TITLE:   GCN CIRCULAR
NUMBER:  21120
SUBJECT: GRB 170519A: NOT optical observations
DATE:    17/05/19 23:53:45 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D. Xu (NAOC), 
D. Malesani (DARK/NBI), K.E. Heintz (DARK/NBI), 
D. Gandolfi (Univ. Turin), and J. Telting (NOT) report on behalf 
of a larger collaboration,

We have observed the field of GRB 170519A (Ukwatta et al., 
GCN 21106) with the 2.5m Nordic Optical Telescope at La 
Palma (Spain). The observations consisted of 3x120s in V-band 
and 5x120s in Sloan i-band. The GRB afterglow is well detected in 
all the individual frames. On an image starting at 21:51 UT (16.68 hr 
after the burst) we detect the optical afterglow at i(AB) = 19.7 mag, 
as compared to SDSS field stars. This confirms the t^(-0.8) decay 
reported by Butler et al. (GCN 21109) and by Zheng et al. 
(GCN 21115) that started 900 s after the GRB trigger.