TITLE:   GCN CIRCULAR
NUMBER:  30273
SUBJECT: GRB 210619B: KAIT Optical Detection
DATE:    21/06/20 13:48:29 GMT
FROM:    Weikang Zheng at UC Berkeley  <weikang@berkeley.edu>

WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on

behalf of the KAIT GRB team:


The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at

Lick Observatory, responded to the Swift GRB 210619B (D'Avanzo et al.,

GCN 30261) starting at ~8.05 hours after the Swift trigger.

A total of 60x60s images were obtained in the clear (roughly R)

filter. The optical afterglow (D'Avanzo et al., GCN 30261; Lipunov et al.,

GCN 30262; Jelinek et al., GCN 30263; Kong, GCN 30265; Pellegrin et al.,

GCN 30268; Perley, GCN 30271) was clearly detected in each single image.

We measured its brightness of 18.5 +/- 0.1 mag at 8.05 hours after burst,

and decayed to be 18.8 +/- 0.1 mag at 11.07 hours after burst, calibrated

to the Pan-STARRS1 catalog.