C/2023 H5 (Lemmon)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2023 H5 (Lemmon) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2025-06-30T05:01:57.311040Z |
| Orbit solution date (soln_date, UTC) | 2026-04-30T15:12:15Z |
| Obs used | 2616 |
| NEO | - |
| M1 | 8.600 |
| K1 | 7.750 |
| PC | 0.030 |
| Discovery observation (MPC, UTC) | 2023-04-19T04:23:52.540800Z |
| Discovery magnitude (MPC) | 20.29 G |
| Discovery observatory (MPC) | G96 · Mt. Lemmon Survey |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2025-01-10.0000000 |
| e | 1.00038775 |
| q (au) | 4.312694 |
| a (au) | -11122.414741 |
| i (deg) | 97.856948 |
| Ω (om, deg) | 159.479810 |
| ω (w, deg) | 60.088586 |
| M (ma, deg) | -0.000144 |
Magnitude
Scatter + Global Linear
$$ M_a = (9.655 + 4.094\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 9.655 |
| n | 4.094 |
| gf | 1.000 |
| gb | -0.748 |
| k | 0.800 |
| δ90 | 9.891 |
| 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 |
|---|---|---|---|
| 2022-12-01 | 2023-05-24 | +21.8660 | -18.675 |
| 2023-05-24 | 2024-06-26 | +3.0256 | -2.351 |
| 2024-06-26 | 2025-06-30 | -2.6605 | +1.650 |
| 2025-06-30 | 2026-05-09 | +14.2272 | -8.887 |
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 | 22:12:51.23 | +64:38:35.1 | HIP 109451 | 23.90 |
| 2026-05-12 12:00 | 22:13:03.60 | +64:40:44.8 | HIP 109435 | 24.44 |
| 2026-05-13 00:00 | 22:13:15.61 | +64:42:54.6 | HIP 109435 | 24.01 |
| 2026-05-13 12:00 | 22:13:27.24 | +64:45:04.6 | HIP 109435 | 23.81 |
| 2026-05-14 00:00 | 22:13:38.49 | +64:47:14.7 | HIP 109435 | 23.83 |
| 2026-05-14 12:00 | 22:13:49.37 | +64:49:24.8 | HIP 110047 | 23.82 |
| 2026-05-15 00:00 | 22:13:59.86 | +64:51:35.0 | HIP 110047 | 23.45 |
| 2026-05-15 12:00 | 22:14:09.98 | +64:53:45.3 | HIP 110047 | 23.37 |
| 2026-05-16 00:00 | 22:14:19.71 | +64:55:55.6 | HIP 110047 | 23.57 |
| 2026-05-16 12:00 | 22:14:29.06 | +64:58:05.9 | HIP 110047 | 24.05 |
| 2026-05-17 00:00 | 22:14:38.03 | +65:00:16.2 | HIP 110047 | 24.78 |
| 2026-05-17 12:00 | 22:14:46.60 | +65:02:26.5 | HIP 110093 | 25.12 |
| 2026-05-18 00:00 | 22:14:54.79 | +65:04:36.8 | HIP 110093 | 25.66 |
| 2026-05-18 12:00 | 22:15:02.59 | +65:06:47.0 | HIP 110007 | 24.27 |
| 2026-05-19 00:00 | 22:15:09.99 | +65:08:57.1 | HIP 110007 | 21.99 |
| 2026-05-19 12:00 | 22:15:17.00 | +65:11:07.2 | HIP 110007 | 19.74 |
| 2026-05-20 00:00 | 22:15:23.61 | +65:13:17.1 | HIP 110007 | 17.53 |
| 2026-05-20 12:00 | 22:15:29.83 | +65:15:26.8 | HIP 110007 | 15.35 |
| 2026-05-21 00:00 | 22:15:35.65 | +65:17:36.5 | HIP 110007 | 13.24 |
| 2026-05-21 12:00 | 22:15:41.07 | +65:19:45.9 | HIP 110007 | 11.20 |
| 2026-05-22 00:00 | 22:15:46.09 | +65:21:55.2 | HIP 110007 | 9.29 |
| 2026-05-22 12:00 | 22:15:50.71 | +65:24:04.2 | HIP 110007 | 7.59 |
| 2026-05-23 00:00 | 22:15:54.93 | +65:26:13.1 | HIP 110007 | 6.25 |
| 2026-05-23 12:00 | 22:15:58.74 | +65:28:21.6 | HIP 110007 | 5.53 |
| 2026-05-24 00:00 | 22:16:02.14 | +65:30:29.9 | HIP 110007 | 5.66 |
| 2026-05-24 12:00 | 22:16:05.14 | +65:32:38.0 | HIP 110007 | 6.58 |
| 2026-05-25 00:00 | 22:16:07.73 | +65:34:45.7 | HIP 110007 | 8.01 |
| 2026-05-25 12:00 | 22:16:09.91 | +65:36:53.1 | HIP 110007 | 9.72 |
| 2026-05-26 00:00 | 22:16:11.69 | +65:39:00.2 | HIP 110007 | 11.58 |
| 2026-05-26 12:00 | 22:16:13.04 | +65:41:06.9 | HIP 109798 | 12.85 |
| 2026-05-27 00:00 | 22:16:13.99 | +65:43:13.2 | HIP 109798 | 12.13 |
| 2026-05-27 12:00 | 22:16:14.52 | +65:45:19.2 | HIP 109798 | 11.69 |
| 2026-05-28 00:00 | 22:16:14.64 | +65:47:24.7 | HIP 109798 | 11.59 |
| 2026-05-28 12:00 | 22:16:14.34 | +65:49:29.8 | HIP 109798 | 11.82 |
| 2026-05-29 00:00 | 22:16:13.62 | +65:51:34.5 | HIP 109798 | 12.35 |
| 2026-05-29 12:00 | 22:16:12.48 | +65:53:38.6 | HIP 109798 | 13.16 |
| 2026-05-30 00:00 | 22:16:10.92 | +65:55:42.3 | HIP 110034 | 13.54 |
| 2026-05-30 12:00 | 22:16:08.94 | +65:57:45.5 | HIP 110034 | 11.86 |
| 2026-05-31 00:00 | 22:16:06.53 | +65:59:48.1 | HIP 110034 | 10.36 |
| 2026-05-31 12:00 | 22:16:03.70 | +66:01:50.2 | HIP 110034 | 9.11 |
| 2026-06-01 00:00 | 22:16:00.45 | +66:03:51.7 | HIP 110034 | 8.23 |
| 2026-06-01 12:00 | 22:15:56.77 | +66:05:52.7 | HIP 110034 | 7.86 |
| 2026-06-02 00:00 | 22:15:52.65 | +66:07:53.0 | HIP 110034 | 8.05 |