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) |
|---|---|---|---|---|
| 2026-05-12 00:00 | 17:58:35.61 | -06:44:36.2 | HIP 88050 | 8.84 |
| 2026-05-12 12:00 | 17:58:16.71 | -06:45:08.8 | HIP 88050 | 12.98 |
| 2026-05-13 00:00 | 17:57:57.69 | -06:45:42.0 | HIP 88050 | 17.45 |
| 2026-05-13 12:00 | 17:57:38.57 | -06:46:15.6 | HIP 87830 | 21.85 |
| 2026-05-14 00:00 | 17:57:19.34 | -06:46:49.7 | HIP 87830 | 18.68 |
| 2026-05-14 12:00 | 17:57:00.00 | -06:47:24.3 | HIP 87799 | 14.58 |
| 2026-05-15 00:00 | 17:56:40.56 | -06:47:59.4 | HIP 87799 | 11.02 |
| 2026-05-15 12:00 | 17:56:21.02 | -06:48:34.9 | HIP 87799 | 8.80 |
| 2026-05-16 00:00 | 17:56:01.38 | -06:49:11.0 | HIP 87799 | 9.03 |
| 2026-05-16 12:00 | 17:55:41.64 | -06:49:47.6 | HIP 87799 | 11.59 |
| 2026-05-17 00:00 | 17:55:21.81 | -06:50:24.7 | HIP 87799 | 15.39 |
| 2026-05-17 12:00 | 17:55:01.88 | -06:51:02.2 | HIP 87799 | 19.73 |
| 2026-05-18 00:00 | 17:54:41.85 | -06:51:40.3 | HIP 87799 | 24.35 |
| 2026-05-18 12:00 | 17:54:21.74 | -06:52:18.9 | HIP 87799 | 29.12 |
| 2026-05-19 00:00 | 17:54:01.53 | -06:52:58.0 | HIP 87799 | 33.99 |
| 2026-05-19 12:00 | 17:53:41.24 | -06:53:37.6 | HIP 87396 | 31.00 |
| 2026-05-20 00:00 | 17:53:20.86 | -06:54:17.8 | HIP 87396 | 26.01 |
| 2026-05-20 12:00 | 17:53:00.39 | -06:54:58.4 | HIP 87396 | 21.05 |
| 2026-05-21 00:00 | 17:52:39.84 | -06:55:39.5 | HIP 87396 | 16.18 |
| 2026-05-21 12:00 | 17:52:19.21 | -06:56:21.2 | HIP 87396 | 11.53 |
| 2026-05-22 00:00 | 17:51:58.51 | -06:57:03.4 | HIP 87396 | 7.58 |
| 2026-05-22 12:00 | 17:51:37.72 | -06:57:46.0 | HIP 87396 | 5.98 |
| 2026-05-23 00:00 | 17:51:16.86 | -06:58:29.2 | HIP 87396 | 8.29 |
| 2026-05-23 12:00 | 17:50:55.92 | -06:59:13.0 | HIP 87396 | 12.52 |
| 2026-05-24 00:00 | 17:50:34.92 | -06:59:57.2 | HIP 87396 | 17.33 |
| 2026-05-24 12:00 | 17:50:13.84 | -07:00:41.9 | HIP 87396 | 22.37 |
| 2026-05-25 00:00 | 17:49:52.69 | -07:01:27.2 | HIP 87396 | 27.52 |
| 2026-05-25 12:00 | 17:49:31.48 | -07:02:12.9 | HIP 87396 | 32.74 |
| 2026-05-26 00:00 | 17:49:10.20 | -07:02:59.2 | HIP 87016 | 36.42 |
| 2026-05-26 12:00 | 17:48:48.86 | -07:03:46.0 | HIP 87016 | 31.71 |
| 2026-05-27 00:00 | 17:48:27.46 | -07:04:33.3 | HIP 87016 | 27.24 |
| 2026-05-27 12:00 | 17:48:06.00 | -07:05:21.2 | HIP 87016 | 23.13 |
| 2026-05-28 00:00 | 17:47:44.48 | -07:06:09.5 | HIP 87016 | 19.66 |
| 2026-05-28 12:00 | 17:47:22.91 | -07:06:58.3 | HIP 87016 | 17.20 |
| 2026-05-29 00:00 | 17:47:01.28 | -07:07:47.7 | HIP 87016 | 16.26 |
| 2026-05-29 12:00 | 17:46:39.60 | -07:08:37.6 | HIP 87016 | 17.10 |
| 2026-05-30 00:00 | 17:46:17.87 | -07:09:27.9 | HIP 87016 | 19.49 |
| 2026-05-30 12:00 | 17:45:56.10 | -07:10:18.8 | HIP 87016 | 22.97 |
| 2026-05-31 00:00 | 17:45:34.27 | -07:11:10.2 | HIP 86833 | 19.87 |
| 2026-05-31 12:00 | 17:45:12.41 | -07:12:02.1 | HIP 86833 | 15.56 |
| 2026-06-01 00:00 | 17:44:50.50 | -07:12:54.6 | HIP 86833 | 12.22 |
| 2026-06-01 12:00 | 17:44:28.54 | -07:13:47.5 | HIP 86833 | 10.81 |
| 2026-06-02 00:00 | 17:44:06.55 | -07:14:40.9 | HIP 86768 | 11.03 |