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
$$ M_a = (6.935 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 6.935 |
| n | 6.000 |
| gf | 1.000 |
| gb | -0.831 |
| k | 0.988 |
| 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 | -1.7475 | +1.113 |
| 2025-11-03 | 2026-04-13 | -4.4369 | +0.751 |
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) |
|---|---|---|---|---|
| 2026-05-12 00:00 | 06:48:47.70 | +20:25:28.2 | HIP 32676 | 8.65 |
| 2026-05-12 12:00 | 06:48:54.33 | +20:25:19.9 | HIP 32676 | 8.53 |
| 2026-05-13 00:00 | 06:49:01.03 | +20:25:11.5 | HIP 32676 | 8.69 |
| 2026-05-13 12:00 | 06:49:07.79 | +20:25:02.9 | HIP 32676 | 9.13 |
| 2026-05-14 00:00 | 06:49:14.61 | +20:24:54.2 | HIP 32676 | 9.82 |
| 2026-05-14 12:00 | 06:49:21.49 | +20:24:45.3 | HIP 32676 | 10.71 |
| 2026-05-15 00:00 | 06:49:28.44 | +20:24:36.3 | HIP 32676 | 11.78 |
| 2026-05-15 12:00 | 06:49:35.44 | +20:24:27.1 | HIP 32676 | 12.97 |
| 2026-05-16 00:00 | 06:49:42.49 | +20:24:17.8 | HIP 32676 | 14.27 |
| 2026-05-16 12:00 | 06:49:49.61 | +20:24:08.4 | HIP 32676 | 15.64 |
| 2026-05-17 00:00 | 06:49:56.78 | +20:23:58.8 | HIP 32676 | 17.08 |
| 2026-05-17 12:00 | 06:50:04.00 | +20:23:49.1 | HIP 32676 | 18.58 |
| 2026-05-18 00:00 | 06:50:11.28 | +20:23:39.2 | HIP 32676 | 20.12 |
| 2026-05-18 12:00 | 06:50:18.60 | +20:23:29.2 | HIP 32676 | 21.69 |
| 2026-05-19 00:00 | 06:50:25.98 | +20:23:19.1 | HIP 32956 | 20.19 |
| 2026-05-19 12:00 | 06:50:33.41 | +20:23:08.8 | HIP 32956 | 18.45 |
| 2026-05-20 00:00 | 06:50:40.88 | +20:22:58.4 | HIP 32956 | 16.69 |
| 2026-05-20 12:00 | 06:50:48.40 | +20:22:47.9 | HIP 32956 | 14.93 |
| 2026-05-21 00:00 | 06:50:55.96 | +20:22:37.2 | HIP 32956 | 13.15 |
| 2026-05-21 12:00 | 06:51:03.57 | +20:22:26.4 | HIP 32956 | 11.37 |
| 2026-05-22 00:00 | 06:51:11.22 | +20:22:15.5 | HIP 32956 | 9.58 |
| 2026-05-22 12:00 | 06:51:18.92 | +20:22:04.5 | HIP 32956 | 7.78 |
| 2026-05-23 00:00 | 06:51:26.65 | +20:21:53.3 | HIP 32956 | 5.98 |
| 2026-05-23 12:00 | 06:51:34.42 | +20:21:42.0 | HIP 32956 | 4.20 |
| 2026-05-24 00:00 | 06:51:42.23 | +20:21:30.6 | HIP 32956 | 2.48 |
| 2026-05-24 12:00 | 06:51:50.08 | +20:21:19.0 | HIP 32956 | 1.20 |
| 2026-05-25 00:00 | 06:51:57.97 | +20:21:07.4 | HIP 32956 | 1.90 |
| 2026-05-25 12:00 | 06:52:05.89 | +20:20:55.6 | HIP 32956 | 3.56 |
| 2026-05-26 00:00 | 06:52:13.84 | +20:20:43.7 | HIP 32956 | 5.37 |
| 2026-05-26 12:00 | 06:52:21.83 | +20:20:31.7 | HIP 33026 | 7.05 |
| 2026-05-27 00:00 | 06:52:29.85 | +20:20:19.5 | HIP 33026 | 5.34 |
| 2026-05-27 12:00 | 06:52:37.90 | +20:20:07.3 | HIP 33026 | 3.81 |
| 2026-05-28 00:00 | 06:52:45.98 | +20:19:54.9 | HIP 33026 | 2.78 |
| 2026-05-28 12:00 | 06:52:54.09 | +20:19:42.4 | HIP 33026 | 2.86 |
| 2026-05-29 00:00 | 06:53:02.23 | +20:19:29.8 | HIP 33026 | 4.01 |
| 2026-05-29 12:00 | 06:53:10.40 | +20:19:17.1 | HIP 33026 | 5.60 |
| 2026-05-30 00:00 | 06:53:18.59 | +20:19:04.3 | HIP 33026 | 7.36 |
| 2026-05-30 12:00 | 06:53:26.81 | +20:18:51.4 | HIP 33026 | 9.19 |
| 2026-05-31 00:00 | 06:53:35.05 | +20:18:38.3 | HIP 33026 | 11.07 |
| 2026-05-31 12:00 | 06:53:43.32 | +20:18:25.2 | HIP 33026 | 12.97 |
| 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 |