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) |
| 2026-07-29 00:00 |
10:01:54.68 |
+57:06:24.2 |
HIP 49195 |
11.52 |
| 2026-07-29 12:00 |
10:02:05.00 |
+57:05:46.1 |
HIP 49195 |
11.67 |
| 2026-07-30 00:00 |
10:02:15.35 |
+57:05:08.6 |
HIP 49195 |
12.00 |
| 2026-07-30 12:00 |
10:02:25.74 |
+57:04:31.5 |
HIP 49195 |
12.50 |
| 2026-07-31 00:00 |
10:02:36.15 |
+57:03:55.0 |
HIP 49195 |
13.16 |
| 2026-07-31 12:00 |
10:02:46.59 |
+57:03:19.0 |
HIP 49195 |
13.95 |
| 2026-08-01 00:00 |
10:02:57.07 |
+57:02:43.5 |
HIP 49195 |
14.85 |
| 2026-08-01 12:00 |
10:03:07.57 |
+57:02:08.5 |
HIP 49195 |
15.84 |
| 2026-08-02 00:00 |
10:03:18.11 |
+57:01:34.1 |
HIP 49195 |
16.91 |
| 2026-08-02 12:00 |
10:03:28.67 |
+57:01:00.2 |
HIP 49195 |
18.04 |
| 2026-08-03 00:00 |
10:03:39.26 |
+57:00:26.8 |
HIP 49195 |
19.22 |
| 2026-08-03 12:00 |
10:03:49.87 |
+56:59:53.9 |
HIP 49262 |
20.19 |
| 2026-08-04 00:00 |
10:04:00.52 |
+56:59:21.6 |
HIP 49262 |
19.99 |
| 2026-08-04 12:00 |
10:04:11.19 |
+56:58:49.8 |
HIP 49262 |
19.92 |
| 2026-08-05 00:00 |
10:04:21.88 |
+56:58:18.5 |
HIP 49262 |
19.97 |
| 2026-08-05 12:00 |
10:04:32.60 |
+56:57:47.8 |
HIP 49262 |
20.16 |
| 2026-08-06 00:00 |
10:04:43.34 |
+56:57:17.6 |
HIP 49262 |
20.48 |
| 2026-08-06 12:00 |
10:04:54.11 |
+56:56:48.0 |
HIP 49262 |
20.91 |
| 2026-08-07 00:00 |
10:05:04.89 |
+56:56:19.0 |
HIP 49262 |
21.46 |
| 2026-08-07 12:00 |
10:05:15.70 |
+56:55:50.4 |
HIP 49262 |
22.12 |
| 2026-08-08 00:00 |
10:05:26.54 |
+56:55:22.5 |
HIP 49262 |
22.87 |
| 2026-08-08 12:00 |
10:05:37.39 |
+56:54:55.1 |
HIP 49262 |
23.70 |
| 2026-08-09 00:00 |
10:05:48.26 |
+56:54:28.3 |
HIP 49262 |
24.62 |
| 2026-08-09 12:00 |
10:05:59.15 |
+56:54:02.0 |
HIP 49614 |
24.60 |
| 2026-08-10 00:00 |
10:06:10.06 |
+56:53:36.3 |
HIP 49614 |
24.23 |
| 2026-08-10 12:00 |
10:06:20.99 |
+56:53:11.2 |
HIP 49614 |
23.95 |
| 2026-08-11 00:00 |
10:06:31.93 |
+56:52:46.6 |
HIP 49614 |
23.76 |
| 2026-08-11 12:00 |
10:06:42.89 |
+56:52:22.7 |
HIP 49614 |
23.65 |
| 2026-08-12 00:00 |
10:06:53.87 |
+56:51:59.3 |
HIP 49614 |
23.64 |
| 2026-08-12 12:00 |
10:07:04.86 |
+56:51:36.5 |
HIP 49614 |
23.71 |
| 2026-08-13 00:00 |
10:07:15.87 |
+56:51:14.3 |
HIP 49614 |
23.87 |
| 2026-08-13 12:00 |
10:07:26.89 |
+56:50:52.6 |
HIP 49614 |
24.13 |
| 2026-08-14 00:00 |
10:07:37.92 |
+56:50:31.6 |
HIP 49614 |
24.46 |
| 2026-08-14 12:00 |
10:07:48.96 |
+56:50:11.2 |
HIP 49614 |
24.88 |
| 2026-08-15 00:00 |
10:08:00.02 |
+56:49:51.4 |
HIP 49614 |
25.37 |
| 2026-08-15 12:00 |
10:08:11.08 |
+56:49:32.1 |
HIP 49614 |
25.94 |
| 2026-08-16 00:00 |
10:08:22.16 |
+56:49:13.5 |
HIP 49614 |
26.58 |
| 2026-08-16 12:00 |
10:08:33.24 |
+56:48:55.5 |
HIP 49614 |
27.27 |
| 2026-08-17 00:00 |
10:08:44.33 |
+56:48:38.1 |
HIP 49614 |
28.03 |
| 2026-08-17 12:00 |
10:08:55.43 |
+56:48:21.3 |
HIP 49614 |
28.84 |
| 2026-08-18 00:00 |
10:09:06.54 |
+56:48:05.1 |
HIP 49614 |
29.70 |
| 2026-08-18 12:00 |
10:09:17.65 |
+56:47:49.5 |
HIP 49614 |
30.60 |
| 2026-08-19 00:00 |
10:09:28.77 |
+56:47:34.5 |
HIP 49614 |
31.54 |