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) |
| 2026-09-25 00:00 |
20:24:16.75 |
+29:30:05.9 |
HIP 100722 |
19.83 |
| 2026-09-25 12:00 |
20:24:13.05 |
+29:28:25.2 |
HIP 100722 |
21.65 |
| 2026-09-26 00:00 |
20:24:09.43 |
+29:26:44.3 |
HIP 100722 |
23.46 |
| 2026-09-26 12:00 |
20:24:05.88 |
+29:25:03.2 |
HIP 100616 |
24.94 |
| 2026-09-27 00:00 |
20:24:02.40 |
+29:23:22.0 |
HIP 100616 |
23.28 |
| 2026-09-27 12:00 |
20:23:58.99 |
+29:21:40.6 |
HIP 100616 |
21.66 |
| 2026-09-28 00:00 |
20:23:55.65 |
+29:19:59.0 |
HIP 100616 |
20.07 |
| 2026-09-28 12:00 |
20:23:52.39 |
+29:18:17.3 |
HIP 100616 |
18.52 |
| 2026-09-29 00:00 |
20:23:49.20 |
+29:16:35.5 |
HIP 100616 |
17.02 |
| 2026-09-29 12:00 |
20:23:46.07 |
+29:14:53.5 |
HIP 100616 |
15.59 |
| 2026-09-30 00:00 |
20:23:43.03 |
+29:13:11.4 |
HIP 100616 |
14.24 |
| 2026-09-30 12:00 |
20:23:40.05 |
+29:11:29.2 |
HIP 100616 |
13.00 |
| 2026-10-01 00:00 |
20:23:37.15 |
+29:09:46.9 |
HIP 100616 |
11.90 |
| 2026-10-01 12:00 |
20:23:34.32 |
+29:08:04.5 |
HIP 100616 |
10.98 |
| 2026-10-02 00:00 |
20:23:31.56 |
+29:06:22.0 |
HIP 100616 |
10.29 |
| 2026-10-02 12:00 |
20:23:28.88 |
+29:04:39.4 |
HIP 100616 |
9.87 |
| 2026-10-03 00:00 |
20:23:26.27 |
+29:02:56.7 |
HIP 100616 |
9.76 |
| 2026-10-03 12:00 |
20:23:23.74 |
+29:01:13.9 |
HIP 100616 |
9.96 |
| 2026-10-04 00:00 |
20:23:21.28 |
+28:59:31.1 |
HIP 100616 |
10.45 |
| 2026-10-04 12:00 |
20:23:18.89 |
+28:57:48.2 |
HIP 100616 |
11.20 |
| 2026-10-05 00:00 |
20:23:16.58 |
+28:56:05.3 |
HIP 100616 |
12.16 |
| 2026-10-05 12:00 |
20:23:14.34 |
+28:54:22.3 |
HIP 100616 |
13.27 |
| 2026-10-06 00:00 |
20:23:12.18 |
+28:52:39.3 |
HIP 100439 |
14.24 |
| 2026-10-06 12:00 |
20:23:10.09 |
+28:50:56.3 |
HIP 100439 |
13.62 |
| 2026-10-07 00:00 |
20:23:08.07 |
+28:49:13.2 |
HIP 100439 |
13.24 |
| 2026-10-07 12:00 |
20:23:06.14 |
+28:47:30.2 |
HIP 100439 |
13.10 |
| 2026-10-08 00:00 |
20:23:04.27 |
+28:45:47.1 |
HIP 100439 |
13.21 |
| 2026-10-08 12:00 |
20:23:02.49 |
+28:44:04.0 |
HIP 100439 |
13.57 |
| 2026-10-09 00:00 |
20:23:00.77 |
+28:42:21.0 |
HIP 100439 |
14.15 |
| 2026-10-09 12:00 |
20:22:59.14 |
+28:40:37.9 |
HIP 100439 |
14.93 |
| 2026-10-10 00:00 |
20:22:57.58 |
+28:38:54.9 |
HIP 100439 |
15.88 |
| 2026-10-10 12:00 |
20:22:56.09 |
+28:37:12.0 |
HIP 100439 |
16.97 |
| 2026-10-11 00:00 |
20:22:54.68 |
+28:35:29.0 |
HIP 100439 |
18.17 |
| 2026-10-11 12:00 |
20:22:53.35 |
+28:33:46.2 |
HIP 100439 |
19.45 |
| 2026-10-12 00:00 |
20:22:52.09 |
+28:32:03.4 |
HIP 100402 |
18.74 |
| 2026-10-12 12:00 |
20:22:50.91 |
+28:30:20.6 |
HIP 100402 |
17.73 |
| 2026-10-13 00:00 |
20:22:49.80 |
+28:28:38.0 |
HIP 100402 |
16.84 |
| 2026-10-13 12:00 |
20:22:48.77 |
+28:26:55.4 |
HIP 100402 |
16.12 |
| 2026-10-14 00:00 |
20:22:47.82 |
+28:25:12.9 |
HIP 100402 |
15.56 |
| 2026-10-14 12:00 |
20:22:46.94 |
+28:23:30.5 |
HIP 100402 |
15.20 |
| 2026-10-15 00:00 |
20:22:46.13 |
+28:21:48.2 |
HIP 100402 |
15.04 |
| 2026-10-15 12:00 |
20:22:45.41 |
+28:20:06.0 |
HIP 100402 |
15.10 |
| 2026-10-16 00:00 |
20:22:44.75 |
+28:18:24.0 |
HIP 100402 |
15.36 |