Xianggao Wang (UC Berkeley, GXU, UNLV), 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) at
Lick Observatory responded to Swift GRB 150811A (Evans et al.,
GCN 18119) starting at 04:09:05 UT, 176 s 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. Due to a focus problem, the first useful image
started at about 364 s after burst, and observations lasted
about 5.5 hours later. The optical afterglow (Butler et al.,
GCN 18120; GCN 18132, Zheng et al., GCN 18121, Kuin et al., GCN
18122; 18131, Japelj et al., GCN 12123, Perley & Cenko, GCN 12125,
Moskivitin, GCN 12128) was well detected in I filters.
We confirm the peak of the OT around ~13 m reported by
Perley & Cenko (GCN 12125). After 3 ks after the burst, the
light curve can be fit by a power law with index of -1.02,
consistent with the value reported by Butler et al. (GCN 18132).
A preliminary light curve is posted at: