[vsnet-grb-info 23541] LIGO/Virgo S190901ap : SVOM/GWAC-F60A observation of transient ZTFabvizsw

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25640
SUBJECT: LIGO/Virgo S190901ap : SVOM/GWAC-F60A observation of transient ZTFabvizsw
DATE:    19/09/04 01:42:35 GMT
FROM:    Liping Xin at NAOC, SVOM  <xlp at nao.cas.cn>

J. Y. Wei (NAOC), L. P. Xin (NAOC), S. Antier (CNRS/APC), J. Wang (GXU),
N. Leroy (CNRS/LCL), D. Turpin (NAOC)

on behalf of the SVOM Multi Messenger Astronomy and GWAC teams:
http://www.svom.fr/en/svom-mma-and-gwac-team

We used the 60cm SVOM/GWAC-F60A telescope to observe the transient found
by the Zwicky Transient Facility ZTF19abvizsw (Kool et al. GCN 25616)
localized in the region of the gravitational wave trigger S190901ap
(LVC et al. GCN 25606, GCN 25614) during 17:28:07 and 18:45:07 UT on 02th,
Sep. 2019.  

After stacking the images for 31*150 sec, the source was detected with a
brightness of R=20.53+/-0.16 mag calibrated by nearby USNO R2 magnitudes.
Comparing with the reported by Kool et al., GCN 25616, the source was
fading for about one magnitude. 

Considering its fast decay, a featureless  continuum superimposed 
with a number of narrow absorption lines and the large distance of z=1.26
(Burdge et al., GCN 25639), it is possible an orphan GRB afterglow.

The stacked image observed by GWAC-F60A is shown here,
http://cmm.svom.cn/gwpub/O3/S190901ap/ZTF19abvizsw_F60_findingchart.png
(user:svomo3 pwd:gwo3)

SVOM/GWAC-F60A is a dedicated telescope for  follow-ups of SVOM/GWAC
system, and is operated by Guangxi university and NAOC, CAS, at Xinglong
observatory, China.