メタデータ
| 項目 |
値 |
| Designation |
C/2021 A9 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2023-12-01T09:07:05.606400Z |
| Orbit solution date (soln_date, UTC) |
2026-03-07T11:42:49Z |
| Obs used |
449 |
| NEO |
- |
| M1 |
6.600 |
| K1 |
9.250 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-01-12T15:24:10.569600Z |
| Discovery magnitude (MPC) |
21.44 w |
| Discovery observatory (MPC) |
F51 · Pan-STARRS 1, Haleakala |
オスキュレーティング軌道要素
| 項目 |
値 |
| Epoch (epoch_cal, TDB) |
2022-09-29.0000000 |
| e |
1.00315922 |
| q (au) |
7.760340 |
| a (au) |
-2456.412915 |
| i (deg) |
158.022662 |
| Ω (om, deg) |
314.842967 |
| ω (w, deg) |
211.451996 |
| M (ma, deg) |
-0.003468 |
等級
散乱 + 全体線形
$$
M_a = (1.616 + 5.710\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
1.616 |
| n |
5.710 |
| gf |
0.906 |
| gb |
-0.970 |
| k |
1.000 |
| δ90 |
1.000 |
| 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 |
| 2020-12-12 |
2023-11-25 |
+3.7459 |
-3.703 |
| 2023-12-04 |
2026-01-19 |
+13.1211 |
-11.601 |
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 |
03:55:29.27 |
-01:21:25.1 |
HIP 18317 |
9.60 |
| 2026-07-29 12:00 |
03:55:29.27 |
-01:22:31.8 |
HIP 18317 |
10.29 |
| 2026-07-30 00:00 |
03:55:29.19 |
-01:23:39.2 |
HIP 18317 |
11.04 |
| 2026-07-30 12:00 |
03:55:29.01 |
-01:24:47.1 |
HIP 18317 |
11.85 |
| 2026-07-31 00:00 |
03:55:28.75 |
-01:25:55.5 |
HIP 18317 |
12.69 |
| 2026-07-31 12:00 |
03:55:28.40 |
-01:27:04.5 |
HIP 18317 |
13.58 |
| 2026-08-01 00:00 |
03:55:27.96 |
-01:28:14.1 |
HIP 18317 |
14.50 |
| 2026-08-01 12:00 |
03:55:27.43 |
-01:29:24.2 |
HIP 18317 |
15.45 |
| 2026-08-02 00:00 |
03:55:26.81 |
-01:30:34.9 |
HIP 18317 |
16.43 |
| 2026-08-02 12:00 |
03:55:26.10 |
-01:31:46.2 |
HIP 18317 |
17.43 |
| 2026-08-03 00:00 |
03:55:25.30 |
-01:32:58.0 |
HIP 18317 |
18.46 |
| 2026-08-03 12:00 |
03:55:24.40 |
-01:34:10.3 |
HIP 18317 |
19.51 |
| 2026-08-04 00:00 |
03:55:23.42 |
-01:35:23.2 |
HIP 18462 |
19.93 |
| 2026-08-04 12:00 |
03:55:22.34 |
-01:36:36.7 |
HIP 18462 |
20.30 |
| 2026-08-05 00:00 |
03:55:21.17 |
-01:37:50.7 |
HIP 18462 |
20.76 |
| 2026-08-05 12:00 |
03:55:19.91 |
-01:39:05.2 |
HIP 18462 |
21.32 |
| 2026-08-06 00:00 |
03:55:18.55 |
-01:40:20.3 |
HIP 18462 |
21.96 |
| 2026-08-06 12:00 |
03:55:17.10 |
-01:41:35.9 |
HIP 18462 |
22.68 |
| 2026-08-07 00:00 |
03:55:15.55 |
-01:42:52.1 |
HIP 18462 |
23.48 |
| 2026-08-07 12:00 |
03:55:13.91 |
-01:44:08.8 |
HIP 18462 |
24.35 |
| 2026-08-08 00:00 |
03:55:12.17 |
-01:45:26.0 |
HIP 18462 |
25.29 |
| 2026-08-08 12:00 |
03:55:10.33 |
-01:46:43.8 |
HIP 18462 |
26.28 |
| 2026-08-09 00:00 |
03:55:08.40 |
-01:48:02.1 |
HIP 18462 |
27.34 |
| 2026-08-09 12:00 |
03:55:06.37 |
-01:49:20.9 |
HIP 18462 |
28.45 |
| 2026-08-10 00:00 |
03:55:04.24 |
-01:50:40.3 |
HIP 18171 |
29.60 |
| 2026-08-10 12:00 |
03:55:02.01 |
-01:52:00.2 |
HIP 18171 |
28.68 |
| 2026-08-11 00:00 |
03:54:59.69 |
-01:53:20.6 |
HIP 18171 |
27.77 |
| 2026-08-11 12:00 |
03:54:57.26 |
-01:54:41.5 |
HIP 18171 |
26.89 |
| 2026-08-12 00:00 |
03:54:54.74 |
-01:56:02.9 |
HIP 18171 |
26.04 |
| 2026-08-12 12:00 |
03:54:52.11 |
-01:57:24.9 |
HIP 18171 |
25.22 |
| 2026-08-13 00:00 |
03:54:49.38 |
-01:58:47.3 |
HIP 18171 |
24.44 |
| 2026-08-13 12:00 |
03:54:46.56 |
-02:00:10.3 |
HIP 18171 |
23.72 |
| 2026-08-14 00:00 |
03:54:43.63 |
-02:01:33.7 |
HIP 18171 |
23.04 |
| 2026-08-14 12:00 |
03:54:40.60 |
-02:02:57.7 |
HIP 18171 |
22.44 |
| 2026-08-15 00:00 |
03:54:37.46 |
-02:04:22.1 |
HIP 18171 |
21.91 |
| 2026-08-15 12:00 |
03:54:34.22 |
-02:05:47.0 |
HIP 18171 |
21.46 |
| 2026-08-16 00:00 |
03:54:30.89 |
-02:07:12.5 |
HIP 18171 |
21.11 |
| 2026-08-16 12:00 |
03:54:27.44 |
-02:08:38.4 |
HIP 18171 |
20.87 |
| 2026-08-17 00:00 |
03:54:23.90 |
-02:10:04.7 |
HIP 18171 |
20.74 |
| 2026-08-17 12:00 |
03:54:20.25 |
-02:11:31.6 |
HIP 18171 |
20.73 |
| 2026-08-18 00:00 |
03:54:16.49 |
-02:12:58.9 |
HIP 18171 |
20.84 |
| 2026-08-18 12:00 |
03:54:12.63 |
-02:14:26.7 |
HIP 18171 |
21.09 |
| 2026-08-19 00:00 |
03:54:08.67 |
-02:15:54.9 |
HIP 18171 |
21.46 |