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
$$ M_a = (7.358 + 5.638\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 7.358 |
| n | 5.638 |
| gf | 0.999 |
| gb | -0.803 |
| k | 0.985 |
| 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 | -1.6278 | +1.089 |
| 2025-11-03 | 2026-01-06 | -0.4756 | -0.427 |
| 2026-01-06 | 2026-04-13 | -6.1414 | +2.505 |
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) |
|---|---|---|---|---|
| 2026-06-01 00:00 | 06:53:51.62 | +20:18:11.9 | HIP 33026 | 14.89 |
| 2026-06-01 12:00 | 06:53:59.93 | +20:17:58.6 | HIP 33026 | 16.83 |
| 2026-06-02 00:00 | 06:54:08.27 | +20:17:45.1 | HIP 33026 | 18.78 |
| 2026-06-02 12:00 | 06:54:16.62 | +20:17:31.5 | HIP 33286 | 17.50 |
| 2026-06-03 00:00 | 06:54:25.00 | +20:17:17.9 | HIP 33286 | 15.58 |
| 2026-06-03 12:00 | 06:54:33.40 | +20:17:04.1 | HIP 33286 | 13.67 |
| 2026-06-04 00:00 | 06:54:41.81 | +20:16:50.2 | HIP 33286 | 11.79 |
| 2026-06-04 12:00 | 06:54:50.25 | +20:16:36.2 | HIP 33286 | 9.94 |
| 2026-06-05 00:00 | 06:54:58.70 | +20:16:22.2 | HIP 33286 | 8.15 |
| 2026-06-05 12:00 | 06:55:07.16 | +20:16:08.0 | HIP 33286 | 6.49 |
| 2026-06-06 00:00 | 06:55:15.64 | +20:15:53.7 | HIP 33286 | 5.07 |
| 2026-06-06 12:00 | 06:55:24.14 | +20:15:39.3 | HIP 33286 | 4.15 |
| 2026-06-07 00:00 | 06:55:32.65 | +20:15:24.9 | HIP 33286 | 4.11 |
| 2026-06-07 12:00 | 06:55:41.17 | +20:15:10.3 | HIP 33286 | 4.96 |
| 2026-06-08 00:00 | 06:55:49.70 | +20:14:55.6 | HIP 33286 | 6.36 |
| 2026-06-08 12:00 | 06:55:58.25 | +20:14:40.9 | HIP 33286 | 8.03 |
| 2026-06-09 00:00 | 06:56:06.81 | +20:14:26.0 | HIP 33286 | 9.84 |
| 2026-06-09 12:00 | 06:56:15.37 | +20:14:11.1 | HIP 33286 | 11.71 |
| 2026-06-10 00:00 | 06:56:23.95 | +20:13:56.0 | HIP 33286 | 13.64 |
| 2026-06-10 12:00 | 06:56:32.54 | +20:13:40.9 | HIP 33286 | 15.59 |
| 2026-06-11 00:00 | 06:56:41.13 | +20:13:25.7 | HIP 33286 | 17.56 |
| 2026-06-11 12:00 | 06:56:49.73 | +20:13:10.4 | HIP 33286 | 19.54 |
| 2026-06-12 00:00 | 06:56:58.33 | +20:12:55.0 | HIP 33496 | 18.76 |
| 2026-06-12 12:00 | 06:57:06.94 | +20:12:39.5 | HIP 33496 | 17.85 |
| 2026-06-13 00:00 | 06:57:15.56 | +20:12:23.9 | HIP 33496 | 17.14 |
| 2026-06-13 12:00 | 06:57:24.18 | +20:12:08.3 | HIP 33496 | 16.65 |
| 2026-06-14 00:00 | 06:57:32.80 | +20:11:52.5 | HIP 33496 | 16.40 |
| 2026-06-14 12:00 | 06:57:41.43 | +20:11:36.7 | HIP 33496 | 16.41 |
| 2026-06-15 00:00 | 06:57:50.05 | +20:11:20.8 | HIP 33496 | 16.67 |
| 2026-06-15 12:00 | 06:57:58.68 | +20:11:04.8 | HIP 33496 | 17.16 |
| 2026-06-16 00:00 | 06:58:07.31 | +20:10:48.8 | HIP 33496 | 17.88 |
| 2026-06-16 12:00 | 06:58:15.93 | +20:10:32.6 | HIP 33496 | 18.80 |
| 2026-06-17 00:00 | 06:58:24.55 | +20:10:16.4 | HIP 33496 | 19.88 |
| 2026-06-17 12:00 | 06:58:33.18 | +20:10:00.1 | HIP 33647 | 20.36 |
| 2026-06-18 00:00 | 06:58:41.79 | +20:09:43.7 | HIP 33647 | 19.51 |
| 2026-06-18 12:00 | 06:58:50.41 | +20:09:27.3 | HIP 33647 | 18.84 |
| 2026-06-19 00:00 | 06:58:59.01 | +20:09:10.8 | HIP 33647 | 18.39 |
| 2026-06-19 12:00 | 06:59:07.62 | +20:08:54.2 | HIP 33647 | 18.15 |
| 2026-06-20 00:00 | 06:59:16.21 | +20:08:37.5 | HIP 33647 | 18.14 |
| 2026-06-20 12:00 | 06:59:24.80 | +20:08:20.8 | HIP 33647 | 18.35 |
| 2026-06-21 00:00 | 06:59:33.38 | +20:08:04.0 | HIP 33647 | 18.79 |
| 2026-06-21 12:00 | 06:59:41.95 | +20:07:47.2 | HIP 33647 | 19.43 |
| 2026-06-22 00:00 | 06:59:50.51 | +20:07:30.2 | HIP 33647 | 20.26 |