C/2020 Y2 (ATLAS)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2020 Y2 (ATLAS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2022-06-17T16:46:06.738240Z |
| Orbit solution date (soln_date, UTC) | 2024-12-26T20:12:24Z |
| Obs used | 1775 |
| NEO | - |
| M1 | 10.500 |
| K1 | 4.500 |
| PC | - |
| Discovery observation (MPC, UTC) | 2020-12-28T15:18:23.155200Z |
| Discovery magnitude (MPC) | 18.30 o |
| Discovery observatory (MPC) | T08 · ATLAS-MLO, Mauna Loa |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2022-09-03.0000000 |
| e | 0.99700512 |
| q (au) | 3.132490 |
| a (au) | 1045.948256 |
| i (deg) | 101.297766 |
| Ω (om, deg) | 26.515016 |
| ω (w, deg) | 266.105810 |
| M (ma, deg) | 0.002252 |
Magnitude
Scatter + Global Linear
$$ M_a = (11.072 + 2.941\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 11.072 |
| n | 2.941 |
| gf | 1.000 |
| gb | -0.718 |
| 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 |
|---|---|---|---|
| 2020-03-25 | 2021-01-29 | +12.9145 | -9.677 |
| 2021-01-29 | 2021-05-17 | -5.4955 | +4.015 |
| 2021-05-17 | 2022-06-01 | -2.1125 | +1.423 |
| 2022-06-19 | 2023-12-12 | -1.0342 | +0.680 |
| 2023-12-12 | 2024-10-29 | +16.6054 | -12.913 |
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) |
|---|---|---|---|---|
| 2026-07-29 00:00 | 00:56:37.18 | +33:16:16.8 | HIP 4416 | 9.92 |
| 2026-07-29 12:00 | 00:56:31.59 | +33:17:25.2 | HIP 4416 | 11.07 |
| 2026-07-30 00:00 | 00:56:25.90 | +33:18:33.0 | HIP 4416 | 12.33 |
| 2026-07-30 12:00 | 00:56:20.13 | +33:19:40.2 | HIP 4416 | 13.66 |
| 2026-07-31 00:00 | 00:56:14.26 | +33:20:46.8 | HIP 4416 | 15.05 |
| 2026-07-31 12:00 | 00:56:08.30 | +33:21:52.9 | HIP 4416 | 16.48 |
| 2026-08-01 00:00 | 00:56:02.25 | +33:22:58.4 | HIP 4416 | 17.96 |
| 2026-08-01 12:00 | 00:55:56.11 | +33:24:03.3 | HIP 4416 | 19.46 |
| 2026-08-02 00:00 | 00:55:49.87 | +33:25:07.6 | HIP 4416 | 20.99 |
| 2026-08-02 12:00 | 00:55:43.55 | +33:26:11.3 | HIP 4416 | 22.54 |
| 2026-08-03 00:00 | 00:55:37.13 | +33:27:14.4 | HIP 4416 | 24.12 |
| 2026-08-03 12:00 | 00:55:30.62 | +33:28:16.9 | HIP 4191 | 25.00 |
| 2026-08-04 00:00 | 00:55:24.02 | +33:29:18.8 | HIP 4191 | 23.55 |
| 2026-08-04 12:00 | 00:55:17.33 | +33:30:20.1 | HIP 4191 | 22.11 |
| 2026-08-05 00:00 | 00:55:10.56 | +33:31:20.8 | HIP 4191 | 20.71 |
| 2026-08-05 12:00 | 00:55:03.69 | +33:32:20.8 | HIP 4191 | 19.34 |
| 2026-08-06 00:00 | 00:54:56.73 | +33:33:20.2 | HIP 4191 | 18.01 |
| 2026-08-06 12:00 | 00:54:49.68 | +33:34:19.0 | HIP 4191 | 16.75 |
| 2026-08-07 00:00 | 00:54:42.54 | +33:35:17.1 | HIP 4191 | 15.56 |
| 2026-08-07 12:00 | 00:54:35.31 | +33:36:14.6 | HIP 4191 | 14.47 |
| 2026-08-08 00:00 | 00:54:27.99 | +33:37:11.4 | HIP 4191 | 13.51 |
| 2026-08-08 12:00 | 00:54:20.59 | +33:38:07.6 | HIP 4191 | 12.71 |
| 2026-08-09 00:00 | 00:54:13.09 | +33:39:03.1 | HIP 4191 | 12.11 |
| 2026-08-09 12:00 | 00:54:05.51 | +33:39:58.0 | HIP 4191 | 11.74 |
| 2026-08-10 00:00 | 00:53:57.84 | +33:40:52.2 | HIP 4191 | 11.62 |
| 2026-08-10 12:00 | 00:53:50.08 | +33:41:45.7 | HIP 4191 | 11.78 |
| 2026-08-11 00:00 | 00:53:42.24 | +33:42:38.5 | HIP 4191 | 12.21 |
| 2026-08-11 12:00 | 00:53:34.31 | +33:43:30.6 | HIP 4175 | 12.34 |
| 2026-08-12 00:00 | 00:53:26.29 | +33:44:22.1 | HIP 4175 | 11.18 |
| 2026-08-12 12:00 | 00:53:18.19 | +33:45:12.8 | HIP 4175 | 10.24 |
| 2026-08-13 00:00 | 00:53:10.00 | +33:46:02.9 | HIP 4175 | 9.60 |
| 2026-08-13 12:00 | 00:53:01.72 | +33:46:52.2 | HIP 4175 | 9.33 |
| 2026-08-14 00:00 | 00:52:53.36 | +33:47:40.9 | HIP 4175 | 9.46 |
| 2026-08-14 12:00 | 00:52:44.92 | +33:48:28.8 | HIP 4175 | 9.98 |
| 2026-08-15 00:00 | 00:52:36.40 | +33:49:16.0 | HIP 4058 | 9.15 |
| 2026-08-15 12:00 | 00:52:27.79 | +33:50:02.5 | HIP 4058 | 7.20 |
| 2026-08-16 00:00 | 00:52:19.10 | +33:50:48.3 | HIP 4058 | 5.25 |
| 2026-08-16 12:00 | 00:52:10.32 | +33:51:33.4 | HIP 4058 | 3.31 |
| 2026-08-17 00:00 | 00:52:01.47 | +33:52:17.7 | HIP 4058 | 1.43 |
| 2026-08-17 12:00 | 00:51:52.53 | +33:53:01.3 | HIP 4058 | 1.02 |
| 2026-08-18 00:00 | 00:51:43.52 | +33:53:44.1 | HIP 4058 | 2.84 |
| 2026-08-18 12:00 | 00:51:34.42 | +33:54:26.2 | HIP 4058 | 4.82 |
| 2026-08-19 00:00 | 00:51:25.25 | +33:55:07.6 | HIP 4058 | 6.83 |