メタデータ
| 項目 |
値 |
| Designation |
C/2020 A2 (Iwamoto) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2020-01-08T07:41:43.028160Z |
| Orbit solution date (soln_date, UTC) |
2022-12-31T16:12:34Z |
| Obs used |
529 |
| NEO |
- |
| M1 |
15.100 |
| K1 |
10.750 |
| PC |
0.030 |
オスキュレーティング軌道要素
| 項目 |
値 |
| Epoch (epoch_cal, TDB) |
2020-02-23.0000000 |
| e |
0.99907770 |
| q (au) |
0.978012 |
| a (au) |
1060.410619 |
| i (deg) |
120.750132 |
| Ω (om, deg) |
286.379413 |
| ω (w, deg) |
68.209203 |
| M (ma, deg) |
0.001304 |
等級
散乱 + 全体線形
$$
M_a = (11.896 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
11.896 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.500 |
| 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 |
| 2020-01-08 |
2020-03-22 |
-3.5046 |
-0.515 |
| 2020-03-22 |
2020-04-15 |
+14.5888 |
-2.691 |
log10 r = log10(太陽距離/AU)、Δ = 地球距離(AU)
天体暦
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
05:30:14.94 |
-09:56:07.1 |
HIP 25840 |
14.07 |
| 2026-06-01 12:00 |
05:30:20.67 |
-09:55:58.5 |
HIP 25840 |
13.09 |
| 2026-06-02 00:00 |
05:30:26.42 |
-09:55:50.2 |
HIP 25840 |
12.18 |
| 2026-06-02 12:00 |
05:30:32.17 |
-09:55:42.3 |
HIP 25840 |
11.38 |
| 2026-06-03 00:00 |
05:30:37.93 |
-09:55:34.8 |
HIP 25840 |
10.70 |
| 2026-06-03 12:00 |
05:30:43.69 |
-09:55:27.8 |
HIP 25840 |
10.17 |
| 2026-06-04 00:00 |
05:30:49.47 |
-09:55:21.1 |
HIP 25840 |
9.81 |
| 2026-06-04 12:00 |
05:30:55.25 |
-09:55:14.8 |
HIP 25840 |
9.64 |
| 2026-06-05 00:00 |
05:31:01.04 |
-09:55:09.0 |
HIP 25840 |
9.67 |
| 2026-06-05 12:00 |
05:31:06.83 |
-09:55:03.5 |
HIP 25840 |
9.91 |
| 2026-06-06 00:00 |
05:31:12.63 |
-09:54:58.5 |
HIP 25840 |
10.34 |
| 2026-06-06 12:00 |
05:31:18.44 |
-09:54:53.8 |
HIP 25840 |
10.93 |
| 2026-06-07 00:00 |
05:31:24.25 |
-09:54:49.6 |
HIP 25931 |
10.39 |
| 2026-06-07 12:00 |
05:31:30.07 |
-09:54:45.8 |
HIP 25931 |
9.19 |
| 2026-06-08 00:00 |
05:31:35.89 |
-09:54:42.4 |
HIP 25931 |
8.07 |
| 2026-06-08 12:00 |
05:31:41.71 |
-09:54:39.3 |
HIP 25931 |
7.06 |
| 2026-06-09 00:00 |
05:31:47.54 |
-09:54:36.7 |
HIP 25931 |
6.21 |
| 2026-06-09 12:00 |
05:31:53.38 |
-09:54:34.5 |
HIP 25931 |
5.59 |
| 2026-06-10 00:00 |
05:31:59.21 |
-09:54:32.8 |
HIP 25931 |
5.30 |
| 2026-06-10 12:00 |
05:32:05.05 |
-09:54:31.4 |
HIP 25931 |
5.38 |
| 2026-06-11 00:00 |
05:32:10.89 |
-09:54:30.4 |
HIP 25931 |
5.82 |
| 2026-06-11 12:00 |
05:32:16.73 |
-09:54:29.9 |
HIP 25931 |
6.55 |
| 2026-06-12 00:00 |
05:32:22.58 |
-09:54:29.7 |
HIP 25931 |
7.48 |
| 2026-06-12 12:00 |
05:32:28.42 |
-09:54:30.0 |
HIP 25931 |
8.55 |
| 2026-06-13 00:00 |
05:32:34.27 |
-09:54:30.7 |
HIP 25931 |
9.71 |
| 2026-06-13 12:00 |
05:32:40.11 |
-09:54:31.8 |
HIP 25931 |
10.94 |
| 2026-06-14 00:00 |
05:32:45.96 |
-09:54:33.3 |
HIP 25931 |
12.21 |
| 2026-06-14 12:00 |
05:32:51.81 |
-09:54:35.3 |
HIP 25931 |
13.51 |
| 2026-06-15 00:00 |
05:32:57.65 |
-09:54:37.6 |
HIP 25931 |
14.83 |
| 2026-06-15 12:00 |
05:33:03.49 |
-09:54:40.4 |
HIP 25931 |
16.17 |
| 2026-06-16 00:00 |
05:33:09.34 |
-09:54:43.5 |
HIP 25931 |
17.52 |
| 2026-06-16 12:00 |
05:33:15.18 |
-09:54:47.1 |
HIP 25931 |
18.89 |
| 2026-06-17 00:00 |
05:33:21.01 |
-09:54:51.1 |
HIP 25931 |
20.26 |
| 2026-06-17 12:00 |
05:33:26.85 |
-09:54:55.6 |
HIP 26179 |
20.81 |
| 2026-06-18 00:00 |
05:33:32.68 |
-09:55:00.4 |
HIP 26179 |
19.37 |
| 2026-06-18 12:00 |
05:33:38.50 |
-09:55:05.7 |
HIP 26179 |
17.94 |
| 2026-06-19 00:00 |
05:33:44.33 |
-09:55:11.3 |
HIP 26179 |
16.51 |
| 2026-06-19 12:00 |
05:33:50.15 |
-09:55:17.4 |
HIP 26179 |
15.08 |
| 2026-06-20 00:00 |
05:33:55.96 |
-09:55:23.9 |
HIP 26179 |
13.66 |
| 2026-06-20 12:00 |
05:34:01.77 |
-09:55:30.8 |
HIP 26179 |
12.24 |
| 2026-06-21 00:00 |
05:34:07.57 |
-09:55:38.1 |
HIP 26179 |
10.82 |
| 2026-06-21 12:00 |
05:34:13.37 |
-09:55:45.9 |
HIP 26179 |
9.41 |
| 2026-06-22 00:00 |
05:34:19.16 |
-09:55:54.0 |
HIP 26179 |
8.02 |