C/2022 U1 (Leonard)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2022 U1 (Leonard) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2024-03-25T21:34:52.720320Z |
| Orbit solution date (soln_date, UTC) | 2025-10-28T16:12:34Z |
| Obs used | 1325 |
| NEO | - |
| M1 | 10.200 |
| K1 | 7.000 |
| PC | 0.030 |
| Discovery observation (MPC, UTC) | 2022-10-20T08:05:31.920000Z |
| Discovery magnitude (MPC) | 19.84 G |
| Discovery observatory (MPC) | G96 · Mt. Lemmon Survey |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2024-05-01.0000000 |
| e | 0.99936570 |
| q (au) | 4.202017 |
| a (au) | 6624.693105 |
| i (deg) | 128.149455 |
| Ω (om, deg) | 72.526035 |
| ω (w, deg) | 78.588952 |
| M (ma, deg) | 0.000066 |
Magnitude
Scatter + Global Linear
$$ M_a = (9.049 + 2.890\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 9.049 |
| n | 2.890 |
| gf | 0.998 |
| gb | -0.501 |
| 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 |
|---|---|---|---|
| 2022-09-23 | 2024-02-17 | +0.7895 | -0.107 |
| 2024-04-10 | 2025-08-18 | -1.8554 | +0.902 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Finding Chart
Ephemeris
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-03-26 00:00 | 18:17:57.20 | -06:21:10.3 | HIP 89712 | 17.18 |
| 2026-03-26 12:00 | 18:17:51.92 | -06:21:14.3 | HIP 89712 | 17.95 |
| 2026-03-27 00:00 | 18:17:46.49 | -06:21:18.3 | HIP 89712 | 18.80 |
| 2026-03-27 12:00 | 18:17:40.90 | -06:21:22.5 | HIP 89712 | 19.74 |
| 2026-03-28 00:00 | 18:17:35.16 | -06:21:26.8 | HIP 89712 | 20.76 |
| 2026-03-28 12:00 | 18:17:29.26 | -06:21:31.1 | HIP 89712 | 21.85 |
| 2026-03-29 00:00 | 18:17:23.21 | -06:21:35.6 | HIP 89712 | 23.01 |
| 2026-03-29 12:00 | 18:17:17.00 | -06:21:40.2 | HIP 89712 | 24.24 |
| 2026-03-30 00:00 | 18:17:10.64 | -06:21:44.8 | HIP 89712 | 25.54 |
| 2026-03-30 12:00 | 18:17:04.13 | -06:21:49.7 | HIP 89712 | 26.90 |
| 2026-03-31 00:00 | 18:16:57.46 | -06:21:54.6 | HIP 89712 | 28.32 |
| 2026-03-31 12:00 | 18:16:50.63 | -06:21:59.7 | HIP 89712 | 29.80 |
| 2026-04-01 00:00 | 18:16:43.65 | -06:22:04.9 | HIP 89712 | 31.34 |
| 2026-04-01 12:00 | 18:16:36.51 | -06:22:10.2 | HIP 89712 | 32.93 |
| 2026-04-02 00:00 | 18:16:29.22 | -06:22:15.7 | HIP 89427 | 32.41 |
| 2026-04-02 12:00 | 18:16:21.77 | -06:22:21.4 | HIP 89427 | 31.16 |
| 2026-04-03 00:00 | 18:16:14.17 | -06:22:27.2 | HIP 89427 | 29.95 |
| 2026-04-03 12:00 | 18:16:06.41 | -06:22:33.1 | HIP 89427 | 28.79 |
| 2026-04-04 00:00 | 18:15:58.49 | -06:22:39.3 | HIP 89427 | 27.70 |
| 2026-04-04 12:00 | 18:15:50.42 | -06:22:45.6 | HIP 89427 | 26.69 |
| 2026-04-05 00:00 | 18:15:42.19 | -06:22:52.0 | HIP 89427 | 25.77 |
| 2026-04-05 12:00 | 18:15:33.80 | -06:22:58.7 | HIP 89427 | 24.98 |
| 2026-04-06 00:00 | 18:15:25.26 | -06:23:05.5 | HIP 89427 | 24.33 |
| 2026-04-06 12:00 | 18:15:16.56 | -06:23:12.5 | HIP 89427 | 23.85 |
| 2026-04-07 00:00 | 18:15:07.70 | -06:23:19.8 | HIP 89427 | 23.55 |
| 2026-04-07 12:00 | 18:14:58.68 | -06:23:27.2 | HIP 89427 | 23.45 |
| 2026-04-08 00:00 | 18:14:49.51 | -06:23:34.8 | HIP 89427 | 23.57 |
| 2026-04-08 12:00 | 18:14:40.18 | -06:23:42.6 | HIP 89427 | 23.91 |
| 2026-04-09 00:00 | 18:14:30.70 | -06:23:50.7 | HIP 89427 | 24.48 |
| 2026-04-09 12:00 | 18:14:21.06 | -06:23:58.9 | HIP 89427 | 25.27 |
| 2026-04-10 00:00 | 18:14:11.26 | -06:24:07.4 | HIP 89427 | 26.27 |
| 2026-04-10 12:00 | 18:14:01.30 | -06:24:16.2 | HIP 89427 | 27.48 |
| 2026-04-11 00:00 | 18:13:51.18 | -06:24:25.1 | HIP 89427 | 28.86 |
| 2026-04-11 12:00 | 18:13:40.91 | -06:24:34.3 | HIP 89226 | 27.60 |
| 2026-04-12 00:00 | 18:13:30.49 | -06:24:43.7 | HIP 89226 | 26.15 |
| 2026-04-12 12:00 | 18:13:19.90 | -06:24:53.4 | HIP 89226 | 24.88 |
| 2026-04-13 00:00 | 18:13:09.16 | -06:25:03.4 | HIP 89226 | 23.82 |
| 2026-04-13 12:00 | 18:12:58.26 | -06:25:13.6 | HIP 89226 | 23.01 |
| 2026-04-14 00:00 | 18:12:47.21 | -06:25:24.1 | HIP 89226 | 22.50 |
| 2026-04-14 12:00 | 18:12:36.00 | -06:25:34.8 | HIP 89226 | 22.32 |
| 2026-04-15 00:00 | 18:12:24.63 | -06:25:45.9 | HIP 89226 | 22.50 |
| 2026-04-15 12:00 | 18:12:13.11 | -06:25:57.2 | HIP 89226 | 23.04 |
| 2026-04-16 00:00 | 18:12:01.44 | -06:26:08.8 | HIP 89226 | 23.93 |