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) |
| 2026-05-12 00:00 |
10:56:26.82 |
+33:51:28.1 |
HIP 53488 |
12.76 |
| 2026-05-12 12:00 |
10:56:47.73 |
+33:45:50.9 |
HIP 53488 |
7.84 |
| 2026-05-13 00:00 |
10:57:08.87 |
+33:40:12.8 |
HIP 53488 |
7.85 |
| 2026-05-13 12:00 |
10:57:30.24 |
+33:34:33.9 |
HIP 53488 |
12.87 |
| 2026-05-14 00:00 |
10:57:51.85 |
+33:28:54.2 |
HIP 53673 |
16.30 |
| 2026-05-14 12:00 |
10:58:13.68 |
+33:23:13.7 |
HIP 53673 |
9.40 |
| 2026-05-15 00:00 |
10:58:35.73 |
+33:17:32.5 |
HIP 53673 |
4.08 |
| 2026-05-15 12:00 |
10:58:58.01 |
+33:11:50.5 |
HIP 53673 |
7.23 |
| 2026-05-16 00:00 |
10:59:20.51 |
+33:06:07.8 |
HIP 53677 |
10.77 |
| 2026-05-16 12:00 |
10:59:43.22 |
+33:00:24.4 |
HIP 53677 |
10.33 |
| 2026-05-17 00:00 |
11:00:06.16 |
+32:54:40.3 |
HIP 53677 |
14.49 |
| 2026-05-17 12:00 |
11:00:29.30 |
+32:48:55.5 |
HIP 53677 |
20.68 |
| 2026-05-18 00:00 |
11:00:52.65 |
+32:43:10.1 |
HIP 53677 |
27.59 |
| 2026-05-18 12:00 |
11:01:16.22 |
+32:37:24.0 |
HIP 54056 |
34.30 |
| 2026-05-19 00:00 |
11:01:39.98 |
+32:31:37.3 |
HIP 54058 |
28.98 |
| 2026-05-19 12:00 |
11:02:03.95 |
+32:25:50.1 |
HIP 54058 |
22.01 |
| 2026-05-20 00:00 |
11:02:28.12 |
+32:20:02.2 |
HIP 54058 |
15.67 |
| 2026-05-20 12:00 |
11:02:52.49 |
+32:14:13.8 |
HIP 54058 |
11.18 |
| 2026-05-21 00:00 |
11:03:17.05 |
+32:08:24.9 |
HIP 54058 |
11.15 |
| 2026-05-21 12:00 |
11:03:41.81 |
+32:02:35.4 |
HIP 54058 |
15.67 |
| 2026-05-22 00:00 |
11:04:06.75 |
+31:56:45.5 |
HIP 54198 |
14.89 |
| 2026-05-22 12:00 |
11:04:31.88 |
+31:50:55.0 |
HIP 54198 |
10.85 |
| 2026-05-23 00:00 |
11:04:57.20 |
+31:45:04.1 |
HIP 54198 |
11.76 |
| 2026-05-23 12:00 |
11:05:22.69 |
+31:39:12.7 |
HIP 54150 |
15.99 |
| 2026-05-24 00:00 |
11:05:48.37 |
+31:33:20.9 |
HIP 54150 |
16.41 |
| 2026-05-24 12:00 |
11:06:14.22 |
+31:27:28.7 |
HIP 54150 |
20.34 |
| 2026-05-25 00:00 |
11:06:40.25 |
+31:21:36.0 |
HIP 54316 |
25.70 |
| 2026-05-25 12:00 |
11:07:06.45 |
+31:15:43.0 |
HIP 54316 |
20.51 |
| 2026-05-26 00:00 |
11:07:32.81 |
+31:09:49.6 |
HIP 54316 |
17.71 |
| 2026-05-26 12:00 |
11:07:59.35 |
+31:03:55.8 |
HIP 54316 |
18.47 |
| 2026-05-27 00:00 |
11:08:26.05 |
+30:58:01.6 |
HIP 54316 |
22.47 |
| 2026-05-27 12:00 |
11:08:52.91 |
+30:52:07.1 |
HIP 54316 |
28.39 |
| 2026-05-28 00:00 |
11:09:19.93 |
+30:46:12.3 |
HIP 54619 |
29.22 |
| 2026-05-28 12:00 |
11:09:47.11 |
+30:40:17.2 |
HIP 54646 |
21.49 |
| 2026-05-29 00:00 |
11:10:14.44 |
+30:34:21.7 |
HIP 54646 |
13.22 |
| 2026-05-29 12:00 |
11:10:41.93 |
+30:28:26.0 |
HIP 54646 |
5.19 |
| 2026-05-30 00:00 |
11:11:09.57 |
+30:22:30.0 |
HIP 54646 |
4.41 |
| 2026-05-30 12:00 |
11:11:37.36 |
+30:16:33.6 |
HIP 54729 |
9.31 |
| 2026-05-31 00:00 |
11:12:05.29 |
+30:10:37.1 |
HIP 54729 |
3.65 |
| 2026-05-31 12:00 |
11:12:33.38 |
+30:04:40.2 |
HIP 54729 |
9.14 |
| 2026-06-01 00:00 |
11:13:01.60 |
+29:58:43.2 |
HIP 54729 |
17.29 |
| 2026-06-01 12:00 |
11:13:29.97 |
+29:52:45.9 |
HIP 54826 |
19.66 |
| 2026-06-02 00:00 |
11:13:58.48 |
+29:46:48.3 |
HIP 54826 |
15.45 |