メタデータ
| 項目 |
値 |
| Designation |
C/2018 Y1 (Iwamoto) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2019-02-07T00:44:05.775360Z |
| Orbit solution date (soln_date, UTC) |
2024-01-04T23:42:43Z |
| Obs used |
2771 |
| NEO |
- |
| M1 |
13.600 |
| K1 |
5.250 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2018-12-18T20:11:02.400000Z |
| Discovery magnitude (MPC) |
12.00 R |
| Discovery observatory (MPC) |
872 · Tokushima |
オスキュレーティング軌道要素
| 項目 |
値 |
| Epoch (epoch_cal, TDB) |
2019-03-03.0000000 |
| e |
0.99107927 |
| q (au) |
1.286994 |
| a (au) |
144.270155 |
| i (deg) |
160.403537 |
| Ω (om, deg) |
147.483562 |
| ω (w, deg) |
358.057218 |
| M (ma, deg) |
0.013633 |
等級
散乱 + 全体線形
$$
M_a = (13.253 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
13.253 |
| n |
2.000 |
| gf |
0.972 |
| gb |
-0.632 |
| k |
0.984 |
| δ90 |
9.902 |
| 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 |
| 2018-12-18 |
2019-02-07 |
+11.1321 |
-3.457 |
| 2019-02-07 |
2019-12-22 |
+2.9643 |
-1.536 |
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 |
23:42:28.25 |
+08:39:34.2 |
HIP 117098 |
28.81 |
| 2026-06-01 12:00 |
23:42:29.23 |
+08:39:53.7 |
HIP 117098 |
28.69 |
| 2026-06-02 00:00 |
23:42:30.17 |
+08:40:12.8 |
HIP 117098 |
28.58 |
| 2026-06-02 12:00 |
23:42:31.06 |
+08:40:31.8 |
HIP 117098 |
28.49 |
| 2026-06-03 00:00 |
23:42:31.91 |
+08:40:50.5 |
HIP 117098 |
28.41 |
| 2026-06-03 12:00 |
23:42:32.72 |
+08:41:08.9 |
HIP 117098 |
28.34 |
| 2026-06-04 00:00 |
23:42:33.47 |
+08:41:27.1 |
HIP 117098 |
28.28 |
| 2026-06-04 12:00 |
23:42:34.19 |
+08:41:45.1 |
HIP 117098 |
28.24 |
| 2026-06-05 00:00 |
23:42:34.86 |
+08:42:02.9 |
HIP 117098 |
28.21 |
| 2026-06-05 12:00 |
23:42:35.49 |
+08:42:20.3 |
HIP 117098 |
28.20 |
| 2026-06-06 00:00 |
23:42:36.07 |
+08:42:37.6 |
HIP 117098 |
28.19 |
| 2026-06-06 12:00 |
23:42:36.60 |
+08:42:54.6 |
HIP 117098 |
28.20 |
| 2026-06-07 00:00 |
23:42:37.10 |
+08:43:11.3 |
HIP 117098 |
28.21 |
| 2026-06-07 12:00 |
23:42:37.54 |
+08:43:27.8 |
HIP 117098 |
28.24 |
| 2026-06-08 00:00 |
23:42:37.94 |
+08:43:44.0 |
HIP 117098 |
28.28 |
| 2026-06-08 12:00 |
23:42:38.30 |
+08:44:00.0 |
HIP 117098 |
28.33 |
| 2026-06-09 00:00 |
23:42:38.61 |
+08:44:15.7 |
HIP 117098 |
28.39 |
| 2026-06-09 12:00 |
23:42:38.87 |
+08:44:31.1 |
HIP 117098 |
28.47 |
| 2026-06-10 00:00 |
23:42:39.09 |
+08:44:46.3 |
HIP 117098 |
28.55 |
| 2026-06-10 12:00 |
23:42:39.26 |
+08:45:01.2 |
HIP 117098 |
28.64 |
| 2026-06-11 00:00 |
23:42:39.39 |
+08:45:15.9 |
HIP 117098 |
28.74 |
| 2026-06-11 12:00 |
23:42:39.47 |
+08:45:30.3 |
HIP 117098 |
28.85 |
| 2026-06-12 00:00 |
23:42:39.51 |
+08:45:44.4 |
HIP 117098 |
28.96 |
| 2026-06-12 12:00 |
23:42:39.49 |
+08:45:58.2 |
HIP 117098 |
29.09 |
| 2026-06-13 00:00 |
23:42:39.43 |
+08:46:11.8 |
HIP 117098 |
29.22 |
| 2026-06-13 12:00 |
23:42:39.33 |
+08:46:25.1 |
HIP 117098 |
29.37 |
| 2026-06-14 00:00 |
23:42:39.18 |
+08:46:38.1 |
HIP 117098 |
29.52 |
| 2026-06-14 12:00 |
23:42:38.98 |
+08:46:50.8 |
HIP 117098 |
29.68 |
| 2026-06-15 00:00 |
23:42:38.74 |
+08:47:03.3 |
HIP 117098 |
29.84 |
| 2026-06-15 12:00 |
23:42:38.44 |
+08:47:15.4 |
HIP 117098 |
30.02 |
| 2026-06-16 00:00 |
23:42:38.11 |
+08:47:27.3 |
HIP 117098 |
30.20 |
| 2026-06-16 12:00 |
23:42:37.72 |
+08:47:38.9 |
HIP 117098 |
30.39 |
| 2026-06-17 00:00 |
23:42:37.29 |
+08:47:50.3 |
HIP 117098 |
30.58 |
| 2026-06-17 12:00 |
23:42:36.81 |
+08:48:01.3 |
HIP 117098 |
30.78 |
| 2026-06-18 00:00 |
23:42:36.28 |
+08:48:12.0 |
HIP 117098 |
30.99 |
| 2026-06-18 12:00 |
23:42:35.71 |
+08:48:22.5 |
HIP 117098 |
31.21 |
| 2026-06-19 00:00 |
23:42:35.09 |
+08:48:32.6 |
HIP 117098 |
31.43 |
| 2026-06-19 12:00 |
23:42:34.42 |
+08:48:42.5 |
HIP 117098 |
31.66 |
| 2026-06-20 00:00 |
23:42:33.71 |
+08:48:52.1 |
HIP 117098 |
31.90 |
| 2026-06-20 12:00 |
23:42:32.95 |
+08:49:01.3 |
HIP 117098 |
32.14 |
| 2026-06-21 00:00 |
23:42:32.14 |
+08:49:10.3 |
HIP 117098 |
32.39 |
| 2026-06-21 12:00 |
23:42:31.29 |
+08:49:19.0 |
HIP 117098 |
32.65 |
| 2026-06-22 00:00 |
23:42:30.39 |
+08:49:27.4 |
HIP 117098 |
32.91 |