Difference: GCNCIRCULAR20745 ( vs. 1)

J.Y. Wei (NAOC), X.H. Han (NAOC), X.M. Meng (NAOC), N. Leroy (LAL), S. Antier (LAL), C. WU (NAOC), L.P. Xin (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), L. Jia (NAOC), S.C. Zou (NAOC), S.F. Liu (NAOC), Q.C. Feng (NAOC), H.L. Li (NAOC), D.W. Xu (NAOC), Y.J. Xiao (NAOC), W.L. Dong (NAOC), Y.T. Zheng (NAOC), E.W.Liang (GXU), X.G.Wang (GXU), Y.G. Yang (HBNU), B. Cordier (CEA), S.N. Zhang (NAOC), D. Dornic (CPPM), B.B. Wu (IHEP), J.L. Atteia (IRAP), D. G?tz (CEA), C.Lachaud (APC), on behalf of the SVOM Gravitational Astronomy group report:

We observed about 3200 square degree (8 sky regions) of the skymap of the advanced LIGO trigger G275404, with SVOM/Mini-GWAC, at Xinglong Observatory of NAOC equipped with U9000 camera (FOV~400 square degree/camera). SVOM/Mini-GWAC 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 46.6% prior probability that these 8 regions contain the true location of the source.

The coordinates of the 8 regions and observation time are list following:

start-obs(UTC) end-obs(UTC) Ra Dec Camera_ID
2017-02-25 19:23:51.9 2017-02-25 20:41:04.7 10:33:59.6 +30:12:22 C3
2017-02-25 19:23:51.9 2017-02-25 20:41:06.2 10:38:05.6 +10:07:57 C4
2017-02-25 19:23:42.2 2017-02-25 22:13:19.6 17:18:04.0 +69:28:00 C5
2017-02-25 19:23:44.7 2017-02-25 22:13:38.0 17:21:47.1 +50:28:32 C6
2017-02-25 13:01:04.2 2017-02-25 21:37:38.1 09:21:25.5 +69:40:01 C7
2017-02-25 13:01:04.2 2017-02-25 21:37:39.7 09:23:01.6 +50:00:25 C8
2017-02-25 21:39:38.3 2017-02-25 22:13:28.5 20:00:36.6 +69:38:42 C7
2017-02-25 21:39:38.3 2017-02-25 22:13:25.5 20:01:12.7 +50:00:21 C8

The first image (which is covered in our routine survey) was taken ~5 hours 29 minutes before the event trigger. No any significant transient is found in our online pipeline. The image analysis is ongoing in detailed processing with our offline pipeline.

-- ThomasKupfer - 27 Feb 2017