メタデータ
| 項目 |
値 |
| Designation |
C/2021 P4 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2022-07-30T09:00:29.151360Z |
| Orbit solution date (soln_date, UTC) |
2024-07-30T14:57:24Z |
| Obs used |
954 |
| NEO |
- |
| M1 |
10.800 |
| K1 |
8.000 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2021-08-10T12:53:31.315200Z |
| Discovery magnitude (MPC) |
19.44 o |
| Discovery observatory (MPC) |
T05 · ATLAS-HKO, Haleakala |
オスキュレーティング軌道要素
| 項目 |
値 |
| Epoch (epoch_cal, TDB) |
2022-01-11.0000000 |
| e |
0.99656560 |
| q (au) |
1.080462 |
| a (au) |
314.600427 |
| i (deg) |
56.310801 |
| Ω (om, deg) |
348.094879 |
| ω (w, deg) |
175.822404 |
| M (ma, deg) |
359.964608 |
等級
散乱 + 全体線形
$$
M_a = (9.803 + 3.189\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
9.803 |
| n |
3.189 |
| gf |
0.800 |
| gb |
-0.502 |
| k |
1.000 |
| δ90 |
10.000 |
| 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 |
| 2021-08-10 |
2022-05-06 |
+2.3130 |
-1.380 |
| 2022-05-06 |
2022-06-13 |
-2.7466 |
+0.127 |
| 2022-06-13 |
2022-07-22 |
+21.5821 |
-2.646 |
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) |
| 2026-09-20 00:00 |
22:35:16.70 |
-43:28:02.7 |
HIP 111389 |
15.49 |
| 2026-09-20 12:00 |
22:35:06.09 |
-43:27:57.3 |
HIP 111389 |
13.74 |
| 2026-09-21 00:00 |
22:34:55.53 |
-43:27:51.0 |
HIP 111389 |
12.05 |
| 2026-09-21 12:00 |
22:34:45.01 |
-43:27:44.0 |
HIP 111389 |
10.43 |
| 2026-09-22 00:00 |
22:34:34.55 |
-43:27:36.1 |
HIP 111389 |
8.93 |
| 2026-09-22 12:00 |
22:34:24.14 |
-43:27:27.4 |
HIP 111389 |
7.61 |
| 2026-09-23 00:00 |
22:34:13.78 |
-43:27:17.9 |
HIP 111389 |
6.56 |
| 2026-09-23 12:00 |
22:34:03.47 |
-43:27:07.6 |
HIP 111389 |
5.94 |
| 2026-09-24 00:00 |
22:33:53.22 |
-43:26:56.5 |
HIP 111389 |
5.86 |
| 2026-09-24 12:00 |
22:33:43.02 |
-43:26:44.6 |
HIP 111389 |
6.34 |
| 2026-09-25 00:00 |
22:33:32.88 |
-43:26:31.9 |
HIP 111389 |
7.27 |
| 2026-09-25 12:00 |
22:33:22.79 |
-43:26:18.4 |
HIP 111389 |
8.48 |
| 2026-09-26 00:00 |
22:33:12.76 |
-43:26:04.1 |
HIP 111389 |
9.88 |
| 2026-09-26 12:00 |
22:33:02.79 |
-43:25:49.0 |
HIP 111389 |
11.39 |
| 2026-09-27 00:00 |
22:32:52.88 |
-43:25:33.1 |
HIP 111219 |
12.30 |
| 2026-09-27 12:00 |
22:32:43.02 |
-43:25:16.5 |
HIP 111237 |
11.09 |
| 2026-09-28 00:00 |
22:32:33.23 |
-43:24:59.0 |
HIP 111237 |
10.01 |
| 2026-09-28 12:00 |
22:32:23.50 |
-43:24:40.8 |
HIP 111237 |
9.16 |
| 2026-09-29 00:00 |
22:32:13.83 |
-43:24:21.8 |
HIP 111237 |
8.59 |
| 2026-09-29 12:00 |
22:32:04.22 |
-43:24:02.0 |
HIP 111237 |
8.35 |
| 2026-09-30 00:00 |
22:31:54.67 |
-43:23:41.4 |
HIP 111237 |
8.48 |
| 2026-09-30 12:00 |
22:31:45.19 |
-43:23:20.1 |
HIP 111237 |
8.94 |
| 2026-10-01 00:00 |
22:31:35.78 |
-43:22:58.0 |
HIP 111237 |
9.68 |
| 2026-10-01 12:00 |
22:31:26.43 |
-43:22:35.1 |
HIP 111237 |
10.65 |
| 2026-10-02 00:00 |
22:31:17.15 |
-43:22:11.5 |
HIP 111237 |
11.78 |
| 2026-10-02 12:00 |
22:31:07.94 |
-43:21:47.1 |
HIP 111237 |
13.03 |
| 2026-10-03 00:00 |
22:30:58.79 |
-43:21:21.9 |
HIP 111237 |
14.36 |
| 2026-10-03 12:00 |
22:30:49.71 |
-43:20:56.0 |
HIP 111237 |
15.75 |
| 2026-10-04 00:00 |
22:30:40.71 |
-43:20:29.3 |
HIP 111237 |
17.18 |
| 2026-10-04 12:00 |
22:30:31.77 |
-43:20:01.8 |
HIP 110997 |
16.81 |
| 2026-10-05 00:00 |
22:30:22.91 |
-43:19:33.6 |
HIP 110997 |
15.83 |
| 2026-10-05 12:00 |
22:30:14.11 |
-43:19:04.7 |
HIP 110997 |
14.98 |
| 2026-10-06 00:00 |
22:30:05.39 |
-43:18:35.0 |
HIP 110997 |
14.29 |
| 2026-10-06 12:00 |
22:29:56.75 |
-43:18:04.6 |
HIP 110997 |
13.79 |
| 2026-10-07 00:00 |
22:29:48.18 |
-43:17:33.4 |
HIP 110997 |
13.49 |
| 2026-10-07 12:00 |
22:29:39.68 |
-43:17:01.5 |
HIP 110997 |
13.41 |
| 2026-10-08 00:00 |
22:29:31.26 |
-43:16:28.8 |
HIP 110997 |
13.53 |
| 2026-10-08 12:00 |
22:29:22.92 |
-43:15:55.5 |
HIP 110997 |
13.86 |
| 2026-10-09 00:00 |
22:29:14.66 |
-43:15:21.3 |
HIP 110997 |
14.38 |
| 2026-10-09 12:00 |
22:29:06.47 |
-43:14:46.5 |
HIP 110997 |
15.06 |
| 2026-10-10 00:00 |
22:28:58.36 |
-43:14:11.0 |
HIP 110997 |
15.88 |
| 2026-10-10 12:00 |
22:28:50.34 |
-43:13:34.7 |
HIP 110997 |
16.82 |
| 2026-10-11 00:00 |
22:28:42.39 |
-43:12:57.7 |
HIP 110997 |
17.86 |