メタデータ
| 項目 |
値 |
| Designation |
C/1967 Y1 (Ikeya-Seki) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1968-02-25T16:56:06.803520Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:17Z |
| Obs used |
197 |
| NEO |
- |
| M1 |
6.400 |
| 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) |
1968-03-18.0000000 |
| e |
0.99915636 |
| q (au) |
1.696579 |
| a (au) |
2011.021687 |
| i (deg) |
129.315339 |
| Ω (om, deg) |
255.321380 |
| ω (w, deg) |
70.864407 |
| M (ma, deg) |
0.000233 |
等級
散乱 + 全体線形
$$
M_a = (2.937 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
2.937 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.991 |
| 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
天体暦
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
02:57:55.20 |
-23:43:49.5 |
HIP 13835 |
7.83 |
| 2026-03-26 12:00 |
02:57:56.28 |
-23:43:37.0 |
HIP 13835 |
7.56 |
| 2026-03-27 00:00 |
02:57:57.37 |
-23:43:24.6 |
HIP 13835 |
7.29 |
| 2026-03-27 12:00 |
02:57:58.48 |
-23:43:12.3 |
HIP 13835 |
7.03 |
| 2026-03-28 00:00 |
02:57:59.59 |
-23:43:00.0 |
HIP 13835 |
6.78 |
| 2026-03-28 12:00 |
02:58:00.70 |
-23:42:47.9 |
HIP 13835 |
6.53 |
| 2026-03-29 00:00 |
02:58:01.83 |
-23:42:35.8 |
HIP 13835 |
6.29 |
| 2026-03-29 12:00 |
02:58:02.96 |
-23:42:23.7 |
HIP 13835 |
6.06 |
| 2026-03-30 00:00 |
02:58:04.11 |
-23:42:11.7 |
HIP 13835 |
5.84 |
| 2026-03-30 12:00 |
02:58:05.26 |
-23:41:59.8 |
HIP 13835 |
5.63 |
| 2026-03-31 00:00 |
02:58:06.41 |
-23:41:48.0 |
HIP 13835 |
5.43 |
| 2026-03-31 12:00 |
02:58:07.58 |
-23:41:36.2 |
HIP 13835 |
5.25 |
| 2026-04-01 00:00 |
02:58:08.75 |
-23:41:24.5 |
HIP 13835 |
5.09 |
| 2026-04-01 12:00 |
02:58:09.93 |
-23:41:12.9 |
HIP 13835 |
4.94 |
| 2026-04-02 00:00 |
02:58:11.11 |
-23:41:01.4 |
HIP 13835 |
4.82 |
| 2026-04-02 12:00 |
02:58:12.31 |
-23:40:49.9 |
HIP 13835 |
4.71 |
| 2026-04-03 00:00 |
02:58:13.51 |
-23:40:38.5 |
HIP 13835 |
4.63 |
| 2026-04-03 12:00 |
02:58:14.72 |
-23:40:27.2 |
HIP 13835 |
4.58 |
| 2026-04-04 00:00 |
02:58:15.93 |
-23:40:16.0 |
HIP 13835 |
4.55 |
| 2026-04-04 12:00 |
02:58:17.15 |
-23:40:04.9 |
HIP 13835 |
4.55 |
| 2026-04-05 00:00 |
02:58:18.38 |
-23:39:53.8 |
HIP 13835 |
4.57 |
| 2026-04-05 12:00 |
02:58:19.62 |
-23:39:42.8 |
HIP 13835 |
4.62 |
| 2026-04-06 00:00 |
02:58:20.86 |
-23:39:31.9 |
HIP 13835 |
4.70 |
| 2026-04-06 12:00 |
02:58:22.11 |
-23:39:21.0 |
HIP 13835 |
4.80 |
| 2026-04-07 00:00 |
02:58:23.36 |
-23:39:10.3 |
HIP 13835 |
4.92 |
| 2026-04-07 12:00 |
02:58:24.62 |
-23:38:59.6 |
HIP 13835 |
5.07 |
| 2026-04-08 00:00 |
02:58:25.89 |
-23:38:49.0 |
HIP 13835 |
5.24 |
| 2026-04-08 12:00 |
02:58:27.16 |
-23:38:38.5 |
HIP 13835 |
5.42 |
| 2026-04-09 00:00 |
02:58:28.44 |
-23:38:28.1 |
HIP 13835 |
5.62 |
| 2026-04-09 12:00 |
02:58:29.73 |
-23:38:17.8 |
HIP 13835 |
5.83 |
| 2026-04-10 00:00 |
02:58:31.02 |
-23:38:07.5 |
HIP 13835 |
6.06 |
| 2026-04-10 12:00 |
02:58:32.32 |
-23:37:57.4 |
HIP 13835 |
6.30 |
| 2026-04-11 00:00 |
02:58:33.62 |
-23:37:47.3 |
HIP 13835 |
6.55 |
| 2026-04-11 12:00 |
02:58:34.93 |
-23:37:37.3 |
HIP 13835 |
6.81 |
| 2026-04-12 00:00 |
02:58:36.24 |
-23:37:27.4 |
HIP 13835 |
7.08 |
| 2026-04-12 12:00 |
02:58:37.56 |
-23:37:17.7 |
HIP 13835 |
7.36 |
| 2026-04-13 00:00 |
02:58:38.88 |
-23:37:07.9 |
HIP 13835 |
7.64 |
| 2026-04-13 12:00 |
02:58:40.21 |
-23:36:58.3 |
HIP 13835 |
7.93 |
| 2026-04-14 00:00 |
02:58:41.55 |
-23:36:48.8 |
HIP 13835 |
8.23 |
| 2026-04-14 12:00 |
02:58:42.89 |
-23:36:39.4 |
HIP 13835 |
8.53 |
| 2026-04-15 00:00 |
02:58:44.23 |
-23:36:30.0 |
HIP 13835 |
8.83 |
| 2026-04-15 12:00 |
02:58:45.58 |
-23:36:20.8 |
HIP 13835 |
9.14 |
| 2026-04-16 00:00 |
02:58:46.94 |
-23:36:11.7 |
HIP 13920 |
8.99 |