メタデータ

項目	値
Designation	C/1980 Y1 (Bradfield)
Type	C
Perihelion (tp_cal, UTC)	1980-12-29T12:59:59.372160Z
Orbit solution date (soln_date, UTC)	2021-04-15T23:29:29Z
Obs used	32
NEO	-
M1	-
K1	-
PC	0.030

オスキュレーティング軌道要素

項目	値
Epoch (epoch_cal, TDB)	1981-01-26.0000000
e	0.99972538
q (au)	0.259823
a (au)	946.110211
i (deg)	138.585179
Ω (om, deg)	115.351543
ω (w, deg)	358.294122
M (ma, deg)	0.000930

等級

散乱 + 全体線形

$$ M_a = (7.110 + 2.589\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$

モデル定数

項目	値
H0	7.110
n	2.589
gf	0.800
gb	-0.500
k	0.800
δ90	1.000

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
1981-01-04	1981-01-13	-4.7670	-1.473
1981-01-13	1981-01-31	+3.4551	+0.349
1981-01-31	1981-08-27	+10.1983	+0.293

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)
2026-09-20 00:00	20:08:00.36	-14:24:37.8	HIP 99228	12.71
2026-09-20 12:00	20:07:59.45	-14:24:42.9	HIP 99228	12.92
2026-09-21 00:00	20:07:58.56	-14:24:48.0	HIP 99228	13.13
2026-09-21 12:00	20:07:57.68	-14:24:53.1	HIP 99228	13.34
2026-09-22 00:00	20:07:56.81	-14:24:58.2	HIP 99228	13.54
2026-09-22 12:00	20:07:55.96	-14:25:03.2	HIP 99228	13.75
2026-09-23 00:00	20:07:55.12	-14:25:08.2	HIP 99228	13.95
2026-09-23 12:00	20:07:54.29	-14:25:13.2	HIP 99228	14.15
2026-09-24 00:00	20:07:53.47	-14:25:18.1	HIP 99228	14.35
2026-09-24 12:00	20:07:52.67	-14:25:23.1	HIP 99228	14.55
2026-09-25 00:00	20:07:51.87	-14:25:27.9	HIP 99228	14.74
2026-09-25 12:00	20:07:51.10	-14:25:32.8	HIP 99228	14.93
2026-09-26 00:00	20:07:50.33	-14:25:37.6	HIP 99228	15.12
2026-09-26 12:00	20:07:49.58	-14:25:42.4	HIP 99228	15.31
2026-09-27 00:00	20:07:48.84	-14:25:47.2	HIP 99228	15.49
2026-09-27 12:00	20:07:48.12	-14:25:51.9	HIP 99228	15.68
2026-09-28 00:00	20:07:47.40	-14:25:56.6	HIP 99228	15.86
2026-09-28 12:00	20:07:46.70	-14:26:01.2	HIP 99228	16.03
2026-09-29 00:00	20:07:46.02	-14:26:05.9	HIP 99228	16.21
2026-09-29 12:00	20:07:45.35	-14:26:10.4	HIP 99228	16.38
2026-09-30 00:00	20:07:44.69	-14:26:15.0	HIP 99228	16.55
2026-09-30 12:00	20:07:44.04	-14:26:19.5	HIP 99228	16.72
2026-10-01 00:00	20:07:43.41	-14:26:24.0	HIP 99228	16.88
2026-10-01 12:00	20:07:42.79	-14:26:28.5	HIP 99228	17.04
2026-10-02 00:00	20:07:42.19	-14:26:32.9	HIP 99228	17.20
2026-10-02 12:00	20:07:41.59	-14:26:37.3	HIP 99228	17.36
2026-10-03 00:00	20:07:41.02	-14:26:41.6	HIP 99228	17.51
2026-10-03 12:00	20:07:40.45	-14:26:46.0	HIP 99228	17.66
2026-10-04 00:00	20:07:39.90	-14:26:50.2	HIP 99228	17.81
2026-10-04 12:00	20:07:39.37	-14:26:54.5	HIP 99228	17.95
2026-10-05 00:00	20:07:38.85	-14:26:58.7	HIP 99228	18.10
2026-10-05 12:00	20:07:38.34	-14:27:02.9	HIP 99228	18.23
2026-10-06 00:00	20:07:37.84	-14:27:07.0	HIP 99228	18.37
2026-10-06 12:00	20:07:37.36	-14:27:11.1	HIP 99228	18.50
2026-10-07 00:00	20:07:36.90	-14:27:15.1	HIP 99228	18.63
2026-10-07 12:00	20:07:36.45	-14:27:19.2	HIP 99228	18.76
2026-10-08 00:00	20:07:36.01	-14:27:23.1	HIP 99228	18.88
2026-10-08 12:00	20:07:35.58	-14:27:27.1	HIP 99228	19.00
2026-10-09 00:00	20:07:35.18	-14:27:31.0	HIP 99228	19.12
2026-10-09 12:00	20:07:34.78	-14:27:34.8	HIP 99228	19.24
2026-10-10 00:00	20:07:34.40	-14:27:38.6	HIP 99228	19.35
2026-10-10 12:00	20:07:34.03	-14:27:42.4	HIP 99228	19.46
2026-10-11 00:00	20:07:33.68	-14:27:46.2	HIP 99228	19.56