メタデータ

項目	値
Designation	C/2023 C2 (ATLAS)
Type	C
Perihelion (tp_cal, UTC)	2024-11-16T18:43:11.533440Z
Orbit solution date (soln_date, UTC)	2026-03-21T13:42:21Z
Obs used	1931
NEO	-
M1	10.900
K1	4.500
PC	0.030
Discovery observation (MPC, UTC)	2023-02-01T06:05:54.758400Z
Discovery magnitude (MPC)	19.12 o
Discovery observatory (MPC)	W68 · ATLAS Chile, Rio Hurtado

オスキュレーティング軌道要素

項目	値
Epoch (epoch_cal, TDB)	2025-03-14.0000000
e	0.99899777
q (au)	2.368470
a (au)	2363.190867
i (deg)	48.322061
Ω (om, deg)	301.004729
ω (w, deg)	357.444244
M (ma, deg)	0.001006

等級

散乱 + 全体線形

$$ M_a = (10.561 + 2.905\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$

モデル定数

項目	値
H0	10.561
n	2.905
gf	0.992
gb	-0.668
k	0.885
δ90	9.638

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
2023-02-01	2024-02-08	+0.2191	+0.133
2024-02-08	2024-04-08	+2.8811	-1.308
2024-04-08	2024-11-13	+2.7043	-1.406
2024-11-28	2025-10-02	-1.0594	+0.561
2025-10-02	2026-03-21	-9.8774	+6.153

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)
2026-03-26 00:00	00:33:39.35	+50:20:44.9	HIP 2602	10.53
2026-03-26 12:00	00:34:17.80	+50:23:01.9	HIP 2602	13.55
2026-03-27 00:00	00:34:56.24	+50:25:19.7	HIP 2602	18.47
2026-03-27 12:00	00:35:34.68	+50:27:38.3	HIP 2602	24.16
2026-03-28 00:00	00:36:13.10	+50:29:57.6	HIP 2921	24.30
2026-03-28 12:00	00:36:51.52	+50:32:17.7	HIP 2921	25.47
2026-03-29 00:00	00:37:29.94	+50:34:38.5	HIP 2921	28.18
2026-03-29 12:00	00:38:08.34	+50:37:00.1	HIP 3080	26.35
2026-03-30 00:00	00:38:46.74	+50:39:22.3	HIP 3080	22.50
2026-03-30 12:00	00:39:25.13	+50:41:45.3	HIP 3080	20.06
2026-03-31 00:00	00:40:03.50	+50:44:09.0	HIP 3217	17.07
2026-03-31 12:00	00:40:41.87	+50:46:33.5	HIP 3217	12.79
2026-04-01 00:00	00:41:20.23	+50:48:58.6	HIP 3217	10.99
2026-04-01 12:00	00:41:58.58	+50:51:24.4	HIP 3217	12.74
2026-04-02 00:00	00:42:36.92	+50:53:50.9	HIP 3217	16.98
2026-04-02 12:00	00:43:15.25	+50:56:18.1	HIP 3217	22.34
2026-04-03 00:00	00:43:53.57	+50:58:46.0	HIP 3217	28.17
2026-04-03 12:00	00:44:31.88	+51:01:14.6	HIP 3698	27.52
2026-04-04 00:00	00:45:10.17	+51:03:43.8	HIP 3698	21.21
2026-04-04 12:00	00:45:48.46	+51:06:13.7	HIP 3698	15.10
2026-04-05 00:00	00:46:26.73	+51:08:44.3	HIP 3698	9.56
2026-04-05 12:00	00:47:04.99	+51:11:15.5	HIP 3698	6.30
2026-04-06 00:00	00:47:43.23	+51:13:47.4	HIP 3703	8.05
2026-04-06 12:00	00:48:21.46	+51:16:19.9	HIP 3736	10.93
2026-04-07 00:00	00:48:59.68	+51:18:53.0	HIP 3736	12.27
2026-04-07 12:00	00:49:37.89	+51:21:26.8	HIP 3956	10.91
2026-04-08 00:00	00:50:16.08	+51:24:01.3	HIP 3956	4.95
2026-04-08 12:00	00:50:54.25	+51:26:36.4	HIP 3956	3.80
2026-04-09 00:00	00:51:32.41	+51:29:12.1	HIP 4023	5.09
2026-04-09 12:00	00:52:10.55	+51:31:48.4	HIP 4023	6.23
2026-04-10 00:00	00:52:48.68	+51:34:25.3	HIP 4023	11.64
2026-04-10 12:00	00:53:26.79	+51:37:02.8	HIP 4161	15.96
2026-04-11 00:00	00:54:04.88	+51:39:41.0	HIP 4161	15.69
2026-04-11 12:00	00:54:42.96	+51:42:19.8	HIP 4161	17.89
2026-04-12 00:00	00:55:21.02	+51:44:59.1	HIP 4161	21.84
2026-04-12 12:00	00:55:59.06	+51:47:39.1	HIP 4161	26.76
2026-04-13 00:00	00:56:37.08	+51:50:19.6	HIP 4523	21.60
2026-04-13 12:00	00:57:15.08	+51:53:00.7	HIP 4523	16.44
2026-04-14 00:00	00:57:53.06	+51:55:42.4	HIP 4523	12.51
2026-04-14 12:00	00:58:31.01	+51:58:24.7	HIP 4523	11.19
2026-04-15 00:00	00:59:08.95	+52:01:07.5	HIP 4523	13.29
2026-04-15 12:00	00:59:46.87	+52:03:51.0	HIP 4766	13.45
2026-04-16 00:00	01:00:24.76	+52:06:34.9	HIP 4766	8.28