C/2020 Y2 (ATLAS)
メタデータ
| 項目 | 値 |
|---|---|
| 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 |
オスキュレーティング軌道要素
| 項目 | 値 |
|---|---|
| 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 |
等級
散乱 + 全体線形
$$ M_a = (11.072 + 2.941\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
モデル定数
| 項目 | 値 |
|---|---|
| H0 | 11.072 |
| n | 2.941 |
| gf | 1.000 |
| gb | -0.718 |
| k | 0.800 |
| δ90 | 10.000 |
| パラメータ | 記号 | 範囲 | 説明 |
|---|---|---|---|
| 太陽・地球距離が1 AUのときの絶対等級 | H0 | -5 to 20 | 彗星の固有の明るさ |
| 測光スロープパラメータ | n | 2 to 6 | 太陽距離に対する明るさ変化率 |
| 前方散乱非対称係数 | gf |
0.8 to 1 | 前方散乱の強さ |
| 後方散乱非対称係数 | gb |
-1 to -0.5 | 後方散乱の強さ |
| 分配係数 | k | 0.8 to 1 | 前方/後方散乱の寄与比 |
| ダスト/ガス明るさ比 | δ90 | 1 to 10 | ダスト散乱とガス放射の相対寄与 |
参考: EPSC-DPS2025-160
残差 (区間線形)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| 開始日 (UTC) | 終了日 (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(太陽距離/AU)、Δ = 地球距離(AU)
ファインディングチャート
天体暦
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-02-03 00:00 | 00:28:53.29 | +25:37:45.4 | HIP 2152 | 22.91 |
| 2026-02-03 12:00 | 00:28:58.19 | +25:38:00.3 | HIP 2152 | 24.04 |
| 2026-02-04 00:00 | 00:29:03.16 | +25:38:15.8 | HIP 2152 | 25.18 |
| 2026-02-04 12:00 | 00:29:08.20 | +25:38:32.1 | HIP 2152 | 26.34 |
| 2026-02-05 00:00 | 00:29:13.30 | +25:38:48.9 | HIP 2152 | 27.52 |
| 2026-02-05 12:00 | 00:29:18.47 | +25:39:06.5 | HIP 2152 | 28.72 |
| 2026-02-06 00:00 | 00:29:23.70 | +25:39:24.8 | HIP 2152 | 29.93 |
| 2026-02-06 12:00 | 00:29:28.99 | +25:39:43.7 | HIP 2152 | 31.16 |
| 2026-02-07 00:00 | 00:29:34.35 | +25:40:03.2 | HIP 2152 | 32.40 |
| 2026-02-07 12:00 | 00:29:39.77 | +25:40:23.5 | HIP 2152 | 33.66 |
| 2026-02-08 00:00 | 00:29:45.25 | +25:40:44.4 | HIP 2152 | 34.94 |
| 2026-02-08 12:00 | 00:29:50.79 | +25:41:06.0 | HIP 2152 | 36.23 |
| 2026-02-09 00:00 | 00:29:56.40 | +25:41:28.3 | HIP 2152 | 37.54 |
| 2026-02-09 12:00 | 00:30:02.06 | +25:41:51.2 | HIP 2546 | 37.39 |
| 2026-02-10 00:00 | 00:30:07.79 | +25:42:14.8 | HIP 2546 | 36.09 |
| 2026-02-10 12:00 | 00:30:13.57 | +25:42:39.0 | HIP 2546 | 34.78 |
| 2026-02-11 00:00 | 00:30:19.41 | +25:43:03.9 | HIP 2546 | 33.45 |
| 2026-02-11 12:00 | 00:30:25.31 | +25:43:29.5 | HIP 2546 | 32.12 |
| 2026-02-12 00:00 | 00:30:31.27 | +25:43:55.7 | HIP 2546 | 30.77 |
| 2026-02-12 12:00 | 00:30:37.28 | +25:44:22.6 | HIP 2546 | 29.41 |
| 2026-02-13 00:00 | 00:30:43.35 | +25:44:50.1 | HIP 2546 | 28.04 |
| 2026-02-13 12:00 | 00:30:49.48 | +25:45:18.3 | HIP 2546 | 26.66 |
| 2026-02-14 00:00 | 00:30:55.66 | +25:45:47.2 | HIP 2546 | 25.28 |
| 2026-02-14 12:00 | 00:31:01.89 | +25:46:16.7 | HIP 2546 | 23.88 |
| 2026-02-15 00:00 | 00:31:08.18 | +25:46:46.8 | HIP 2546 | 22.49 |
| 2026-02-15 12:00 | 00:31:14.52 | +25:47:17.6 | HIP 2546 | 21.09 |
| 2026-02-16 00:00 | 00:31:20.91 | +25:47:49.1 | HIP 2546 | 19.69 |
| 2026-02-16 12:00 | 00:31:27.36 | +25:48:21.2 | HIP 2546 | 18.30 |
| 2026-02-17 00:00 | 00:31:33.86 | +25:48:53.9 | HIP 2546 | 16.92 |
| 2026-02-17 12:00 | 00:31:40.40 | +25:49:27.3 | HIP 2546 | 15.56 |
| 2026-02-18 00:00 | 00:31:47.00 | +25:50:01.3 | HIP 2546 | 14.23 |
| 2026-02-18 12:00 | 00:31:53.64 | +25:50:35.9 | HIP 2546 | 12.94 |
| 2026-02-19 00:00 | 00:32:00.34 | +25:51:11.2 | HIP 2546 | 11.72 |
| 2026-02-19 12:00 | 00:32:07.08 | +25:51:47.1 | HIP 2546 | 10.58 |
| 2026-02-20 00:00 | 00:32:13.87 | +25:52:23.6 | HIP 2546 | 9.58 |
| 2026-02-20 12:00 | 00:32:20.70 | +25:53:00.8 | HIP 2546 | 8.76 |
| 2026-02-21 00:00 | 00:32:27.58 | +25:53:38.6 | HIP 2546 | 8.20 |
| 2026-02-21 12:00 | 00:32:34.51 | +25:54:17.0 | HIP 2546 | 7.94 |
| 2026-02-22 00:00 | 00:32:41.48 | +25:54:56.0 | HIP 2546 | 8.03 |
| 2026-02-22 12:00 | 00:32:48.49 | +25:55:35.6 | HIP 2546 | 8.46 |
| 2026-02-23 00:00 | 00:32:55.55 | +25:56:15.9 | HIP 2546 | 9.20 |
| 2026-02-23 12:00 | 00:33:02.65 | +25:56:56.7 | HIP 2546 | 10.18 |
| 2026-02-24 00:00 | 00:33:09.79 | +25:57:38.2 | HIP 2546 | 11.35 |