WeiKang Zheng 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 180620A (Evans et al.,
GCN 22798) starting at 08:37:19 UT, 141s 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 3 hours.
The optical afterglow (Evans et al., GCN 22790; Butler et al.,
GCN 22799; Elenin et al., GCN 22800; Tyurina et al., GCN 22801;
Guidorzi et al., GCN 22803; Breeveld et al., GCN 22805;
Watson et al., GCN 22806; Zhu et al., GCN 22811) 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 300s (also seen by Butler et al. GCN 22799; Watson et al.,
GCN 22806). After that the light curve shows monotonic decay,
followed by a flat phase between ~1ks to ~3ks.
A preliminary light curve is posted at: