TITLE:   GCN CIRCULAR
NUMBER:  21111
SUBJECT: GRB 170519A: Weihai optical observations
DATE:    17/05/19 14:41:03 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

D. Xu, Z.P. Zhu, H.X. Feng (NAOC), C.M. Zhang, S.M. Hu (SDU), Y.D. Hu 
(IAA-CSIC), Y. Qin (Geneva Observatory) report:

We observed the field of GRB 170519A (Ukwatta et al., GCN 21106) using 
the 1-m telescope located at Weihai, Shandong, China. We obtained 4x360s 
frames in the Sloan r-filter, starting at 11:52:54 UT on 2017-05-19, 
i.e., 6.71 hr after the burst.

The optical afterglow (Ukwatta et al., GCN 21106; Izzo et al., GCN 
21108) is clearly detected in our stacked image, and it has decayed to 
m(r) = 18.92 +/- 0.06 at 6.94 hr post-burst, calibrated with nearby SDSS 
stars.