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GCN Circular 26386

Subject
LIGO/Virgo S191205ah: no counterpart candidate in SVOM/GWAC observations
Date
2019-12-10T16:38:16Z (4 years ago)
From
Raphael Duque at Institut d'Astrophysique de Paris <duque@iap.fr>
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.
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