メタデータ
| 項目 |
値 |
| Designation |
C/2021 A7 (NEOWISE) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-07-15T07:52:29.438400Z |
| Orbit solution date (soln_date, UTC) |
2022-06-28T01:12:46Z |
| Obs used |
295 |
| NEO |
- |
| M1 |
11.600 |
| K1 |
9.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-01-09T02:37:24.384000Z |
| Discovery magnitude (MPC) |
20.00 R |
| Discovery observatory (MPC) |
C51 · WISE |
オスキュレーティング軌道要素
| 項目 |
値 |
| Epoch (epoch_cal, TDB) |
2021-04-15.0000000 |
| e |
0.99972271 |
| q (au) |
1.967689 |
| a (au) |
7096.234707 |
| i (deg) |
78.149198 |
| Ω (om, deg) |
154.518746 |
| ω (w, deg) |
356.065440 |
| M (ma, deg) |
359.999849 |
等級
散乱 + 全体線形
$$
M_a = (11.691 + 4.023\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
11.691 |
| n |
4.023 |
| gf |
1.000 |
| gb |
-0.500 |
| k |
0.800 |
| δ90 |
9.995 |
| 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 |
| 2021-01-09 |
2021-07-08 |
-0.1334 |
-0.114 |
| 2021-11-10 |
2022-06-25 |
-4.5627 |
+3.915 |
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) |
| 2026-07-29 00:00 |
20:37:31.54 |
+31:52:29.4 |
HIP 101762 |
10.83 |
| 2026-07-29 12:00 |
20:37:22.96 |
+31:51:55.3 |
HIP 101762 |
11.44 |
| 2026-07-30 00:00 |
20:37:14.37 |
+31:51:20.4 |
HIP 101762 |
12.32 |
| 2026-07-30 12:00 |
20:37:05.80 |
+31:50:44.6 |
HIP 101762 |
13.44 |
| 2026-07-31 00:00 |
20:36:57.22 |
+31:50:08.0 |
HIP 101762 |
14.73 |
| 2026-07-31 12:00 |
20:36:48.65 |
+31:49:30.6 |
HIP 101762 |
16.16 |
| 2026-08-01 00:00 |
20:36:40.08 |
+31:48:52.3 |
HIP 101762 |
17.69 |
| 2026-08-01 12:00 |
20:36:31.52 |
+31:48:13.2 |
HIP 101765 |
18.88 |
| 2026-08-02 00:00 |
20:36:22.97 |
+31:47:33.3 |
HIP 101765 |
19.71 |
| 2026-08-02 12:00 |
20:36:14.42 |
+31:46:52.6 |
HIP 101765 |
20.68 |
| 2026-08-03 00:00 |
20:36:05.89 |
+31:46:11.0 |
HIP 101561 |
21.02 |
| 2026-08-03 12:00 |
20:35:57.36 |
+31:45:28.7 |
HIP 101561 |
20.45 |
| 2026-08-04 00:00 |
20:35:48.84 |
+31:44:45.5 |
HIP 101561 |
20.07 |
| 2026-08-04 12:00 |
20:35:40.33 |
+31:44:01.5 |
HIP 101561 |
19.88 |
| 2026-08-05 00:00 |
20:35:31.83 |
+31:43:16.6 |
HIP 101561 |
19.90 |
| 2026-08-05 12:00 |
20:35:23.34 |
+31:42:31.0 |
HIP 101561 |
20.12 |
| 2026-08-06 00:00 |
20:35:14.87 |
+31:41:44.6 |
HIP 101561 |
20.54 |
| 2026-08-06 12:00 |
20:35:06.41 |
+31:40:57.3 |
HIP 101561 |
21.15 |
| 2026-08-07 00:00 |
20:34:57.97 |
+31:40:09.3 |
HIP 101561 |
21.93 |
| 2026-08-07 12:00 |
20:34:49.54 |
+31:39:20.4 |
HIP 101411 |
22.22 |
| 2026-08-08 00:00 |
20:34:41.12 |
+31:38:30.8 |
HIP 101411 |
20.45 |
| 2026-08-08 12:00 |
20:34:32.73 |
+31:37:40.4 |
HIP 101411 |
18.73 |
| 2026-08-09 00:00 |
20:34:24.35 |
+31:36:49.1 |
HIP 101411 |
17.06 |
| 2026-08-09 12:00 |
20:34:15.99 |
+31:35:57.1 |
HIP 101411 |
15.48 |
| 2026-08-10 00:00 |
20:34:07.65 |
+31:35:04.3 |
HIP 101411 |
14.00 |
| 2026-08-10 12:00 |
20:33:59.33 |
+31:34:10.7 |
HIP 101411 |
12.68 |
| 2026-08-11 00:00 |
20:33:51.03 |
+31:33:16.4 |
HIP 101411 |
11.55 |
| 2026-08-11 12:00 |
20:33:42.75 |
+31:32:21.2 |
HIP 101411 |
10.69 |
| 2026-08-12 00:00 |
20:33:34.49 |
+31:31:25.3 |
HIP 101411 |
10.16 |
| 2026-08-12 12:00 |
20:33:26.26 |
+31:30:28.6 |
HIP 101411 |
10.02 |
| 2026-08-13 00:00 |
20:33:18.05 |
+31:29:31.2 |
HIP 101411 |
10.28 |
| 2026-08-13 12:00 |
20:33:09.87 |
+31:28:33.0 |
HIP 101411 |
10.92 |
| 2026-08-14 00:00 |
20:33:01.71 |
+31:27:34.1 |
HIP 101411 |
11.88 |
| 2026-08-14 12:00 |
20:32:53.59 |
+31:26:34.4 |
HIP 101411 |
13.08 |
| 2026-08-15 00:00 |
20:32:45.48 |
+31:25:33.9 |
HIP 101411 |
14.48 |
| 2026-08-15 12:00 |
20:32:37.41 |
+31:24:32.8 |
HIP 101411 |
16.01 |
| 2026-08-16 00:00 |
20:32:29.37 |
+31:23:30.8 |
HIP 101411 |
17.64 |
| 2026-08-16 12:00 |
20:32:21.35 |
+31:22:28.2 |
HIP 101411 |
19.35 |
| 2026-08-17 00:00 |
20:32:13.37 |
+31:21:24.9 |
HIP 101411 |
21.12 |
| 2026-08-17 12:00 |
20:32:05.42 |
+31:20:20.8 |
HIP 101411 |
22.93 |
| 2026-08-18 00:00 |
20:31:57.50 |
+31:19:16.0 |
HIP 101411 |
24.78 |
| 2026-08-18 12:00 |
20:31:49.61 |
+31:18:10.5 |
HIP 101411 |
26.66 |
| 2026-08-19 00:00 |
20:31:41.76 |
+31:17:04.3 |
HIP 101408 |
27.32 |