メタデータ
| 項目 |
値 |
| Designation |
C/1987 W1 (Ichimura) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1988-01-10T02:29:58.758720Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:36Z |
| Obs used |
48 |
| NEO |
- |
| M1 |
8.900 |
| K1 |
10.000 |
| PC |
- |
オスキュレーティング軌道要素
| 項目 |
値 |
| Epoch (epoch_cal, TDB) |
1987-11-28.0000000 |
| e |
0.99999939 |
| q (au) |
0.199518 |
| a (au) |
327902.551553 |
| i (deg) |
41.620500 |
| Ω (om, deg) |
226.527901 |
| ω (w, deg) |
329.292632 |
| M (ma, deg) |
360.000000 |
等級
散乱 + 全体線形
$$
M_a = (10.506 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
10.506 |
| n |
2.000 |
| gf |
0.800 |
| gb |
-1.000 |
| k |
0.843 |
| δ90 |
1.000 |
| 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 |
00:22:31.50 |
+27:53:49.3 |
HIP 1699 |
18.35 |
| 2026-03-26 12:00 |
00:22:33.44 |
+27:53:58.8 |
HIP 1699 |
18.79 |
| 2026-03-27 00:00 |
00:22:35.37 |
+27:54:08.3 |
HIP 1699 |
19.24 |
| 2026-03-27 12:00 |
00:22:37.31 |
+27:54:18.0 |
HIP 1699 |
19.69 |
| 2026-03-28 00:00 |
00:22:39.24 |
+27:54:27.8 |
HIP 1699 |
20.14 |
| 2026-03-28 12:00 |
00:22:41.17 |
+27:54:37.7 |
HIP 1699 |
20.59 |
| 2026-03-29 00:00 |
00:22:43.11 |
+27:54:47.7 |
HIP 1699 |
21.04 |
| 2026-03-29 12:00 |
00:22:45.04 |
+27:54:57.7 |
HIP 1699 |
21.49 |
| 2026-03-30 00:00 |
00:22:46.97 |
+27:55:07.9 |
HIP 1699 |
21.95 |
| 2026-03-30 12:00 |
00:22:48.90 |
+27:55:18.2 |
HIP 1699 |
22.40 |
| 2026-03-31 00:00 |
00:22:50.83 |
+27:55:28.5 |
HIP 1699 |
22.86 |
| 2026-03-31 12:00 |
00:22:52.76 |
+27:55:39.0 |
HIP 1699 |
23.31 |
| 2026-04-01 00:00 |
00:22:54.69 |
+27:55:49.5 |
HIP 1699 |
23.77 |
| 2026-04-01 12:00 |
00:22:56.61 |
+27:56:00.1 |
HIP 1699 |
24.23 |
| 2026-04-02 00:00 |
00:22:58.54 |
+27:56:10.9 |
HIP 1699 |
24.69 |
| 2026-04-02 12:00 |
00:23:00.46 |
+27:56:21.7 |
HIP 1699 |
25.14 |
| 2026-04-03 00:00 |
00:23:02.38 |
+27:56:32.6 |
HIP 1699 |
25.60 |
| 2026-04-03 12:00 |
00:23:04.30 |
+27:56:43.6 |
HIP 1699 |
26.06 |
| 2026-04-04 00:00 |
00:23:06.22 |
+27:56:54.7 |
HIP 1699 |
26.52 |
| 2026-04-04 12:00 |
00:23:08.13 |
+27:57:05.8 |
HIP 1699 |
26.98 |
| 2026-04-05 00:00 |
00:23:10.05 |
+27:57:17.1 |
HIP 1699 |
27.44 |
| 2026-04-05 12:00 |
00:23:11.96 |
+27:57:28.4 |
HIP 1990 |
27.23 |
| 2026-04-06 00:00 |
00:23:13.86 |
+27:57:39.9 |
HIP 1990 |
26.78 |
| 2026-04-06 12:00 |
00:23:15.77 |
+27:57:51.4 |
HIP 1990 |
26.32 |
| 2026-04-07 00:00 |
00:23:17.67 |
+27:58:03.0 |
HIP 1990 |
25.86 |
| 2026-04-07 12:00 |
00:23:19.57 |
+27:58:14.6 |
HIP 1990 |
25.41 |
| 2026-04-08 00:00 |
00:23:21.47 |
+27:58:26.4 |
HIP 1990 |
24.95 |
| 2026-04-08 12:00 |
00:23:23.36 |
+27:58:38.2 |
HIP 1990 |
24.50 |
| 2026-04-09 00:00 |
00:23:25.25 |
+27:58:50.2 |
HIP 1990 |
24.05 |
| 2026-04-09 12:00 |
00:23:27.14 |
+27:59:02.2 |
HIP 1990 |
23.59 |
| 2026-04-10 00:00 |
00:23:29.02 |
+27:59:14.2 |
HIP 1990 |
23.14 |
| 2026-04-10 12:00 |
00:23:30.90 |
+27:59:26.4 |
HIP 1990 |
22.69 |
| 2026-04-11 00:00 |
00:23:32.77 |
+27:59:38.6 |
HIP 1990 |
22.24 |
| 2026-04-11 12:00 |
00:23:34.65 |
+27:59:50.9 |
HIP 1990 |
21.79 |
| 2026-04-12 00:00 |
00:23:36.51 |
+28:00:03.3 |
HIP 1990 |
21.35 |
| 2026-04-12 12:00 |
00:23:38.38 |
+28:00:15.8 |
HIP 1990 |
20.90 |
| 2026-04-13 00:00 |
00:23:40.24 |
+28:00:28.3 |
HIP 1990 |
20.46 |
| 2026-04-13 12:00 |
00:23:42.09 |
+28:00:40.9 |
HIP 1990 |
20.01 |
| 2026-04-14 00:00 |
00:23:43.94 |
+28:00:53.6 |
HIP 1990 |
19.57 |
| 2026-04-14 12:00 |
00:23:45.79 |
+28:01:06.3 |
HIP 1990 |
19.13 |
| 2026-04-15 00:00 |
00:23:47.63 |
+28:01:19.2 |
HIP 1990 |
18.69 |
| 2026-04-15 12:00 |
00:23:49.46 |
+28:01:32.0 |
HIP 1990 |
18.26 |
| 2026-04-16 00:00 |
00:23:51.29 |
+28:01:45.0 |
HIP 1990 |
17.82 |