TITLE:   GCN CIRCULAR
NUMBER:  42917
SUBJECT: EP251130a: KAIT optical observations
DATE:    25/12/01 09:16:17 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,  automatically responded to EP251130a (Wu et al.,

GCN 42903) starting at 11:21:40 UT, 831 seconds after the burst.

A set of 10x20s, 10x40s, 60x60s clear (roughly R) filter images

were obtained. We clearly detected the optical afterglow (Dornic

et al., GCN 42904, He et al., GCN 42914; Gupta et al., GCN 42916)

in our coadd image. We measure its brightness decreased from 19.6

+/- 0.1 mag (Vega; mid time 16.45 min) to 20.2 +/- 0.2 mag (mid

time of 91.03 min) with a decay index of 0.46.


Additional 30x60s clear filter images were obtained the following

night at a mid time of 0.89 days after the burst. The OT is still

detected at 19.7 +/- 0.1 mag, indicating the OT has brightened.

More follow-up observations are encouraged.