C/2025 L1 (ATLAS)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2025 L1 (ATLAS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2026-01-12T17:43:51.775680Z |
| Orbit solution date (soln_date, UTC) | 2026-03-21T13:42:22Z |
| Obs used | 129 |
| NEO | - |
| M1 | 14.300 |
| K1 | 4.500 |
| PC | - |
| Discovery observation (MPC, UTC) | 2025-06-06T09:16:16.579200Z |
| Discovery magnitude (MPC) | 18.22 c |
| Discovery observatory (MPC) | W68 · ATLAS Chile, Rio Hurtado |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2025-10-16.0000000 |
| e | 1.00139751 |
| q (au) | 1.679593 |
| a (au) | -1201.846299 |
| i (deg) | 114.137088 |
| Ω (om, deg) | 208.108900 |
| ω (w, deg) | 341.253273 |
| M (ma, deg) | -0.002099 |
Magnitude
Scatter + Global Linear
$$ M_a = (15.932 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 15.932 |
| n | 2.000 |
| gf | 1.000 |
| gb | -0.820 |
| 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 |
|---|---|---|---|
| 2024-10-01 | 2026-01-02 | +6.4711 | -3.204 |
| 2026-01-13 | 2026-03-24 | +49.1465 | -11.832 |
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) |
|---|---|---|---|---|
| 2026-03-26 00:00 | 14:59:11.94 | +24:09:32.6 | HIP 73301 | 5.38 |
| 2026-03-26 12:00 | 14:57:37.05 | +24:48:51.6 | HIP 73203 | 8.48 |
| 2026-03-27 00:00 | 14:56:00.86 | +25:27:56.3 | HIP 73002 | 13.36 |
| 2026-03-27 12:00 | 14:54:23.38 | +26:06:45.4 | HIP 72970 | 23.89 |
| 2026-03-28 00:00 | 14:52:44.61 | +26:45:17.7 | HIP 72805 | 17.50 |
| 2026-03-28 12:00 | 14:51:04.58 | +27:23:32.1 | HIP 72753 | 17.98 |
| 2026-03-29 00:00 | 14:49:23.30 | +28:01:27.5 | HIP 72549 | 24.22 |
| 2026-03-29 12:00 | 14:47:40.78 | +28:39:02.6 | HIP 72256 | 20.95 |
| 2026-03-30 00:00 | 14:45:57.05 | +29:16:16.4 | HIP 72144 | 9.14 |
| 2026-03-30 12:00 | 14:44:12.12 | +29:53:07.9 | HIP 71976 | 16.50 |
| 2026-03-31 00:00 | 14:42:26.02 | +30:29:36.1 | HIP 71984 | 17.51 |
| 2026-03-31 12:00 | 14:40:38.77 | +31:05:39.9 | HIP 71764 | 11.79 |
| 2026-04-01 00:00 | 14:38:50.39 | +31:41:18.5 | HIP 71518 | 16.62 |
| 2026-04-01 12:00 | 14:37:00.91 | +32:16:31.0 | HIP 71644 | 32.60 |
| 2026-04-02 00:00 | 14:35:10.35 | +32:51:16.5 | HIP 71243 | 22.84 |
| 2026-04-02 12:00 | 14:33:18.74 | +33:25:34.2 | HIP 71099 | 18.28 |
| 2026-04-03 00:00 | 14:31:26.12 | +33:59:23.4 | HIP 71009 | 38.82 |
| 2026-04-03 12:00 | 14:29:32.52 | +34:32:43.4 | HIP 70799 | 12.06 |
| 2026-04-04 00:00 | 14:27:37.96 | +35:05:33.5 | HIP 70578 | 17.73 |
| 2026-04-04 12:00 | 14:25:42.48 | +35:37:53.2 | HIP 70568 | 12.98 |
| 2026-04-05 00:00 | 14:23:46.12 | +36:09:41.8 | HIP 70341 | 6.41 |
| 2026-04-05 12:00 | 14:21:48.91 | +36:40:58.8 | HIP 70121 | 20.99 |
| 2026-04-06 00:00 | 14:19:50.90 | +37:11:43.8 | HIP 70142 | 19.83 |
| 2026-04-06 12:00 | 14:17:52.11 | +37:41:56.4 | HIP 69878 | 2.81 |
| 2026-04-07 00:00 | 14:15:52.60 | +38:11:36.2 | HIP 69554 | 20.91 |
| 2026-04-07 12:00 | 14:13:52.40 | +38:40:42.9 | HIP 69520 | 8.48 |
| 2026-04-08 00:00 | 14:11:51.56 | +39:09:16.1 | HIP 69366 | 19.43 |
| 2026-04-08 12:00 | 14:09:50.12 | +39:37:15.7 | HIP 69227 | 8.92 |
| 2026-04-09 00:00 | 14:07:48.13 | +40:04:41.5 | HIP 69158 | 18.71 |
| 2026-04-09 12:00 | 14:05:45.63 | +40:31:33.4 | HIP 68745 | 19.62 |
| 2026-04-10 00:00 | 14:03:42.68 | +40:57:51.2 | HIP 68585 | 27.91 |
| 2026-04-10 12:00 | 14:01:39.31 | +41:23:34.8 | HIP 68497 | 7.09 |
| 2026-04-11 00:00 | 13:59:35.58 | +41:48:44.3 | HIP 68369 | 14.29 |
| 2026-04-11 12:00 | 13:57:31.53 | +42:13:19.7 | HIP 68233 | 13.11 |
| 2026-04-12 00:00 | 13:55:27.23 | +42:37:21.1 | HIP 67985 | 2.30 |
| 2026-04-12 12:00 | 13:53:22.71 | +43:00:48.5 | HIP 67768 | 17.19 |
| 2026-04-13 00:00 | 13:51:18.04 | +43:23:42.0 | HIP 67768 | 19.64 |
| 2026-04-13 12:00 | 13:49:13.25 | +43:46:01.8 | HIP 67396 | 9.51 |
| 2026-04-14 00:00 | 13:47:08.41 | +44:07:48.2 | HIP 67095 | 26.76 |
| 2026-04-14 12:00 | 13:45:03.57 | +44:29:01.3 | HIP 67095 | 5.44 |
| 2026-04-15 00:00 | 13:42:58.77 | +44:49:41.3 | HIP 66698 | 29.62 |
| 2026-04-15 12:00 | 13:40:54.08 | +45:09:48.6 | HIP 66698 | 12.12 |
| 2026-04-16 00:00 | 13:38:49.54 | +45:29:23.5 | HIP 66526 | 8.85 |