C/2020 A2 (Iwamoto)
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) |
| 2026-02-03 00:00 |
05:24:05.71 |
-12:27:32.5 |
HIP 25353 |
19.04 |
| 2026-02-03 12:00 |
05:24:01.10 |
-12:26:53.9 |
HIP 25353 |
20.31 |
| 2026-02-04 00:00 |
05:23:56.55 |
-12:26:15.0 |
HIP 25353 |
21.57 |
| 2026-02-04 12:00 |
05:23:52.05 |
-12:25:35.7 |
HIP 25353 |
22.82 |
| 2026-02-05 00:00 |
05:23:47.60 |
-12:24:56.2 |
HIP 25353 |
24.07 |
| 2026-02-05 12:00 |
05:23:43.21 |
-12:24:16.3 |
HIP 25353 |
25.30 |
| 2026-02-06 00:00 |
05:23:38.87 |
-12:23:36.1 |
HIP 25208 |
24.95 |
| 2026-02-06 12:00 |
05:23:34.59 |
-12:22:55.7 |
HIP 25208 |
24.25 |
| 2026-02-07 00:00 |
05:23:30.36 |
-12:22:14.9 |
HIP 25208 |
23.59 |
| 2026-02-07 12:00 |
05:23:26.19 |
-12:21:33.8 |
HIP 25208 |
22.97 |
| 2026-02-08 00:00 |
05:23:22.08 |
-12:20:52.5 |
HIP 25208 |
22.39 |
| 2026-02-08 12:00 |
05:23:18.02 |
-12:20:10.8 |
HIP 25074 |
21.60 |
| 2026-02-09 00:00 |
05:23:14.02 |
-12:19:28.9 |
HIP 25074 |
20.40 |
| 2026-02-09 12:00 |
05:23:10.07 |
-12:18:46.7 |
HIP 25074 |
19.21 |
| 2026-02-10 00:00 |
05:23:06.18 |
-12:18:04.2 |
HIP 25074 |
18.02 |
| 2026-02-10 12:00 |
05:23:02.35 |
-12:17:21.5 |
HIP 25074 |
16.84 |
| 2026-02-11 00:00 |
05:22:58.57 |
-12:16:38.5 |
HIP 25074 |
15.68 |
| 2026-02-11 12:00 |
05:22:54.86 |
-12:15:55.2 |
HIP 25074 |
14.52 |
| 2026-02-12 00:00 |
05:22:51.20 |
-12:15:11.7 |
HIP 25074 |
13.37 |
| 2026-02-12 12:00 |
05:22:47.60 |
-12:14:27.9 |
HIP 25074 |
12.24 |
| 2026-02-13 00:00 |
05:22:44.05 |
-12:13:43.9 |
HIP 25074 |
11.11 |
| 2026-02-13 12:00 |
05:22:40.57 |
-12:12:59.7 |
HIP 25074 |
9.99 |
| 2026-02-14 00:00 |
05:22:37.14 |
-12:12:15.2 |
HIP 25074 |
8.89 |
| 2026-02-14 12:00 |
05:22:33.77 |
-12:11:30.5 |
HIP 25074 |
7.80 |
| 2026-02-15 00:00 |
05:22:30.46 |
-12:10:45.5 |
HIP 25074 |
6.73 |
| 2026-02-15 12:00 |
05:22:27.21 |
-12:10:00.3 |
HIP 25074 |
5.69 |
| 2026-02-16 00:00 |
05:22:24.02 |
-12:09:14.9 |
HIP 25074 |
4.67 |
| 2026-02-16 12:00 |
05:22:20.89 |
-12:08:29.3 |
HIP 25074 |
3.72 |
| 2026-02-17 00:00 |
05:22:17.81 |
-12:07:43.5 |
HIP 25074 |
2.87 |
| 2026-02-17 12:00 |
05:22:14.80 |
-12:06:57.5 |
HIP 25074 |
2.23 |
| 2026-02-18 00:00 |
05:22:11.85 |
-12:06:11.3 |
HIP 25074 |
2.01 |
| 2026-02-18 12:00 |
05:22:08.95 |
-12:05:24.9 |
HIP 25074 |
2.32 |
| 2026-02-19 00:00 |
05:22:06.12 |
-12:04:38.3 |
HIP 25074 |
2.99 |
| 2026-02-19 12:00 |
05:22:03.34 |
-12:03:51.6 |
HIP 25074 |
3.82 |
| 2026-02-20 00:00 |
05:22:00.63 |
-12:03:04.6 |
HIP 25074 |
4.74 |
| 2026-02-20 12:00 |
05:21:57.98 |
-12:02:17.5 |
HIP 25074 |
5.69 |
| 2026-02-21 00:00 |
05:21:55.38 |
-12:01:30.2 |
HIP 25074 |
6.66 |
| 2026-02-21 12:00 |
05:21:52.85 |
-12:00:42.8 |
HIP 25074 |
7.63 |
| 2026-02-22 00:00 |
05:21:50.38 |
-11:59:55.1 |
HIP 25074 |
8.61 |
| 2026-02-22 12:00 |
05:21:47.97 |
-11:59:07.4 |
HIP 25074 |
9.59 |
| 2026-02-23 00:00 |
05:21:45.61 |
-11:58:19.5 |
HIP 25074 |
10.56 |
| 2026-02-23 12:00 |
05:21:43.32 |
-11:57:31.4 |
HIP 25074 |
11.53 |
| 2026-02-24 00:00 |
05:21:41.09 |
-11:56:43.3 |
HIP 25074 |
12.50 |