GCN Circular 20870

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

J.Y. Wei (NAOC), X.H. Han (NAOC), C. WU (NAOC), N. Leroy (LAL),
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),
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 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.