C/2024 A1 (ATLAS)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2024 A1 (ATLAS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2025-06-13T17:19:25.170240Z |
| Orbit solution date (soln_date, UTC) | 2026-07-06T12:12:23Z |
| Obs used | 1939 |
| NEO | - |
| M1 | 11.200 |
| K1 | 4.750 |
| PC | - |
| Discovery observation (MPC, UTC) | 2024-01-03T04:58:49.900800Z |
| Discovery magnitude (MPC) | 18.80 o |
| Discovery observatory (MPC) | W68 · ATLAS Chile, Rio Hurtado |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2025-04-27.0000000 |
| e | 1.00209496 |
| q (au) | 3.875284 |
| a (au) | -1849.809740 |
| i (deg) | 94.455752 |
| Ω (om, deg) | 112.137086 |
| ω (w, deg) | 353.313546 |
| M (ma, deg) | -0.000591 |
Magnitude
Scatter + Global Linear
$$ M_a = (9.289 + 2.464\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 9.289 |
| n | 2.464 |
| gf | 1.000 |
| gb | -0.500 |
| k | 1.000 |
| 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 |
|---|---|---|---|
| 2024-01-03 | 2025-05-09 | +0.6217 | -0.610 |
| 2025-09-01 | 2026-09-04 | +0.3689 | +0.050 |
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 | 10:30:55.57 | +71:07:11.2 | HIP 51356 | 23.64 |
| 2026-09-20 12:00 | 10:32:12.02 | +71:10:06.8 | HIP 51356 | 28.83 |
| 2026-09-21 00:00 | 10:33:28.72 | +71:13:02.8 | HIP 51356 | 34.63 |
| 2026-09-21 12:00 | 10:34:45.67 | +71:15:59.3 | HIP 51994 | 38.42 |
| 2026-09-22 00:00 | 10:36:02.86 | +71:18:56.2 | HIP 51994 | 39.74 |
| 2026-09-22 12:00 | 10:37:20.31 | +71:21:53.6 | HIP 52440 | 39.39 |
| 2026-09-23 00:00 | 10:38:38.01 | +71:24:51.4 | HIP 52440 | 33.03 |
| 2026-09-23 12:00 | 10:39:55.96 | +71:27:49.6 | HIP 52440 | 26.90 |
| 2026-09-24 00:00 | 10:41:14.17 | +71:30:48.3 | HIP 52440 | 21.20 |
| 2026-09-24 12:00 | 10:42:32.64 | +71:33:47.4 | HIP 52440 | 16.39 |
| 2026-09-25 00:00 | 10:43:51.37 | +71:36:46.8 | HIP 52440 | 13.49 |
| 2026-09-25 12:00 | 10:45:10.36 | +71:39:46.7 | HIP 52796 | 11.66 |
| 2026-09-26 00:00 | 10:46:29.62 | +71:42:47.0 | HIP 52796 | 6.40 |
| 2026-09-26 12:00 | 10:47:49.15 | +71:45:47.7 | HIP 52796 | 6.49 |
| 2026-09-27 00:00 | 10:49:08.95 | +71:48:48.7 | HIP 52796 | 11.82 |
| 2026-09-27 12:00 | 10:50:29.02 | +71:51:50.2 | HIP 52796 | 18.27 |
| 2026-09-28 00:00 | 10:51:49.37 | +71:54:52.0 | HIP 52796 | 25.00 |
| 2026-09-28 12:00 | 10:53:09.99 | +71:57:54.2 | HIP 53415 | 21.33 |
| 2026-09-29 00:00 | 10:54:30.89 | +72:00:56.7 | HIP 53415 | 15.93 |
| 2026-09-29 12:00 | 10:55:52.08 | +72:03:59.6 | HIP 53415 | 12.17 |
| 2026-09-30 00:00 | 10:57:13.55 | +72:07:02.8 | HIP 53415 | 11.77 |
| 2026-09-30 12:00 | 10:58:35.31 | +72:10:06.4 | HIP 53415 | 15.00 |
| 2026-10-01 00:00 | 10:59:57.35 | +72:13:10.3 | HIP 53415 | 20.20 |
| 2026-10-01 12:00 | 11:01:19.69 | +72:16:14.6 | HIP 53415 | 26.23 |
| 2026-10-02 00:00 | 11:02:42.33 | +72:19:19.2 | HIP 54379 | 25.16 |
| 2026-10-02 12:00 | 11:04:05.25 | +72:22:24.1 | HIP 54379 | 21.76 |
| 2026-10-03 00:00 | 11:05:28.48 | +72:25:29.3 | HIP 54379 | 20.34 |
| 2026-10-03 12:00 | 11:06:52.01 | +72:28:34.8 | HIP 54379 | 21.32 |
| 2026-10-04 00:00 | 11:08:15.84 | +72:31:40.6 | HIP 54686 | 17.37 |
| 2026-10-04 12:00 | 11:09:39.97 | +72:34:46.8 | HIP 54686 | 10.34 |
| 2026-10-05 00:00 | 11:11:04.41 | +72:37:53.2 | HIP 54686 | 3.31 |
| 2026-10-05 12:00 | 11:12:29.17 | +72:40:59.9 | HIP 54686 | 3.74 |
| 2026-10-06 00:00 | 11:13:54.23 | +72:44:06.8 | HIP 54686 | 10.78 |
| 2026-10-06 12:00 | 11:15:19.60 | +72:47:14.1 | HIP 54686 | 17.84 |
| 2026-10-07 00:00 | 11:16:45.30 | +72:50:21.6 | HIP 54686 | 24.89 |
| 2026-10-07 12:00 | 11:18:11.30 | +72:53:29.3 | HIP 55647 | 30.16 |
| 2026-10-08 00:00 | 11:19:37.63 | +72:56:37.3 | HIP 55647 | 26.98 |
| 2026-10-08 12:00 | 11:21:04.28 | +72:59:45.5 | HIP 55647 | 25.46 |
| 2026-10-09 00:00 | 11:22:31.26 | +73:02:54.0 | HIP 55647 | 25.91 |
| 2026-10-09 12:00 | 11:23:58.56 | +73:06:02.6 | HIP 55647 | 28.23 |
| 2026-10-10 00:00 | 11:25:26.18 | +73:09:11.5 | HIP 55647 | 32.02 |
| 2026-10-10 12:00 | 11:26:54.14 | +73:12:20.6 | HIP 56499 | 36.55 |
| 2026-10-11 00:00 | 11:28:22.43 | +73:15:29.8 | HIP 56499 | 29.52 |