C/2023 C2 (ATLAS)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2023 C2 (ATLAS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2024-11-16T18:46:38.798400Z |
| Orbit solution date (soln_date, UTC) | 2026-09-08T09:12:17Z |
| Obs used | 1972 |
| 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) | 2025-03-25.0000000 |
| e | 0.99900926 |
| q (au) | 2.368470 |
| a (au) | 2390.599830 |
| i (deg) | 48.322033 |
| Ω (om, deg) | 301.004667 |
| ω (w, deg) | 357.444732 |
| M (ma, deg) | 0.001081 |
Magnitude
Scatter + Global Linear
$$ M_a = (9.903 + 2.593\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 9.903 |
| n | 2.593 |
| gf | 1.000 |
| gb | -0.705 |
| k | 0.975 |
| 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 | +0.9647 | -0.264 |
| 2024-02-08 | 2024-04-08 | +3.7625 | -1.782 |
| 2024-04-08 | 2024-11-13 | +2.8412 | -1.492 |
| 2024-11-28 | 2025-11-18 | -0.8170 | +0.444 |
| 2025-11-18 | 2026-09-25 | +0.3273 | -0.569 |
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) |
|---|---|---|---|---|
| 2026-09-20 00:00 | 02:45:08.11 | +68:13:43.5 | HIP 12641 | 18.28 |
| 2026-09-20 12:00 | 02:44:49.01 | +68:15:33.5 | HIP 12641 | 17.94 |
| 2026-09-21 00:00 | 02:44:29.57 | +68:17:21.9 | HIP 12641 | 17.93 |
| 2026-09-21 12:00 | 02:44:09.78 | +68:19:08.6 | HIP 12585 | 15.66 |
| 2026-09-22 00:00 | 02:43:49.66 | +68:20:53.5 | HIP 12585 | 13.14 |
| 2026-09-22 12:00 | 02:43:29.20 | +68:22:36.8 | HIP 12585 | 10.62 |
| 2026-09-23 00:00 | 02:43:08.41 | +68:24:18.3 | HIP 12585 | 8.11 |
| 2026-09-23 12:00 | 02:42:47.28 | +68:25:58.1 | HIP 12585 | 5.64 |
| 2026-09-24 00:00 | 02:42:25.82 | +68:27:36.1 | HIP 12585 | 3.27 |
| 2026-09-24 12:00 | 02:42:04.04 | +68:29:12.3 | HIP 12585 | 1.59 |
| 2026-09-25 00:00 | 02:41:41.93 | +68:30:46.7 | HIP 12585 | 2.72 |
| 2026-09-25 12:00 | 02:41:19.50 | +68:32:19.2 | HIP 12585 | 5.04 |
| 2026-09-26 00:00 | 02:40:56.76 | +68:33:50.0 | HIP 12585 | 7.51 |
| 2026-09-26 12:00 | 02:40:33.69 | +68:35:18.9 | HIP 12585 | 10.04 |
| 2026-09-27 00:00 | 02:40:10.32 | +68:36:45.9 | HIP 12585 | 12.58 |
| 2026-09-27 12:00 | 02:39:46.63 | +68:38:11.1 | HIP 12585 | 15.13 |
| 2026-09-28 00:00 | 02:39:22.64 | +68:39:34.3 | HIP 12585 | 17.69 |
| 2026-09-28 12:00 | 02:38:58.35 | +68:40:55.6 | HIP 12585 | 20.26 |
| 2026-09-29 00:00 | 02:38:33.76 | +68:42:15.0 | HIP 12237 | 21.83 |
| 2026-09-29 12:00 | 02:38:08.87 | +68:43:32.5 | HIP 12237 | 20.11 |
| 2026-09-30 00:00 | 02:37:43.69 | +68:44:48.0 | HIP 12237 | 18.63 |
| 2026-09-30 12:00 | 02:37:18.22 | +68:46:01.5 | HIP 12237 | 17.45 |
| 2026-10-01 00:00 | 02:36:52.47 | +68:47:13.0 | HIP 12237 | 16.63 |
| 2026-10-01 12:00 | 02:36:26.43 | +68:48:22.5 | HIP 12237 | 16.22 |
| 2026-10-02 00:00 | 02:36:00.12 | +68:49:30.0 | HIP 12237 | 16.28 |
| 2026-10-02 12:00 | 02:35:33.53 | +68:50:35.4 | HIP 12237 | 16.79 |
| 2026-10-03 00:00 | 02:35:06.68 | +68:51:38.7 | HIP 12237 | 17.71 |
| 2026-10-03 12:00 | 02:34:39.56 | +68:52:40.0 | HIP 12237 | 19.00 |
| 2026-10-04 00:00 | 02:34:12.18 | +68:53:39.2 | HIP 12237 | 20.58 |
| 2026-10-04 12:00 | 02:33:44.55 | +68:54:36.3 | HIP 11633 | 21.44 |
| 2026-10-05 00:00 | 02:33:16.67 | +68:55:31.2 | HIP 11633 | 19.58 |
| 2026-10-05 12:00 | 02:32:48.54 | +68:56:24.1 | HIP 11633 | 17.89 |
| 2026-10-06 00:00 | 02:32:20.16 | +68:57:14.7 | HIP 11633 | 16.43 |
| 2026-10-06 12:00 | 02:31:51.56 | +68:58:03.2 | HIP 11633 | 15.28 |
| 2026-10-07 00:00 | 02:31:22.72 | +68:58:49.6 | HIP 11633 | 14.50 |
| 2026-10-07 12:00 | 02:30:53.66 | +68:59:33.7 | HIP 11633 | 14.16 |
| 2026-10-08 00:00 | 02:30:24.38 | +69:00:15.6 | HIP 11633 | 14.30 |
| 2026-10-08 12:00 | 02:29:54.89 | +69:00:55.3 | HIP 11633 | 14.91 |
| 2026-10-09 00:00 | 02:29:25.19 | +69:01:32.8 | HIP 11633 | 15.95 |
| 2026-10-09 12:00 | 02:28:55.29 | +69:02:08.0 | HIP 11633 | 17.33 |
| 2026-10-10 00:00 | 02:28:25.19 | +69:02:41.0 | HIP 11633 | 18.98 |
| 2026-10-10 12:00 | 02:27:54.91 | +69:03:11.7 | HIP 11633 | 20.85 |
| 2026-10-11 00:00 | 02:27:24.44 | +69:03:40.1 | HIP 11633 | 22.88 |