242P/Spahr
メタデータ
| 項目 | 値 |
|---|---|
| Designation | 242P/Spahr |
| Type | P |
| Perihelion (tp_cal, UTC) | 2025-01-05T23:02:16.198080Z |
| Orbit solution date (soln_date, UTC) | 2026-07-28T14:12:26Z |
| Obs used | 1567 |
| NEO | - |
| M1 | 11.400 |
| K1 | 6.750 |
| PC | - |
オスキュレーティング軌道要素
| 項目 | 値 |
|---|---|
| Epoch (epoch_cal, TDB) | 2020-03-09.0000000 |
| e | 0.27787164 |
| q (au) | 3.954618 |
| a (au) | 5.476336 |
| i (deg) | 32.479998 |
| Ω (om, deg) | 180.500982 |
| ω (w, deg) | 246.291835 |
| M (ma, deg) | 224.338183 |
等級
散乱 + 全体線形
$$ M_a = (11.528 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
モデル定数
| 項目 | 値 |
|---|---|
| H0 | 11.528 |
| n | 2.000 |
| gf | 1.000 |
| gb | -0.512 |
| k | 1.000 |
| 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 |
|---|---|---|---|
| 2023-07-28 | 2025-01-05 | +22.5723 | -13.313 |
| 2025-01-06 | 2026-04-07 | -14.1768 | +8.451 |
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) |
|---|---|---|---|---|
| 2026-07-29 00:00 | 09:06:26.19 | -01:42:32.6 | HIP 44854 | 28.30 |
| 2026-07-29 12:00 | 09:06:55.91 | -01:43:28.7 | HIP 44854 | 20.98 |
| 2026-07-30 00:00 | 09:07:25.62 | -01:44:25.7 | HIP 44854 | 13.84 |
| 2026-07-30 12:00 | 09:07:55.33 | -01:45:23.6 | HIP 44854 | 7.42 |
| 2026-07-31 00:00 | 09:08:25.03 | -01:46:22.2 | HIP 44854 | 5.55 |
| 2026-07-31 12:00 | 09:08:54.72 | -01:47:21.6 | HIP 44854 | 10.90 |
| 2026-08-01 00:00 | 09:09:24.41 | -01:48:21.8 | HIP 44931 | 13.68 |
| 2026-08-01 12:00 | 09:09:54.09 | -01:49:22.9 | HIP 44931 | 18.12 |
| 2026-08-02 00:00 | 09:10:23.76 | -01:50:24.7 | HIP 45087 | 20.24 |
| 2026-08-02 12:00 | 09:10:53.42 | -01:51:27.3 | HIP 45087 | 18.72 |
| 2026-08-03 00:00 | 09:11:23.07 | -01:52:30.7 | HIP 45087 | 20.09 |
| 2026-08-03 12:00 | 09:11:52.71 | -01:53:34.9 | HIP 45142 | 20.54 |
| 2026-08-04 00:00 | 09:12:22.35 | -01:54:39.8 | HIP 45142 | 20.94 |
| 2026-08-04 12:00 | 09:12:51.97 | -01:55:45.6 | HIP 45142 | 23.80 |
| 2026-08-05 00:00 | 09:13:21.58 | -01:56:52.1 | HIP 45267 | 26.84 |
| 2026-08-05 12:00 | 09:13:51.18 | -01:57:59.3 | HIP 45267 | 26.02 |
| 2026-08-06 00:00 | 09:14:20.77 | -01:59:07.4 | HIP 45378 | 25.14 |
| 2026-08-06 12:00 | 09:14:50.35 | -02:00:16.1 | HIP 45378 | 25.05 |
| 2026-08-07 00:00 | 09:15:19.91 | -02:01:25.7 | HIP 45378 | 27.12 |
| 2026-08-07 12:00 | 09:15:49.46 | -02:02:36.0 | HIP 45378 | 30.91 |
| 2026-08-08 00:00 | 09:16:19.00 | -02:03:47.0 | HIP 45378 | 35.89 |
| 2026-08-08 12:00 | 09:16:48.52 | -02:04:58.8 | HIP 45710 | 41.38 |
| 2026-08-09 00:00 | 09:17:18.02 | -02:06:11.3 | HIP 45710 | 34.66 |
| 2026-08-09 12:00 | 09:17:47.51 | -02:07:24.5 | HIP 45710 | 28.33 |
| 2026-08-10 00:00 | 09:18:16.99 | -02:08:38.4 | HIP 45710 | 22.68 |
| 2026-08-10 12:00 | 09:18:46.45 | -02:09:53.1 | HIP 45710 | 18.36 |
| 2026-08-11 00:00 | 09:19:15.89 | -02:11:08.5 | HIP 45710 | 16.47 |
| 2026-08-11 12:00 | 09:19:45.31 | -02:12:24.6 | HIP 45710 | 17.78 |
| 2026-08-12 00:00 | 09:20:14.71 | -02:13:41.4 | HIP 45710 | 21.72 |
| 2026-08-12 12:00 | 09:20:44.10 | -02:14:58.9 | HIP 45710 | 27.16 |
| 2026-08-13 00:00 | 09:21:13.46 | -02:16:17.1 | HIP 45916 | 32.25 |
| 2026-08-13 12:00 | 09:21:42.80 | -02:17:36.0 | HIP 45916 | 29.98 |
| 2026-08-14 00:00 | 09:22:12.12 | -02:18:55.5 | HIP 45916 | 29.45 |
| 2026-08-14 12:00 | 09:22:41.42 | -02:20:15.8 | HIP 45931 | 30.40 |
| 2026-08-15 00:00 | 09:23:10.70 | -02:21:36.7 | HIP 45931 | 32.74 |
| 2026-08-15 12:00 | 09:23:39.95 | -02:22:58.2 | HIP 46209 | 29.40 |
| 2026-08-16 00:00 | 09:24:09.18 | -02:24:20.4 | HIP 46209 | 22.81 |
| 2026-08-16 12:00 | 09:24:38.39 | -02:25:43.3 | HIP 46209 | 16.92 |
| 2026-08-17 00:00 | 09:25:07.57 | -02:27:06.8 | HIP 46209 | 12.73 |
| 2026-08-17 12:00 | 09:25:36.73 | -02:28:31.0 | HIP 46209 | 12.15 |
| 2026-08-18 00:00 | 09:26:05.85 | -02:29:55.7 | HIP 46209 | 15.59 |
| 2026-08-18 12:00 | 09:26:34.96 | -02:31:21.1 | HIP 46209 | 21.16 |
| 2026-08-19 00:00 | 09:27:04.03 | -02:32:47.2 | HIP 46209 | 27.60 |