TITLE:   GCN CIRCULAR
NUMBER:  21115
SUBJECT: GRB 170519A: KAIT Optical Observations
DATE:    17/05/19 18:44:38 GMT
FROM:    Weikang Zheng at UC Berkeley  <weikang@berkeley.edu>

WeiKang Zheng, Max Genecov, and Alex Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:

The 0.76-m Katzman Automatic Imaging Telescope (KAIT) at
Lick Observatory responded to Swift GRB 170519A (Ukwatta et al.,
GCN 21106) starting at 05:14:24 UT, 262s after the burst.
Observations were performed with an automatic sequence in the
V, I, and clear (roughly R) filters, and the exposure time was
20 s per image, observations lasted about 2 hours.
The optical afterglow (Ukwatta et al., GCN 21106; Izzo et al.,
GCN 21108; Butler et al., GCN 21109; Guidorzi et al., GCN 21110;
Xu et al., GCN 21111; Hentunen & Nissinen, GCN 21113) was well
detected in our V, I and clear filter images. A preliminary
analysis shows that the afterglow rises at early time and peaked
around 1 ks. After 3 ks after the burst, the light curve can be
fitted by a power law with index of -0.83.
A preliminary light curve is posted at:
http://astro.berkeley.edu/~zwk/grb/GRB170519A/GRB170519A_kait.png