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) |
| 2026-05-12 00:00 |
23:41:14.62 |
+08:23:45.5 |
HIP 116837 |
6.93 |
| 2026-05-12 12:00 |
23:41:17.24 |
+08:24:12.8 |
HIP 116837 |
7.72 |
| 2026-05-13 00:00 |
23:41:19.82 |
+08:24:39.9 |
HIP 116837 |
8.51 |
| 2026-05-13 12:00 |
23:41:22.36 |
+08:25:06.9 |
HIP 116837 |
9.28 |
| 2026-05-14 00:00 |
23:41:24.87 |
+08:25:33.8 |
HIP 116837 |
10.04 |
| 2026-05-14 12:00 |
23:41:27.33 |
+08:26:00.5 |
HIP 116837 |
10.80 |
| 2026-05-15 00:00 |
23:41:29.76 |
+08:26:27.0 |
HIP 116837 |
11.54 |
| 2026-05-15 12:00 |
23:41:32.15 |
+08:26:53.3 |
HIP 116837 |
12.28 |
| 2026-05-16 00:00 |
23:41:34.50 |
+08:27:19.5 |
HIP 116837 |
13.00 |
| 2026-05-16 12:00 |
23:41:36.82 |
+08:27:45.5 |
HIP 116837 |
13.72 |
| 2026-05-17 00:00 |
23:41:39.09 |
+08:28:11.3 |
HIP 116837 |
14.43 |
| 2026-05-17 12:00 |
23:41:41.32 |
+08:28:37.0 |
HIP 116837 |
15.12 |
| 2026-05-18 00:00 |
23:41:43.52 |
+08:29:02.4 |
HIP 116837 |
15.81 |
| 2026-05-18 12:00 |
23:41:45.67 |
+08:29:27.7 |
HIP 116837 |
16.49 |
| 2026-05-19 00:00 |
23:41:47.79 |
+08:29:52.8 |
HIP 116837 |
17.16 |
| 2026-05-19 12:00 |
23:41:49.86 |
+08:30:17.7 |
HIP 116837 |
17.82 |
| 2026-05-20 00:00 |
23:41:51.90 |
+08:30:42.4 |
HIP 116837 |
18.46 |
| 2026-05-20 12:00 |
23:41:53.89 |
+08:31:07.0 |
HIP 116837 |
19.10 |
| 2026-05-21 00:00 |
23:41:55.85 |
+08:31:31.3 |
HIP 116837 |
19.73 |
| 2026-05-21 12:00 |
23:41:57.76 |
+08:31:55.4 |
HIP 116837 |
20.35 |
| 2026-05-22 00:00 |
23:41:59.63 |
+08:32:19.4 |
HIP 116837 |
20.96 |
| 2026-05-22 12:00 |
23:42:01.46 |
+08:32:43.1 |
HIP 116837 |
21.56 |
| 2026-05-23 00:00 |
23:42:03.25 |
+08:33:06.7 |
HIP 116837 |
22.15 |
| 2026-05-23 12:00 |
23:42:05.00 |
+08:33:30.0 |
HIP 116837 |
22.72 |
| 2026-05-24 00:00 |
23:42:06.71 |
+08:33:53.2 |
HIP 116837 |
23.29 |
| 2026-05-24 12:00 |
23:42:08.37 |
+08:34:16.1 |
HIP 116837 |
23.85 |
| 2026-05-25 00:00 |
23:42:09.99 |
+08:34:38.8 |
HIP 116837 |
24.40 |
| 2026-05-25 12:00 |
23:42:11.57 |
+08:35:01.3 |
HIP 116837 |
24.94 |
| 2026-05-26 00:00 |
23:42:13.11 |
+08:35:23.6 |
HIP 116837 |
25.46 |
| 2026-05-26 12:00 |
23:42:14.61 |
+08:35:45.7 |
HIP 116837 |
25.98 |
| 2026-05-27 00:00 |
23:42:16.06 |
+08:36:07.6 |
HIP 116837 |
26.49 |
| 2026-05-27 12:00 |
23:42:17.48 |
+08:36:29.3 |
HIP 116837 |
26.99 |
| 2026-05-28 00:00 |
23:42:18.85 |
+08:36:50.7 |
HIP 116837 |
27.47 |
| 2026-05-28 12:00 |
23:42:20.17 |
+08:37:11.9 |
HIP 116837 |
27.95 |
| 2026-05-29 00:00 |
23:42:21.46 |
+08:37:32.9 |
HIP 116837 |
28.41 |
| 2026-05-29 12:00 |
23:42:22.70 |
+08:37:53.7 |
HIP 116837 |
28.87 |
| 2026-05-30 00:00 |
23:42:23.90 |
+08:38:14.3 |
HIP 116837 |
29.31 |
| 2026-05-30 12:00 |
23:42:25.05 |
+08:38:34.6 |
HIP 117098 |
29.27 |
| 2026-05-31 00:00 |
23:42:26.16 |
+08:38:54.7 |
HIP 117098 |
29.10 |
| 2026-05-31 12:00 |
23:42:27.23 |
+08:39:14.6 |
HIP 117098 |
28.95 |
| 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 |