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
$$ M_a = (9.075 + 2.876\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 9.075 |
| n | 2.876 |
| gf | 0.999 |
| gb | -0.500 |
| 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 | +0.8239 | -0.133 |
| 2024-04-10 | 2025-08-18 | -1.7564 | +0.828 |
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) |
|---|---|---|---|---|
| 2026-02-03 00:00 | 18:15:02.75 | -06:05:43.9 | HIP 89391 | 32.25 |
| 2026-02-03 12:00 | 18:15:10.12 | -06:06:06.6 | HIP 89391 | 33.12 |
| 2026-02-04 00:00 | 18:15:17.41 | -06:06:28.9 | HIP 89391 | 34.06 |
| 2026-02-04 12:00 | 18:15:24.61 | -06:06:50.7 | HIP 89391 | 35.06 |
| 2026-02-05 00:00 | 18:15:31.73 | -06:07:12.2 | HIP 89391 | 36.11 |
| 2026-02-05 12:00 | 18:15:38.76 | -06:07:33.2 | HIP 89391 | 37.20 |
| 2026-02-06 00:00 | 18:15:45.70 | -06:07:53.8 | HIP 89391 | 38.32 |
| 2026-02-06 12:00 | 18:15:52.55 | -06:08:14.1 | HIP 89391 | 39.48 |
| 2026-02-07 00:00 | 18:15:59.31 | -06:08:33.9 | HIP 89712 | 38.26 |
| 2026-02-07 12:00 | 18:16:05.98 | -06:08:53.3 | HIP 89712 | 36.62 |
| 2026-02-08 00:00 | 18:16:12.56 | -06:09:12.3 | HIP 89712 | 35.01 |
| 2026-02-08 12:00 | 18:16:19.04 | -06:09:31.0 | HIP 89712 | 33.43 |
| 2026-02-09 00:00 | 18:16:25.43 | -06:09:49.3 | HIP 89712 | 31.88 |
| 2026-02-09 12:00 | 18:16:31.73 | -06:10:07.2 | HIP 89712 | 30.36 |
| 2026-02-10 00:00 | 18:16:37.93 | -06:10:24.7 | HIP 89712 | 28.87 |
| 2026-02-10 12:00 | 18:16:44.03 | -06:10:41.8 | HIP 89712 | 27.41 |
| 2026-02-11 00:00 | 18:16:50.04 | -06:10:58.6 | HIP 89712 | 25.98 |
| 2026-02-11 12:00 | 18:16:55.95 | -06:11:15.0 | HIP 89712 | 24.59 |
| 2026-02-12 00:00 | 18:17:01.76 | -06:11:31.0 | HIP 89712 | 23.23 |
| 2026-02-12 12:00 | 18:17:07.47 | -06:11:46.7 | HIP 89712 | 21.91 |
| 2026-02-13 00:00 | 18:17:13.08 | -06:12:02.1 | HIP 89712 | 20.63 |
| 2026-02-13 12:00 | 18:17:18.58 | -06:12:17.1 | HIP 89712 | 19.38 |
| 2026-02-14 00:00 | 18:17:23.99 | -06:12:31.8 | HIP 89712 | 18.19 |
| 2026-02-14 12:00 | 18:17:29.29 | -06:12:46.1 | HIP 89712 | 17.04 |
| 2026-02-15 00:00 | 18:17:34.49 | -06:13:00.1 | HIP 89712 | 15.94 |
| 2026-02-15 12:00 | 18:17:39.58 | -06:13:13.8 | HIP 89712 | 14.90 |
| 2026-02-16 00:00 | 18:17:44.56 | -06:13:27.2 | HIP 89712 | 13.91 |
| 2026-02-16 12:00 | 18:17:49.44 | -06:13:40.2 | HIP 89712 | 13.00 |
| 2026-02-17 00:00 | 18:17:54.21 | -06:13:52.9 | HIP 89712 | 12.16 |
| 2026-02-17 12:00 | 18:17:58.87 | -06:14:05.4 | HIP 89712 | 11.40 |
| 2026-02-18 00:00 | 18:18:03.42 | -06:14:17.5 | HIP 89712 | 10.73 |
| 2026-02-18 12:00 | 18:18:07.86 | -06:14:29.3 | HIP 89712 | 10.16 |
| 2026-02-19 00:00 | 18:18:12.19 | -06:14:40.9 | HIP 89712 | 9.70 |
| 2026-02-19 12:00 | 18:18:16.40 | -06:14:52.1 | HIP 89712 | 9.36 |
| 2026-02-20 00:00 | 18:18:20.51 | -06:15:03.1 | HIP 89712 | 9.12 |
| 2026-02-20 12:00 | 18:18:24.50 | -06:15:13.8 | HIP 89712 | 9.01 |
| 2026-02-21 00:00 | 18:18:28.37 | -06:15:24.2 | HIP 89712 | 9.01 |
| 2026-02-21 12:00 | 18:18:32.13 | -06:15:34.4 | HIP 89712 | 9.11 |
| 2026-02-22 00:00 | 18:18:35.77 | -06:15:44.3 | HIP 89712 | 9.29 |
| 2026-02-22 12:00 | 18:18:39.30 | -06:15:54.0 | HIP 89712 | 9.56 |
| 2026-02-23 00:00 | 18:18:42.71 | -06:16:03.4 | HIP 89712 | 9.89 |
| 2026-02-23 12:00 | 18:18:46.00 | -06:16:12.6 | HIP 89712 | 10.26 |
| 2026-02-24 00:00 | 18:18:49.17 | -06:16:21.5 | HIP 89712 | 10.68 |