メタデータ

項目	値
Designation	C/2020 Y2 (ATLAS)
Type	C
Perihelion (tp_cal, UTC)	2022-06-17T16:46:06.738240Z
Orbit solution date (soln_date, UTC)	2024-12-26T20:12:24Z
Obs used	1775
NEO	-
M1	10.500
K1	4.500
PC	-
Discovery observation (MPC, UTC)	2020-12-28T15:18:23.155200Z
Discovery magnitude (MPC)	18.30 o
Discovery observatory (MPC)	T08 · ATLAS-MLO, Mauna Loa

オスキュレーティング軌道要素

項目	値
Epoch (epoch_cal, TDB)	2022-09-03.0000000
e	0.99700512
q (au)	3.132490
a (au)	1045.948256
i (deg)	101.297766
Ω (om, deg)	26.515016
ω (w, deg)	266.105810
M (ma, deg)	0.002252

等級

散乱 + 全体線形

$$ M_a = (11.072 + 2.941\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$

モデル定数

項目	値
H0	11.072
n	2.941
gf	1.000
gb	-0.718
k	0.800
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
2020-03-25	2021-01-29	+12.9145	-9.677
2021-01-29	2021-05-17	-5.4955	+4.015
2021-05-17	2022-06-01	-2.1125	+1.423
2022-06-19	2023-12-12	-1.0342	+0.680
2023-12-12	2024-10-29	+16.6054	-12.913

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)
2026-06-01 00:00	00:57:17.28	+30:21:55.6	HIP 4531	10.00
2026-06-01 12:00	00:57:21.54	+30:23:36.8	HIP 4531	9.82
2026-06-02 00:00	00:57:25.74	+30:25:18.1	HIP 4531	10.03
2026-06-02 12:00	00:57:29.87	+30:26:59.3	HIP 4531	10.60
2026-06-03 00:00	00:57:33.93	+30:28:40.5	HIP 4531	11.46
2026-06-03 12:00	00:57:37.92	+30:30:21.6	HIP 4531	12.57
2026-06-04 00:00	00:57:41.85	+30:32:02.7	HIP 4531	13.84
2026-06-04 12:00	00:57:45.71	+30:33:43.7	HIP 4531	15.25
2026-06-05 00:00	00:57:49.50	+30:35:24.7	HIP 4531	16.75
2026-06-05 12:00	00:57:53.23	+30:37:05.7	HIP 4531	18.32
2026-06-06 00:00	00:57:56.88	+30:38:46.5	HIP 4531	19.94
2026-06-06 12:00	00:58:00.47	+30:40:27.4	HIP 4531	21.60
2026-06-07 00:00	00:58:03.98	+30:42:08.1	HIP 4531	23.29
2026-06-07 12:00	00:58:07.42	+30:43:48.8	HIP 4531	24.99
2026-06-08 00:00	00:58:10.79	+30:45:29.4	HIP 4531	26.71
2026-06-08 12:00	00:58:14.09	+30:47:09.9	HIP 4531	28.44
2026-06-09 00:00	00:58:17.32	+30:48:50.4	HIP 4531	30.18
2026-06-09 12:00	00:58:20.48	+30:50:30.7	HIP 4531	31.92
2026-06-10 00:00	00:58:23.56	+30:52:11.0	HIP 4531	33.67
2026-06-10 12:00	00:58:26.57	+30:53:51.2	HIP 4469	35.37
2026-06-11 00:00	00:58:29.51	+30:55:31.3	HIP 4469	34.14
2026-06-11 12:00	00:58:32.37	+30:57:11.2	HIP 4469	32.96
2026-06-12 00:00	00:58:35.15	+30:58:51.1	HIP 4469	31.82
2026-06-12 12:00	00:58:37.86	+31:00:30.8	HIP 4469	30.74
2026-06-13 00:00	00:58:40.50	+31:02:10.5	HIP 4469	29.71
2026-06-13 12:00	00:58:43.06	+31:03:50.0	HIP 4469	28.75
2026-06-14 00:00	00:58:45.54	+31:05:29.3	HIP 4469	27.85
2026-06-14 12:00	00:58:47.95	+31:07:08.6	HIP 4469	27.02
2026-06-15 00:00	00:58:50.27	+31:08:47.7	HIP 4469	26.27
2026-06-15 12:00	00:58:52.52	+31:10:26.7	HIP 4469	25.60
2026-06-16 00:00	00:58:54.69	+31:12:05.5	HIP 4469	25.02
2026-06-16 12:00	00:58:56.78	+31:13:44.1	HIP 4469	24.53
2026-06-17 00:00	00:58:58.80	+31:15:22.7	HIP 4469	24.14
2026-06-17 12:00	00:59:00.73	+31:17:01.0	HIP 4469	23.85
2026-06-18 00:00	00:59:02.58	+31:18:39.2	HIP 4469	23.66
2026-06-18 12:00	00:59:04.36	+31:20:17.2	HIP 4469	23.57
2026-06-19 00:00	00:59:06.05	+31:21:55.0	HIP 4469	23.58
2026-06-19 12:00	00:59:07.66	+31:23:32.7	HIP 4469	23.70
2026-06-20 00:00	00:59:09.19	+31:25:10.2	HIP 4469	23.91
2026-06-20 12:00	00:59:10.64	+31:26:47.5	HIP 4469	24.22
2026-06-21 00:00	00:59:12.00	+31:28:24.6	HIP 4469	24.61
2026-06-21 12:00	00:59:13.29	+31:30:01.5	HIP 4670	23.25
2026-06-22 00:00	00:59:14.49	+31:31:38.2	HIP 4670	21.68