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
$$ M_a = (9.264 + 2.480\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 9.264 |
| n | 2.480 |
| gf | 1.000 |
| gb | -0.920 |
| 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 | +0.5821 | -0.585 |
| 2025-09-01 | 2026-07-20 | +1.6864 | -0.782 |
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 | 08:34:30.56 | +66:48:30.3 | HIP 42068 | 22.84 |
| 2026-07-29 12:00 | 08:35:27.77 | +66:50:27.0 | HIP 42068 | 21.70 |
| 2026-07-30 00:00 | 08:36:25.13 | +66:52:24.2 | HIP 42068 | 22.13 |
| 2026-07-30 12:00 | 08:37:22.64 | +66:54:22.0 | HIP 42220 | 23.95 |
| 2026-07-31 00:00 | 08:38:20.29 | +66:56:20.4 | HIP 42220 | 24.03 |
| 2026-07-31 12:00 | 08:39:18.09 | +66:58:19.3 | HIP 42220 | 25.52 |
| 2026-08-01 00:00 | 08:40:16.04 | +67:00:18.7 | HIP 42220 | 28.22 |
| 2026-08-01 12:00 | 08:41:14.13 | +67:02:18.7 | HIP 42220 | 31.82 |
| 2026-08-02 00:00 | 08:42:12.38 | +67:04:19.3 | HIP 42220 | 36.05 |
| 2026-08-02 12:00 | 08:43:10.77 | +67:06:20.4 | HIP 43228 | 36.36 |
| 2026-08-03 00:00 | 08:44:09.31 | +67:08:22.1 | HIP 43228 | 30.58 |
| 2026-08-03 12:00 | 08:45:08.01 | +67:10:24.3 | HIP 43228 | 24.91 |
| 2026-08-04 00:00 | 08:46:06.85 | +67:12:27.0 | HIP 43228 | 19.44 |
| 2026-08-04 12:00 | 08:47:05.85 | +67:14:30.4 | HIP 43228 | 14.43 |
| 2026-08-05 00:00 | 08:48:05.00 | +67:16:34.3 | HIP 43228 | 10.55 |
| 2026-08-05 12:00 | 08:49:04.30 | +67:18:38.7 | HIP 43228 | 9.36 |
| 2026-08-06 00:00 | 08:50:03.75 | +67:20:43.7 | HIP 43228 | 11.74 |
| 2026-08-06 12:00 | 08:51:03.35 | +67:22:49.3 | HIP 43228 | 16.18 |
| 2026-08-07 00:00 | 08:52:03.11 | +67:24:55.5 | HIP 43411 | 18.55 |
| 2026-08-07 12:00 | 08:53:03.02 | +67:27:02.2 | HIP 43411 | 20.27 |
| 2026-08-08 00:00 | 08:54:03.09 | +67:29:09.4 | HIP 43411 | 23.48 |
| 2026-08-08 12:00 | 08:55:03.31 | +67:31:17.3 | HIP 44015 | 20.76 |
| 2026-08-09 00:00 | 08:56:03.68 | +67:33:25.7 | HIP 44015 | 18.56 |
| 2026-08-09 12:00 | 08:57:04.21 | +67:35:34.7 | HIP 44015 | 18.29 |
| 2026-08-10 00:00 | 08:58:04.90 | +67:37:44.3 | HIP 44015 | 20.04 |
| 2026-08-10 12:00 | 08:59:05.74 | +67:39:54.5 | HIP 44390 | 19.80 |
| 2026-08-11 00:00 | 09:00:06.73 | +67:42:05.2 | HIP 44390 | 14.52 |
| 2026-08-11 12:00 | 09:01:07.88 | +67:44:16.5 | HIP 44390 | 10.35 |
| 2026-08-12 00:00 | 09:02:09.19 | +67:46:28.5 | HIP 44390 | 8.98 |
| 2026-08-12 12:00 | 09:03:10.65 | +67:48:40.9 | HIP 44390 | 11.49 |
| 2026-08-13 00:00 | 09:04:12.28 | +67:50:54.0 | HIP 44390 | 16.16 |
| 2026-08-13 12:00 | 09:05:14.05 | +67:53:07.7 | HIP 44645 | 13.39 |
| 2026-08-14 00:00 | 09:06:15.99 | +67:55:21.9 | HIP 44645 | 11.03 |
| 2026-08-14 12:00 | 09:07:18.08 | +67:57:36.8 | HIP 44645 | 11.89 |
| 2026-08-15 00:00 | 09:08:20.33 | +67:59:52.2 | HIP 44645 | 15.44 |
| 2026-08-15 12:00 | 09:09:22.74 | +68:02:08.2 | HIP 44645 | 20.33 |
| 2026-08-16 00:00 | 09:10:25.31 | +68:04:24.8 | HIP 44645 | 25.82 |
| 2026-08-16 12:00 | 09:11:28.03 | +68:06:42.0 | HIP 45501 | 27.89 |
| 2026-08-17 00:00 | 09:12:30.92 | +68:08:59.8 | HIP 45501 | 21.65 |
| 2026-08-17 12:00 | 09:13:33.96 | +68:11:18.1 | HIP 45501 | 15.46 |
| 2026-08-18 00:00 | 09:14:37.17 | +68:13:37.1 | HIP 45501 | 9.40 |
| 2026-08-18 12:00 | 09:15:40.54 | +68:15:56.6 | HIP 45501 | 4.18 |
| 2026-08-19 00:00 | 09:16:44.07 | +68:18:16.7 | HIP 45501 | 5.17 |