C/2021 A9 (PANSTARRS)
メタデータ
| 項目 |
値 |
| Designation |
C/2021 A9 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2023-12-01T09:02:04.796160Z |
| Orbit solution date (soln_date, UTC) |
2025-12-02T15:12:34Z |
| Obs used |
446 |
| 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) |
2022-09-24.0000000 |
| e |
1.00317956 |
| q (au) |
7.760337 |
| a (au) |
-2440.696436 |
| i (deg) |
158.022762 |
| Ω (om, deg) |
314.842990 |
| ω (w, deg) |
211.451947 |
| M (ma, deg) |
-0.003542 |
等級
散乱 + 全体線形
$$
M_a = (6.319 + 5.523\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
6.319 |
| n |
5.523 |
| gf |
0.993 |
| gb |
-0.804 |
| k |
0.817 |
| δ90 |
8.959 |
| 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
天体暦
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
03:40:20.15 |
-02:55:22.0 |
HIP 17072 |
12.58 |
| 2026-02-03 12:00 |
03:40:11.86 |
-02:54:41.0 |
HIP 17072 |
10.40 |
| 2026-02-04 00:00 |
03:40:03.70 |
-02:53:59.6 |
HIP 17072 |
8.26 |
| 2026-02-04 12:00 |
03:39:55.66 |
-02:53:17.8 |
HIP 17072 |
6.14 |
| 2026-02-05 00:00 |
03:39:47.76 |
-02:52:35.6 |
HIP 17072 |
4.06 |
| 2026-02-05 12:00 |
03:39:39.98 |
-02:51:52.9 |
HIP 17072 |
2.03 |
| 2026-02-06 00:00 |
03:39:32.33 |
-02:51:09.9 |
HIP 17072 |
0.62 |
| 2026-02-06 12:00 |
03:39:24.81 |
-02:50:26.5 |
HIP 17072 |
2.21 |
| 2026-02-07 00:00 |
03:39:17.41 |
-02:49:42.6 |
HIP 17072 |
4.15 |
| 2026-02-07 12:00 |
03:39:10.15 |
-02:48:58.5 |
HIP 17072 |
6.10 |
| 2026-02-08 00:00 |
03:39:03.01 |
-02:48:13.9 |
HIP 17072 |
8.03 |
| 2026-02-08 12:00 |
03:38:55.99 |
-02:47:29.0 |
HIP 17072 |
9.93 |
| 2026-02-09 00:00 |
03:38:49.11 |
-02:46:43.7 |
HIP 17072 |
11.81 |
| 2026-02-09 12:00 |
03:38:42.35 |
-02:45:58.1 |
HIP 17072 |
13.66 |
| 2026-02-10 00:00 |
03:38:35.71 |
-02:45:12.1 |
HIP 16971 |
12.56 |
| 2026-02-10 12:00 |
03:38:29.21 |
-02:44:25.8 |
HIP 16971 |
11.32 |
| 2026-02-11 00:00 |
03:38:22.82 |
-02:43:39.2 |
HIP 16971 |
10.24 |
| 2026-02-11 12:00 |
03:38:16.57 |
-02:42:52.2 |
HIP 16971 |
9.36 |
| 2026-02-12 00:00 |
03:38:10.43 |
-02:42:04.9 |
HIP 16971 |
8.74 |
| 2026-02-12 12:00 |
03:38:04.43 |
-02:41:17.4 |
HIP 16971 |
8.42 |
| 2026-02-13 00:00 |
03:37:58.54 |
-02:40:29.5 |
HIP 16971 |
8.41 |
| 2026-02-13 12:00 |
03:37:52.78 |
-02:39:41.3 |
HIP 16971 |
8.70 |
| 2026-02-14 00:00 |
03:37:47.15 |
-02:38:52.8 |
HIP 16933 |
8.37 |
| 2026-02-14 12:00 |
03:37:41.63 |
-02:38:04.0 |
HIP 16933 |
8.02 |
| 2026-02-15 00:00 |
03:37:36.24 |
-02:37:15.0 |
HIP 16933 |
7.95 |
| 2026-02-15 12:00 |
03:37:30.98 |
-02:36:25.7 |
HIP 16933 |
8.17 |
| 2026-02-16 00:00 |
03:37:25.83 |
-02:35:36.1 |
HIP 16933 |
8.64 |
| 2026-02-16 12:00 |
03:37:20.81 |
-02:34:46.2 |
HIP 16933 |
9.31 |
| 2026-02-17 00:00 |
03:37:15.91 |
-02:33:56.2 |
HIP 16933 |
10.13 |
| 2026-02-17 12:00 |
03:37:11.13 |
-02:33:05.8 |
HIP 16933 |
11.05 |
| 2026-02-18 00:00 |
03:37:06.47 |
-02:32:15.3 |
HIP 16933 |
12.05 |
| 2026-02-18 12:00 |
03:37:01.93 |
-02:31:24.5 |
HIP 16933 |
13.11 |
| 2026-02-19 00:00 |
03:36:57.50 |
-02:30:33.5 |
HIP 16933 |
14.19 |
| 2026-02-19 12:00 |
03:36:53.20 |
-02:29:42.2 |
HIP 16933 |
15.30 |
| 2026-02-20 00:00 |
03:36:49.02 |
-02:28:50.8 |
HIP 16933 |
16.42 |
| 2026-02-20 12:00 |
03:36:44.95 |
-02:27:59.1 |
HIP 16933 |
17.54 |
| 2026-02-21 00:00 |
03:36:41.01 |
-02:27:07.3 |
HIP 16933 |
18.66 |
| 2026-02-21 12:00 |
03:36:37.17 |
-02:26:15.3 |
HIP 16933 |
19.78 |
| 2026-02-22 00:00 |
03:36:33.46 |
-02:25:23.1 |
HIP 16933 |
20.89 |
| 2026-02-22 12:00 |
03:36:29.86 |
-02:24:30.7 |
HIP 16933 |
21.99 |
| 2026-02-23 00:00 |
03:36:26.38 |
-02:23:38.1 |
HIP 16933 |
23.08 |
| 2026-02-23 12:00 |
03:36:23.01 |
-02:22:45.4 |
HIP 16933 |
24.15 |
| 2026-02-24 00:00 |
03:36:19.75 |
-02:21:52.6 |
HIP 16933 |
25.22 |