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) |
|---|---|---|---|---|
| 2026-07-29 00:00 | 14:06:45.29 | -00:03:20.8 | HIP 69009 | 15.85 |
| 2026-07-29 12:00 | 14:06:47.43 | -00:03:03.0 | HIP 69009 | 15.55 |
| 2026-07-30 00:00 | 14:06:49.68 | -00:02:45.8 | HIP 69025 | 15.11 |
| 2026-07-30 12:00 | 14:06:52.05 | -00:02:29.4 | HIP 69025 | 14.53 |
| 2026-07-31 00:00 | 14:06:54.54 | -00:02:13.7 | HIP 69025 | 13.93 |
| 2026-07-31 12:00 | 14:06:57.15 | -00:01:58.6 | HIP 69025 | 13.30 |
| 2026-08-01 00:00 | 14:06:59.87 | -00:01:44.2 | HIP 69025 | 12.66 |
| 2026-08-01 12:00 | 14:07:02.71 | -00:01:30.5 | HIP 69025 | 11.98 |
| 2026-08-02 00:00 | 14:07:05.67 | -00:01:17.5 | HIP 69025 | 11.29 |
| 2026-08-02 12:00 | 14:07:08.74 | -00:01:05.1 | HIP 69025 | 10.58 |
| 2026-08-03 00:00 | 14:07:11.92 | -00:00:53.4 | HIP 69025 | 9.85 |
| 2026-08-03 12:00 | 14:07:15.22 | -00:00:42.3 | HIP 69025 | 9.11 |
| 2026-08-04 00:00 | 14:07:18.64 | -00:00:31.8 | HIP 69025 | 8.35 |
| 2026-08-04 12:00 | 14:07:22.17 | -00:00:22.0 | HIP 69025 | 7.59 |
| 2026-08-05 00:00 | 14:07:25.80 | -00:00:12.8 | HIP 69025 | 6.83 |
| 2026-08-05 12:00 | 14:07:29.56 | -00:00:04.2 | HIP 69025 | 6.09 |
| 2026-08-06 00:00 | 14:07:33.42 | +00:00:03.8 | HIP 69025 | 5.39 |
| 2026-08-06 12:00 | 14:07:37.39 | +00:00:11.1 | HIP 69025 | 4.76 |
| 2026-08-07 00:00 | 14:07:41.48 | +00:00:17.9 | HIP 69025 | 4.24 |
| 2026-08-07 12:00 | 14:07:45.67 | +00:00:24.1 | HIP 69025 | 3.92 |
| 2026-08-08 00:00 | 14:07:49.97 | +00:00:29.7 | HIP 69025 | 3.85 |
| 2026-08-08 12:00 | 14:07:54.38 | +00:00:34.7 | HIP 69025 | 4.08 |
| 2026-08-09 00:00 | 14:07:58.90 | +00:00:39.2 | HIP 69025 | 4.58 |
| 2026-08-09 12:00 | 14:08:03.53 | +00:00:43.1 | HIP 69025 | 5.29 |
| 2026-08-10 00:00 | 14:08:08.26 | +00:00:46.4 | HIP 69025 | 6.14 |
| 2026-08-10 12:00 | 14:08:13.10 | +00:00:49.2 | HIP 69025 | 7.11 |
| 2026-08-11 00:00 | 14:08:18.05 | +00:00:51.5 | HIP 69025 | 8.17 |
| 2026-08-11 12:00 | 14:08:23.10 | +00:00:53.2 | HIP 69025 | 9.28 |
| 2026-08-12 00:00 | 14:08:28.25 | +00:00:54.4 | HIP 69025 | 10.45 |
| 2026-08-12 12:00 | 14:08:33.51 | +00:00:55.1 | HIP 69025 | 11.67 |
| 2026-08-13 00:00 | 14:08:38.87 | +00:00:55.3 | HIP 69025 | 12.93 |
| 2026-08-13 12:00 | 14:08:44.34 | +00:00:54.9 | HIP 69025 | 14.22 |
| 2026-08-14 00:00 | 14:08:49.90 | +00:00:54.1 | HIP 69025 | 15.55 |
| 2026-08-14 12:00 | 14:08:55.57 | +00:00:52.8 | HIP 69025 | 16.91 |
| 2026-08-15 00:00 | 14:09:01.34 | +00:00:51.0 | HIP 69025 | 18.31 |
| 2026-08-15 12:00 | 14:09:07.20 | +00:00:48.8 | HIP 69025 | 19.73 |
| 2026-08-16 00:00 | 14:09:13.17 | +00:00:46.1 | HIP 69025 | 21.18 |
| 2026-08-16 12:00 | 14:09:19.23 | +00:00:42.9 | HIP 69025 | 22.66 |
| 2026-08-17 00:00 | 14:09:25.39 | +00:00:39.3 | HIP 69219 | 22.47 |
| 2026-08-17 12:00 | 14:09:31.65 | +00:00:35.2 | HIP 69219 | 21.58 |
| 2026-08-18 00:00 | 14:09:38.00 | +00:00:30.7 | HIP 69219 | 20.74 |
| 2026-08-18 12:00 | 14:09:44.45 | +00:00:25.8 | HIP 69219 | 19.98 |
| 2026-08-19 00:00 | 14:09:50.99 | +00:00:20.5 | HIP 69219 | 19.32 |