LIGO/Virgo G277583: SVOM/Mini-GWAC observations of the initial skymap

We observed about 4800 square degree (12 sky regions) of the skymap of the advanced LIGO trigger G277583, with SVOM/Mini-GWAC, at Xinglong Observatory of NAOC equipped with U9000 camera (FOV~400 square degree/camera). SVOM/Mini-GWAC comprises 8 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 46.9% prior probability that these 12 regions contain the true location of the source. The coordinates of the 12 regions and observation time are list following: start-obs(UTC) end-obs(UTC) Ra Dec Camera_ID 2017-03-14 11:10:29 2017-03-14 17:59:02 09:10:29.8 +29:50:17 C1 2017-03-14 11:10:55 2017-03-14 17:59:54 09:13:10.6 +10:17:08 C2 2017-03-14 11:10:45 2017-03-14 16:40:29 07:46:15.6 +29:57:47 C3 2017-03-14 16:50:46 2017-03-14 21:30:00 16:14:18.2 +30:03:36 C3 2017-03-14 11:10:45 2017-03-14 16:40:01 07:50:25.4 +09:54:53 C4 2017-03-14 16:50:38 2017-03-14 21:30:00 16:18:18.2 +09:59:04 C4 2017-03-14 11:10:30 2017-03-14 13:33:01 04:55:10.8 +29:25:59 C5 2017-03-14 13:34:31 2017-03-14 21:30:00 14:36:21.1 +69:30:06 C5 2017-03-14 11:10:11 2017-03-14 13:33:39 04:58:00.5 +10:28:12 C6 2017-03-14 13:34:09 2017-03-14 21:30:00 14:40:07.7 +50:29:58 C6 2017-03-14 12:45:41 2017-03-14 14:56:37 06:18:37.7 +29:46:06 C7 2017-03-14 12:45:01 2017-03-14 15:56:16 06:20:02.3 +10:21:24 C8 The first image was taken ~12 hours 30 minutes after the event trigger. Note that the observations have been done under poor conditions (partly cloudy and full moon). The limit magnitude is ~10 mag in R band. No any significant transient is found in our online pipeline. The image analysis is ongoing in detailed processing with our offline pipeline.