22:19:13.15 |
+61:18:57.8 |
HIP 110094 |
13.56 |
| 2026-06-15 12:00 |
22:19:03.41 |
+61:20:58.6 |
HIP 110094 |
14.64 |
| 2026-06-16 00:00 |
22:18:53.47 |
+61:22:58.6 |
HIP 110094 |
15.97 |
| 2026-06-16 12:00 |
22:18:43.32 |
+61:24:58.0 |
HIP 110304 |
16.02 |
| 2026-06-17 00:00 |
22:18:32.98 |
+61:26:56.6 |
HIP 110304 |
15.97 |
| 2026-06-17 12:00 |
22:18:22.44 |
+61:28:54.4 |
HIP 110304 |
16.28 |
| 2026-06-18 00:00 |
22:18:11.70 |
+61:30:51.5 |
HIP 110304 |
16.93 |
| 2026-06-18 12:00 |
22:18:00.76 |
+61:32:47.8 |
HIP 110304 |
17.89 |
| 2026-06-19 00:00 |
22:17:49.62 |
+61:34:43.3 |
HIP 110304 |
19.11 |
| 2026-06-19 12:00 |
22:17:38.28 |
+61:36:38.0 |
HIP 109856 |
19.33 |
| 2026-06-20 00:00 |
22:17:26.74 |
+61:38:31.9 |
HIP 109856 |
17.58 |
| 2026-06-20 12:00 |
22:17:15.01 |
+61:40:25.0 |
HIP 109856 |
15.96 |
| 2026-06-21 00:00 |
22:17:03.08 |
+61:42:17.2 |
HIP 109856 |
14.51 |
| 2026-06-21 12:00 |
22:16:50.95 |
+61:44:08.6 |
HIP 109856 |
13.31 |
| 2026-06-22 00:00 |
22:16:38.63 |
+61:45:59.1 |
HIP 109856 |
12.41 |