メタデータ
| 項目 |
値 |
| Designation |
171P/Spahr |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2019-01-13T17:32:17.119680Z |
| Orbit solution date (soln_date, UTC) |
2026-03-07T15:25:06Z |
| Obs used |
681 |
| NEO |
- |
| M1 |
11.600 |
| K1 |
22.750 |
| PC |
0.030 |
オスキュレーティング軌道要素
| 項目 |
値 |
| Epoch (epoch_cal, TDB) |
2018-04-24.0000000 |
| e |
0.50194793 |
| q (au) |
1.772172 |
| a (au) |
3.558207 |
| i (deg) |
21.933094 |
| Ω (om, deg) |
101.699366 |
| ω (w, deg) |
347.157914 |
| M (ma, deg) |
321.125775 |
等級
散乱 + 全体線形
$$
M_a = (13.733 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
13.733 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.500 |
| k |
1.000 |
| 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
天体暦
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
10:47:51.02 |
+40:25:51.0 |
HIP 52760 |
19.45 |
| 2026-03-26 12:00 |
10:47:38.13 |
+40:24:06.7 |
HIP 52760 |
20.53 |
| 2026-03-27 00:00 |
10:47:25.65 |
+40:22:17.5 |
HIP 52760 |
22.05 |
| 2026-03-27 12:00 |
10:47:13.60 |
+40:20:23.5 |
HIP 52760 |
23.93 |
| 2026-03-28 00:00 |
10:47:01.97 |
+40:18:24.7 |
HIP 52571 |
24.18 |
| 2026-03-28 12:00 |
10:46:50.75 |
+40:16:21.2 |
HIP 52571 |
22.60 |
| 2026-03-29 00:00 |
10:46:39.97 |
+40:14:13.1 |
HIP 52571 |
21.42 |
| 2026-03-29 12:00 |
10:46:29.61 |
+40:12:00.3 |
HIP 52571 |
20.71 |
| 2026-03-30 00:00 |
10:46:19.67 |
+40:09:43.1 |
HIP 52571 |
20.52 |
| 2026-03-30 12:00 |
10:46:10.16 |
+40:07:21.5 |
HIP 52571 |
20.86 |
| 2026-03-31 00:00 |
10:46:01.08 |
+40:04:55.4 |
HIP 52571 |
21.72 |
| 2026-03-31 12:00 |
10:45:52.43 |
+40:02:25.1 |
HIP 52510 |
20.51 |
| 2026-04-01 00:00 |
10:45:44.20 |
+39:59:50.5 |
HIP 52510 |
18.23 |
| 2026-04-01 12:00 |
10:45:36.41 |
+39:57:11.8 |
HIP 52510 |
16.25 |
| 2026-04-02 00:00 |
10:45:29.04 |
+39:54:28.9 |
HIP 52510 |
14.73 |
| 2026-04-02 12:00 |
10:45:22.10 |
+39:51:42.1 |
HIP 52510 |
13.83 |
| 2026-04-03 00:00 |
10:45:15.59 |
+39:48:51.2 |
HIP 52510 |
13.68 |
| 2026-04-03 12:00 |
10:45:09.50 |
+39:45:56.4 |
HIP 52510 |
14.34 |
| 2026-04-04 00:00 |
10:45:03.84 |
+39:42:57.8 |
HIP 52510 |
15.71 |
| 2026-04-04 12:00 |
10:44:58.61 |
+39:39:55.3 |
HIP 52659 |
16.48 |
| 2026-04-05 00:00 |
10:44:53.81 |
+39:36:49.1 |
HIP 52659 |
15.58 |
| 2026-04-05 12:00 |
10:44:49.43 |
+39:33:39.3 |
HIP 52659 |
15.22 |
| 2026-04-06 00:00 |
10:44:45.48 |
+39:30:25.8 |
HIP 52659 |
15.48 |
| 2026-04-06 12:00 |
10:44:41.94 |
+39:27:08.7 |
HIP 52531 |
14.40 |
| 2026-04-07 00:00 |
10:44:38.84 |
+39:23:48.2 |
HIP 52531 |
11.01 |
| 2026-04-07 12:00 |
10:44:36.15 |
+39:20:24.2 |
HIP 52531 |
7.59 |
| 2026-04-08 00:00 |
10:44:33.88 |
+39:16:56.8 |
HIP 52531 |
4.17 |
| 2026-04-08 12:00 |
10:44:32.04 |
+39:13:26.0 |
HIP 52531 |
1.32 |
| 2026-04-09 00:00 |
10:44:30.61 |
+39:09:52.0 |
HIP 52531 |
3.39 |
| 2026-04-09 12:00 |
10:44:29.60 |
+39:06:14.7 |
HIP 52531 |
6.91 |
| 2026-04-10 00:00 |
10:44:29.01 |
+39:02:34.3 |
HIP 52531 |
10.56 |
| 2026-04-10 12:00 |
10:44:28.82 |
+38:58:50.7 |
HIP 52601 |
10.66 |
| 2026-04-11 00:00 |
10:44:29.06 |
+38:55:04.0 |
HIP 52601 |
10.40 |
| 2026-04-11 12:00 |
10:44:29.70 |
+38:51:14.4 |
HIP 52601 |
11.40 |
| 2026-04-12 00:00 |
10:44:30.75 |
+38:47:21.7 |
HIP 52601 |
13.43 |
| 2026-04-12 12:00 |
10:44:32.21 |
+38:43:26.2 |
HIP 52600 |
15.98 |
| 2026-04-13 00:00 |
10:44:34.07 |
+38:39:27.7 |
HIP 52600 |
12.77 |
| 2026-04-13 12:00 |
10:44:36.34 |
+38:35:26.4 |
HIP 52600 |
10.03 |
| 2026-04-14 00:00 |
10:44:39.01 |
+38:31:22.4 |
HIP 52600 |
8.34 |
| 2026-04-14 12:00 |
10:44:42.09 |
+38:27:15.6 |
HIP 52600 |
8.44 |
| 2026-04-15 00:00 |
10:44:45.56 |
+38:23:06.1 |
HIP 52600 |
10.35 |
| 2026-04-15 12:00 |
10:44:49.42 |
+38:18:54.0 |
HIP 52579 |
11.99 |
| 2026-04-16 00:00 |
10:44:53.68 |
+38:14:39.3 |
HIP 52579 |
7.67 |