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 · University of Arizona 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 | 0.999 |
| gb | -0.707 |
| k | 1.000 |
| δ90 | 9.999 |
| 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 | +0.7893 | -0.107 |
| 2024-04-10 | 2025-08-18 | -1.8556 | +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) |
|---|---|---|---|---|
| 2026-07-29 00:00 | 17:06:06.68 | -09:42:44.2 | HIP 83605 | 12.57 |
| 2026-07-29 12:00 | 17:05:52.22 | -09:44:19.5 | HIP 83605 | 10.31 |
| 2026-07-30 00:00 | 17:05:37.89 | -09:45:54.9 | HIP 83605 | 9.25 |
| 2026-07-30 12:00 | 17:05:23.71 | -09:47:30.4 | HIP 83605 | 9.74 |
| 2026-07-31 00:00 | 17:05:09.66 | -09:49:06.2 | HIP 83605 | 11.56 |
| 2026-07-31 12:00 | 17:04:55.75 | -09:50:42.0 | HIP 83605 | 14.18 |
| 2026-08-01 00:00 | 17:04:41.99 | -09:52:18.0 | HIP 83605 | 17.22 |
| 2026-08-01 12:00 | 17:04:28.36 | -09:53:54.2 | HIP 83605 | 20.48 |
| 2026-08-02 00:00 | 17:04:14.87 | -09:55:30.5 | HIP 83605 | 23.85 |
| 2026-08-02 12:00 | 17:04:01.53 | -09:57:06.9 | HIP 83605 | 27.28 |
| 2026-08-03 00:00 | 17:03:48.33 | -09:58:43.5 | HIP 83605 | 30.73 |
| 2026-08-03 12:00 | 17:03:35.27 | -10:00:20.1 | HIP 83605 | 34.20 |
| 2026-08-04 00:00 | 17:03:22.35 | -10:01:57.0 | HIP 83298 | 33.30 |
| 2026-08-04 12:00 | 17:03:09.58 | -10:03:33.9 | HIP 83298 | 31.58 |
| 2026-08-05 00:00 | 17:02:56.94 | -10:05:10.9 | HIP 83298 | 30.20 |
| 2026-08-05 12:00 | 17:02:44.46 | -10:06:48.1 | HIP 83298 | 29.21 |
| 2026-08-06 00:00 | 17:02:32.11 | -10:08:25.4 | HIP 83298 | 28.63 |
| 2026-08-06 12:00 | 17:02:19.92 | -10:10:02.8 | HIP 83298 | 28.48 |
| 2026-08-07 00:00 | 17:02:07.86 | -10:11:40.3 | HIP 83298 | 28.75 |
| 2026-08-07 12:00 | 17:01:55.95 | -10:13:17.9 | HIP 83298 | 29.42 |
| 2026-08-08 00:00 | 17:01:44.19 | -10:14:55.6 | HIP 83298 | 30.45 |
| 2026-08-08 12:00 | 17:01:32.57 | -10:16:33.4 | HIP 83298 | 31.81 |
| 2026-08-09 00:00 | 17:01:21.10 | -10:18:11.3 | HIP 83298 | 33.43 |
| 2026-08-09 12:00 | 17:01:09.78 | -10:19:49.3 | HIP 83298 | 35.28 |
| 2026-08-10 00:00 | 17:00:58.60 | -10:21:27.4 | HIP 83298 | 37.31 |
| 2026-08-10 12:00 | 17:00:47.57 | -10:23:05.6 | HIP 83048 | 39.39 |
| 2026-08-11 00:00 | 17:00:36.68 | -10:24:43.8 | HIP 83048 | 36.41 |
| 2026-08-11 12:00 | 17:00:25.95 | -10:26:22.1 | HIP 83048 | 33.49 |
| 2026-08-12 00:00 | 17:00:15.36 | -10:28:00.5 | HIP 83048 | 30.64 |
| 2026-08-12 12:00 | 17:00:04.91 | -10:29:39.0 | HIP 83048 | 27.87 |
| 2026-08-13 00:00 | 16:59:54.62 | -10:31:17.6 | HIP 83048 | 25.21 |
| 2026-08-13 12:00 | 16:59:44.47 | -10:32:56.2 | HIP 83048 | 22.68 |
| 2026-08-14 00:00 | 16:59:34.48 | -10:34:34.8 | HIP 83048 | 20.30 |
| 2026-08-14 12:00 | 16:59:24.63 | -10:36:13.5 | HIP 83048 | 18.13 |
| 2026-08-15 00:00 | 16:59:14.92 | -10:37:52.3 | HIP 83048 | 16.24 |
| 2026-08-15 12:00 | 16:59:05.37 | -10:39:31.1 | HIP 83048 | 14.72 |
| 2026-08-16 00:00 | 16:58:55.96 | -10:41:10.0 | HIP 83048 | 13.66 |
| 2026-08-16 12:00 | 16:58:46.71 | -10:42:48.9 | HIP 83048 | 13.16 |
| 2026-08-17 00:00 | 16:58:37.60 | -10:44:27.9 | HIP 83048 | 13.28 |
| 2026-08-17 12:00 | 16:58:28.63 | -10:46:06.9 | HIP 83048 | 13.97 |
| 2026-08-18 00:00 | 16:58:19.82 | -10:47:45.9 | HIP 83048 | 15.14 |
| 2026-08-18 12:00 | 16:58:11.15 | -10:49:25.0 | HIP 82979 | 13.89 |
| 2026-08-19 00:00 | 16:58:02.63 | -10:51:04.0 | HIP 82979 | 11.23 |