TITLE: GCN CIRCULAR NUMBER: 27406 SUBJECT: LIGO/Virgo S200316bj: no counterpart candidate in SVOM/GWAC observations DATE: 20/03/18 13:23:05 GMT FROM: Nicolas Dagoneau at CEA/IRFU/DAp/SVOM J. Wang (GXU), N. Dagoneau (CEA/AIM), J. Y. Wei (NAOC), S.Schanne(CEA/AIM), X. H. Han (NAOC) report on behalf of the SVOM Multi Messenger Astronomy and GWAC teams (http://www.svom.fr/en/svom-mma-and-gwac-team): We observed 10 (~1500 square deg) sky regions to cover the skymap of the advanced LIGO/Virgo trigger S200316bj (GCN # 27388), with SVOM/GWAC, at Xinglong Observatory. SVOM/GWAC is equipped with two sets of wide angle cameras: - FFOV cameras (FOV~900 square degrees/camera, aperture = 3.5 cm), - JFOV cameras (FOV~150 square degrees/camera, aperture = 18 cm). SVOM/GWAC currently comprises 4 FFOV cameras and 16 JFOV cameras, working in the unfiltered band. The observations are operated in time-series mode, taking one exposure every 25 seconds (20s exposure + 5s readout). The observed and processed regions enclosed an estimated 63% of the probability of the advanced LIGO/Virgo skymap. Images were taken between ~13.5 hours and ~17.5 hours after the GW trigger time. The coordinates of the 10 sky regions observed and their observation times and covered probability are listed below: Id Ra Dec start (UTC) end (UTC) Proba. Cam. 1 02:34:09.77 30:19:13.80 2020-03-17 11:39:57 2020-03-17 11:54:32 0.015 JFOV 2 03:31:10.58 30:35:14.64 2020-03-17 11:26:26 2020-03-17 11:54:32 0.108 JFOV 3 03:29:18.05 18:22:54.48 2020-03-17 11:26:26 2020-03-17 11:54:32 0.008 JFOV 4 02:36:20.71 18:10:29.28 2020-03-17 11:47:14 2020-03-17 11:53:43 0.032 JFOV 5 04:06:14.40 47:32:12.84 2020-03-17 12:14:47 2020-03-17 12:20:51 0.055 JFOV 6 04:01:13.15 35:21:24.84 2020-03-17 11:57:21 2020-03-17 12:24:30 0.075 JFOV 7 04:37:03.24 48:22:58.44 2020-03-17 11:50:53 2020-03-17 11:53:43 0.077 JFOV 8 05:47:55.37 47:51:16.92 2020-03-17 11:46:51 2020-03-17 11:50:53 0.353 JFOV 9 05:38:05.45 36:07:21.72 2020-03-17 11:50:30 2020-03-17 11:53:44 0.005 JFOV 10 06:03:29.86 48:27:41.40 2020-03-17 11:56:37 2020-03-17 11:57:01 0.342 JFOV The sky coverage map is available at: http://cmm.svom.cn/gwpub/O3/S200316bj/S200316bj.png (user:svomo3 pwd:gwo3). Weather conditions were clear during the observations. An average 3-sigma limiting magnitude of 16 mag in the R band was obtained in the single frames. No credible new source was detected by our online pipeline during follow-up observations. A more detailed image analysis including co-addition is ongoing with our offline pipeline to search for transient.