メタデータ
| 項目 |
値 |
| Designation |
C/2021 D2 (ZTF) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2022-02-03T23:30:34.882560Z |
| Orbit solution date (soln_date, UTC) |
2026-01-13T08:12:19Z |
| Obs used |
654 |
| NEO |
- |
| M1 |
13.300 |
| K1 |
4.500 |
| PC |
- |
オスキュレーティング軌道要素
| 項目 |
値 |
| Epoch (epoch_cal, TDB) |
2021-11-09.0000000 |
| e |
1.00133730 |
| q (au) |
2.946303 |
| a (au) |
-2203.174195 |
| i (deg) |
83.831242 |
| Ω (om, deg) |
305.677385 |
| ω (w, deg) |
125.029250 |
| M (ma, deg) |
-0.000829 |
等級
散乱 + 全体線形
$$
M_a = (15.473 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
15.473 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.788 |
| k |
0.800 |
| 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 |
| 2021-02-19 |
2021-05-22 |
+15.6409 |
-9.727 |
| 2021-05-22 |
2021-08-10 |
-4.4730 |
+2.199 |
| 2021-08-10 |
2022-02-03 |
+4.5999 |
-2.464 |
| 2022-02-21 |
2023-04-22 |
+12.0730 |
-5.101 |
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 |
08:08:12.94 |
-47:24:05.3 |
HIP 39768 |
10.35 |
| 2026-09-20 12:00 |
08:08:18.98 |
-47:26:17.4 |
HIP 39768 |
12.76 |
| 2026-09-21 00:00 |
08:08:24.94 |
-47:28:30.0 |
HIP 39953 |
14.05 |
| 2026-09-21 12:00 |
08:08:30.81 |
-47:30:43.0 |
HIP 39953 |
14.75 |
| 2026-09-22 00:00 |
08:08:36.60 |
-47:32:56.4 |
HIP 39953 |
15.81 |
| 2026-09-22 12:00 |
08:08:42.31 |
-47:35:10.3 |
HIP 39953 |
17.17 |
| 2026-09-23 00:00 |
08:08:47.93 |
-47:37:24.5 |
HIP 39992 |
17.06 |
| 2026-09-23 12:00 |
08:08:53.47 |
-47:39:39.2 |
HIP 39992 |
14.87 |
| 2026-09-24 00:00 |
08:08:58.92 |
-47:41:54.2 |
HIP 39992 |
12.78 |
| 2026-09-24 12:00 |
08:09:04.28 |
-47:44:09.6 |
HIP 39992 |
10.85 |
| 2026-09-25 00:00 |
08:09:09.56 |
-47:46:25.5 |
HIP 39992 |
9.17 |
| 2026-09-25 12:00 |
08:09:14.75 |
-47:48:41.7 |
HIP 39992 |
7.91 |
| 2026-09-26 00:00 |
08:09:19.85 |
-47:50:58.2 |
HIP 39970 |
6.55 |
| 2026-09-26 12:00 |
08:09:24.87 |
-47:53:15.2 |
HIP 39970 |
4.28 |
| 2026-09-27 00:00 |
08:09:29.79 |
-47:55:32.5 |
HIP 39970 |
2.34 |
| 2026-09-27 12:00 |
08:09:34.63 |
-47:57:50.1 |
HIP 39970 |
2.15 |
| 2026-09-28 00:00 |
08:09:39.38 |
-48:00:08.1 |
HIP 39970 |
3.95 |
| 2026-09-28 12:00 |
08:09:44.03 |
-48:02:26.5 |
HIP 39970 |
6.21 |
| 2026-09-29 00:00 |
08:09:48.60 |
-48:04:45.1 |
HIP 40019 |
5.93 |
| 2026-09-29 12:00 |
08:09:53.07 |
-48:07:04.1 |
HIP 40019 |
6.00 |
| 2026-09-30 00:00 |
08:09:57.45 |
-48:09:23.5 |
HIP 40027 |
6.19 |
| 2026-09-30 12:00 |
08:10:01.74 |
-48:11:43.1 |
HIP 40027 |
5.21 |
| 2026-10-01 00:00 |
08:10:05.94 |
-48:14:03.1 |
HIP 40027 |
5.29 |
| 2026-10-01 12:00 |
08:10:10.04 |
-48:16:23.4 |
HIP 40027 |
6.40 |
| 2026-10-02 00:00 |
08:10:14.04 |
-48:18:43.9 |
HIP 40027 |
8.12 |
| 2026-10-02 12:00 |
08:10:17.95 |
-48:21:04.8 |
HIP 40027 |
10.14 |
| 2026-10-03 00:00 |
08:10:21.77 |
-48:23:25.9 |
HIP 40077 |
9.20 |
| 2026-10-03 12:00 |
08:10:25.49 |
-48:25:47.3 |
HIP 40077 |
7.76 |
| 2026-10-04 00:00 |
08:10:29.11 |
-48:28:09.0 |
HIP 40077 |
6.92 |
| 2026-10-04 12:00 |
08:10:32.64 |
-48:30:30.9 |
HIP 40077 |
6.91 |
| 2026-10-05 00:00 |
08:10:36.06 |
-48:32:53.1 |
HIP 40077 |
7.73 |
| 2026-10-05 12:00 |
08:10:39.39 |
-48:35:15.6 |
HIP 40077 |
9.16 |
| 2026-10-06 00:00 |
08:10:42.62 |
-48:37:38.3 |
HIP 40077 |
10.96 |
| 2026-10-06 12:00 |
08:10:45.75 |
-48:40:01.2 |
HIP 40077 |
12.98 |
| 2026-10-07 00:00 |
08:10:48.78 |
-48:42:24.3 |
HIP 40077 |
15.13 |
| 2026-10-07 12:00 |
08:10:51.71 |
-48:44:47.7 |
HIP 39919 |
17.26 |
| 2026-10-08 00:00 |
08:10:54.53 |
-48:47:11.2 |
HIP 40011 |
16.19 |
| 2026-10-08 12:00 |
08:10:57.25 |
-48:49:35.0 |
HIP 40011 |
14.22 |
| 2026-10-09 00:00 |
08:10:59.87 |
-48:51:59.0 |
HIP 40011 |
12.41 |
| 2026-10-09 12:00 |
08:11:02.39 |
-48:54:23.1 |
HIP 40011 |
10.83 |
| 2026-10-10 00:00 |
08:11:04.80 |
-48:56:47.4 |
HIP 40011 |
9.59 |
| 2026-10-10 12:00 |
08:11:07.11 |
-48:59:11.9 |
HIP 40011 |
8.85 |
| 2026-10-11 00:00 |
08:11:09.32 |
-49:01:36.5 |
HIP 40011 |
8.74 |