TITLE: GCN CIRCULAR NUMBER: 26386 SUBJECT: LIGO/Virgo S191205ah: no counterpart candidate in SVOM/GWAC observations DATE: 19/12/10 16:38:16 GMT FROM: Raphael Duque at Institut d'Astrophysique de Paris D. Dornic (CNRS/CPPM), X. Han (NAOC), D. Gotz (CEA/AIM), J.R. Mao (YNAO), S.S. Sun (GXU), R. Duque (CNRS/IAP) report on behalf of the SVOM Multi Messenger Astronomy and GWAC teams (http://www.svom.fr/en/svom-mma-and-gwac-team): We observed 12 150-sq. deg sky regions to cover the skymap of the advanced LIGO/Virgo trigger S191205ah (GCN #26350), 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 25.9% of the probability of the advanced LIGO/Virgo skymap. Images were taken between ~7 minutes and ~22.5 hours after the GW trigger time. The coordinates of the 12 sky regions observed after the trigger and their observation times and covered probability are listed below: Id Ra Dec start (UTC) end (UTC) Cov. Cam. 1 12:05:32.64 -03:22:57.94 19-12-05 21:59:09 19-12-05 22:20:13 0.7% JFOV 2 08:16:07.92 -14:28:35.7 19-12-06 16:32:38 19-12-06 16:37:05 0.3% JFOV 3 10:39:20.16 02:31:31.94 19-12-06 17:21:46 19-12-06 17:49:41 1.9% JFOV 4 10:07:08.40 18:26:41.64 19-12-06 17:08:21 19-12-06 17:37:50 0.8% JFOV 5 11:06:05.52 14:50:59.28 19-12-06 18:31:04 19-12-06 18:49:16 1.3% JFOV 6 10:52:45.12 01:28:54.44 19-12-06 20:32:32 19-12-06 21:02:13 2.6% JFOV 7 18:56:49.68 63:55:28.92 19-12-06 11:33:20 19-12-06 11:57:39 0.1% JFOV 8 19:13:00.96 52:01:22.44 19-12-06 11:41:51 19-12-06 11:57:39 0.3% JFOV 9 21:39:30.48 -15:41:03.1 19-12-06 10:19:18 19-12-06 10:47:15 2.7% JFOV 10 22:40:14.64 18:12:15.48 19-12-06 11:01:14 19-12-06 12:31:10 1.7% JFOV 11 22:52:48.48 01:15:04.39 19-12-06 09:48:02 19-12-06 10:15:59 6.9% JFOV 12 23:05:58.80 14:37:07.68 19-12-06 11:53:33 19-12-06 12:08:33 9.4% JFOV The sky coverage map is available at: http://cmm.svom.cn/gwpub/O3/S191205ah/S191205ah.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 candidates.