メタデータ
| 項目 |
値 |
| Designation |
C/1987 U3 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1987-12-11T22:32:44.332800Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:36Z |
| Obs used |
106 |
| NEO |
- |
| M1 |
6.100 |
| K1 |
17.250 |
| PC |
- |
オスキュレーティング軌道要素
| 項目 |
値 |
| Epoch (epoch_cal, TDB) |
1988-01-08.0000000 |
| e |
0.99855807 |
| q (au) |
0.841167 |
| a (au) |
583.363126 |
| i (deg) |
97.126481 |
| Ω (om, deg) |
261.341785 |
| ω (w, deg) |
17.409142 |
| M (ma, deg) |
0.001893 |
等級
散乱 + 全体線形
$$
M_a = (4.978 + 3.538\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
4.978 |
| n |
3.538 |
| 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
残差 (区間線形)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| 開始日 (UTC) |
終了日 (UTC) |
a |
b |
| 1987-12-27 |
1988-02-01 |
-7.4131 |
+0.143 |
| 1988-02-01 |
1988-02-18 |
+3.8294 |
-0.662 |
| 1988-02-18 |
1988-03-22 |
+3.4165 |
-0.549 |
| 1988-03-22 |
1988-05-10 |
-6.7830 |
+2.088 |
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 |
05:24:49.07 |
+18:36:22.7 |
HIP 25204 |
18.59 |
| 2026-09-20 12:00 |
05:24:48.86 |
+18:36:19.7 |
HIP 25204 |
18.53 |
| 2026-09-21 00:00 |
05:24:48.63 |
+18:36:16.7 |
HIP 25204 |
18.48 |
| 2026-09-21 12:00 |
05:24:48.38 |
+18:36:13.6 |
HIP 25204 |
18.42 |
| 2026-09-22 00:00 |
05:24:48.11 |
+18:36:10.6 |
HIP 25204 |
18.36 |
| 2026-09-22 12:00 |
05:24:47.83 |
+18:36:07.5 |
HIP 25204 |
18.29 |
| 2026-09-23 00:00 |
05:24:47.54 |
+18:36:04.4 |
HIP 25204 |
18.22 |
| 2026-09-23 12:00 |
05:24:47.22 |
+18:36:01.3 |
HIP 25204 |
18.14 |
| 2026-09-24 00:00 |
05:24:46.89 |
+18:35:58.2 |
HIP 25204 |
18.07 |
| 2026-09-24 12:00 |
05:24:46.54 |
+18:35:55.1 |
HIP 25204 |
17.98 |
| 2026-09-25 00:00 |
05:24:46.17 |
+18:35:52.0 |
HIP 25204 |
17.90 |
| 2026-09-25 12:00 |
05:24:45.79 |
+18:35:48.8 |
HIP 25204 |
17.81 |
| 2026-09-26 00:00 |
05:24:45.39 |
+18:35:45.7 |
HIP 25204 |
17.71 |
| 2026-09-26 12:00 |
05:24:44.98 |
+18:35:42.5 |
HIP 25204 |
17.62 |
| 2026-09-27 00:00 |
05:24:44.54 |
+18:35:39.3 |
HIP 25204 |
17.52 |
| 2026-09-27 12:00 |
05:24:44.10 |
+18:35:36.2 |
HIP 25204 |
17.41 |
| 2026-09-28 00:00 |
05:24:43.63 |
+18:35:33.0 |
HIP 25204 |
17.30 |
| 2026-09-28 12:00 |
05:24:43.15 |
+18:35:29.7 |
HIP 25204 |
17.19 |
| 2026-09-29 00:00 |
05:24:42.65 |
+18:35:26.5 |
HIP 25204 |
17.07 |
| 2026-09-29 12:00 |
05:24:42.13 |
+18:35:23.3 |
HIP 25204 |
16.95 |
| 2026-09-30 00:00 |
05:24:41.60 |
+18:35:20.0 |
HIP 25204 |
16.83 |
| 2026-09-30 12:00 |
05:24:41.05 |
+18:35:16.8 |
HIP 25204 |
16.70 |
| 2026-10-01 00:00 |
05:24:40.48 |
+18:35:13.5 |
HIP 25204 |
16.57 |
| 2026-10-01 12:00 |
05:24:39.90 |
+18:35:10.3 |
HIP 25204 |
16.43 |
| 2026-10-02 00:00 |
05:24:39.30 |
+18:35:07.0 |
HIP 25204 |
16.30 |
| 2026-10-02 12:00 |
05:24:38.69 |
+18:35:03.7 |
HIP 25204 |
16.15 |
| 2026-10-03 00:00 |
05:24:38.05 |
+18:35:00.4 |
HIP 25204 |
16.01 |
| 2026-10-03 12:00 |
05:24:37.41 |
+18:34:57.1 |
HIP 25204 |
15.86 |
| 2026-10-04 00:00 |
05:24:36.74 |
+18:34:53.7 |
HIP 25204 |
15.70 |
| 2026-10-04 12:00 |
05:24:36.06 |
+18:34:50.4 |
HIP 25204 |
15.55 |
| 2026-10-05 00:00 |
05:24:35.36 |
+18:34:47.1 |
HIP 25204 |
15.39 |
| 2026-10-05 12:00 |
05:24:34.65 |
+18:34:43.7 |
HIP 25204 |
15.22 |
| 2026-10-06 00:00 |
05:24:33.92 |
+18:34:40.4 |
HIP 25204 |
15.06 |
| 2026-10-06 12:00 |
05:24:33.17 |
+18:34:37.0 |
HIP 25204 |
14.88 |
| 2026-10-07 00:00 |
05:24:32.40 |
+18:34:33.6 |
HIP 25204 |
14.71 |
| 2026-10-07 12:00 |
05:24:31.62 |
+18:34:30.2 |
HIP 25204 |
14.53 |
| 2026-10-08 00:00 |
05:24:30.83 |
+18:34:26.9 |
HIP 25204 |
14.35 |
| 2026-10-08 12:00 |
05:24:30.02 |
+18:34:23.5 |
HIP 25204 |
14.17 |
| 2026-10-09 00:00 |
05:24:29.19 |
+18:34:20.1 |
HIP 25204 |
13.98 |
| 2026-10-09 12:00 |
05:24:28.34 |
+18:34:16.7 |
HIP 25204 |
13.79 |
| 2026-10-10 00:00 |
05:24:27.48 |
+18:34:13.2 |
HIP 25204 |
13.59 |
| 2026-10-10 12:00 |
05:24:26.61 |
+18:34:09.8 |
HIP 25204 |
13.39 |
| 2026-10-11 00:00 |
05:24:25.72 |
+18:34:06.4 |
HIP 25204 |
13.19 |