TITLE: GCN CIRCULAR NUMBER: 20369 SUBJECT: LIGO/Virgo G268556: observation regions by Project Mini-GWAC of SVOM DATE: 17/01/05 15:52:45 GMT FROM: Chao Wu at NAOC J.Y. Wei (NAOC), X.H. Han (NAOC), N.Leroy (LAL), C. WU (NAOC), S. Antier (LAL), L.P. Xin (NAOC), X.M. Meng (NAOC), L. Huang (NAOC), Y. Xu (NAOC), H.B. Cai (NAOC), J. Wang (NAOC), X.M. Lu (NAOC), Y.L. Qiu (NAOC), J.S. Deng (NAOC), L. Cao (NAOC), S. Wang (NAOC), E.W.Liang (GXU), Y.G. Yang (HBNU), B. Cordier (CEA), S.N. Zhang (NAOC), S. Basa (LAM), B.B. Wu (IHEP), Jean-Luc Atteia (IRAP), D. Götz (CEA), C. Lachaud (APC) on behalf of the SVOM Gravitational Astronomy group report: We observed about 5600 square degree (14 sky regions) of the skymap of the advanced LIGO trigger G268556, with Mini-GWAC (Mini Ground Wide Angle Camera), at Xinglong Observatory of NAOC equipped with U9000 camera (FOV~400 square degree/camera). Mini-GWAC, as a part of ground instruments of SVOM mission, comprises 12 wide field angle cameras (aperture=7cm), working with unfiltered band. The observations are operated in time-series mode, taking one exposure in 15 seconds (10s exposure + 5s readout). The limit magnitude is ~12 mag in R band. We estimate a 84.4% prior probability that these 14 regions contain the true location of the source. The coordinates of the 14 regions and observation time are list following: Ra Dec Camera_ID start-obs(UTC) end-obs(UTC) Camera_ID start-obs(UTC) end-obs(UTC) 07:46:49.578 +29:35:33.46 C1 12:30:41.1 13:49:41.5 C3 19:14:39.9 21:17:22:8 07:48:54.239 +10:34:56.09 C2 12:30:41.1 13:49:49.5 C4 19:14:39.9 21:17:36.8 09:10:51.599 +29:36:54.60 C1 13:50:29.3 15:14:52.1 09:12:54.096 +10:36:25.88 C2 13:50:29.3 15:14:44.2 10:34:57.404 +29:33:02.67 C1 15:15:28.4 16:22:20.7 10:36:57.072 +10:32:32.51 C2 15:15:28.4 16:22:07.9 09:17:21.644 +69:37:03.40 C1 19:14:27.3 22:39:37.7 09:21:25.794 +50:35:59.26 C2 19:14:27.3 22:39:25.3 11:52:01.006 +70:06:03.83 C3 16:21:28.7 17:57:31.9 C5 19:14:32.9 22:39:31.9 12:02:07.741 +50:03:10.98 C4 16:22:17.5 17:57:30.2 C6 19:14:32.9 22:39:25.2 06:34:42.357 +69:28:01.79 C5 14:55:58.2 17:57:22.7 06:40:16.529 +50:28:28.89 C6 14:56:10.4 17:57:35.7 14:34:10.239 +70:01:52.84 C7 19:14:55.3 22:39:18.3 14:44:41.102 +49:56:05.18 C8 19:14:55.3 22:39:21.9 Mini-GWAC is working in sky survey mode. The first image was taken 2 hours 20 minutes after event. No any significant transient is found in our online pipeline. The image analysis is ongoing in detailed processing with our offline pipeline. Further observations of these fields are planned.