メタデータ
| 項目 |
値 |
| Designation |
C/1921 E1 (Reid) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1921-05-10T10:47:48.370560Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:02Z |
| Obs used |
20 |
| NEO |
- |
| M1 |
- |
| K1 |
- |
| PC |
- |
オスキュレーティング軌道要素
| 項目 |
値 |
| Epoch (epoch_cal, TDB) |
1921-04-10.0000000 |
| e |
1.00057570 |
| q (au) |
1.008454 |
| a (au) |
-1751.685065 |
| i (deg) |
132.188784 |
| Ω (om, deg) |
269.441203 |
| ω (w, deg) |
64.493054 |
| M (ma, deg) |
-0.000409 |
等級
散乱 + 全体線形
$$
M_a = (H_0 + n\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
- |
| n |
- |
| gf |
- |
| gb |
- |
| k |
- |
| δ90 |
- |
| 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 |
03:40:26.19 |
-18:21:02.6 |
HIP 17345 |
39.37 |
| 2026-07-29 12:00 |
03:40:26.52 |
-18:21:09.8 |
HIP 17345 |
39.24 |
| 2026-07-30 00:00 |
03:40:26.85 |
-18:21:17.0 |
HIP 17345 |
39.11 |
| 2026-07-30 12:00 |
03:40:27.18 |
-18:21:24.3 |
HIP 17345 |
38.98 |
| 2026-07-31 00:00 |
03:40:27.49 |
-18:21:31.7 |
HIP 17345 |
38.85 |
| 2026-07-31 12:00 |
03:40:27.80 |
-18:21:39.0 |
HIP 17345 |
38.72 |
| 2026-08-01 00:00 |
03:40:28.10 |
-18:21:46.5 |
HIP 17345 |
38.59 |
| 2026-08-01 12:00 |
03:40:28.39 |
-18:21:53.9 |
HIP 17345 |
38.46 |
| 2026-08-02 00:00 |
03:40:28.67 |
-18:22:01.5 |
HIP 17345 |
38.34 |
| 2026-08-02 12:00 |
03:40:28.95 |
-18:22:09.0 |
HIP 17345 |
38.22 |
| 2026-08-03 00:00 |
03:40:29.22 |
-18:22:16.6 |
HIP 17345 |
38.09 |
| 2026-08-03 12:00 |
03:40:29.48 |
-18:22:24.3 |
HIP 17345 |
37.97 |
| 2026-08-04 00:00 |
03:40:29.73 |
-18:22:32.0 |
HIP 17345 |
37.85 |
| 2026-08-04 12:00 |
03:40:29.98 |
-18:22:39.7 |
HIP 17345 |
37.74 |
| 2026-08-05 00:00 |
03:40:30.22 |
-18:22:47.5 |
HIP 17345 |
37.62 |
| 2026-08-05 12:00 |
03:40:30.45 |
-18:22:55.3 |
HIP 17345 |
37.50 |
| 2026-08-06 00:00 |
03:40:30.67 |
-18:23:03.2 |
HIP 17345 |
37.39 |
| 2026-08-06 12:00 |
03:40:30.88 |
-18:23:11.1 |
HIP 17345 |
37.28 |
| 2026-08-07 00:00 |
03:40:31.09 |
-18:23:19.0 |
HIP 17345 |
37.16 |
| 2026-08-07 12:00 |
03:40:31.29 |
-18:23:27.0 |
HIP 17345 |
37.05 |
| 2026-08-08 00:00 |
03:40:31.48 |
-18:23:35.0 |
HIP 17345 |
36.95 |
| 2026-08-08 12:00 |
03:40:31.67 |
-18:23:43.0 |
HIP 17345 |
36.84 |
| 2026-08-09 00:00 |
03:40:31.84 |
-18:23:51.1 |
HIP 17345 |
36.73 |
| 2026-08-09 12:00 |
03:40:32.01 |
-18:23:59.2 |
HIP 17345 |
36.63 |
| 2026-08-10 00:00 |
03:40:32.17 |
-18:24:07.4 |
HIP 17345 |
36.53 |
| 2026-08-10 12:00 |
03:40:32.32 |
-18:24:15.6 |
HIP 17345 |
36.43 |
| 2026-08-11 00:00 |
03:40:32.46 |
-18:24:23.8 |
HIP 17345 |
36.33 |
| 2026-08-11 12:00 |
03:40:32.60 |
-18:24:32.0 |
HIP 17345 |
36.23 |
| 2026-08-12 00:00 |
03:40:32.73 |
-18:24:40.3 |
HIP 17345 |
36.13 |
| 2026-08-12 12:00 |
03:40:32.84 |
-18:24:48.7 |
HIP 17345 |
36.04 |
| 2026-08-13 00:00 |
03:40:32.96 |
-18:24:57.0 |
HIP 17345 |
35.95 |
| 2026-08-13 12:00 |
03:40:33.06 |
-18:25:05.4 |
HIP 17345 |
35.86 |
| 2026-08-14 00:00 |
03:40:33.15 |
-18:25:13.8 |
HIP 17345 |
35.77 |
| 2026-08-14 12:00 |
03:40:33.24 |
-18:25:22.3 |
HIP 17345 |
35.68 |
| 2026-08-15 00:00 |
03:40:33.32 |
-18:25:30.8 |
HIP 17345 |
35.59 |
| 2026-08-15 12:00 |
03:40:33.39 |
-18:25:39.3 |
HIP 17345 |
35.51 |
| 2026-08-16 00:00 |
03:40:33.45 |
-18:25:47.8 |
HIP 17345 |
35.43 |
| 2026-08-16 12:00 |
03:40:33.51 |
-18:25:56.4 |
HIP 17345 |
35.35 |
| 2026-08-17 00:00 |
03:40:33.55 |
-18:26:05.0 |
HIP 17345 |
35.27 |
| 2026-08-17 12:00 |
03:40:33.59 |
-18:26:13.6 |
HIP 17345 |
35.20 |
| 2026-08-18 00:00 |
03:40:33.62 |
-18:26:22.2 |
HIP 17345 |
35.12 |
| 2026-08-18 12:00 |
03:40:33.64 |
-18:26:30.9 |
HIP 17345 |
35.05 |
| 2026-08-19 00:00 |
03:40:33.66 |
-18:26:39.6 |
HIP 17345 |
34.98 |