TITLE:   GCN CIRCULAR
NUMBER:  40400
SUBJECT: GRB 250507A: KAIT optical upper limit
DATE:    25/05/08 18:37:31 GMT
FROM:    Weikang Zheng at UC Berkeley <weikang@berkeley.edu>

WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and

Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team:


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

Lick Observatory, observed the field of SVOM GRB 250507A (Wang

et al., GCN 40374) starting at 06:37:30, May 07 UT, 165 seconds

after the burst. Observations were performed in 3 x 3 tiling mode,

and a set of clear (roughly R) filter images were obtained.

Preliminary analysis do not reveal any new optical counterpart

candidate within the X-ray afterglow error circles (Maggi et al.,

GCN 40381; Zhang et al., GCN 40385; Osborne et al., GCN 40389),

neither in single image, nor in the co-add images. We estimate

the limiting magnitude of our coadd image to be ~20.0 mag at a

mid-time of 15.0 minutes after the burst, consistent with the

upper limit reported by other groups (Ducoin et al., GCN 40376;

Xin et al., GCN 40379; Brivio et al., GCN 40380)