メタデータ
| 項目 |
値 |
| Designation |
C/1991 A2 (Arai) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1990-12-10T21:20:14.118720Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:38Z |
| Obs used |
110 |
| NEO |
- |
| M1 |
6.400 |
| K1 |
32.000 |
| PC |
- |
オスキュレーティング軌道要素
| 項目 |
値 |
| Epoch (epoch_cal, TDB) |
1991-01-21.0000000 |
| e |
0.99066384 |
| q (au) |
1.434192 |
| a (au) |
153.616954 |
| i (deg) |
70.980280 |
| Ω (om, deg) |
115.522769 |
| ω (w, deg) |
337.640099 |
| M (ma, deg) |
0.021282 |
等級
散乱 + 全体線形
$$
M_a = (8.566 + 5.072\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
8.566 |
| n |
5.072 |
| gf |
1.000 |
| gb |
-0.998 |
| 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
天体暦
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
18:39:53.18 |
+13:17:50.4 |
HIP 91569 |
8.24 |
| 2026-03-26 12:00 |
18:39:53.39 |
+13:18:08.3 |
HIP 91569 |
8.04 |
| 2026-03-27 00:00 |
18:39:53.57 |
+13:18:26.3 |
HIP 91569 |
7.85 |
| 2026-03-27 12:00 |
18:39:53.74 |
+13:18:44.2 |
HIP 91569 |
7.68 |
| 2026-03-28 00:00 |
18:39:53.89 |
+13:19:02.2 |
HIP 91569 |
7.52 |
| 2026-03-28 12:00 |
18:39:54.02 |
+13:19:20.1 |
HIP 91569 |
7.37 |
| 2026-03-29 00:00 |
18:39:54.13 |
+13:19:38.0 |
HIP 91569 |
7.23 |
| 2026-03-29 12:00 |
18:39:54.23 |
+13:19:55.9 |
HIP 91569 |
7.11 |
| 2026-03-30 00:00 |
18:39:54.31 |
+13:20:13.8 |
HIP 91569 |
7.00 |
| 2026-03-30 12:00 |
18:39:54.36 |
+13:20:31.7 |
HIP 91569 |
6.91 |
| 2026-03-31 00:00 |
18:39:54.40 |
+13:20:49.6 |
HIP 91569 |
6.83 |
| 2026-03-31 12:00 |
18:39:54.42 |
+13:21:07.5 |
HIP 91569 |
6.77 |
| 2026-04-01 00:00 |
18:39:54.43 |
+13:21:25.3 |
HIP 91569 |
6.73 |
| 2026-04-01 12:00 |
18:39:54.41 |
+13:21:43.1 |
HIP 91569 |
6.71 |
| 2026-04-02 00:00 |
18:39:54.38 |
+13:22:01.0 |
HIP 91569 |
6.70 |
| 2026-04-02 12:00 |
18:39:54.32 |
+13:22:18.8 |
HIP 91569 |
6.71 |
| 2026-04-03 00:00 |
18:39:54.25 |
+13:22:36.5 |
HIP 91569 |
6.74 |
| 2026-04-03 12:00 |
18:39:54.16 |
+13:22:54.3 |
HIP 91569 |
6.79 |
| 2026-04-04 00:00 |
18:39:54.05 |
+13:23:12.0 |
HIP 91569 |
6.85 |
| 2026-04-04 12:00 |
18:39:53.93 |
+13:23:29.7 |
HIP 91569 |
6.93 |
| 2026-04-05 00:00 |
18:39:53.78 |
+13:23:47.4 |
HIP 91569 |
7.02 |
| 2026-04-05 12:00 |
18:39:53.62 |
+13:24:05.1 |
HIP 91569 |
7.13 |
| 2026-04-06 00:00 |
18:39:53.44 |
+13:24:22.7 |
HIP 91569 |
7.26 |
| 2026-04-06 12:00 |
18:39:53.24 |
+13:24:40.3 |
HIP 91569 |
7.40 |
| 2026-04-07 00:00 |
18:39:53.02 |
+13:24:57.9 |
HIP 91569 |
7.55 |
| 2026-04-07 12:00 |
18:39:52.78 |
+13:25:15.4 |
HIP 91569 |
7.72 |
| 2026-04-08 00:00 |
18:39:52.53 |
+13:25:32.9 |
HIP 91569 |
7.89 |
| 2026-04-08 12:00 |
18:39:52.25 |
+13:25:50.4 |
HIP 91569 |
8.08 |
| 2026-04-09 00:00 |
18:39:51.96 |
+13:26:07.8 |
HIP 91569 |
8.28 |
| 2026-04-09 12:00 |
18:39:51.65 |
+13:26:25.2 |
HIP 91569 |
8.48 |
| 2026-04-10 00:00 |
18:39:51.32 |
+13:26:42.5 |
HIP 91569 |
8.70 |
| 2026-04-10 12:00 |
18:39:50.98 |
+13:26:59.9 |
HIP 91569 |
8.92 |
| 2026-04-11 00:00 |
18:39:50.61 |
+13:27:17.1 |
HIP 91569 |
9.15 |
| 2026-04-11 12:00 |
18:39:50.23 |
+13:27:34.4 |
HIP 91569 |
9.39 |
| 2026-04-12 00:00 |
18:39:49.83 |
+13:27:51.6 |
HIP 91569 |
9.64 |
| 2026-04-12 12:00 |
18:39:49.41 |
+13:28:08.7 |
HIP 91569 |
9.89 |
| 2026-04-13 00:00 |
18:39:48.97 |
+13:28:25.8 |
HIP 91569 |
10.15 |
| 2026-04-13 12:00 |
18:39:48.52 |
+13:28:42.8 |
HIP 91569 |
10.41 |
| 2026-04-14 00:00 |
18:39:48.04 |
+13:28:59.8 |
HIP 91569 |
10.68 |
| 2026-04-14 12:00 |
18:39:47.55 |
+13:29:16.8 |
HIP 91569 |
10.95 |
| 2026-04-15 00:00 |
18:39:47.04 |
+13:29:33.7 |
HIP 91569 |
11.23 |
| 2026-04-15 12:00 |
18:39:46.52 |
+13:29:50.5 |
HIP 91569 |
11.51 |
| 2026-04-16 00:00 |
18:39:45.97 |
+13:30:07.3 |
HIP 91569 |
11.79 |