メタデータ
| 項目 |
値 |
| Designation |
C/2018 W2 (Africano) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2019-09-05T17:29:59.596800Z |
| Orbit solution date (soln_date, UTC) |
2021-08-24T14:05:51Z |
| Obs used |
1995 |
| NEO |
- |
| M1 |
13.400 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2018-11-27T12:43:12.864000Z |
| Discovery magnitude (MPC) |
18.30 G |
| Discovery observatory (MPC) |
G96 · University of Arizona Mt. Lemmon Survey |
オスキュレーティング軌道要素
| 項目 |
値 |
| Epoch (epoch_cal, TDB) |
2019-07-27.0000000 |
| e |
1.00075966 |
| q (au) |
1.454668 |
| a (au) |
-1914.899581 |
| i (deg) |
116.615771 |
| Ω (om, deg) |
181.849455 |
| ω (w, deg) |
157.972854 |
| M (ma, deg) |
-0.000479 |
等級
散乱 + 全体線形
$$
M_a = (13.119 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
13.119 |
| n |
2.000 |
| gf |
0.994 |
| gb |
-0.500 |
| k |
0.800 |
| δ90 |
1.652 |
| 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 |
| 2018-08-24 |
2018-12-01 |
-96.0365 |
+55.664 |
| 2018-12-01 |
2019-09-05 |
+4.8869 |
-2.512 |
| 2019-09-05 |
2020-06-15 |
-2.6714 |
+0.118 |
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) |
| 2026-06-01 00:00 |
12:06:26.12 |
-55:22:19.0 |
HIP 58883 |
15.76 |
| 2026-06-01 12:00 |
12:06:22.40 |
-55:20:48.9 |
HIP 58883 |
15.67 |
| 2026-06-02 00:00 |
12:06:18.78 |
-55:19:18.8 |
HIP 58883 |
15.75 |
| 2026-06-02 12:00 |
12:06:15.24 |
-55:17:48.7 |
HIP 59009 |
15.37 |
| 2026-06-03 00:00 |
12:06:11.79 |
-55:16:18.5 |
HIP 59009 |
13.81 |
| 2026-06-03 12:00 |
12:06:08.43 |
-55:14:48.4 |
HIP 59009 |
12.26 |
| 2026-06-04 00:00 |
12:06:05.16 |
-55:13:18.4 |
HIP 59009 |
10.73 |
| 2026-06-04 12:00 |
12:06:01.98 |
-55:11:48.3 |
HIP 59009 |
9.20 |
| 2026-06-05 00:00 |
12:05:58.89 |
-55:10:18.3 |
HIP 59009 |
7.69 |
| 2026-06-05 12:00 |
12:05:55.88 |
-55:08:48.3 |
HIP 59009 |
6.21 |
| 2026-06-06 00:00 |
12:05:52.97 |
-55:07:18.3 |
HIP 59009 |
4.79 |
| 2026-06-06 12:00 |
12:05:50.14 |
-55:05:48.4 |
HIP 59009 |
3.46 |
| 2026-06-07 00:00 |
12:05:47.40 |
-55:04:18.6 |
HIP 59009 |
2.42 |
| 2026-06-07 12:00 |
12:05:44.75 |
-55:02:48.8 |
HIP 59009 |
2.12 |
| 2026-06-08 00:00 |
12:05:42.19 |
-55:01:19.0 |
HIP 59009 |
2.80 |
| 2026-06-08 12:00 |
12:05:39.71 |
-54:59:49.4 |
HIP 59009 |
3.98 |
| 2026-06-09 00:00 |
12:05:37.33 |
-54:58:19.8 |
HIP 59009 |
5.33 |
| 2026-06-09 12:00 |
12:05:35.03 |
-54:56:50.3 |
HIP 59009 |
6.75 |
| 2026-06-10 00:00 |
12:05:32.82 |
-54:55:21.0 |
HIP 59009 |
8.21 |
| 2026-06-10 12:00 |
12:05:30.70 |
-54:53:51.7 |
HIP 59009 |
9.68 |
| 2026-06-11 00:00 |
12:05:28.67 |
-54:52:22.5 |
HIP 59009 |
11.15 |
| 2026-06-11 12:00 |
12:05:26.73 |
-54:50:53.4 |
HIP 59009 |
12.63 |
| 2026-06-12 00:00 |
12:05:24.87 |
-54:49:24.4 |
HIP 59009 |
14.11 |
| 2026-06-12 12:00 |
12:05:23.11 |
-54:47:55.6 |
HIP 58816 |
14.66 |
| 2026-06-13 00:00 |
12:05:21.43 |
-54:46:26.9 |
HIP 58816 |
13.99 |
| 2026-06-13 12:00 |
12:05:19.84 |
-54:44:58.4 |
HIP 58816 |
13.47 |
| 2026-06-14 00:00 |
12:05:18.33 |
-54:43:30.0 |
HIP 58816 |
13.10 |
| 2026-06-14 12:00 |
12:05:16.92 |
-54:42:01.7 |
HIP 58816 |
12.92 |
| 2026-06-15 00:00 |
12:05:15.59 |
-54:40:33.6 |
HIP 58816 |
12.91 |
| 2026-06-15 12:00 |
12:05:14.35 |
-54:39:05.7 |
HIP 58816 |
13.08 |
| 2026-06-16 00:00 |
12:05:13.20 |
-54:37:37.9 |
HIP 58816 |
13.43 |
| 2026-06-16 12:00 |
12:05:12.13 |
-54:36:10.3 |
HIP 58816 |
13.93 |
| 2026-06-17 00:00 |
12:05:11.15 |
-54:34:42.9 |
HIP 58816 |
14.57 |
| 2026-06-17 12:00 |
12:05:10.26 |
-54:33:15.7 |
HIP 58816 |
15.34 |
| 2026-06-18 00:00 |
12:05:09.45 |
-54:31:48.7 |
HIP 58816 |
16.20 |
| 2026-06-18 12:00 |
12:05:08.73 |
-54:30:21.9 |
HIP 59016 |
16.75 |
| 2026-06-19 00:00 |
12:05:08.10 |
-54:28:55.3 |
HIP 59016 |
15.53 |
| 2026-06-19 12:00 |
12:05:07.55 |
-54:27:29.0 |
HIP 59016 |
14.35 |
| 2026-06-20 00:00 |
12:05:07.09 |
-54:26:02.8 |
HIP 59016 |
13.21 |
| 2026-06-20 12:00 |
12:05:06.71 |
-54:24:36.9 |
HIP 59016 |
12.13 |
| 2026-06-21 00:00 |
12:05:06.42 |
-54:23:11.2 |
HIP 59016 |
11.12 |
| 2026-06-21 12:00 |
12:05:06.21 |
-54:21:45.7 |
HIP 59016 |
10.21 |
| 2026-06-22 00:00 |
12:05:06.09 |
-54:20:20.5 |
HIP 59016 |
9.42 |