C/2025 R2 (SWAN)
メタデータ
| 項目 | 値 |
|---|---|
| Designation | C/2025 R2 (SWAN) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2025-09-12T20:18:14.512320Z |
| Orbit solution date (soln_date, UTC) | 2026-03-31T09:42:19Z |
| Obs used | 2322 |
| NEO | - |
| M1 | 13.900 |
| K1 | 10.000 |
| PC | - |
| Discovery observation (MPC, UTC) | 2025-09-11T23:33:15.552000Z |
| Discovery magnitude (MPC) | 7.50 V |
| Discovery observatory (MPC) | 247 · Roving Observer |
オスキュレーティング軌道要素
| 項目 | 値 |
|---|---|
| Epoch (epoch_cal, TDB) | 2025-11-11.0000000 |
| e | 0.99419736 |
| q (au) | 0.504084 |
| a (au) | 86.871582 |
| i (deg) | 4.472978 |
| Ω (om, deg) | 335.325999 |
| ω (w, deg) | 308.358672 |
| M (ma, deg) | 0.072006 |
等級
散乱 + 全体線形
$$ M_a = (12.726 + 4.952\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
モデル定数
| 項目 | 値 |
|---|---|
| H0 | 12.726 |
| n | 4.952 |
| gf | 1.000 |
| gb | -1.000 |
| k | 0.932 |
| δ90 | 9.994 |
| 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 |
|---|---|---|---|
| 2025-09-12 | 2026-03-09 | -1.7108 | -0.928 |
log10 r = log10(太陽距離/AU)、Δ = 地球距離(AU)
ファインディングチャート
天体暦
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-03-26 00:00 | 02:49:25.03 | +20:06:38.0 | HIP 13094 | 16.41 |
| 2026-03-26 12:00 | 02:50:01.81 | +20:09:05.7 | HIP 13229 | 21.18 |
| 2026-03-27 00:00 | 02:50:38.57 | +20:11:33.0 | HIP 13229 | 18.94 |
| 2026-03-27 12:00 | 02:51:15.30 | +20:14:00.0 | HIP 13229 | 20.73 |
| 2026-03-28 00:00 | 02:51:52.00 | +20:16:26.4 | HIP 13418 | 15.68 |
| 2026-03-28 12:00 | 02:52:28.68 | +20:18:52.4 | HIP 13418 | 12.15 |
| 2026-03-29 00:00 | 02:53:05.32 | +20:21:18.0 | HIP 13418 | 14.46 |
| 2026-03-29 12:00 | 02:53:41.94 | +20:23:43.2 | HIP 13532 | 13.20 |
| 2026-03-30 00:00 | 02:54:18.52 | +20:26:08.0 | HIP 13532 | 7.82 |
| 2026-03-30 12:00 | 02:54:55.08 | +20:28:32.3 | HIP 13571 | 6.28 |
| 2026-03-31 00:00 | 02:55:31.61 | +20:30:56.2 | HIP 13571 | 13.00 |
| 2026-03-31 12:00 | 02:56:08.11 | +20:33:19.6 | HIP 13571 | 21.36 |
| 2026-04-01 00:00 | 02:56:44.58 | +20:35:42.7 | HIP 13834 | 19.34 |
| 2026-04-01 12:00 | 02:57:21.02 | +20:38:05.2 | HIP 13834 | 10.51 |
| 2026-04-02 00:00 | 02:57:57.44 | +20:40:27.4 | HIP 13834 | 1.82 |
| 2026-04-02 12:00 | 02:58:33.82 | +20:42:49.1 | HIP 13834 | 7.24 |
| 2026-04-03 00:00 | 02:59:10.17 | +20:45:10.4 | HIP 13834 | 16.04 |
| 2026-04-03 12:00 | 02:59:46.49 | +20:47:31.2 | HIP 13834 | 24.84 |
| 2026-04-04 00:00 | 03:00:22.78 | +20:49:51.6 | HIP 13834 | 33.63 |
| 2026-04-04 12:00 | 03:00:59.05 | +20:52:11.6 | HIP 13914 | 37.58 |
| 2026-04-05 00:00 | 03:01:35.28 | +20:54:31.1 | HIP 14203 | 40.82 |
| 2026-04-05 12:00 | 03:02:11.48 | +20:56:50.2 | HIP 14203 | 39.10 |
| 2026-04-06 00:00 | 03:02:47.65 | +20:59:08.8 | HIP 14292 | 35.64 |
| 2026-04-06 12:00 | 03:03:23.79 | +21:01:27.1 | HIP 14292 | 29.47 |
| 2026-04-07 00:00 | 03:03:59.90 | +21:03:44.8 | HIP 14378 | 23.17 |
| 2026-04-07 12:00 | 03:04:35.98 | +21:06:02.1 | HIP 14378 | 17.37 |
| 2026-04-08 00:00 | 03:05:12.03 | +21:08:19.0 | HIP 14378 | 14.80 |
| 2026-04-08 12:00 | 03:05:48.04 | +21:10:35.5 | HIP 14378 | 16.96 |
| 2026-04-09 00:00 | 03:06:24.03 | +21:12:51.5 | HIP 14481 | 22.15 |
| 2026-04-09 12:00 | 03:06:59.98 | +21:15:07.0 | HIP 14481 | 23.46 |
| 2026-04-10 00:00 | 03:07:35.91 | +21:17:22.2 | HIP 14481 | 27.58 |
| 2026-04-10 12:00 | 03:08:11.80 | +21:19:36.8 | HIP 14727 | 28.78 |
| 2026-04-11 00:00 | 03:08:47.66 | +21:21:51.1 | HIP 14727 | 20.98 |
| 2026-04-11 12:00 | 03:09:23.48 | +21:24:04.8 | HIP 14727 | 14.20 |
| 2026-04-12 00:00 | 03:09:59.28 | +21:26:18.2 | HIP 14727 | 10.60 |
| 2026-04-12 12:00 | 03:10:35.04 | +21:28:31.1 | HIP 14727 | 13.10 |
| 2026-04-13 00:00 | 03:11:10.77 | +21:30:43.5 | HIP 14727 | 19.47 |
| 2026-04-13 12:00 | 03:11:46.46 | +21:32:55.5 | HIP 14993 | 21.34 |
| 2026-04-14 00:00 | 03:12:22.12 | +21:35:07.0 | HIP 14993 | 12.77 |
| 2026-04-14 12:00 | 03:12:57.75 | +21:37:18.1 | HIP 14993 | 4.21 |
| 2026-04-15 00:00 | 03:13:33.35 | +21:39:28.8 | HIP 14993 | 4.36 |
| 2026-04-15 12:00 | 03:14:08.91 | +21:41:39.0 | HIP 14993 | 12.90 |
| 2026-04-16 00:00 | 03:14:44.43 | +21:43:48.7 | HIP 14993 | 21.43 |