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) |
|---|---|---|---|---|
| 2026-06-01 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 |
| 2026-06-02 12:00 | 17:43:44.53 | -07:15:34.9 | HIP 86768 | 10.82 |
| 2026-06-03 00:00 | 17:43:22.47 | -07:16:29.3 | HIP 86768 | 13.20 |
| 2026-06-03 12:00 | 17:43:00.37 | -07:17:24.3 | HIP 86768 | 17.13 |
| 2026-06-04 00:00 | 17:42:38.25 | -07:18:19.7 | HIP 86768 | 21.79 |
| 2026-06-04 12:00 | 17:42:16.09 | -07:19:15.7 | HIP 86768 | 26.81 |
| 2026-06-05 00:00 | 17:41:53.91 | -07:20:12.1 | HIP 86509 | 31.29 |
| 2026-06-05 12:00 | 17:41:31.70 | -07:21:09.1 | HIP 86509 | 27.74 |
| 2026-06-06 00:00 | 17:41:09.47 | -07:22:06.6 | HIP 86509 | 24.94 |
| 2026-06-06 12:00 | 17:40:47.22 | -07:23:04.5 | HIP 86509 | 23.16 |
| 2026-06-07 00:00 | 17:40:24.94 | -07:24:03.0 | HIP 86509 | 22.66 |
| 2026-06-07 12:00 | 17:40:02.65 | -07:25:02.0 | HIP 86509 | 23.51 |
| 2026-06-08 00:00 | 17:39:40.35 | -07:26:01.4 | HIP 86509 | 25.59 |
| 2026-06-08 12:00 | 17:39:18.03 | -07:27:01.4 | HIP 86509 | 28.64 |
| 2026-06-09 00:00 | 17:38:55.70 | -07:28:01.8 | HIP 86509 | 32.38 |
| 2026-06-09 12:00 | 17:38:33.36 | -07:29:02.8 | HIP 86509 | 36.60 |
| 2026-06-10 00:00 | 17:38:11.01 | -07:30:04.2 | HIP 86240 | 34.19 |
| 2026-06-10 12:00 | 17:37:48.66 | -07:31:06.1 | HIP 86240 | 31.70 |
| 2026-06-11 00:00 | 17:37:26.30 | -07:32:08.5 | HIP 86240 | 30.07 |
| 2026-06-11 12:00 | 17:37:03.94 | -07:33:11.4 | HIP 86240 | 29.44 |
| 2026-06-12 00:00 | 17:36:41.59 | -07:34:14.8 | HIP 86240 | 29.86 |
| 2026-06-12 12:00 | 17:36:19.23 | -07:35:18.7 | HIP 86240 | 31.31 |
| 2026-06-13 00:00 | 17:35:56.88 | -07:36:23.1 | HIP 86240 | 33.64 |
| 2026-06-13 12:00 | 17:35:34.54 | -07:37:27.9 | HIP 85929 | 30.35 |
| 2026-06-14 00:00 | 17:35:12.21 | -07:38:33.3 | HIP 85929 | 25.43 |
| 2026-06-14 12:00 | 17:34:49.88 | -07:39:39.1 | HIP 85929 | 20.89 |
| 2026-06-15 00:00 | 17:34:27.58 | -07:40:45.3 | HIP 85929 | 17.03 |
| 2026-06-15 12:00 | 17:34:05.28 | -07:41:52.1 | HIP 85936 | 13.95 |
| 2026-06-16 00:00 | 17:33:43.01 | -07:42:59.3 | HIP 85936 | 12.10 |
| 2026-06-16 12:00 | 17:33:20.75 | -07:44:07.0 | HIP 85936 | 12.71 |
| 2026-06-17 00:00 | 17:32:58.52 | -07:45:15.2 | HIP 85936 | 15.48 |
| 2026-06-17 12:00 | 17:32:36.31 | -07:46:23.8 | HIP 85936 | 19.51 |
| 2026-06-18 00:00 | 17:32:14.13 | -07:47:32.9 | HIP 85721 | 20.49 |
| 2026-06-18 12:00 | 17:31:51.97 | -07:48:42.5 | HIP 85721 | 15.14 |
| 2026-06-19 00:00 | 17:31:29.85 | -07:49:52.5 | HIP 85721 | 10.08 |
| 2026-06-19 12:00 | 17:31:07.75 | -07:51:02.9 | HIP 85721 | 6.05 |
| 2026-06-20 00:00 | 17:30:45.70 | -07:52:13.8 | HIP 85721 | 5.84 |
| 2026-06-20 12:00 | 17:30:23.68 | -07:53:25.2 | HIP 85721 | 9.69 |
| 2026-06-21 00:00 | 17:30:01.69 | -07:54:37.0 | HIP 85618 | 7.78 |
| 2026-06-21 12:00 | 17:29:39.75 | -07:55:49.2 | HIP 85618 | 5.33 |
| 2026-06-22 00:00 | 17:29:17.85 | -07:57:01.9 | HIP 85618 | 7.62 |