メタデータ
| 項目 |
値 |
| Designation |
C/2021 C4 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-01-17T01:15:25.960320Z |
| Orbit solution date (soln_date, UTC) |
2025-10-28T16:12:33Z |
| Obs used |
234 |
| NEO |
- |
| M1 |
6.900 |
| K1 |
13.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-02-12T14:39:53.769600Z |
| Discovery magnitude (MPC) |
18.73 c |
| 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) |
2021-06-12.0000000 |
| e |
0.99919682 |
| q (au) |
4.504185 |
| a (au) |
5607.929825 |
| i (deg) |
132.842626 |
| Ω (om, deg) |
194.276215 |
| ω (w, deg) |
320.231119 |
| M (ma, deg) |
0.000343 |
等級
散乱 + 全体線形
$$
M_a = (5.414 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
5.414 |
| n |
6.000 |
| gf |
0.942 |
| gb |
-0.980 |
| 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
天体暦
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
10:05:39.34 |
+61:06:47.6 |
HIP 49578 |
16.32 |
| 2026-03-26 12:00 |
10:05:22.70 |
+61:06:33.0 |
HIP 49578 |
17.64 |
| 2026-03-27 00:00 |
10:05:06.16 |
+61:06:17.4 |
HIP 49578 |
19.06 |
| 2026-03-27 12:00 |
10:04:49.74 |
+61:06:00.8 |
HIP 49257 |
17.71 |
| 2026-03-28 00:00 |
10:04:33.44 |
+61:05:43.3 |
HIP 49257 |
16.32 |
| 2026-03-28 12:00 |
10:04:17.25 |
+61:05:24.9 |
HIP 49257 |
15.06 |
| 2026-03-29 00:00 |
10:04:01.18 |
+61:05:05.5 |
HIP 49257 |
13.95 |
| 2026-03-29 12:00 |
10:03:45.22 |
+61:04:45.2 |
HIP 49257 |
13.05 |
| 2026-03-30 00:00 |
10:03:29.39 |
+61:04:23.9 |
HIP 49257 |
12.37 |
| 2026-03-30 12:00 |
10:03:13.67 |
+61:04:01.8 |
HIP 49257 |
11.96 |
| 2026-03-31 00:00 |
10:02:58.08 |
+61:03:38.8 |
HIP 49257 |
11.85 |
| 2026-03-31 12:00 |
10:02:42.61 |
+61:03:14.8 |
HIP 49257 |
12.02 |
| 2026-04-01 00:00 |
10:02:27.26 |
+61:02:50.0 |
HIP 49257 |
12.48 |
| 2026-04-01 12:00 |
10:02:12.04 |
+61:02:24.3 |
HIP 49257 |
13.17 |
| 2026-04-02 00:00 |
10:01:56.94 |
+61:01:57.7 |
HIP 49257 |
14.07 |
| 2026-04-02 12:00 |
10:01:41.97 |
+61:01:30.3 |
HIP 49257 |
15.13 |
| 2026-04-03 00:00 |
10:01:27.13 |
+61:01:02.0 |
HIP 49257 |
16.31 |
| 2026-04-03 12:00 |
10:01:12.41 |
+61:00:32.8 |
HIP 49257 |
17.60 |
| 2026-04-04 00:00 |
10:00:57.83 |
+61:00:02.8 |
HIP 49257 |
18.96 |
| 2026-04-04 12:00 |
10:00:43.37 |
+60:59:32.0 |
HIP 49257 |
20.37 |
| 2026-04-05 00:00 |
10:00:29.04 |
+60:59:00.4 |
HIP 49257 |
21.83 |
| 2026-04-05 12:00 |
10:00:14.85 |
+60:58:27.9 |
HIP 49257 |
23.32 |
| 2026-04-06 00:00 |
10:00:00.78 |
+60:57:54.6 |
HIP 49257 |
24.84 |
| 2026-04-06 12:00 |
09:59:46.86 |
+60:57:20.5 |
HIP 49257 |
26.37 |
| 2026-04-07 00:00 |
09:59:33.06 |
+60:56:45.6 |
HIP 49257 |
27.91 |
| 2026-04-07 12:00 |
09:59:19.40 |
+60:56:09.9 |
HIP 49257 |
29.47 |
| 2026-04-08 00:00 |
09:59:05.87 |
+60:55:33.5 |
HIP 49257 |
31.03 |
| 2026-04-08 12:00 |
09:58:52.49 |
+60:54:56.2 |
HIP 48638 |
30.25 |
| 2026-04-09 00:00 |
09:58:39.23 |
+60:54:18.2 |
HIP 48638 |
29.06 |
| 2026-04-09 12:00 |
09:58:26.12 |
+60:53:39.5 |
HIP 48638 |
27.95 |
| 2026-04-10 00:00 |
09:58:13.14 |
+60:53:00.0 |
HIP 48638 |
26.91 |
| 2026-04-10 12:00 |
09:58:00.31 |
+60:52:19.7 |
HIP 48638 |
25.97 |
| 2026-04-11 00:00 |
09:57:47.61 |
+60:51:38.8 |
HIP 48638 |
25.13 |
| 2026-04-11 12:00 |
09:57:35.05 |
+60:50:57.1 |
HIP 48638 |
24.39 |
| 2026-04-12 00:00 |
09:57:22.64 |
+60:50:14.6 |
HIP 48638 |
23.77 |
| 2026-04-12 12:00 |
09:57:10.37 |
+60:49:31.5 |
HIP 48638 |
23.27 |
| 2026-04-13 00:00 |
09:56:58.23 |
+60:48:47.7 |
HIP 48638 |
22.90 |
| 2026-04-13 12:00 |
09:56:46.24 |
+60:48:03.1 |
HIP 48638 |
22.67 |
| 2026-04-14 00:00 |
09:56:34.40 |
+60:47:17.9 |
HIP 48638 |
22.56 |
| 2026-04-14 12:00 |
09:56:22.70 |
+60:46:32.0 |
HIP 48638 |
22.59 |
| 2026-04-15 00:00 |
09:56:11.14 |
+60:45:45.5 |
HIP 48638 |
22.75 |
| 2026-04-15 12:00 |
09:55:59.73 |
+60:44:58.3 |
HIP 48638 |
23.04 |
| 2026-04-16 00:00 |
09:55:48.46 |
+60:44:10.4 |
HIP 48638 |
23.44 |