TITLE:   GCN CIRCULAR
NUMBER:  21117
SUBJECT: GRB 170519A: BOOTES-5/JGT early optical detection
DATE:    17/05/19 22:58:31 GMT
FROM:    Alberto Castro-Tirado at Inst.de Astro. de Andalucia  <ajct@iaa.es>

A. J. Castro-Tirado (IAA-CSIC & ISA-UMA), J. C. Tello, R. Cunniffe, 
B.-B. Zhang, Y. Hu and A. Gonzalez-Rodriguez (IAA-CSIC), A. Castellon 
(Univ. de Malaga), D. Hiriart, W. H. Lee (UNAM), S. Jeong and I. H. Park (SKKU)
and P. Kubanek (Inst. of Physics, CZ) on behalf of a larger collaboration, report:

The 60 cm BOOTES-5/Javier Gorosabel Telescope at Observatorio 
Astronómico Nacional in San Pedro Mártir (México) automatically 
responded to the Swift trigger of GRB 170519A (Ukwatta et al., GCN 
21106). The first unfiltered images (60 s exposures) were obtained at 
05:15:08.9 UT (5 min after the burst). At the position of the Swift 
X-ray afterglow, we confirm the optical afterglow detected by UVOT, at a 
magnitude of 16.6+/-0.1 when compared to the GSC2.3 catalog, and fading 
during the late-time BOOTES-5/JGT observation.

We thank the staff at Observatorio Astronómico Nacional in San Pedro 
Mártir for its excellent support.

[GCN OPS NOTE(19may17),  At the request of the author, the last 3 authors
were added.]