C/2023 C2 (ATLAS)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2023 C2 (ATLAS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2024-11-16T18:47:37.800960Z |
| Orbit solution date (soln_date, UTC) | 2026-01-13T08:12:19Z |
| Obs used | 1840 |
| NEO | - |
| M1 | 10.800 |
| K1 | 4.750 |
| 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) | 2025-02-25.0000000 |
| e | 0.99900962 |
| q (au) | 2.368484 |
| a (au) | 2391.484757 |
| i (deg) | 48.321944 |
| Ω (om, deg) | 301.004606 |
| ω (w, deg) | 357.445445 |
| M (ma, deg) | 0.000845 |
Magnitude
Scatter + Global Linear
$$ M_a = (10.763 + 3.102\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 10.763 |
| n | 3.102 |
| gf | 0.999 |
| gb | -0.653 |
| k | 0.800 |
| 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 | -0.3393 | +0.404 |
| 2024-02-08 | 2024-04-08 | +2.3342 | -1.043 |
| 2024-04-08 | 2024-11-13 | +2.2274 | -1.177 |
| 2024-11-28 | 2025-11-13 | -1.4963 | +0.759 |
| 2025-11-13 | 2026-02-04 | -9.7743 | +5.901 |
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) |
|---|---|---|---|---|
| 2026-02-03 00:00 | 23:29:23.23 | +47:55:43.5 | HIP 115758 | 22.66 |
| 2026-02-03 12:00 | 23:29:59.42 | +47:56:06.3 | HIP 115972 | 26.07 |
| 2026-02-04 00:00 | 23:30:35.66 | +47:56:30.5 | HIP 116135 | 26.99 |
| 2026-02-04 12:00 | 23:31:11.95 | +47:56:56.2 | HIP 116135 | 25.04 |
| 2026-02-05 00:00 | 23:31:48.30 | +47:57:23.3 | HIP 116135 | 24.54 |
| 2026-02-05 12:00 | 23:32:24.70 | +47:57:51.8 | HIP 116192 | 24.51 |
| 2026-02-06 00:00 | 23:33:01.15 | +47:58:21.8 | HIP 116192 | 24.45 |
| 2026-02-06 12:00 | 23:33:37.66 | +47:58:53.2 | HIP 116192 | 25.85 |
| 2026-02-07 00:00 | 23:34:14.21 | +47:59:26.1 | HIP 116192 | 28.50 |
| 2026-02-07 12:00 | 23:34:50.81 | +48:00:00.3 | HIP 116514 | 23.32 |
| 2026-02-08 00:00 | 23:35:27.46 | +48:00:36.0 | HIP 116514 | 18.45 |
| 2026-02-08 12:00 | 23:36:04.16 | +48:01:13.0 | HIP 116514 | 14.55 |
| 2026-02-09 00:00 | 23:36:40.90 | +48:01:51.5 | HIP 116514 | 12.59 |
| 2026-02-09 12:00 | 23:37:17.69 | +48:02:31.4 | HIP 116514 | 13.44 |
| 2026-02-10 00:00 | 23:37:54.53 | +48:03:12.6 | HIP 116514 | 16.69 |
| 2026-02-10 12:00 | 23:38:31.41 | +48:03:55.2 | HIP 116605 | 18.64 |
| 2026-02-11 00:00 | 23:39:08.34 | +48:04:39.2 | HIP 116605 | 22.24 |
| 2026-02-11 12:00 | 23:39:45.31 | +48:05:24.6 | HIP 116605 | 26.84 |
| 2026-02-12 00:00 | 23:40:22.33 | +48:06:11.4 | HIP 116911 | 21.79 |
| 2026-02-12 12:00 | 23:40:59.39 | +48:06:59.5 | HIP 116911 | 17.31 |
| 2026-02-13 00:00 | 23:41:36.49 | +48:07:48.9 | HIP 116911 | 14.19 |
| 2026-02-13 12:00 | 23:42:13.63 | +48:08:39.7 | HIP 116911 | 13.42 |
| 2026-02-14 00:00 | 23:42:50.81 | +48:09:31.8 | HIP 116911 | 15.37 |
| 2026-02-14 12:00 | 23:43:28.03 | +48:10:25.3 | HIP 116911 | 19.24 |
| 2026-02-15 00:00 | 23:44:05.29 | +48:11:20.1 | HIP 117115 | 22.74 |
| 2026-02-15 12:00 | 23:44:42.58 | +48:12:16.2 | HIP 117115 | 23.22 |
| 2026-02-16 00:00 | 23:45:19.92 | +48:13:13.7 | HIP 117115 | 25.35 |
| 2026-02-16 12:00 | 23:45:57.29 | +48:14:12.4 | HIP 117115 | 28.75 |
| 2026-02-17 00:00 | 23:46:34.70 | +48:15:12.4 | HIP 117435 | 28.47 |
| 2026-02-17 12:00 | 23:47:12.14 | +48:16:13.8 | HIP 117435 | 23.37 |
| 2026-02-18 00:00 | 23:47:49.62 | +48:17:16.4 | HIP 117435 | 18.99 |
| 2026-02-18 12:00 | 23:48:27.13 | +48:18:20.3 | HIP 117435 | 15.94 |
| 2026-02-19 00:00 | 23:49:04.68 | +48:19:25.5 | HIP 117435 | 15.05 |
| 2026-02-19 12:00 | 23:49:42.25 | +48:20:32.0 | HIP 117435 | 16.68 |
| 2026-02-20 00:00 | 23:50:19.86 | +48:21:39.7 | HIP 117435 | 20.24 |
| 2026-02-20 12:00 | 23:50:57.50 | +48:22:48.6 | HIP 117754 | 19.63 |
| 2026-02-21 00:00 | 23:51:35.17 | +48:23:58.9 | HIP 117754 | 13.35 |
| 2026-02-21 12:00 | 23:52:12.87 | +48:25:10.3 | HIP 117754 | 7.20 |
| 2026-02-22 00:00 | 23:52:50.59 | +48:26:23.0 | HIP 117754 | 2.53 |
| 2026-02-22 12:00 | 23:53:28.35 | +48:27:36.9 | HIP 117754 | 6.48 |
| 2026-02-23 00:00 | 23:54:06.13 | +48:28:52.0 | HIP 117867 | 9.55 |
| 2026-02-23 12:00 | 23:54:43.93 | +48:30:08.3 | HIP 117867 | 8.27 |
| 2026-02-24 00:00 | 23:55:21.77 | +48:31:25.8 | HIP 117867 | 11.26 |