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) |
| 2026-03-26 00:00 |
05:21:15.86 |
-11:07:06.7 |
HIP 24901 |
15.33 |
| 2026-03-26 12:00 |
05:21:17.19 |
-11:06:18.3 |
HIP 24901 |
15.52 |
| 2026-03-27 00:00 |
05:21:18.57 |
-11:05:30.1 |
HIP 24901 |
15.76 |
| 2026-03-27 12:00 |
05:21:20.00 |
-11:04:42.0 |
HIP 24901 |
16.07 |
| 2026-03-28 00:00 |
05:21:21.49 |
-11:03:54.0 |
HIP 24901 |
16.42 |
| 2026-03-28 12:00 |
05:21:23.03 |
-11:03:06.2 |
HIP 24901 |
16.83 |
| 2026-03-29 00:00 |
05:21:24.62 |
-11:02:18.5 |
HIP 24901 |
17.28 |
| 2026-03-29 12:00 |
05:21:26.26 |
-11:01:31.0 |
HIP 24901 |
17.78 |
| 2026-03-30 00:00 |
05:21:27.95 |
-11:00:43.6 |
HIP 24901 |
18.33 |
| 2026-03-30 12:00 |
05:21:29.70 |
-10:59:56.3 |
HIP 24901 |
18.91 |
| 2026-03-31 00:00 |
05:21:31.50 |
-10:59:09.2 |
HIP 24901 |
19.52 |
| 2026-03-31 12:00 |
05:21:33.35 |
-10:58:22.3 |
HIP 24901 |
20.17 |
| 2026-04-01 00:00 |
05:21:35.25 |
-10:57:35.5 |
HIP 24901 |
20.85 |
| 2026-04-01 12:00 |
05:21:37.20 |
-10:56:48.8 |
HIP 24901 |
21.55 |
| 2026-04-02 00:00 |
05:21:39.20 |
-10:56:02.4 |
HIP 24901 |
22.29 |
| 2026-04-02 12:00 |
05:21:41.25 |
-10:55:16.1 |
HIP 24901 |
23.04 |
| 2026-04-03 00:00 |
05:21:43.35 |
-10:54:30.0 |
HIP 24901 |
23.82 |
| 2026-04-03 12:00 |
05:21:45.50 |
-10:53:44.0 |
HIP 25131 |
24.44 |
| 2026-04-04 00:00 |
05:21:47.70 |
-10:52:58.2 |
HIP 25131 |
23.51 |
| 2026-04-04 12:00 |
05:21:49.95 |
-10:52:12.6 |
HIP 25131 |
22.57 |
| 2026-04-05 00:00 |
05:21:52.25 |
-10:51:27.2 |
HIP 25131 |
21.63 |
| 2026-04-05 12:00 |
05:21:54.59 |
-10:50:42.0 |
HIP 25131 |
20.68 |
| 2026-04-06 00:00 |
05:21:56.99 |
-10:49:57.0 |
HIP 25131 |
19.73 |
| 2026-04-06 12:00 |
05:21:59.43 |
-10:49:12.1 |
HIP 25131 |
18.77 |
| 2026-04-07 00:00 |
05:22:01.92 |
-10:48:27.5 |
HIP 25131 |
17.81 |
| 2026-04-07 12:00 |
05:22:04.46 |
-10:47:43.0 |
HIP 25131 |
16.84 |
| 2026-04-08 00:00 |
05:22:07.05 |
-10:46:58.8 |
HIP 25131 |
15.87 |
| 2026-04-08 12:00 |
05:22:09.68 |
-10:46:14.7 |
HIP 25131 |
14.90 |
| 2026-04-09 00:00 |
05:22:12.36 |
-10:45:30.9 |
HIP 25131 |
13.93 |
| 2026-04-09 12:00 |
05:22:15.09 |
-10:44:47.3 |
HIP 25131 |
12.95 |
| 2026-04-10 00:00 |
05:22:17.86 |
-10:44:03.9 |
HIP 25131 |
11.97 |
| 2026-04-10 12:00 |
05:22:20.68 |
-10:43:20.7 |
HIP 25131 |
10.99 |
| 2026-04-11 00:00 |
05:22:23.55 |
-10:42:37.7 |
HIP 25131 |
10.02 |
| 2026-04-11 12:00 |
05:22:26.46 |
-10:41:54.9 |
HIP 25131 |
9.05 |
| 2026-04-12 00:00 |
05:22:29.42 |
-10:41:12.4 |
HIP 25131 |
8.08 |
| 2026-04-12 12:00 |
05:22:32.42 |
-10:40:30.1 |
HIP 25131 |
7.13 |
| 2026-04-13 00:00 |
05:22:35.46 |
-10:39:48.1 |
HIP 25131 |
6.20 |
| 2026-04-13 12:00 |
05:22:38.55 |
-10:39:06.2 |
HIP 25131 |
5.30 |
| 2026-04-14 00:00 |
05:22:41.69 |
-10:38:24.6 |
HIP 25131 |
4.47 |
| 2026-04-14 12:00 |
05:22:44.86 |
-10:37:43.3 |
HIP 25131 |
3.75 |
| 2026-04-15 00:00 |
05:22:48.09 |
-10:37:02.2 |
HIP 25131 |
3.21 |
| 2026-04-15 12:00 |
05:22:51.35 |
-10:36:21.3 |
HIP 25131 |
2.97 |
| 2026-04-16 00:00 |
05:22:54.66 |
-10:35:40.7 |
HIP 25131 |
3.10 |