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) |
|---|---|---|---|---|
| 2026-09-20 00:00 | 00:39:26.55 | +34:11:34.7 | HIP 3074 | 9.39 |
| 2026-09-20 12:00 | 00:39:13.88 | +34:11:23.2 | HIP 3074 | 8.28 |
| 2026-09-21 00:00 | 00:39:01.19 | +34:11:10.9 | HIP 3074 | 7.94 |
| 2026-09-21 12:00 | 00:38:48.48 | +34:10:57.8 | HIP 3074 | 8.46 |
| 2026-09-22 00:00 | 00:38:35.75 | +34:10:43.9 | HIP 3074 | 9.71 |
| 2026-09-22 12:00 | 00:38:23.00 | +34:10:29.1 | HIP 3074 | 11.46 |
| 2026-09-23 00:00 | 00:38:10.24 | +34:10:13.6 | HIP 3074 | 13.51 |
| 2026-09-23 12:00 | 00:37:57.46 | +34:09:57.2 | HIP 3074 | 15.76 |
| 2026-09-24 00:00 | 00:37:44.66 | +34:09:40.0 | HIP 3074 | 18.12 |
| 2026-09-24 12:00 | 00:37:31.85 | +34:09:22.1 | HIP 3074 | 20.57 |
| 2026-09-25 00:00 | 00:37:19.03 | +34:09:03.3 | HIP 3074 | 23.07 |
| 2026-09-25 12:00 | 00:37:06.20 | +34:08:43.7 | HIP 3074 | 25.62 |
| 2026-09-26 00:00 | 00:36:53.35 | +34:08:23.4 | HIP 2912 | 25.23 |
| 2026-09-26 12:00 | 00:36:40.50 | +34:08:02.3 | HIP 2801 | 24.27 |
| 2026-09-27 00:00 | 00:36:27.63 | +34:07:40.3 | HIP 2801 | 23.33 |
| 2026-09-27 12:00 | 00:36:14.76 | +34:07:17.6 | HIP 2801 | 22.68 |
| 2026-09-28 00:00 | 00:36:01.88 | +34:06:54.1 | HIP 2801 | 22.36 |
| 2026-09-28 12:00 | 00:35:49.00 | +34:06:29.8 | HIP 2801 | 22.37 |
| 2026-09-29 00:00 | 00:35:36.12 | +34:06:04.8 | HIP 2801 | 22.71 |
| 2026-09-29 12:00 | 00:35:23.23 | +34:05:39.0 | HIP 2801 | 23.37 |
| 2026-09-30 00:00 | 00:35:10.33 | +34:05:12.4 | HIP 2801 | 24.33 |
| 2026-09-30 12:00 | 00:34:57.44 | +34:04:45.0 | HIP 2801 | 25.55 |
| 2026-10-01 00:00 | 00:34:44.55 | +34:04:16.9 | HIP 2603 | 24.95 |
| 2026-10-01 12:00 | 00:34:31.66 | +34:03:48.0 | HIP 2603 | 22.47 |
| 2026-10-02 00:00 | 00:34:18.77 | +34:03:18.4 | HIP 2603 | 20.04 |
| 2026-10-02 12:00 | 00:34:05.88 | +34:02:48.0 | HIP 2603 | 17.69 |
| 2026-10-03 00:00 | 00:33:53.00 | +34:02:16.9 | HIP 2603 | 15.44 |
| 2026-10-03 12:00 | 00:33:40.12 | +34:01:45.0 | HIP 2603 | 13.37 |
| 2026-10-04 00:00 | 00:33:27.25 | +34:01:12.4 | HIP 2603 | 11.56 |
| 2026-10-04 12:00 | 00:33:14.39 | +34:00:39.1 | HIP 2603 | 10.15 |
| 2026-10-05 00:00 | 00:33:01.54 | +34:00:05.0 | HIP 2603 | 9.33 |
| 2026-10-05 12:00 | 00:32:48.70 | +33:59:30.2 | HIP 2603 | 9.25 |
| 2026-10-06 00:00 | 00:32:35.87 | +33:58:54.7 | HIP 2603 | 9.95 |
| 2026-10-06 12:00 | 00:32:23.05 | +33:58:18.5 | HIP 2603 | 11.26 |
| 2026-10-07 00:00 | 00:32:10.25 | +33:57:41.5 | HIP 2603 | 13.02 |
| 2026-10-07 12:00 | 00:31:57.46 | +33:57:03.9 | HIP 2603 | 15.06 |
| 2026-10-08 00:00 | 00:31:44.69 | +33:56:25.5 | HIP 2429 | 13.48 |
| 2026-10-08 12:00 | 00:31:31.94 | +33:55:46.5 | HIP 2429 | 12.28 |
| 2026-10-09 00:00 | 00:31:19.20 | +33:55:06.8 | HIP 2429 | 11.63 |
| 2026-10-09 12:00 | 00:31:06.49 | +33:54:26.3 | HIP 2429 | 11.60 |
| 2026-10-10 00:00 | 00:30:53.79 | +33:53:45.3 | HIP 2429 | 12.20 |
| 2026-10-10 12:00 | 00:30:41.12 | +33:53:03.5 | HIP 2429 | 13.36 |
| 2026-10-11 00:00 | 00:30:28.47 | +33:52:21.1 | HIP 2429 | 14.93 |