[vsnet-grb-info 16902] KAIT Optical Upper Limits for GRB 120422A, 120724A, 120803B, 120911A, and 120923A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18183
SUBJECT: KAIT Optical Upper Limits for GRB 120422A, 120724A, 120803B, 120911A, and 120923A
DATE:    15/08/20 18:55:59 GMT
FROM:    Xiang-Gao Wang at GuangXi U  <wangxg at gxu.edu.cn>

Xianggao Wang (UC Berkeley, GXU, UNLV), WeiKang Zheng,
Alexei V. Filippenko (UC Berkeley), and S. Bradley Cenko
(GSFC) report on behalf of the KAIT GRB team:

The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to Swift GRBs 120422A (Troja et al.,
GCN 13243), 120724A (D'Avanzo et al., GCN 13510), 120803B
(Racusin et al. GCN 13566), 120911A (Cannizzo et al., GCN 13744),
and 120923A (Yershov et al., GCN 13796) at 510 s, 202 s, 196 s, 147 s,
and 236 s after the burst, respectively. Observations were performed
with an automatic sequence in the clear (roughly R), V, and I filters,
and the exposure time was 20 s per image. We do not detect any new 
sources within the XRT error circles. We estimate the following upper 
limits (magnitudes) in clear-band images for each GRB calibrated to 
USNO B1.0:

GRB       Start-Time  Coadd-Images  Mid-time   Upper-Limit (3 sigma)
120422A   510 s        20 s x 6           758 s              20.6
120724A   202 s        20 s x 10         647 s              20.7
120803B   196 s        20 s x 10         644 s              21.7
120911A   147 s        20 s x 6          501 s               20.9
120923A   236 s        20 s x 6          563 s               21.0