C/2023 H5 (Lemmon)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2023 H5 (Lemmon) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2025-06-30T05:02:24.190080Z |
| Orbit solution date (soln_date, UTC) | 2026-05-28T12:12:15Z |
| Obs used | 2624 |
| 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 · University of Arizona Mt. Lemmon Survey |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2025-01-11.0000000 |
| e | 1.00038878 |
| q (au) | 4.312693 |
| a (au) | -11093.017371 |
| i (deg) | 97.856917 |
| Ω (om, deg) | 159.479789 |
| ω (w, deg) | 60.088639 |
| M (ma, deg) | -0.000144 |
Magnitude
Scatter + Global Linear
$$ M_a = (8.911 + 4.146\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 8.911 |
| n | 4.146 |
| gf | 0.972 |
| gb | -0.756 |
| k | 0.901 |
| δ90 | 7.982 |
| 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 | +21.5984 | -18.456 |
| 2023-05-24 | 2024-06-26 | +2.9831 | -2.325 |
| 2024-06-26 | 2025-06-30 | -2.6614 | +1.645 |
| 2025-06-30 | 2026-06-02 | +12.4843 | -7.768 |
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 | 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 |
| 2026-06-02 12:00 | 22:15:48.11 | +66:09:52.7 | HIP 110034 | 8.76 |
| 2026-06-03 00:00 | 22:15:43.14 | +66:11:51.7 | HIP 110034 | 9.90 |
| 2026-06-03 12:00 | 22:15:37.74 | +66:13:50.0 | HIP 110034 | 11.32 |
| 2026-06-04 00:00 | 22:15:31.91 | +66:15:47.7 | HIP 110034 | 12.93 |
| 2026-06-04 12:00 | 22:15:25.64 | +66:17:44.6 | HIP 110034 | 14.68 |
| 2026-06-05 00:00 | 22:15:18.93 | +66:19:40.8 | HIP 110034 | 16.52 |
| 2026-06-05 12:00 | 22:15:11.79 | +66:21:36.2 | HIP 110034 | 18.42 |
| 2026-06-06 00:00 | 22:15:04.21 | +66:23:30.8 | HIP 110034 | 20.37 |
| 2026-06-06 12:00 | 22:14:56.20 | +66:25:24.6 | HIP 110034 | 22.35 |
| 2026-06-07 00:00 | 22:14:47.74 | +66:27:17.5 | HIP 109518 | 21.95 |
| 2026-06-07 12:00 | 22:14:38.84 | +66:29:09.6 | HIP 109518 | 21.10 |
| 2026-06-08 00:00 | 22:14:29.50 | +66:31:00.9 | HIP 109518 | 20.38 |
| 2026-06-08 12:00 | 22:14:19.72 | +66:32:51.2 | HIP 109518 | 19.80 |
| 2026-06-09 00:00 | 22:14:09.50 | +66:34:40.5 | HIP 109518 | 19.39 |
| 2026-06-09 12:00 | 22:13:58.83 | +66:36:28.9 | HIP 109518 | 19.15 |
| 2026-06-10 00:00 | 22:13:47.72 | +66:38:16.3 | HIP 109776 | 17.77 |
| 2026-06-10 12:00 | 22:13:36.16 | +66:40:02.7 | HIP 109776 | 16.18 |
| 2026-06-11 00:00 | 22:13:24.16 | +66:41:48.0 | HIP 109776 | 14.76 |
| 2026-06-11 12:00 | 22:13:11.71 | +66:43:32.3 | HIP 109635 | 13.52 |
| 2026-06-12 00:00 | 22:12:58.81 | +66:45:15.5 | HIP 109635 | 11.54 |
| 2026-06-12 12:00 | 22:12:45.47 | +66:46:57.5 | HIP 109635 | 9.63 |
| 2026-06-13 00:00 | 22:12:31.67 | +66:48:38.4 | HIP 109635 | 7.88 |
| 2026-06-13 12:00 | 22:12:17.43 | +66:50:18.1 | HIP 109635 | 6.40 |
| 2026-06-14 00:00 | 22:12:02.75 | +66:51:56.5 | HIP 109635 | 5.46 |
| 2026-06-14 12:00 | 22:11:47.61 | +66:53:33.8 | HIP 109635 | 5.35 |
| 2026-06-15 00:00 | 22:11:32.03 | +66:55:09.7 | HIP 109635 | 6.13 |
| 2026-06-15 12:00 | 22:11:16.00 | +66:56:44.4 | HIP 109635 | 7.55 |
| 2026-06-16 00:00 | 22:10:59.52 | +66:58:17.7 | HIP 109635 | 9.33 |
| 2026-06-16 12:00 | 22:10:42.60 | +66:59:49.6 | HIP 109635 | 11.30 |
| 2026-06-17 00:00 | 22:10:25.24 | +67:01:20.2 | HIP 109635 | 13.40 |
| 2026-06-17 12:00 | 22:10:07.43 | +67:02:49.3 | HIP 109635 | 15.57 |
| 2026-06-18 00:00 | 22:09:49.17 | +67:04:17.0 | HIP 109635 | 17.79 |
| 2026-06-18 12:00 | 22:09:30.48 | +67:05:43.2 | HIP 109635 | 20.06 |
| 2026-06-19 00:00 | 22:09:11.34 | +67:07:07.8 | HIP 109635 | 22.36 |
| 2026-06-19 12:00 | 22:08:51.77 | +67:08:31.0 | HIP 109635 | 24.70 |
| 2026-06-20 00:00 | 22:08:31.75 | +67:09:52.5 | HIP 109635 | 27.05 |
| 2026-06-20 12:00 | 22:08:11.30 | +67:11:12.5 | HIP 108894 | 27.81 |
| 2026-06-21 00:00 | 22:07:50.42 | +67:12:30.8 | HIP 108894 | 26.08 |
| 2026-06-21 12:00 | 22:07:29.10 | +67:13:47.5 | HIP 108894 | 24.42 |
| 2026-06-22 00:00 | 22:07:07.35 | +67:15:02.5 | HIP 108894 | 22.85 |