C/2025 Y1 (ATLAS)
メタデータ
| 項目 | 値 |
|---|---|
| Designation | C/2025 Y1 (ATLAS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2027-10-14T01:19:44.313600Z |
| Orbit solution date (soln_date, UTC) | 2026-07-28T14:12:18Z |
| Obs used | 1409 |
| NEO | - |
| M1 | 6.400 |
| K1 | 9.250 |
| PC | 0.030 |
| Discovery observation (MPC, UTC) | 2025-12-26T13:40:40.656000Z |
| Discovery magnitude (MPC) | 18.75 o |
| Discovery observatory (MPC) | T05 · ATLAS-HKO, Haleakala |
オスキュレーティング軌道要素
| 項目 | 値 |
|---|---|
| Epoch (epoch_cal, TDB) | 2026-04-02.0000000 |
| e | 0.99954143 |
| q (au) | 2.601925 |
| a (au) | 5673.989994 |
| i (deg) | 14.557065 |
| Ω (om, deg) | 166.551977 |
| ω (w, deg) | 124.298160 |
| M (ma, deg) | 359.998708 |
等級
散乱 + 全体線形
$$ M_a = (1.373 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
モデル定数
| 項目 | 値 |
|---|---|
| H0 | 1.373 |
| n | 6.000 |
| gf | 1.000 |
| gb | -0.898 |
| k | 1.000 |
| 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 |
|---|---|---|---|
| 2025-11-19 | 2026-04-23 | +4.1673 | -3.193 |
| 2026-04-23 | 2026-07-27 | +0.2711 | -0.331 |
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) |
|---|---|---|---|---|
| 2026-07-29 00:00 | 12:52:27.15 | +02:59:30.1 | HIP 62757 | 13.14 |
| 2026-07-29 12:00 | 12:52:42.50 | +02:57:43.8 | HIP 62757 | 17.33 |
| 2026-07-30 00:00 | 12:52:57.98 | +02:55:56.9 | HIP 62924 | 19.64 |
| 2026-07-30 12:00 | 12:53:13.59 | +02:54:09.3 | HIP 62924 | 16.10 |
| 2026-07-31 00:00 | 12:53:29.34 | +02:52:21.0 | HIP 62924 | 13.00 |
| 2026-07-31 12:00 | 12:53:45.22 | +02:50:32.0 | HIP 62924 | 10.77 |
| 2026-08-01 00:00 | 12:54:01.24 | +02:48:42.3 | HIP 62924 | 10.07 |
| 2026-08-01 12:00 | 12:54:17.39 | +02:46:51.9 | HIP 62966 | 9.01 |
| 2026-08-02 00:00 | 12:54:33.67 | +02:45:00.9 | HIP 62966 | 9.03 |
| 2026-08-02 12:00 | 12:54:50.09 | +02:43:09.2 | HIP 62966 | 11.06 |
| 2026-08-03 00:00 | 12:55:06.63 | +02:41:16.9 | HIP 62966 | 14.30 |
| 2026-08-03 12:00 | 12:55:23.31 | +02:39:23.9 | HIP 62966 | 18.14 |
| 2026-08-04 00:00 | 12:55:40.12 | +02:37:30.2 | HIP 63037 | 19.90 |
| 2026-08-04 12:00 | 12:55:57.06 | +02:35:35.9 | HIP 63037 | 20.73 |
| 2026-08-05 00:00 | 12:56:14.13 | +02:33:41.0 | HIP 63037 | 22.53 |
| 2026-08-05 12:00 | 12:56:31.33 | +02:31:45.4 | HIP 63037 | 25.10 |
| 2026-08-06 00:00 | 12:56:48.66 | +02:29:49.2 | HIP 63037 | 28.26 |
| 2026-08-06 12:00 | 12:57:06.12 | +02:27:52.4 | HIP 63037 | 31.84 |
| 2026-08-07 00:00 | 12:57:23.70 | +02:25:55.0 | HIP 63037 | 35.73 |
| 2026-08-07 12:00 | 12:57:41.42 | +02:23:56.9 | HIP 63455 | 36.80 |
| 2026-08-08 00:00 | 12:57:59.26 | +02:21:58.2 | HIP 63455 | 32.35 |
| 2026-08-08 12:00 | 12:58:17.23 | +02:19:59.0 | HIP 63455 | 28.02 |
| 2026-08-09 00:00 | 12:58:35.32 | +02:17:59.1 | HIP 63455 | 23.87 |
| 2026-08-09 12:00 | 12:58:53.55 | +02:15:58.6 | HIP 63455 | 20.06 |
| 2026-08-10 00:00 | 12:59:11.89 | +02:13:57.6 | HIP 63455 | 16.85 |
| 2026-08-10 12:00 | 12:59:30.37 | +02:11:55.9 | HIP 63455 | 14.67 |
| 2026-08-11 00:00 | 12:59:48.97 | +02:09:53.7 | HIP 63455 | 14.05 |
| 2026-08-11 12:00 | 13:00:07.69 | +02:07:50.9 | HIP 63455 | 15.20 |
| 2026-08-12 00:00 | 13:00:26.53 | +02:05:47.6 | HIP 63455 | 17.82 |
| 2026-08-12 12:00 | 13:00:45.50 | +02:03:43.7 | HIP 63455 | 21.39 |
| 2026-08-13 00:00 | 13:01:04.59 | +02:01:39.2 | HIP 63455 | 25.54 |
| 2026-08-13 12:00 | 13:01:23.81 | +01:59:34.2 | HIP 63560 | 28.40 |
| 2026-08-14 00:00 | 13:01:43.14 | +01:57:28.7 | HIP 63560 | 26.45 |
| 2026-08-14 12:00 | 13:02:02.60 | +01:55:22.7 | HIP 63560 | 25.46 |
| 2026-08-15 00:00 | 13:02:22.17 | +01:53:16.1 | HIP 63560 | 25.56 |
| 2026-08-15 12:00 | 13:02:41.87 | +01:51:09.0 | HIP 63560 | 26.76 |
| 2026-08-16 00:00 | 13:03:01.68 | +01:49:01.3 | HIP 63560 | 28.93 |
| 2026-08-16 12:00 | 13:03:21.62 | +01:46:53.2 | HIP 63560 | 31.90 |
| 2026-08-17 00:00 | 13:03:41.67 | +01:44:44.6 | HIP 63884 | 27.57 |
| 2026-08-17 12:00 | 13:04:01.83 | +01:42:35.5 | HIP 63884 | 22.98 |
| 2026-08-18 00:00 | 13:04:22.12 | +01:40:25.9 | HIP 63884 | 18.86 |
| 2026-08-18 12:00 | 13:04:42.52 | +01:38:15.8 | HIP 63884 | 15.59 |
| 2026-08-19 00:00 | 13:05:03.03 | +01:36:05.3 | HIP 63884 | 13.84 |