C/2022 S4 (Lemmon)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2022 S4 (Lemmon) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2024-07-18T11:28:03.768960Z |
| Orbit solution date (soln_date, UTC) | 2025-06-26T10:12:44Z |
| Obs used | 755 |
| NEO | - |
| M1 | 11.100 |
| K1 | 6.250 |
| PC | 0.030 |
| Discovery observation (MPC, UTC) | 2022-09-19T11:42:45.187200Z |
| Discovery magnitude (MPC) | 20.67 G |
| Discovery observatory (MPC) | G96 · University of Arizona Mt. Lemmon Survey |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2023-09-26.0000000 |
| e | 0.99886708 |
| q (au) | 2.763069 |
| a (au) | 2438.893835 |
| i (deg) | 101.220290 |
| Ω (om, deg) | 220.174408 |
| ω (w, deg) | 268.485380 |
| M (ma, deg) | 359.997574 |
Magnitude
Scatter + Global Linear
$$ M_a = (11.854 + 3.414\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 11.854 |
| n | 3.414 |
| gf | 1.000 |
| gb | -0.683 |
| k | 0.800 |
| 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 |
|---|---|---|---|
| 2022-08-26 | 2023-02-15 | +16.0365 | -12.988 |
| 2023-02-15 | 2024-07-18 | -5.8712 | +3.359 |
| 2024-08-08 | 2025-06-03 | +13.2985 | -4.851 |
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 | 14:18:02.39 | -02:27:53.1 | HIP 70012 | 25.50 |
| 2026-06-01 12:00 | 14:17:48.50 | -02:25:31.3 | HIP 70012 | 27.71 |
| 2026-06-02 00:00 | 14:17:34.73 | -02:23:10.6 | HIP 70012 | 30.31 |
| 2026-06-02 12:00 | 14:17:21.09 | -02:20:51.2 | HIP 70012 | 33.21 |
| 2026-06-03 00:00 | 14:17:07.58 | -02:18:33.1 | HIP 70012 | 36.31 |
| 2026-06-03 12:00 | 14:16:54.20 | -02:16:16.2 | HIP 69997 | 38.94 |
| 2026-06-04 00:00 | 14:16:40.95 | -02:14:00.5 | HIP 69997 | 41.64 |
| 2026-06-04 12:00 | 14:16:27.83 | -02:11:46.1 | HIP 69531 | 43.57 |
| 2026-06-05 00:00 | 14:16:14.84 | -02:09:33.0 | HIP 69531 | 39.64 |
| 2026-06-05 12:00 | 14:16:01.99 | -02:07:21.0 | HIP 69531 | 35.75 |
| 2026-06-06 00:00 | 14:15:49.27 | -02:05:10.4 | HIP 69531 | 31.89 |
| 2026-06-06 12:00 | 14:15:36.68 | -02:03:01.0 | HIP 69531 | 28.08 |
| 2026-06-07 00:00 | 14:15:24.23 | -02:00:52.9 | HIP 69531 | 24.31 |
| 2026-06-07 12:00 | 14:15:11.91 | -01:58:46.0 | HIP 69531 | 20.57 |
| 2026-06-08 00:00 | 14:14:59.73 | -01:56:40.3 | HIP 69531 | 16.88 |
| 2026-06-08 12:00 | 14:14:47.68 | -01:54:36.0 | HIP 69531 | 13.23 |
| 2026-06-09 00:00 | 14:14:35.77 | -01:52:32.9 | HIP 69531 | 9.62 |
| 2026-06-09 12:00 | 14:14:24.00 | -01:50:31.0 | HIP 69531 | 6.05 |
| 2026-06-10 00:00 | 14:14:12.37 | -01:48:30.4 | HIP 69531 | 2.54 |
| 2026-06-10 12:00 | 14:14:00.88 | -01:46:31.1 | HIP 69531 | 1.09 |
| 2026-06-11 00:00 | 14:13:49.52 | -01:44:33.0 | HIP 69531 | 4.47 |
| 2026-06-11 12:00 | 14:13:38.31 | -01:42:36.2 | HIP 69531 | 7.87 |
| 2026-06-12 00:00 | 14:13:27.24 | -01:40:40.6 | HIP 69531 | 11.24 |
| 2026-06-12 12:00 | 14:13:16.31 | -01:38:46.3 | HIP 69531 | 14.57 |
| 2026-06-13 00:00 | 14:13:05.52 | -01:36:53.3 | HIP 69531 | 17.86 |
| 2026-06-13 12:00 | 14:12:54.87 | -01:35:01.5 | HIP 69531 | 21.11 |
| 2026-06-14 00:00 | 14:12:44.37 | -01:33:11.0 | HIP 69531 | 24.31 |
| 2026-06-14 12:00 | 14:12:34.01 | -01:31:21.7 | HIP 69409 | 27.18 |
| 2026-06-15 00:00 | 14:12:23.79 | -01:29:33.7 | HIP 69409 | 29.25 |
| 2026-06-15 12:00 | 14:12:13.72 | -01:27:46.9 | HIP 69409 | 31.47 |
| 2026-06-16 00:00 | 14:12:03.80 | -01:26:01.4 | HIP 69409 | 33.79 |
| 2026-06-16 12:00 | 14:11:54.01 | -01:24:17.1 | HIP 69409 | 36.19 |
| 2026-06-17 00:00 | 14:11:44.38 | -01:22:34.0 | HIP 69145 | 37.53 |
| 2026-06-17 12:00 | 14:11:34.89 | -01:20:52.2 | HIP 69145 | 35.66 |
| 2026-06-18 00:00 | 14:11:25.54 | -01:19:11.6 | HIP 69145 | 33.97 |
| 2026-06-18 12:00 | 14:11:16.35 | -01:17:32.3 | HIP 69145 | 32.47 |
| 2026-06-19 00:00 | 14:11:07.29 | -01:15:54.1 | HIP 69145 | 31.18 |
| 2026-06-19 12:00 | 14:10:58.39 | -01:14:17.2 | HIP 69145 | 30.11 |
| 2026-06-20 00:00 | 14:10:49.63 | -01:12:41.6 | HIP 69145 | 29.28 |
| 2026-06-20 12:00 | 14:10:41.02 | -01:11:07.1 | HIP 69145 | 28.69 |
| 2026-06-21 00:00 | 14:10:32.55 | -01:09:33.8 | HIP 69145 | 28.35 |
| 2026-06-21 12:00 | 14:10:24.24 | -01:08:01.8 | HIP 69145 | 28.26 |
| 2026-06-22 00:00 | 14:10:16.07 | -01:06:30.9 | HIP 69190 | 28.00 |