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) |
| 2026-05-12 00:00 |
05:26:36.98 |
-10:07:14.7 |
HIP 25524 |
16.23 |
| 2026-05-12 12:00 |
05:26:42.05 |
-10:06:50.6 |
HIP 25524 |
14.99 |
| 2026-05-13 00:00 |
05:26:47.15 |
-10:06:26.9 |
HIP 25524 |
13.76 |
| 2026-05-13 12:00 |
05:26:52.28 |
-10:06:03.6 |
HIP 25524 |
12.56 |
| 2026-05-14 00:00 |
05:26:57.43 |
-10:05:40.6 |
HIP 25524 |
11.38 |
| 2026-05-14 12:00 |
05:27:02.60 |
-10:05:18.0 |
HIP 25524 |
10.23 |
| 2026-05-15 00:00 |
05:27:07.79 |
-10:04:55.7 |
HIP 25524 |
9.14 |
| 2026-05-15 12:00 |
05:27:13.01 |
-10:04:33.8 |
HIP 25524 |
8.12 |
| 2026-05-16 00:00 |
05:27:18.25 |
-10:04:12.3 |
HIP 25524 |
7.20 |
| 2026-05-16 12:00 |
05:27:23.50 |
-10:03:51.2 |
HIP 25524 |
6.45 |
| 2026-05-17 00:00 |
05:27:28.78 |
-10:03:30.4 |
HIP 25524 |
5.91 |
| 2026-05-17 12:00 |
05:27:34.09 |
-10:03:10.0 |
HIP 25524 |
5.65 |
| 2026-05-18 00:00 |
05:27:39.41 |
-10:02:50.0 |
HIP 25524 |
5.71 |
| 2026-05-18 12:00 |
05:27:44.75 |
-10:02:30.4 |
HIP 25524 |
6.10 |
| 2026-05-19 00:00 |
05:27:50.11 |
-10:02:11.1 |
HIP 25524 |
6.74 |
| 2026-05-19 12:00 |
05:27:55.49 |
-10:01:52.3 |
HIP 25524 |
7.58 |
| 2026-05-20 00:00 |
05:28:00.88 |
-10:01:33.8 |
HIP 25524 |
8.57 |
| 2026-05-20 12:00 |
05:28:06.30 |
-10:01:15.7 |
HIP 25524 |
9.65 |
| 2026-05-21 00:00 |
05:28:11.73 |
-10:00:58.0 |
HIP 25524 |
10.81 |
| 2026-05-21 12:00 |
05:28:17.18 |
-10:00:40.7 |
HIP 25524 |
12.01 |
| 2026-05-22 00:00 |
05:28:22.65 |
-10:00:23.7 |
HIP 25524 |
13.26 |
| 2026-05-22 12:00 |
05:28:28.13 |
-10:00:07.2 |
HIP 25524 |
14.53 |
| 2026-05-23 00:00 |
05:28:33.63 |
-09:59:51.0 |
HIP 25524 |
15.82 |
| 2026-05-23 12:00 |
05:28:39.15 |
-09:59:35.2 |
HIP 25524 |
17.14 |
| 2026-05-24 00:00 |
05:28:44.68 |
-09:59:19.8 |
HIP 25524 |
18.47 |
| 2026-05-24 12:00 |
05:28:50.22 |
-09:59:04.9 |
HIP 25524 |
19.81 |
| 2026-05-25 00:00 |
05:28:55.78 |
-09:58:50.2 |
HIP 25524 |
21.16 |
| 2026-05-25 12:00 |
05:29:01.36 |
-09:58:36.0 |
HIP 25524 |
22.51 |
| 2026-05-26 00:00 |
05:29:06.94 |
-09:58:22.2 |
HIP 25524 |
23.88 |
| 2026-05-26 12:00 |
05:29:12.54 |
-09:58:08.8 |
HIP 25524 |
25.25 |
| 2026-05-27 00:00 |
05:29:18.16 |
-09:57:55.7 |
HIP 25840 |
25.96 |
| 2026-05-27 12:00 |
05:29:23.79 |
-09:57:43.1 |
HIP 25840 |
24.69 |
| 2026-05-28 00:00 |
05:29:29.42 |
-09:57:30.8 |
HIP 25840 |
23.43 |
| 2026-05-28 12:00 |
05:29:35.08 |
-09:57:19.0 |
HIP 25840 |
22.18 |
| 2026-05-29 00:00 |
05:29:40.74 |
-09:57:07.5 |
HIP 25840 |
20.94 |
| 2026-05-29 12:00 |
05:29:46.41 |
-09:56:56.5 |
HIP 25840 |
19.72 |
| 2026-05-30 00:00 |
05:29:52.10 |
-09:56:45.8 |
HIP 25840 |
18.52 |
| 2026-05-30 12:00 |
05:29:57.79 |
-09:56:35.5 |
HIP 25840 |
17.35 |
| 2026-05-31 00:00 |
05:30:03.50 |
-09:56:25.7 |
HIP 25840 |
16.21 |
| 2026-05-31 12:00 |
05:30:09.21 |
-09:56:16.2 |
HIP 25840 |
15.12 |
| 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 |