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) |
| 2026-06-01 00:00 |
03:48:07.64 |
-00:18:57.0 |
HIP 17701 |
9.97 |
| 2026-06-01 12:00 |
03:48:13.84 |
-00:18:56.1 |
HIP 17701 |
11.48 |
| 2026-06-02 00:00 |
03:48:20.01 |
-00:18:55.8 |
HIP 17701 |
13.00 |
| 2026-06-02 12:00 |
03:48:26.17 |
-00:18:56.0 |
HIP 17701 |
14.51 |
| 2026-06-03 00:00 |
03:48:32.31 |
-00:18:56.7 |
HIP 17882 |
14.76 |
| 2026-06-03 12:00 |
03:48:38.42 |
-00:18:57.9 |
HIP 17882 |
13.25 |
| 2026-06-04 00:00 |
03:48:44.52 |
-00:18:59.8 |
HIP 17882 |
11.75 |
| 2026-06-04 12:00 |
03:48:50.60 |
-00:19:02.1 |
HIP 17882 |
10.25 |
| 2026-06-05 00:00 |
03:48:56.66 |
-00:19:05.0 |
HIP 17882 |
8.77 |
| 2026-06-05 12:00 |
03:49:02.69 |
-00:19:08.5 |
HIP 17882 |
7.31 |
| 2026-06-06 00:00 |
03:49:08.71 |
-00:19:12.5 |
HIP 17882 |
5.87 |
| 2026-06-06 12:00 |
03:49:14.70 |
-00:19:17.0 |
HIP 17882 |
4.47 |
| 2026-06-07 00:00 |
03:49:20.67 |
-00:19:22.1 |
HIP 17882 |
3.17 |
| 2026-06-07 12:00 |
03:49:26.61 |
-00:19:27.8 |
HIP 17882 |
2.13 |
| 2026-06-08 00:00 |
03:49:32.53 |
-00:19:34.0 |
HIP 17882 |
1.85 |
| 2026-06-08 12:00 |
03:49:38.42 |
-00:19:40.8 |
HIP 17882 |
2.58 |
| 2026-06-09 00:00 |
03:49:44.29 |
-00:19:48.1 |
HIP 17882 |
3.77 |
| 2026-06-09 12:00 |
03:49:50.12 |
-00:19:56.0 |
HIP 17882 |
5.09 |
| 2026-06-10 00:00 |
03:49:55.94 |
-00:20:04.4 |
HIP 17882 |
6.47 |
| 2026-06-10 12:00 |
03:50:01.72 |
-00:20:13.4 |
HIP 17882 |
7.87 |
| 2026-06-11 00:00 |
03:50:07.48 |
-00:20:23.0 |
HIP 17882 |
9.28 |
| 2026-06-11 12:00 |
03:50:13.20 |
-00:20:33.2 |
HIP 17882 |
10.69 |
| 2026-06-12 00:00 |
03:50:18.90 |
-00:20:43.9 |
HIP 17882 |
12.10 |
| 2026-06-12 12:00 |
03:50:24.56 |
-00:20:55.2 |
HIP 17882 |
13.51 |
| 2026-06-13 00:00 |
03:50:30.20 |
-00:21:07.1 |
HIP 17882 |
14.91 |
| 2026-06-13 12:00 |
03:50:35.80 |
-00:21:19.5 |
HIP 17882 |
16.31 |
| 2026-06-14 00:00 |
03:50:41.37 |
-00:21:32.5 |
HIP 17882 |
17.70 |
| 2026-06-14 12:00 |
03:50:46.90 |
-00:21:46.1 |
HIP 17882 |
19.09 |
| 2026-06-15 00:00 |
03:50:52.40 |
-00:22:00.3 |
HIP 17882 |
20.47 |
| 2026-06-15 12:00 |
03:50:57.87 |
-00:22:15.1 |
HIP 17882 |
21.85 |
| 2026-06-16 00:00 |
03:51:03.30 |
-00:22:30.4 |
HIP 17882 |
23.21 |
| 2026-06-16 12:00 |
03:51:08.69 |
-00:22:46.3 |
HIP 18109 |
23.81 |
| 2026-06-17 00:00 |
03:51:14.05 |
-00:23:02.8 |
HIP 18109 |
22.66 |
| 2026-06-17 12:00 |
03:51:19.37 |
-00:23:19.9 |
HIP 18109 |
21.55 |
| 2026-06-18 00:00 |
03:51:24.65 |
-00:23:37.6 |
HIP 18109 |
20.46 |
| 2026-06-18 12:00 |
03:51:29.89 |
-00:23:55.8 |
HIP 18109 |
19.41 |
| 2026-06-19 00:00 |
03:51:35.09 |
-00:24:14.7 |
HIP 18109 |
18.39 |
| 2026-06-19 12:00 |
03:51:40.25 |
-00:24:34.1 |
HIP 18109 |
17.40 |
| 2026-06-20 00:00 |
03:51:45.37 |
-00:24:54.1 |
HIP 18109 |
16.47 |
| 2026-06-20 12:00 |
03:51:50.44 |
-00:25:14.7 |
HIP 18109 |
15.59 |
| 2026-06-21 00:00 |
03:51:55.48 |
-00:25:35.9 |
HIP 18109 |
14.76 |
| 2026-06-21 12:00 |
03:52:00.47 |
-00:25:57.6 |
HIP 18109 |
14.01 |
| 2026-06-22 00:00 |
03:52:05.42 |
-00:26:20.0 |
HIP 18109 |
13.33 |