C/2023 C2 (ATLAS)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2023 C2 (ATLAS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2024-11-16T18:42:57.139200Z |
| Orbit solution date (soln_date, UTC) | 2026-04-14T13:42:19Z |
| Obs used | 1938 |
| NEO | - |
| M1 | 10.900 |
| K1 | 4.500 |
| PC | 0.030 |
| Discovery observation (MPC, UTC) | 2023-02-01T06:05:54.758400Z |
| Discovery magnitude (MPC) | 19.12 o |
| Discovery observatory (MPC) | W68 · ATLAS Chile, Rio Hurtado |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2025-03-15.0000000 |
| e | 0.99899713 |
| q (au) | 2.368469 |
| a (au) | 2361.685725 |
| i (deg) | 48.322065 |
| Ω (om, deg) | 301.004734 |
| ω (w, deg) | 357.444180 |
| M (ma, deg) | 0.001015 |
Magnitude
Scatter + Global Linear
$$ M_a = (10.299 + 2.916\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 10.299 |
| n | 2.916 |
| gf | 1.000 |
| gb | -0.683 |
| k | 0.921 |
| 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 |
|---|---|---|---|
| 2023-02-01 | 2024-02-08 | +0.2898 | +0.092 |
| 2024-02-08 | 2024-04-08 | +2.9163 | -1.328 |
| 2024-04-08 | 2024-11-13 | +2.7119 | -1.411 |
| 2024-11-28 | 2025-10-02 | -1.0712 | +0.567 |
| 2025-10-02 | 2026-04-12 | -8.8098 | +5.478 |
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 | 01:32:30.29 | +54:39:25.5 | HIP 7171 | 10.44 |
| 2026-05-12 12:00 | 01:33:06.22 | +54:42:32.3 | HIP 7253 | 14.45 |
| 2026-05-13 00:00 | 01:33:42.10 | +54:45:39.4 | HIP 7253 | 11.27 |
| 2026-05-13 12:00 | 01:34:17.92 | +54:48:46.7 | HIP 7253 | 10.85 |
| 2026-05-14 00:00 | 01:34:53.69 | +54:51:54.5 | HIP 7253 | 13.43 |
| 2026-05-14 12:00 | 01:35:29.41 | +54:55:02.5 | HIP 7494 | 15.73 |
| 2026-05-15 00:00 | 01:36:05.07 | +54:58:10.9 | HIP 7563 | 12.97 |
| 2026-05-15 12:00 | 01:36:40.67 | +55:01:19.5 | HIP 7563 | 7.00 |
| 2026-05-16 00:00 | 01:37:16.22 | +55:04:28.5 | HIP 7563 | 1.29 |
| 2026-05-16 12:00 | 01:37:51.71 | +55:07:37.8 | HIP 7563 | 5.10 |
| 2026-05-17 00:00 | 01:38:27.14 | +55:10:47.4 | HIP 7563 | 11.03 |
| 2026-05-17 12:00 | 01:39:02.51 | +55:13:57.3 | HIP 7563 | 16.97 |
| 2026-05-18 00:00 | 01:39:37.83 | +55:17:07.5 | HIP 7763 | 21.29 |
| 2026-05-18 12:00 | 01:40:13.08 | +55:20:17.9 | HIP 7763 | 18.15 |
| 2026-05-19 00:00 | 01:40:48.27 | +55:23:28.7 | HIP 7763 | 16.59 |
| 2026-05-19 12:00 | 01:41:23.39 | +55:26:39.7 | HIP 7763 | 17.04 |
| 2026-05-20 00:00 | 01:41:58.46 | +55:29:51.0 | HIP 7763 | 19.35 |
| 2026-05-20 12:00 | 01:42:33.45 | +55:33:02.6 | HIP 8081 | 22.18 |
| 2026-05-21 00:00 | 01:43:08.39 | +55:36:14.4 | HIP 8081 | 17.29 |
| 2026-05-21 12:00 | 01:43:43.26 | +55:39:26.5 | HIP 8081 | 13.22 |
| 2026-05-22 00:00 | 01:44:18.06 | +55:42:38.9 | HIP 8081 | 10.91 |
| 2026-05-22 12:00 | 01:44:52.79 | +55:45:51.5 | HIP 8081 | 11.46 |
| 2026-05-23 00:00 | 01:45:27.46 | +55:49:04.4 | HIP 8081 | 14.54 |
| 2026-05-23 12:00 | 01:46:02.05 | +55:52:17.5 | HIP 8081 | 18.94 |
| 2026-05-24 00:00 | 01:46:36.58 | +55:55:30.8 | HIP 8406 | 20.38 |
| 2026-05-24 12:00 | 01:47:11.04 | +55:58:44.4 | HIP 8406 | 19.57 |
| 2026-05-25 00:00 | 01:47:45.43 | +56:01:58.2 | HIP 8406 | 20.47 |
| 2026-05-25 12:00 | 01:48:19.74 | +56:05:12.3 | HIP 8582 | 22.68 |
| 2026-05-26 00:00 | 01:48:53.99 | +56:08:26.6 | HIP 8582 | 20.45 |
| 2026-05-26 12:00 | 01:49:28.16 | +56:11:41.1 | HIP 8582 | 19.73 |
| 2026-05-27 00:00 | 01:50:02.26 | +56:14:55.8 | HIP 8582 | 20.67 |
| 2026-05-27 12:00 | 01:50:36.28 | +56:18:10.8 | HIP 8582 | 23.07 |
| 2026-05-28 00:00 | 01:51:10.24 | +56:21:25.9 | HIP 8582 | 26.52 |
| 2026-05-28 12:00 | 01:51:44.11 | +56:24:41.3 | HIP 8929 | 28.45 |
| 2026-05-29 00:00 | 01:52:17.91 | +56:27:56.9 | HIP 8929 | 22.95 |
| 2026-05-29 12:00 | 01:52:51.63 | +56:31:12.7 | HIP 8929 | 17.59 |
| 2026-05-30 00:00 | 01:53:25.28 | +56:34:28.7 | HIP 8929 | 12.55 |
| 2026-05-30 12:00 | 01:53:58.84 | +56:37:45.0 | HIP 8929 | 8.40 |
| 2026-05-31 00:00 | 01:54:32.33 | +56:41:01.4 | HIP 8929 | 6.92 |
| 2026-05-31 12:00 | 01:55:05.74 | +56:44:18.0 | HIP 8929 | 9.44 |
| 2026-06-01 00:00 | 01:55:39.07 | +56:47:34.8 | HIP 8929 | 13.93 |
| 2026-06-01 12:00 | 01:56:12.31 | +56:50:51.9 | HIP 9048 | 9.14 |
| 2026-06-02 00:00 | 01:56:45.48 | +56:54:09.1 | HIP 9048 | 5.59 |