メタデータ

項目	値
Designation	185P/Petriew
Type	P
Perihelion (tp_cal, UTC)	2012-08-13T01:18:02.707200Z
Orbit solution date (soln_date, UTC)	2024-02-22T12:37:21Z
Obs used	715
NEO	Yes
M1	13.600
K1	10.250
PC	0.030

オスキュレーティング軌道要素

項目	値
Epoch (epoch_cal, TDB)	2015-04-17.0000000
e	0.69879499
q (au)	0.933837
a (au)	3.100337
i (deg)	13.997316
Ω (om, deg)	214.100822
ω (w, deg)	181.937558
M (ma, deg)	176.384777

等級

散乱 + 全体線形

$$ M_a = (14.159 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$

モデル定数

項目	値
H0	14.159
n	6.000
gf	1.000
gb	-0.827
k	0.988
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

天体暦

Date/Time (UTC)	RA (J2000)	Dec (J2000)	Nearest HIP	Dist from HIP (arcmin)
2026-07-29 00:00	13:53:35.01	-09:48:59.8	HIP 67968	27.12
2026-07-29 12:00	13:53:42.30	-09:49:29.2	HIP 67968	25.91
2026-07-30 00:00	13:53:49.75	-09:49:59.4	HIP 67968	24.75
2026-07-30 12:00	13:53:57.35	-09:50:30.6	HIP 67968	23.67
2026-07-31 00:00	13:54:05.11	-09:51:02.5	HIP 67968	22.70
2026-07-31 12:00	13:54:13.01	-09:51:35.4	HIP 67968	21.85
2026-08-01 00:00	13:54:21.08	-09:52:09.0	HIP 67968	21.15
2026-08-01 12:00	13:54:29.29	-09:52:43.5	HIP 67968	20.62
2026-08-02 00:00	13:54:37.65	-09:53:18.9	HIP 68038	20.24
2026-08-02 12:00	13:54:46.17	-09:53:55.1	HIP 68038	18.60
2026-08-03 00:00	13:54:54.83	-09:54:32.1	HIP 68038	17.06
2026-08-03 12:00	13:55:03.64	-09:55:09.9	HIP 68038	15.67
2026-08-04 00:00	13:55:12.60	-09:55:48.5	HIP 68038	14.48
2026-08-04 12:00	13:55:21.71	-09:56:27.9	HIP 68038	13.57
2026-08-05 00:00	13:55:30.97	-09:57:08.2	HIP 68038	13.02
2026-08-05 12:00	13:55:40.37	-09:57:49.2	HIP 68038	12.89
2026-08-06 00:00	13:55:49.92	-09:58:31.1	HIP 68107	12.00
2026-08-06 12:00	13:55:59.62	-09:59:13.7	HIP 68107	9.51
2026-08-07 00:00	13:56:09.46	-09:59:57.1	HIP 68107	6.98
2026-08-07 12:00	13:56:19.44	-10:00:41.3	HIP 68107	4.42
2026-08-08 00:00	13:56:29.56	-10:01:26.2	HIP 68107	1.81
2026-08-08 12:00	13:56:39.83	-10:02:11.9	HIP 68107	0.83
2026-08-09 00:00	13:56:50.24	-10:02:58.4	HIP 68107	3.50
2026-08-09 12:00	13:57:00.79	-10:03:45.6	HIP 68107	6.22
2026-08-10 00:00	13:57:11.49	-10:04:33.6	HIP 68107	8.97
2026-08-10 12:00	13:57:22.32	-10:05:22.3	HIP 68107	11.76
2026-08-11 00:00	13:57:33.29	-10:06:11.8	HIP 68107	14.58
2026-08-11 12:00	13:57:44.40	-10:07:02.0	HIP 68107	17.44
2026-08-12 00:00	13:57:55.65	-10:07:52.9	HIP 68107	20.33
2026-08-12 12:00	13:58:07.03	-10:08:44.5	HIP 68107	23.26
2026-08-13 00:00	13:58:18.55	-10:09:36.8	HIP 68107	26.23
2026-08-13 12:00	13:58:30.21	-10:10:29.9	HIP 68376	24.60
2026-08-14 00:00	13:58:42.00	-10:11:23.6	HIP 68376	21.83
2026-08-14 12:00	13:58:53.92	-10:12:18.0	HIP 68376	19.11
2026-08-15 00:00	13:59:05.98	-10:13:13.1	HIP 68376	16.48
2026-08-15 12:00	13:59:18.17	-10:14:08.9	HIP 68376	14.03
2026-08-16 00:00	13:59:30.49	-10:15:05.4	HIP 68376	11.88
2026-08-16 12:00	13:59:42.94	-10:16:02.5	HIP 68376	10.26
2026-08-17 00:00	13:59:55.52	-10:17:00.3	HIP 68376	9.48
2026-08-17 12:00	14:00:08.22	-10:17:58.7	HIP 68376	9.78
2026-08-18 00:00	14:00:21.06	-10:18:57.8	HIP 68376	11.10
2026-08-18 12:00	14:00:34.02	-10:19:57.5	HIP 68483	10.19
2026-08-19 00:00	14:00:47.11	-10:20:57.8	HIP 68483	6.82