C/2025 K1 (ATLAS)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2025 K1 (ATLAS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2025-10-08T10:33:16.145280Z |
| Orbit solution date (soln_date, UTC) | 2026-03-12T09:29:53Z |
| Obs used | 2395 |
| NEO | - |
| M1 | 14.200 |
| K1 | 4.500 |
| PC | - |
| Discovery observation (MPC, UTC) | 2025-05-24T08:29:05.942400Z |
| Discovery magnitude (MPC) | 18.66 c |
| Discovery observatory (MPC) | W68 · ATLAS Chile, Rio Hurtado |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2025-09-22.0000000 |
| e | 1.00025924 |
| q (au) | 0.334213 |
| a (au) | -1289.208262 |
| i (deg) | 147.864795 |
| Ω (om, deg) | 97.556954 |
| ω (w, deg) | 271.023834 |
| M (ma, deg) | -0.000350 |
Magnitude
Scatter + Global Linear
$$ M_a = (13.130 + 4.029\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 13.130 |
| n | 4.029 |
| gf | 1.000 |
| gb | -1.000 |
| k | 0.930 |
| 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 |
|---|---|---|---|
| 2025-04-08 | 2025-07-11 | +2.3412 | -1.028 |
| 2025-07-11 | 2025-09-05 | -1.3077 | +0.316 |
| 2025-09-05 | 2025-09-25 | +3.9915 | +0.381 |
| 2025-10-18 | 2025-11-19 | +0.3479 | -1.075 |
| 2025-11-19 | 2025-12-04 | -0.8963 | -0.629 |
| 2025-12-04 | 2026-01-22 | +7.0045 | -1.216 |
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 | 02:44:42.76 | +38:25:29.9 | HIP 12861 | 22.56 |
| 2026-06-01 12:00 | 02:45:00.52 | +38:28:21.0 | HIP 12861 | 24.51 |
| 2026-06-02 00:00 | 02:45:18.17 | +38:31:12.3 | HIP 12861 | 27.08 |
| 2026-06-02 12:00 | 02:45:35.70 | +38:34:04.0 | HIP 12861 | 30.11 |
| 2026-06-03 00:00 | 02:45:53.12 | +38:36:55.9 | HIP 12968 | 31.68 |
| 2026-06-03 12:00 | 02:46:10.43 | +38:39:48.1 | HIP 12968 | 27.93 |
| 2026-06-04 00:00 | 02:46:27.62 | +38:42:40.6 | HIP 12968 | 24.41 |
| 2026-06-04 12:00 | 02:46:44.69 | +38:45:33.4 | HIP 12968 | 21.22 |
| 2026-06-05 00:00 | 02:47:01.65 | +38:48:26.4 | HIP 12968 | 18.52 |
| 2026-06-05 12:00 | 02:47:18.49 | +38:51:19.7 | HIP 12968 | 16.55 |
| 2026-06-06 00:00 | 02:47:35.21 | +38:54:13.2 | HIP 12968 | 15.56 |
| 2026-06-06 12:00 | 02:47:51.81 | +38:57:07.1 | HIP 12968 | 15.73 |
| 2026-06-07 00:00 | 02:48:08.29 | +39:00:01.2 | HIP 12968 | 17.01 |
| 2026-06-07 12:00 | 02:48:24.65 | +39:02:55.5 | HIP 12968 | 19.18 |
| 2026-06-08 00:00 | 02:48:40.88 | +39:05:50.2 | HIP 12968 | 21.95 |
| 2026-06-08 12:00 | 02:48:56.98 | +39:08:45.0 | HIP 12968 | 25.12 |
| 2026-06-09 00:00 | 02:49:12.97 | +39:11:40.2 | HIP 13057 | 24.81 |
| 2026-06-09 12:00 | 02:49:28.82 | +39:14:35.6 | HIP 13057 | 25.01 |
| 2026-06-10 00:00 | 02:49:44.54 | +39:17:31.2 | HIP 13057 | 25.88 |
| 2026-06-10 12:00 | 02:50:00.14 | +39:20:27.2 | HIP 13057 | 27.35 |
| 2026-06-11 00:00 | 02:50:15.60 | +39:23:23.3 | HIP 13057 | 29.33 |
| 2026-06-11 12:00 | 02:50:30.93 | +39:26:19.7 | HIP 13057 | 31.71 |
| 2026-06-12 00:00 | 02:50:46.13 | +39:29:16.4 | HIP 13057 | 34.40 |
| 2026-06-12 12:00 | 02:51:01.19 | +39:32:13.3 | HIP 13352 | 37.09 |
| 2026-06-13 00:00 | 02:51:16.11 | +39:35:10.5 | HIP 13352 | 33.60 |
| 2026-06-13 12:00 | 02:51:30.90 | +39:38:07.9 | HIP 13352 | 30.27 |
| 2026-06-14 00:00 | 02:51:45.55 | +39:41:05.5 | HIP 13352 | 27.15 |
| 2026-06-14 12:00 | 02:52:00.05 | +39:44:03.4 | HIP 13352 | 24.30 |
| 2026-06-15 00:00 | 02:52:14.42 | +39:47:01.5 | HIP 13352 | 21.83 |
| 2026-06-15 12:00 | 02:52:28.64 | +39:49:59.8 | HIP 13352 | 19.87 |
| 2026-06-16 00:00 | 02:52:42.71 | +39:52:58.3 | HIP 13352 | 18.57 |
| 2026-06-16 12:00 | 02:52:56.64 | +39:55:57.1 | HIP 13352 | 18.06 |
| 2026-06-17 00:00 | 02:53:10.42 | +39:58:56.1 | HIP 13352 | 18.40 |
| 2026-06-17 12:00 | 02:53:24.05 | +40:01:55.3 | HIP 13352 | 19.53 |
| 2026-06-18 00:00 | 02:53:37.53 | +40:04:54.7 | HIP 13352 | 21.31 |
| 2026-06-18 12:00 | 02:53:50.86 | +40:07:54.3 | HIP 13352 | 23.59 |
| 2026-06-19 00:00 | 02:54:04.03 | +40:10:54.2 | HIP 13352 | 26.23 |
| 2026-06-19 12:00 | 02:54:17.05 | +40:13:54.2 | HIP 13352 | 29.13 |
| 2026-06-20 00:00 | 02:54:29.91 | +40:16:54.4 | HIP 13753 | 29.19 |
| 2026-06-20 12:00 | 02:54:42.62 | +40:19:54.8 | HIP 13753 | 27.13 |
| 2026-06-21 00:00 | 02:54:55.17 | +40:22:55.4 | HIP 13753 | 25.51 |
| 2026-06-21 12:00 | 02:55:07.56 | +40:25:56.2 | HIP 13753 | 24.44 |
| 2026-06-22 00:00 | 02:55:19.78 | +40:28:57.2 | HIP 13753 | 23.97 |