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) |
|---|---|---|---|---|
| 2026-09-20 00:00 | 14:19:35.46 | -00:14:51.5 | HIP 70002 | 14.22 |
| 2026-09-20 12:00 | 14:19:46.72 | -00:15:10.1 | HIP 70002 | 15.19 |
| 2026-09-21 00:00 | 14:19:58.03 | -00:15:28.8 | HIP 70002 | 16.61 |
| 2026-09-21 12:00 | 14:20:09.38 | -00:15:47.5 | HIP 70002 | 18.36 |
| 2026-09-22 00:00 | 14:20:20.79 | -00:16:06.1 | HIP 70002 | 20.38 |
| 2026-09-22 12:00 | 14:20:32.25 | -00:16:24.7 | HIP 70002 | 22.59 |
| 2026-09-23 00:00 | 14:20:43.75 | -00:16:43.4 | HIP 70002 | 24.94 |
| 2026-09-23 12:00 | 14:20:55.30 | -00:17:01.9 | HIP 70002 | 27.41 |
| 2026-09-24 00:00 | 14:21:06.90 | -00:17:20.5 | HIP 70081 | 29.81 |
| 2026-09-24 12:00 | 14:21:18.54 | -00:17:39.0 | HIP 70282 | 30.10 |
| 2026-09-25 00:00 | 14:21:30.23 | -00:17:57.5 | HIP 70282 | 27.81 |
| 2026-09-25 12:00 | 14:21:41.96 | -00:18:15.9 | HIP 70282 | 25.65 |
| 2026-09-26 00:00 | 14:21:53.74 | -00:18:34.3 | HIP 70282 | 23.66 |
| 2026-09-26 12:00 | 14:22:05.56 | -00:18:52.6 | HIP 70282 | 21.88 |
| 2026-09-27 00:00 | 14:22:17.42 | -00:19:10.9 | HIP 70282 | 20.38 |
| 2026-09-27 12:00 | 14:22:29.33 | -00:19:29.0 | HIP 70282 | 19.22 |
| 2026-09-28 00:00 | 14:22:41.28 | -00:19:47.2 | HIP 70282 | 18.48 |
| 2026-09-28 12:00 | 14:22:53.26 | -00:20:05.2 | HIP 70282 | 18.22 |
| 2026-09-29 00:00 | 14:23:05.29 | -00:20:23.1 | HIP 70282 | 18.45 |
| 2026-09-29 12:00 | 14:23:17.36 | -00:20:41.0 | HIP 70282 | 19.17 |
| 2026-09-30 00:00 | 14:23:29.47 | -00:20:58.8 | HIP 70282 | 20.33 |
| 2026-09-30 12:00 | 14:23:41.62 | -00:21:16.5 | HIP 70457 | 18.21 |
| 2026-10-01 00:00 | 14:23:53.80 | -00:21:34.0 | HIP 70457 | 15.75 |
| 2026-10-01 12:00 | 14:24:06.02 | -00:21:51.5 | HIP 70457 | 13.53 |
| 2026-10-02 00:00 | 14:24:18.29 | -00:22:08.9 | HIP 70457 | 11.70 |
| 2026-10-02 12:00 | 14:24:30.58 | -00:22:26.1 | HIP 70457 | 10.46 |
| 2026-10-03 00:00 | 14:24:42.92 | -00:22:43.2 | HIP 70457 | 10.05 |
| 2026-10-03 12:00 | 14:24:55.28 | -00:23:00.2 | HIP 70457 | 10.57 |
| 2026-10-04 00:00 | 14:25:07.69 | -00:23:17.0 | HIP 70457 | 11.91 |
| 2026-10-04 12:00 | 14:25:20.12 | -00:23:33.7 | HIP 70457 | 13.84 |
| 2026-10-05 00:00 | 14:25:32.59 | -00:23:50.3 | HIP 70457 | 16.14 |
| 2026-10-05 12:00 | 14:25:45.10 | -00:24:06.7 | HIP 70566 | 17.96 |
| 2026-10-06 00:00 | 14:25:57.63 | -00:24:23.0 | HIP 70566 | 17.17 |
| 2026-10-06 12:00 | 14:26:10.20 | -00:24:39.1 | HIP 70566 | 16.94 |
| 2026-10-07 00:00 | 14:26:22.80 | -00:24:55.0 | HIP 70566 | 17.30 |
| 2026-10-07 12:00 | 14:26:35.43 | -00:25:10.8 | HIP 70566 | 18.21 |
| 2026-10-08 00:00 | 14:26:48.09 | -00:25:26.3 | HIP 70566 | 19.61 |
| 2026-10-08 12:00 | 14:27:00.78 | -00:25:41.7 | HIP 70566 | 21.39 |
| 2026-10-09 00:00 | 14:27:13.49 | -00:25:56.9 | HIP 70566 | 23.48 |
| 2026-10-09 12:00 | 14:27:26.24 | -00:26:11.9 | HIP 70566 | 25.81 |
| 2026-10-10 00:00 | 14:27:39.01 | -00:26:26.8 | HIP 70702 | 27.65 |
| 2026-10-10 12:00 | 14:27:51.81 | -00:26:41.4 | HIP 70702 | 27.59 |
| 2026-10-11 00:00 | 14:28:04.63 | -00:26:55.7 | HIP 70702 | 27.91 |