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 |
+15.6411 |
-9.727 |
| 2021-05-22 |
2021-08-10 |
-4.4729 |
+2.199 |
| 2021-08-10 |
2022-02-03 |
+4.5999 |
-2.464 |
| 2022-02-21 |
2023-04-22 |
+12.0731 |
-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) |
| 2026-05-12 00:00 |
07:25:35.13 |
-45:02:18.0 |
HIP 35971 |
10.73 |
| 2026-05-12 12:00 |
07:25:41.41 |
-45:00:59.8 |
HIP 35971 |
12.43 |
| 2026-05-13 00:00 |
07:25:47.77 |
-44:59:42.3 |
HIP 35971 |
14.13 |
| 2026-05-13 12:00 |
07:25:54.22 |
-44:58:25.5 |
HIP 35971 |
15.84 |
| 2026-05-14 00:00 |
07:26:00.75 |
-44:57:09.4 |
HIP 35971 |
17.55 |
| 2026-05-14 12:00 |
07:26:07.36 |
-44:55:54.0 |
HIP 36216 |
16.29 |
| 2026-05-15 00:00 |
07:26:14.05 |
-44:54:39.3 |
HIP 36216 |
14.70 |
| 2026-05-15 12:00 |
07:26:20.82 |
-44:53:25.4 |
HIP 36216 |
13.13 |
| 2026-05-16 00:00 |
07:26:27.68 |
-44:52:12.1 |
HIP 36216 |
11.60 |
| 2026-05-16 12:00 |
07:26:34.61 |
-44:50:59.6 |
HIP 36216 |
10.12 |
| 2026-05-17 00:00 |
07:26:41.62 |
-44:49:47.8 |
HIP 36216 |
8.71 |
| 2026-05-17 12:00 |
07:26:48.70 |
-44:48:36.8 |
HIP 36216 |
7.42 |
| 2026-05-18 00:00 |
07:26:55.87 |
-44:47:26.5 |
HIP 36216 |
6.33 |
| 2026-05-18 12:00 |
07:27:03.11 |
-44:46:16.9 |
HIP 36216 |
5.55 |
| 2026-05-19 00:00 |
07:27:10.43 |
-44:45:08.1 |
HIP 36216 |
5.22 |
| 2026-05-19 12:00 |
07:27:17.82 |
-44:44:00.1 |
HIP 36216 |
5.44 |
| 2026-05-20 00:00 |
07:27:25.28 |
-44:42:52.8 |
HIP 36216 |
6.14 |
| 2026-05-20 12:00 |
07:27:32.82 |
-44:41:46.3 |
HIP 36216 |
7.19 |
| 2026-05-21 00:00 |
07:27:40.43 |
-44:40:40.5 |
HIP 36216 |
8.46 |
| 2026-05-21 12:00 |
07:27:48.12 |
-44:39:35.6 |
HIP 36216 |
9.87 |
| 2026-05-22 00:00 |
07:27:55.87 |
-44:38:31.4 |
HIP 36216 |
11.36 |
| 2026-05-22 12:00 |
07:28:03.70 |
-44:37:28.0 |
HIP 36216 |
12.91 |
| 2026-05-23 00:00 |
07:28:11.59 |
-44:36:25.4 |
HIP 36216 |
14.50 |
| 2026-05-23 12:00 |
07:28:19.55 |
-44:35:23.6 |
HIP 36216 |
16.12 |
| 2026-05-24 00:00 |
07:28:27.58 |
-44:34:22.6 |
HIP 36216 |
17.76 |
| 2026-05-24 12:00 |
07:28:35.68 |
-44:33:22.4 |
HIP 36216 |
19.41 |
| 2026-05-25 00:00 |
07:28:43.84 |
-44:32:23.0 |
HIP 36219 |
20.05 |
| 2026-05-25 12:00 |
07:28:52.07 |
-44:31:24.4 |
HIP 36219 |
20.33 |
| 2026-05-26 00:00 |
07:29:00.37 |
-44:30:26.5 |
HIP 36219 |
20.77 |
| 2026-05-26 12:00 |
07:29:08.73 |
-44:29:29.6 |
HIP 36219 |
21.37 |
| 2026-05-27 00:00 |
07:29:17.15 |
-44:28:33.4 |
HIP 36219 |
22.12 |
| 2026-05-27 12:00 |
07:29:25.64 |
-44:27:38.0 |
HIP 36219 |
22.99 |
| 2026-05-28 00:00 |
07:29:34.19 |
-44:26:43.5 |
HIP 36407 |
23.38 |
| 2026-05-28 12:00 |
07:29:42.80 |
-44:25:49.8 |
HIP 36407 |
22.60 |
| 2026-05-29 00:00 |
07:29:51.48 |
-44:24:56.9 |
HIP 36407 |
21.96 |
| 2026-05-29 12:00 |
07:30:00.21 |
-44:24:04.8 |
HIP 36407 |
21.46 |
| 2026-05-30 00:00 |
07:30:09.00 |
-44:23:13.6 |
HIP 36407 |
21.13 |
| 2026-05-30 12:00 |
07:30:17.86 |
-44:22:23.2 |
HIP 36407 |
20.95 |
| 2026-05-31 00:00 |
07:30:26.77 |
-44:21:33.6 |
HIP 36592 |
20.45 |
| 2026-05-31 12:00 |
07:30:35.74 |
-44:20:44.9 |
HIP 36592 |
18.87 |
| 2026-06-01 00:00 |
07:30:44.76 |
-44:19:57.0 |
HIP 36592 |
17.35 |
| 2026-06-01 12:00 |
07:30:53.85 |
-44:19:09.9 |
HIP 36592 |
15.89 |
| 2026-06-02 00:00 |
07:31:02.99 |
-44:18:23.7 |
HIP 36592 |
14.51 |