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) |
|---|---|---|---|---|
| 2026-09-20 00:00 | 09:56:45.89 | -04:22:04.7 | HIP 48737 | 32.09 |
| 2026-09-20 12:00 | 09:57:12.11 | -04:23:59.6 | HIP 48737 | 35.44 |
| 2026-09-21 00:00 | 09:57:38.26 | -04:25:54.8 | HIP 48737 | 39.69 |
| 2026-09-21 12:00 | 09:58:04.36 | -04:27:50.2 | HIP 49072 | 44.30 |
| 2026-09-22 00:00 | 09:58:30.38 | -04:29:45.9 | HIP 49072 | 38.74 |
| 2026-09-22 12:00 | 09:58:56.35 | -04:31:41.8 | HIP 49021 | 33.58 |
| 2026-09-23 00:00 | 09:59:22.25 | -04:33:37.9 | HIP 49021 | 29.05 |
| 2026-09-23 12:00 | 09:59:48.08 | -04:35:34.2 | HIP 49021 | 25.50 |
| 2026-09-24 00:00 | 10:00:13.85 | -04:37:30.8 | HIP 49021 | 23.38 |
| 2026-09-24 12:00 | 10:00:39.55 | -04:39:27.5 | HIP 49021 | 23.08 |
| 2026-09-25 00:00 | 10:01:05.19 | -04:41:24.5 | HIP 49021 | 24.66 |
| 2026-09-25 12:00 | 10:01:30.75 | -04:43:21.7 | HIP 49021 | 27.77 |
| 2026-09-26 00:00 | 10:01:56.25 | -04:45:19.0 | HIP 49021 | 31.97 |
| 2026-09-26 12:00 | 10:02:21.69 | -04:47:16.6 | HIP 49021 | 36.88 |
| 2026-09-27 00:00 | 10:02:47.05 | -04:49:14.3 | HIP 49021 | 42.25 |
| 2026-09-27 12:00 | 10:03:12.34 | -04:51:12.2 | HIP 49231 | 46.04 |
| 2026-09-28 00:00 | 10:03:37.56 | -04:53:10.2 | HIP 49231 | 45.08 |
| 2026-09-28 12:00 | 10:04:02.72 | -04:55:08.4 | HIP 49465 | 41.19 |
| 2026-09-29 00:00 | 10:04:27.80 | -04:57:06.8 | HIP 49465 | 35.65 |
| 2026-09-29 12:00 | 10:04:52.81 | -04:59:05.4 | HIP 49465 | 30.52 |
| 2026-09-30 00:00 | 10:05:17.75 | -05:01:04.0 | HIP 49465 | 26.03 |
| 2026-09-30 12:00 | 10:05:42.61 | -05:03:02.9 | HIP 49465 | 22.55 |
| 2026-10-01 00:00 | 10:06:07.40 | -05:05:01.8 | HIP 49465 | 20.58 |
| 2026-10-01 12:00 | 10:06:32.12 | -05:07:00.9 | HIP 49465 | 20.56 |
| 2026-10-02 00:00 | 10:06:56.76 | -05:09:00.1 | HIP 49465 | 22.46 |
| 2026-10-02 12:00 | 10:07:21.33 | -05:10:59.4 | HIP 49557 | 23.30 |
| 2026-10-03 00:00 | 10:07:45.82 | -05:12:58.9 | HIP 49557 | 23.23 |
| 2026-10-03 12:00 | 10:08:10.23 | -05:14:58.4 | HIP 49557 | 24.85 |
| 2026-10-04 00:00 | 10:08:34.57 | -05:16:58.1 | HIP 49557 | 27.87 |
| 2026-10-04 12:00 | 10:08:58.83 | -05:18:57.8 | HIP 49832 | 23.14 |
| 2026-10-05 00:00 | 10:09:23.01 | -05:20:57.6 | HIP 49832 | 16.83 |
| 2026-10-05 12:00 | 10:09:47.11 | -05:22:57.5 | HIP 49832 | 10.59 |
| 2026-10-06 00:00 | 10:10:11.13 | -05:24:57.4 | HIP 49832 | 4.58 |
| 2026-10-06 12:00 | 10:10:35.07 | -05:26:57.5 | HIP 49832 | 3.02 |
| 2026-10-07 00:00 | 10:10:58.93 | -05:28:57.5 | HIP 49832 | 8.71 |
| 2026-10-07 12:00 | 10:11:22.70 | -05:30:57.6 | HIP 49832 | 14.85 |
| 2026-10-08 00:00 | 10:11:46.39 | -05:32:57.8 | HIP 49832 | 21.04 |
| 2026-10-08 12:00 | 10:12:10.00 | -05:34:58.0 | HIP 50058 | 27.10 |
| 2026-10-09 00:00 | 10:12:33.52 | -05:36:58.2 | HIP 50058 | 25.96 |
| 2026-10-09 12:00 | 10:12:56.95 | -05:38:58.4 | HIP 50058 | 26.26 |
| 2026-10-10 00:00 | 10:13:20.30 | -05:40:58.7 | HIP 50058 | 27.96 |
| 2026-10-10 12:00 | 10:13:43.56 | -05:42:58.9 | HIP 50105 | 29.80 |
| 2026-10-11 00:00 | 10:14:06.73 | -05:44:59.1 | HIP 50105 | 32.20 |