3I = C/2025 N1 (ATLAS)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2025 N1 (ATLAS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2025-10-29T11:53:10.705920Z |
| Orbit solution date (soln_date, UTC) | 2026-02-19T09:10:47Z |
| Obs used | 782 |
| NEO | - |
| M1 | 12.500 |
| K1 | 4.500 |
| PC | - |
| Discovery observation (MPC, UTC) | 2025-07-01T05:15:11.232000Z |
| Discovery magnitude (MPC) | 17.72 o |
| Discovery observatory (MPC) | W68 · ATLAS Chile, Rio Hurtado |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2026-02-19.0000000 |
| e | 6.14135145 |
| q (au) | 1.356481 |
| a (au) | -0.263837 |
| i (deg) | 175.116457 |
| Ω (om, deg) | 322.169609 |
| ω (w, deg) | 128.022870 |
| M (ma, deg) | 818.220246 |
Magnitude
Scatter + Global Linear
$$ M_a = (6.925 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 6.925 |
| n | 6.000 |
| gf | 1.000 |
| gb | -0.832 |
| k | 0.989 |
| 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 |
|---|---|---|---|
| 2025-05-08 | 2025-10-02 | -1.7532 | +1.113 |
| 2025-11-03 | 2026-03-21 | -4.4304 | +0.750 |
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 | 06:47:09.71 | +20:24:33.5 | HIP 32456 | 20.45 |
| 2026-03-26 12:00 | 06:47:02.02 | +20:24:45.8 | HIP 32456 | 19.42 |
| 2026-03-27 00:00 | 06:46:54.61 | +20:24:57.7 | HIP 32456 | 18.55 |
| 2026-03-27 12:00 | 06:46:47.48 | +20:25:09.3 | HIP 32456 | 17.83 |
| 2026-03-28 00:00 | 06:46:40.61 | +20:25:20.6 | HIP 32456 | 17.26 |
| 2026-03-28 12:00 | 06:46:34.02 | +20:25:31.5 | HIP 32456 | 16.84 |
| 2026-03-29 00:00 | 06:46:27.68 | +20:25:42.1 | HIP 32456 | 16.57 |
| 2026-03-29 12:00 | 06:46:21.61 | +20:25:52.3 | HIP 32456 | 16.42 |
| 2026-03-30 00:00 | 06:46:15.79 | +20:26:02.3 | HIP 32456 | 16.40 |
| 2026-03-30 12:00 | 06:46:10.23 | +20:26:11.9 | HIP 32456 | 16.48 |
| 2026-03-31 00:00 | 06:46:04.92 | +20:26:21.1 | HIP 32456 | 16.66 |
| 2026-03-31 12:00 | 06:45:59.85 | +20:26:30.1 | HIP 32456 | 16.91 |
| 2026-04-01 00:00 | 06:45:55.02 | +20:26:38.8 | HIP 32456 | 17.22 |
| 2026-04-01 12:00 | 06:45:50.43 | +20:26:47.1 | HIP 32456 | 17.58 |
| 2026-04-02 00:00 | 06:45:46.07 | +20:26:55.2 | HIP 32456 | 17.97 |
| 2026-04-02 12:00 | 06:45:41.95 | +20:27:03.0 | HIP 32456 | 18.38 |
| 2026-04-03 00:00 | 06:45:38.05 | +20:27:10.5 | HIP 32456 | 18.81 |
| 2026-04-03 12:00 | 06:45:34.38 | +20:27:17.6 | HIP 32456 | 19.24 |
| 2026-04-04 00:00 | 06:45:30.93 | +20:27:24.6 | HIP 32456 | 19.67 |
| 2026-04-04 12:00 | 06:45:27.70 | +20:27:31.2 | HIP 32295 | 19.48 |
| 2026-04-05 00:00 | 06:45:24.68 | +20:27:37.5 | HIP 32295 | 18.92 |
| 2026-04-05 12:00 | 06:45:21.88 | +20:27:43.6 | HIP 32295 | 18.41 |
| 2026-04-06 00:00 | 06:45:19.29 | +20:27:49.5 | HIP 32295 | 17.94 |
| 2026-04-06 12:00 | 06:45:16.90 | +20:27:55.0 | HIP 32295 | 17.52 |
| 2026-04-07 00:00 | 06:45:14.72 | +20:28:00.3 | HIP 32295 | 17.13 |
| 2026-04-07 12:00 | 06:45:12.73 | +20:28:05.3 | HIP 32295 | 16.79 |
| 2026-04-08 00:00 | 06:45:10.95 | +20:28:10.1 | HIP 32295 | 16.48 |
| 2026-04-08 12:00 | 06:45:09.36 | +20:28:14.7 | HIP 32295 | 16.20 |
| 2026-04-09 00:00 | 06:45:07.96 | +20:28:18.9 | HIP 32295 | 15.96 |
| 2026-04-09 12:00 | 06:45:06.76 | +20:28:23.0 | HIP 32295 | 15.75 |
| 2026-04-10 00:00 | 06:45:05.74 | +20:28:26.8 | HIP 32295 | 15.56 |
| 2026-04-10 12:00 | 06:45:04.90 | +20:28:30.3 | HIP 32295 | 15.41 |
| 2026-04-11 00:00 | 06:45:04.25 | +20:28:33.6 | HIP 32295 | 15.28 |
| 2026-04-11 12:00 | 06:45:03.78 | +20:28:36.7 | HIP 32295 | 15.18 |
| 2026-04-12 00:00 | 06:45:03.48 | +20:28:39.5 | HIP 32295 | 15.10 |
| 2026-04-12 12:00 | 06:45:03.36 | +20:28:42.1 | HIP 32295 | 15.05 |
| 2026-04-13 00:00 | 06:45:03.41 | +20:28:44.5 | HIP 32295 | 15.02 |
| 2026-04-13 12:00 | 06:45:03.63 | +20:28:46.6 | HIP 32295 | 15.02 |
| 2026-04-14 00:00 | 06:45:04.02 | +20:28:48.6 | HIP 32295 | 15.04 |
| 2026-04-14 12:00 | 06:45:04.57 | +20:28:50.3 | HIP 32295 | 15.09 |
| 2026-04-15 00:00 | 06:45:05.29 | +20:28:51.7 | HIP 32295 | 15.16 |
| 2026-04-15 12:00 | 06:45:06.16 | +20:28:53.0 | HIP 32295 | 15.25 |
| 2026-04-16 00:00 | 06:45:07.20 | +20:28:54.0 | HIP 32295 | 15.37 |