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) |
|---|---|---|---|---|
| 2026-02-03 00:00 | 15:09:45.87 | -14:47:41.2 | HIP 74050 | 28.66 |
| 2026-02-03 12:00 | 15:09:47.41 | -14:45:32.8 | HIP 74050 | 28.17 |
| 2026-02-04 00:00 | 15:09:48.78 | -14:43:23.4 | HIP 74050 | 27.80 |
| 2026-02-04 12:00 | 15:09:49.98 | -14:41:13.0 | HIP 74050 | 27.55 |
| 2026-02-05 00:00 | 15:09:51.01 | -14:39:01.7 | HIP 74050 | 27.43 |
| 2026-02-05 12:00 | 15:09:51.86 | -14:36:49.5 | HIP 74050 | 27.45 |
| 2026-02-06 00:00 | 15:09:52.55 | -14:34:36.3 | HIP 74050 | 27.60 |
| 2026-02-06 12:00 | 15:09:53.06 | -14:32:22.2 | HIP 74050 | 27.90 |
| 2026-02-07 00:00 | 15:09:53.39 | -14:30:07.2 | HIP 74050 | 28.32 |
| 2026-02-07 12:00 | 15:09:53.56 | -14:27:51.2 | HIP 74050 | 28.88 |
| 2026-02-08 00:00 | 15:09:53.55 | -14:25:34.2 | HIP 74145 | 28.43 |
| 2026-02-08 12:00 | 15:09:53.36 | -14:23:16.3 | HIP 74145 | 26.36 |
| 2026-02-09 00:00 | 15:09:53.00 | -14:20:57.4 | HIP 74145 | 24.30 |
| 2026-02-09 12:00 | 15:09:52.47 | -14:18:37.6 | HIP 74145 | 22.24 |
| 2026-02-10 00:00 | 15:09:51.76 | -14:16:16.8 | HIP 74145 | 20.22 |
| 2026-02-10 12:00 | 15:09:50.87 | -14:13:55.1 | HIP 74145 | 18.23 |
| 2026-02-11 00:00 | 15:09:49.81 | -14:11:32.4 | HIP 74145 | 16.30 |
| 2026-02-11 12:00 | 15:09:48.56 | -14:09:08.7 | HIP 74145 | 14.46 |
| 2026-02-12 00:00 | 15:09:47.15 | -14:06:44.1 | HIP 74145 | 12.78 |
| 2026-02-12 12:00 | 15:09:45.55 | -14:04:18.5 | HIP 74145 | 11.32 |
| 2026-02-13 00:00 | 15:09:43.77 | -14:01:52.0 | HIP 74145 | 10.20 |
| 2026-02-13 12:00 | 15:09:41.82 | -13:59:24.5 | HIP 74145 | 9.57 |
| 2026-02-14 00:00 | 15:09:39.69 | -13:56:56.0 | HIP 74145 | 9.54 |
| 2026-02-14 12:00 | 15:09:37.38 | -13:54:26.6 | HIP 74145 | 10.13 |
| 2026-02-15 00:00 | 15:09:34.89 | -13:51:56.2 | HIP 74145 | 11.26 |
| 2026-02-15 12:00 | 15:09:32.22 | -13:49:24.8 | HIP 74145 | 12.80 |
| 2026-02-16 00:00 | 15:09:29.37 | -13:46:52.5 | HIP 74145 | 14.65 |
| 2026-02-16 12:00 | 15:09:26.34 | -13:44:19.2 | HIP 74145 | 16.70 |
| 2026-02-17 00:00 | 15:09:23.13 | -13:41:44.9 | HIP 74145 | 18.91 |
| 2026-02-17 12:00 | 15:09:19.74 | -13:39:09.7 | HIP 74145 | 21.24 |
| 2026-02-18 00:00 | 15:09:16.17 | -13:36:33.5 | HIP 74145 | 23.66 |
| 2026-02-18 12:00 | 15:09:12.42 | -13:33:56.4 | HIP 74145 | 26.15 |
| 2026-02-19 00:00 | 15:09:08.49 | -13:31:18.3 | HIP 74145 | 28.71 |
| 2026-02-19 12:00 | 15:09:04.38 | -13:28:39.3 | HIP 74145 | 31.33 |
| 2026-02-20 00:00 | 15:09:00.09 | -13:25:59.3 | HIP 74210 | 30.34 |
| 2026-02-20 12:00 | 15:08:55.62 | -13:23:18.3 | HIP 74210 | 28.46 |
| 2026-02-21 00:00 | 15:08:50.97 | -13:20:36.4 | HIP 74210 | 26.78 |
| 2026-02-21 12:00 | 15:08:46.14 | -13:17:53.6 | HIP 74210 | 25.34 |
| 2026-02-22 00:00 | 15:08:41.13 | -13:15:09.8 | HIP 74210 | 24.20 |
| 2026-02-22 12:00 | 15:08:35.94 | -13:12:25.1 | HIP 74210 | 23.41 |
| 2026-02-23 00:00 | 15:08:30.58 | -13:09:39.4 | HIP 74210 | 23.03 |
| 2026-02-23 12:00 | 15:08:25.03 | -13:06:52.8 | HIP 74210 | 23.09 |
| 2026-02-24 00:00 | 15:08:19.30 | -13:04:05.3 | HIP 74210 | 23.59 |