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 | +2.3424 | -1.028 |
| 2025-07-11 | 2025-09-05 | -1.3084 | +0.317 |
| 2025-09-05 | 2025-09-25 | +3.9933 | +0.381 |
| 2025-10-18 | 2025-11-19 | +0.3489 | -1.075 |
| 2025-11-19 | 2025-12-04 | -0.8988 | -0.629 |
| 2025-12-04 | 2026-01-22 | +7.0053 | -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) |
|---|---|---|---|---|
| 2026-05-12 00:00 | 02:31:31.37 | +36:35:32.8 | HIP 11784 | 27.61 |
| 2026-05-12 12:00 | 02:31:52.84 | +36:38:11.3 | HIP 11784 | 29.48 |
| 2026-05-13 00:00 | 02:32:14.24 | +36:40:50.1 | HIP 11752 | 29.87 |
| 2026-05-13 12:00 | 02:32:35.56 | +36:43:29.2 | HIP 11752 | 28.76 |
| 2026-05-14 00:00 | 02:32:56.81 | +36:46:08.8 | HIP 11752 | 28.49 |
| 2026-05-14 12:00 | 02:33:17.98 | +36:48:48.6 | HIP 11752 | 29.08 |
| 2026-05-15 00:00 | 02:33:39.07 | +36:51:28.9 | HIP 12100 | 29.69 |
| 2026-05-15 12:00 | 02:34:00.09 | +36:54:09.5 | HIP 12100 | 24.77 |
| 2026-05-16 00:00 | 02:34:21.02 | +36:56:50.4 | HIP 12100 | 19.90 |
| 2026-05-16 12:00 | 02:34:41.87 | +36:59:31.8 | HIP 12100 | 15.12 |
| 2026-05-17 00:00 | 02:35:02.64 | +37:02:13.4 | HIP 12100 | 10.52 |
| 2026-05-17 12:00 | 02:35:23.33 | +37:04:55.4 | HIP 12100 | 6.47 |
| 2026-05-18 00:00 | 02:35:43.93 | +37:07:37.7 | HIP 12100 | 4.68 |
| 2026-05-18 12:00 | 02:36:04.45 | +37:10:20.4 | HIP 12100 | 7.10 |
| 2026-05-19 00:00 | 02:36:24.88 | +37:13:03.4 | HIP 12183 | 10.43 |
| 2026-05-19 12:00 | 02:36:45.22 | +37:15:46.7 | HIP 12183 | 5.99 |
| 2026-05-20 00:00 | 02:37:05.48 | +37:18:30.4 | HIP 12183 | 3.22 |
| 2026-05-20 12:00 | 02:37:25.64 | +37:21:14.4 | HIP 12183 | 5.65 |
| 2026-05-21 00:00 | 02:37:45.72 | +37:23:58.7 | HIP 12183 | 10.01 |
| 2026-05-21 12:00 | 02:38:05.71 | +37:26:43.3 | HIP 12183 | 14.65 |
| 2026-05-22 00:00 | 02:38:25.60 | +37:29:28.2 | HIP 12287 | 14.22 |
| 2026-05-22 12:00 | 02:38:45.40 | +37:32:13.5 | HIP 12287 | 12.62 |
| 2026-05-23 00:00 | 02:39:05.10 | +37:34:59.0 | HIP 12287 | 12.72 |
| 2026-05-23 12:00 | 02:39:24.71 | +37:37:44.9 | HIP 12287 | 14.47 |
| 2026-05-24 00:00 | 02:39:44.23 | +37:40:31.1 | HIP 12287 | 17.36 |
| 2026-05-24 12:00 | 02:40:03.65 | +37:43:17.6 | HIP 12287 | 20.92 |
| 2026-05-25 00:00 | 02:40:22.97 | +37:46:04.3 | HIP 12287 | 24.85 |
| 2026-05-25 12:00 | 02:40:42.19 | +37:48:51.4 | HIP 12577 | 25.83 |
| 2026-05-26 00:00 | 02:41:01.31 | +37:51:38.8 | HIP 12577 | 21.71 |
| 2026-05-26 12:00 | 02:41:20.34 | +37:54:26.4 | HIP 12577 | 17.87 |
| 2026-05-27 00:00 | 02:41:39.26 | +37:57:14.4 | HIP 12577 | 14.52 |
| 2026-05-27 12:00 | 02:41:58.08 | +38:00:02.7 | HIP 12577 | 12.07 |
| 2026-05-28 00:00 | 02:42:16.80 | +38:02:51.2 | HIP 12577 | 11.10 |
| 2026-05-28 12:00 | 02:42:35.42 | +38:05:40.0 | HIP 12577 | 11.96 |
| 2026-05-29 00:00 | 02:42:53.93 | +38:08:29.1 | HIP 12577 | 14.31 |
| 2026-05-29 12:00 | 02:43:12.34 | +38:11:18.6 | HIP 12577 | 17.55 |
| 2026-05-30 00:00 | 02:43:30.64 | +38:14:08.3 | HIP 12577 | 21.27 |
| 2026-05-30 12:00 | 02:43:48.83 | +38:16:58.2 | HIP 12861 | 21.98 |
| 2026-05-31 00:00 | 02:44:06.92 | +38:19:48.5 | HIP 12861 | 21.21 |
| 2026-05-31 12:00 | 02:44:24.89 | +38:22:39.0 | HIP 12861 | 21.42 |
| 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 |