メタデータ
| 項目 |
値 |
| Designation |
C/2012 X2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2013-03-31T07:31:18.105600Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:29Z |
| Obs used |
186 |
| NEO |
- |
| M1 |
12.600 |
| 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) |
2013-05-10.0000000 |
| e |
0.77049741 |
| q (au) |
4.748158 |
| a (au) |
20.688908 |
| i (deg) |
34.123911 |
| Ω (om, deg) |
271.023294 |
| ω (w, deg) |
215.631135 |
| M (ma, deg) |
0.415663 |
等級
散乱 + 全体線形
$$
M_a = (10.863 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
10.863 |
| n |
2.000 |
| gf |
0.969 |
| gb |
-1.000 |
| k |
1.000 |
| δ90 |
9.860 |
| 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 |
| 2012-01-11 |
2013-03-14 |
+4.8190 |
-2.841 |
| 2013-03-31 |
2014-04-24 |
-8.5260 |
+5.540 |
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) |
| 2026-07-29 00:00 |
17:55:03.92 |
-23:49:58.5 |
HIP 87880 |
28.95 |
| 2026-07-29 12:00 |
17:54:59.83 |
-23:49:51.5 |
HIP 87880 |
29.89 |
| 2026-07-30 00:00 |
17:54:55.77 |
-23:49:44.4 |
HIP 87880 |
30.82 |
| 2026-07-30 12:00 |
17:54:51.75 |
-23:49:37.4 |
HIP 87880 |
31.75 |
| 2026-07-31 00:00 |
17:54:47.75 |
-23:49:30.3 |
HIP 87880 |
32.66 |
| 2026-07-31 12:00 |
17:54:43.80 |
-23:49:23.3 |
HIP 87880 |
33.57 |
| 2026-08-01 00:00 |
17:54:39.88 |
-23:49:16.2 |
HIP 87527 |
33.64 |
| 2026-08-01 12:00 |
17:54:35.99 |
-23:49:09.1 |
HIP 87527 |
33.09 |
| 2026-08-02 00:00 |
17:54:32.14 |
-23:49:02.1 |
HIP 87527 |
32.57 |
| 2026-08-02 12:00 |
17:54:28.32 |
-23:48:55.0 |
HIP 87527 |
32.08 |
| 2026-08-03 00:00 |
17:54:24.54 |
-23:48:48.0 |
HIP 87527 |
31.60 |
| 2026-08-03 12:00 |
17:54:20.79 |
-23:48:40.9 |
HIP 87527 |
31.14 |
| 2026-08-04 00:00 |
17:54:17.09 |
-23:48:33.8 |
HIP 87527 |
30.71 |
| 2026-08-04 12:00 |
17:54:13.41 |
-23:48:26.8 |
HIP 87527 |
30.30 |
| 2026-08-05 00:00 |
17:54:09.78 |
-23:48:19.7 |
HIP 87527 |
29.92 |
| 2026-08-05 12:00 |
17:54:06.18 |
-23:48:12.7 |
HIP 87527 |
29.55 |
| 2026-08-06 00:00 |
17:54:02.62 |
-23:48:05.6 |
HIP 87527 |
29.22 |
| 2026-08-06 12:00 |
17:53:59.10 |
-23:47:58.6 |
HIP 87527 |
28.90 |
| 2026-08-07 00:00 |
17:53:55.62 |
-23:47:51.5 |
HIP 87527 |
28.61 |
| 2026-08-07 12:00 |
17:53:52.17 |
-23:47:44.5 |
HIP 87527 |
28.34 |
| 2026-08-08 00:00 |
17:53:48.77 |
-23:47:37.4 |
HIP 87527 |
28.10 |
| 2026-08-08 12:00 |
17:53:45.40 |
-23:47:30.4 |
HIP 87527 |
27.88 |
| 2026-08-09 00:00 |
17:53:42.08 |
-23:47:23.3 |
HIP 87527 |
27.68 |
| 2026-08-09 12:00 |
17:53:38.79 |
-23:47:16.3 |
HIP 87527 |
27.51 |
| 2026-08-10 00:00 |
17:53:35.54 |
-23:47:09.3 |
HIP 87527 |
27.36 |
| 2026-08-10 12:00 |
17:53:32.34 |
-23:47:02.2 |
HIP 87399 |
26.69 |
| 2026-08-11 00:00 |
17:53:29.17 |
-23:46:55.2 |
HIP 87399 |
25.96 |
| 2026-08-11 12:00 |
17:53:26.05 |
-23:46:48.2 |
HIP 87399 |
25.23 |
| 2026-08-12 00:00 |
17:53:22.96 |
-23:46:41.2 |
HIP 87399 |
24.52 |
| 2026-08-12 12:00 |
17:53:19.92 |
-23:46:34.2 |
HIP 87399 |
23.82 |
| 2026-08-13 00:00 |
17:53:16.92 |
-23:46:27.2 |
HIP 87399 |
23.12 |
| 2026-08-13 12:00 |
17:53:13.97 |
-23:46:20.2 |
HIP 87399 |
22.44 |
| 2026-08-14 00:00 |
17:53:11.05 |
-23:46:13.2 |
HIP 87399 |
21.77 |
| 2026-08-14 12:00 |
17:53:08.18 |
-23:46:06.2 |
HIP 87399 |
21.10 |
| 2026-08-15 00:00 |
17:53:05.35 |
-23:45:59.2 |
HIP 87399 |
20.45 |
| 2026-08-15 12:00 |
17:53:02.56 |
-23:45:52.2 |
HIP 87399 |
19.80 |
| 2026-08-16 00:00 |
17:52:59.82 |
-23:45:45.3 |
HIP 87399 |
19.16 |
| 2026-08-16 12:00 |
17:52:57.12 |
-23:45:38.3 |
HIP 87399 |
18.54 |
| 2026-08-17 00:00 |
17:52:54.47 |
-23:45:31.4 |
HIP 87399 |
17.92 |
| 2026-08-17 12:00 |
17:52:51.86 |
-23:45:24.4 |
HIP 87399 |
17.32 |
| 2026-08-18 00:00 |
17:52:49.29 |
-23:45:17.5 |
HIP 87399 |
16.72 |
| 2026-08-18 12:00 |
17:52:46.77 |
-23:45:10.5 |
HIP 87399 |
16.13 |
| 2026-08-19 00:00 |
17:52:44.29 |
-23:45:03.6 |
HIP 87399 |
15.56 |