C/2017 K2 (PANSTARRS)
メタデータ
| 項目 | 値 |
|---|---|
| Designation | C/2017 K2 (PANSTARRS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2022-12-19T17:27:53.064000Z |
| Orbit solution date (soln_date, UTC) | 2026-04-27T13:42:20Z |
| Obs used | 3106 |
| NEO | - |
| M1 | 8.500 |
| K1 | 4.500 |
| PC | - |
オスキュレーティング軌道要素
| 項目 | 値 |
|---|---|
| Epoch (epoch_cal, TDB) | 2021-09-08.0000000 |
| e | 1.00061514 |
| q (au) | 1.797287 |
| a (au) | -2921.753852 |
| i (deg) | 87.554809 |
| Ω (om, deg) | 88.241180 |
| ω (w, deg) | 236.192285 |
| M (ma, deg) | -0.002919 |
等級
散乱 + 全体線形
$$ M_a = (8.414 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
モデル定数
| 項目 | 値 |
|---|---|
| H0 | 8.414 |
| n | 2.000 |
| gf | 1.000 |
| gb | -0.822 |
| k | 0.988 |
| 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 |
|---|---|---|---|
| 2013-05-12 | 2022-05-07 | +0.2827 | -0.719 |
| 2022-05-07 | 2022-12-13 | +8.2159 | -3.820 |
| 2022-12-20 | 2024-01-29 | +5.9897 | -3.787 |
| 2024-01-29 | 2026-03-22 | +3.2192 | -2.277 |
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) |
|---|---|---|---|---|
| 2026-06-01 00:00 | 05:46:25.97 | +31:52:39.4 | HIP 27163 | 24.20 |
| 2026-06-01 12:00 | 05:46:36.82 | +31:53:01.4 | HIP 27163 | 25.11 |
| 2026-06-02 00:00 | 05:46:47.68 | +31:53:23.5 | HIP 27163 | 26.20 |
| 2026-06-02 12:00 | 05:46:58.56 | +31:53:45.7 | HIP 27163 | 27.45 |
| 2026-06-03 00:00 | 05:47:09.45 | +31:54:08.1 | HIP 27163 | 28.83 |
| 2026-06-03 12:00 | 05:47:20.37 | +31:54:30.5 | HIP 27163 | 30.34 |
| 2026-06-04 00:00 | 05:47:31.30 | +31:54:53.0 | HIP 27538 | 31.59 |
| 2026-06-04 12:00 | 05:47:42.24 | +31:55:15.6 | HIP 27538 | 29.45 |
| 2026-06-05 00:00 | 05:47:53.20 | +31:55:38.4 | HIP 27538 | 27.33 |
| 2026-06-05 12:00 | 05:48:04.17 | +31:56:01.2 | HIP 27538 | 25.26 |
| 2026-06-06 00:00 | 05:48:15.15 | +31:56:24.1 | HIP 27538 | 23.24 |
| 2026-06-06 12:00 | 05:48:26.15 | +31:56:47.1 | HIP 27538 | 21.29 |
| 2026-06-07 00:00 | 05:48:37.16 | +31:57:10.2 | HIP 27538 | 19.43 |
| 2026-06-07 12:00 | 05:48:48.19 | +31:57:33.5 | HIP 27538 | 17.69 |
| 2026-06-08 00:00 | 05:48:59.22 | +31:57:56.8 | HIP 27538 | 16.11 |
| 2026-06-08 12:00 | 05:49:10.26 | +31:58:20.2 | HIP 27538 | 14.75 |
| 2026-06-09 00:00 | 05:49:21.32 | +31:58:43.7 | HIP 27571 | 12.83 |
| 2026-06-09 12:00 | 05:49:32.38 | +31:59:07.4 | HIP 27571 | 10.46 |
| 2026-06-10 00:00 | 05:49:43.45 | +31:59:31.1 | HIP 27571 | 8.09 |
| 2026-06-10 12:00 | 05:49:54.54 | +31:59:54.9 | HIP 27571 | 5.72 |
| 2026-06-11 00:00 | 05:50:05.62 | +32:00:18.9 | HIP 27571 | 3.38 |
| 2026-06-11 12:00 | 05:50:16.72 | +32:00:42.9 | HIP 27571 | 1.23 |
| 2026-06-12 00:00 | 05:50:27.82 | +32:01:07.1 | HIP 27571 | 1.72 |
| 2026-06-12 12:00 | 05:50:38.93 | +32:01:31.3 | HIP 27571 | 3.98 |
| 2026-06-13 00:00 | 05:50:50.04 | +32:01:55.6 | HIP 27571 | 6.34 |
| 2026-06-13 12:00 | 05:51:01.16 | +32:02:20.1 | HIP 27661 | 7.32 |
| 2026-06-14 00:00 | 05:51:12.28 | +32:02:44.6 | HIP 27661 | 5.53 |
| 2026-06-14 12:00 | 05:51:23.41 | +32:03:09.3 | HIP 27661 | 4.36 |
| 2026-06-15 00:00 | 05:51:34.54 | +32:03:34.1 | HIP 27661 | 4.33 |
| 2026-06-15 12:00 | 05:51:45.67 | +32:03:58.9 | HIP 27661 | 5.48 |
| 2026-06-16 00:00 | 05:51:56.80 | +32:04:23.9 | HIP 27661 | 7.26 |
| 2026-06-16 12:00 | 05:52:07.93 | +32:04:48.9 | HIP 27661 | 9.32 |
| 2026-06-17 00:00 | 05:52:19.06 | +32:05:14.1 | HIP 27661 | 11.51 |
| 2026-06-17 12:00 | 05:52:30.19 | +32:05:39.4 | HIP 27661 | 13.77 |
| 2026-06-18 00:00 | 05:52:41.32 | +32:06:04.8 | HIP 27661 | 16.06 |
| 2026-06-18 12:00 | 05:52:52.45 | +32:06:30.3 | HIP 27661 | 18.38 |
| 2026-06-19 00:00 | 05:53:03.57 | +32:06:55.9 | HIP 27661 | 20.72 |
| 2026-06-19 12:00 | 05:53:14.69 | +32:07:21.6 | HIP 27661 | 23.07 |
| 2026-06-20 00:00 | 05:53:25.81 | +32:07:47.4 | HIP 27661 | 25.42 |
| 2026-06-20 12:00 | 05:53:36.92 | +32:08:13.3 | HIP 27661 | 27.78 |
| 2026-06-21 00:00 | 05:53:48.03 | +32:08:39.3 | HIP 27784 | 28.59 |
| 2026-06-21 12:00 | 05:53:59.13 | +32:09:05.4 | HIP 27784 | 29.35 |
| 2026-06-22 00:00 | 05:54:10.23 | +32:09:31.6 | HIP 27973 | 29.30 |