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 · 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 | 0.998 |
| 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) |
|---|---|---|---|---|
| 2026-05-12 00:00 | 14:28:49.83 | -04:18:38.3 | HIP 70906 | 17.95 |
| 2026-05-12 12:00 | 14:28:31.82 | -04:15:30.8 | HIP 70906 | 22.04 |
| 2026-05-13 00:00 | 14:28:13.89 | -04:12:24.2 | HIP 70653 | 21.99 |
| 2026-05-13 12:00 | 14:27:56.03 | -04:09:18.7 | HIP 70653 | 20.91 |
| 2026-05-14 00:00 | 14:27:38.24 | -04:06:14.1 | HIP 70653 | 21.20 |
| 2026-05-14 12:00 | 14:27:20.53 | -04:03:10.6 | HIP 70653 | 22.79 |
| 2026-05-15 00:00 | 14:27:02.90 | -04:00:08.1 | HIP 70556 | 23.76 |
| 2026-05-15 12:00 | 14:26:45.36 | -03:57:06.7 | HIP 70556 | 18.60 |
| 2026-05-16 00:00 | 14:26:27.89 | -03:54:06.2 | HIP 70556 | 13.58 |
| 2026-05-16 12:00 | 14:26:10.51 | -03:51:06.9 | HIP 70556 | 8.91 |
| 2026-05-17 00:00 | 14:25:53.22 | -03:48:08.6 | HIP 70556 | 5.48 |
| 2026-05-17 12:00 | 14:25:36.02 | -03:45:11.4 | HIP 70556 | 5.95 |
| 2026-05-18 00:00 | 14:25:18.91 | -03:42:15.3 | HIP 70556 | 9.73 |
| 2026-05-18 12:00 | 14:25:01.89 | -03:39:20.2 | HIP 70556 | 14.38 |
| 2026-05-19 00:00 | 14:24:44.96 | -03:36:26.3 | HIP 70556 | 19.26 |
| 2026-05-19 12:00 | 14:24:28.13 | -03:33:33.5 | HIP 70556 | 24.21 |
| 2026-05-20 00:00 | 14:24:11.39 | -03:30:41.8 | HIP 70258 | 28.01 |
| 2026-05-20 12:00 | 14:23:54.76 | -03:27:51.2 | HIP 70258 | 26.02 |
| 2026-05-21 00:00 | 14:23:38.22 | -03:25:01.8 | HIP 70258 | 24.91 |
| 2026-05-21 12:00 | 14:23:21.79 | -03:22:13.5 | HIP 70258 | 24.77 |
| 2026-05-22 00:00 | 14:23:05.46 | -03:19:26.4 | HIP 70258 | 25.60 |
| 2026-05-22 12:00 | 14:22:49.23 | -03:16:40.4 | HIP 70309 | 24.99 |
| 2026-05-23 00:00 | 14:22:33.11 | -03:13:55.6 | HIP 70309 | 23.41 |
| 2026-05-23 12:00 | 14:22:17.10 | -03:11:12.0 | HIP 70309 | 22.78 |
| 2026-05-24 00:00 | 14:22:01.19 | -03:08:29.5 | HIP 70309 | 23.17 |
| 2026-05-24 12:00 | 14:21:45.40 | -03:05:48.2 | HIP 70309 | 24.50 |
| 2026-05-25 00:00 | 14:21:29.71 | -03:03:08.1 | HIP 70309 | 26.62 |
| 2026-05-25 12:00 | 14:21:14.14 | -03:00:29.1 | HIP 70309 | 29.33 |
| 2026-05-26 00:00 | 14:20:58.68 | -02:57:51.4 | HIP 70138 | 28.07 |
| 2026-05-26 12:00 | 14:20:43.34 | -02:55:14.9 | HIP 70138 | 26.01 |
| 2026-05-27 00:00 | 14:20:28.11 | -02:52:39.5 | HIP 70138 | 24.68 |
| 2026-05-27 12:00 | 14:20:13.00 | -02:50:05.4 | HIP 70138 | 24.16 |
| 2026-05-28 00:00 | 14:19:58.00 | -02:47:32.5 | HIP 70138 | 24.50 |
| 2026-05-28 12:00 | 14:19:43.12 | -02:45:00.8 | HIP 70138 | 25.63 |
| 2026-05-29 00:00 | 14:19:28.37 | -02:42:30.3 | HIP 70012 | 26.61 |
| 2026-05-29 12:00 | 14:19:13.73 | -02:40:01.1 | HIP 70012 | 24.55 |
| 2026-05-30 00:00 | 14:18:59.22 | -02:37:33.0 | HIP 70012 | 23.18 |
| 2026-05-30 12:00 | 14:18:44.82 | -02:35:06.2 | HIP 70012 | 22.59 |
| 2026-05-31 00:00 | 14:18:30.55 | -02:32:40.6 | HIP 70012 | 22.82 |
| 2026-05-31 12:00 | 14:18:16.41 | -02:30:16.3 | HIP 70012 | 23.83 |
| 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 |