C/2018 Y1 (Iwamoto)
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
$$
M_a = (13.241 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
モデル定数
| 項目 |
値 |
| H0 |
13.241 |
| n |
2.000 |
| gf |
0.984 |
| gb |
-0.633 |
| k |
0.985 |
| 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 |
| 2018-12-18 |
2019-02-07 |
+11.6131 |
-3.509 |
| 2019-02-07 |
2019-12-22 |
+2.8863 |
-1.495 |
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) |
| 2026-02-03 00:00 |
23:26:45.08 |
+06:52:51.2 |
HIP 115600 |
27.66 |
| 2026-02-03 12:00 |
23:26:49.22 |
+06:53:04.7 |
HIP 115600 |
28.56 |
| 2026-02-04 00:00 |
23:26:53.38 |
+06:53:18.6 |
HIP 115600 |
29.47 |
| 2026-02-04 12:00 |
23:26:57.56 |
+06:53:32.7 |
HIP 115600 |
30.40 |
| 2026-02-05 00:00 |
23:27:01.78 |
+06:53:47.0 |
HIP 115600 |
31.34 |
| 2026-02-05 12:00 |
23:27:06.01 |
+06:54:01.7 |
HIP 115600 |
32.30 |
| 2026-02-06 00:00 |
23:27:10.27 |
+06:54:16.7 |
HIP 115600 |
33.27 |
| 2026-02-06 12:00 |
23:27:14.56 |
+06:54:31.9 |
HIP 115830 |
33.58 |
| 2026-02-07 00:00 |
23:27:18.86 |
+06:54:47.4 |
HIP 115830 |
33.50 |
| 2026-02-07 12:00 |
23:27:23.20 |
+06:55:03.1 |
HIP 115883 |
33.42 |
| 2026-02-08 00:00 |
23:27:27.55 |
+06:55:19.2 |
HIP 115883 |
32.58 |
| 2026-02-08 12:00 |
23:27:31.93 |
+06:55:35.5 |
HIP 115883 |
31.74 |
| 2026-02-09 00:00 |
23:27:36.33 |
+06:55:52.1 |
HIP 115883 |
30.92 |
| 2026-02-09 12:00 |
23:27:40.75 |
+06:56:08.9 |
HIP 115883 |
30.11 |
| 2026-02-10 00:00 |
23:27:45.20 |
+06:56:26.0 |
HIP 115883 |
29.31 |
| 2026-02-10 12:00 |
23:27:49.66 |
+06:56:43.4 |
HIP 115883 |
28.53 |
| 2026-02-11 00:00 |
23:27:54.15 |
+06:57:01.1 |
HIP 115883 |
27.77 |
| 2026-02-11 12:00 |
23:27:58.66 |
+06:57:19.0 |
HIP 115883 |
27.03 |
| 2026-02-12 00:00 |
23:28:03.19 |
+06:57:37.1 |
HIP 115883 |
26.32 |
| 2026-02-12 12:00 |
23:28:07.74 |
+06:57:55.5 |
HIP 115883 |
25.63 |
| 2026-02-13 00:00 |
23:28:12.31 |
+06:58:14.2 |
HIP 115883 |
24.98 |
| 2026-02-13 12:00 |
23:28:16.90 |
+06:58:33.1 |
HIP 115883 |
24.36 |
| 2026-02-14 00:00 |
23:28:21.50 |
+06:58:52.3 |
HIP 115883 |
23.77 |
| 2026-02-14 12:00 |
23:28:26.13 |
+06:59:11.7 |
HIP 115883 |
23.23 |
| 2026-02-15 00:00 |
23:28:30.77 |
+06:59:31.3 |
HIP 115883 |
22.73 |
| 2026-02-15 12:00 |
23:28:35.43 |
+06:59:51.3 |
HIP 115883 |
22.28 |
| 2026-02-16 00:00 |
23:28:40.11 |
+07:00:11.4 |
HIP 115883 |
21.88 |
| 2026-02-16 12:00 |
23:28:44.81 |
+07:00:31.8 |
HIP 115883 |
21.54 |
| 2026-02-17 00:00 |
23:28:49.52 |
+07:00:52.4 |
HIP 115883 |
21.26 |
| 2026-02-17 12:00 |
23:28:54.25 |
+07:01:13.3 |
HIP 115883 |
21.04 |
| 2026-02-18 00:00 |
23:28:59.00 |
+07:01:34.4 |
HIP 115883 |
20.89 |
| 2026-02-18 12:00 |
23:29:03.76 |
+07:01:55.7 |
HIP 115883 |
20.81 |
| 2026-02-19 00:00 |
23:29:08.54 |
+07:02:17.2 |
HIP 115883 |
20.80 |
| 2026-02-19 12:00 |
23:29:13.33 |
+07:02:39.0 |
HIP 115883 |
20.86 |
| 2026-02-20 00:00 |
23:29:18.14 |
+07:03:01.0 |
HIP 115883 |
20.99 |
| 2026-02-20 12:00 |
23:29:22.96 |
+07:03:23.3 |
HIP 115883 |
21.19 |
| 2026-02-21 00:00 |
23:29:27.79 |
+07:03:45.7 |
HIP 115883 |
21.47 |
| 2026-02-21 12:00 |
23:29:32.64 |
+07:04:08.4 |
HIP 115883 |
21.81 |
| 2026-02-22 00:00 |
23:29:37.50 |
+07:04:31.2 |
HIP 115883 |
22.21 |
| 2026-02-22 12:00 |
23:29:42.37 |
+07:04:54.3 |
HIP 115883 |
22.68 |
| 2026-02-23 00:00 |
23:29:47.26 |
+07:05:17.6 |
HIP 115883 |
23.21 |
| 2026-02-23 12:00 |
23:29:52.15 |
+07:05:41.1 |
HIP 115883 |
23.79 |
| 2026-02-24 00:00 |
23:29:57.06 |
+07:06:04.8 |
HIP 115883 |
24.43 |