TITLE:   GCN CIRCULAR
NUMBER:  15124
SUBJECT: GRB 130821A: Weihai optical upper limit
DATE:    13/08/24 15:56:19 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark@gmail.com>

D. Xu (DARK/NBI), D.-Y. Ren, C. Cao, S.-M. Hu (SDU) report:

We observed the XRT field of GRB 130821A (Jenke et al., GCN 15113;
Kocevski et al., GCN 15115; Page et al., GCN 15123) centered at
RA(J2000)  =  20h 56m 38.44s and Dec(J2000) = -12d 02' 36.53", using
the 1m telescope located in Weihai, Shandong, China. We obtained
9x300s SDSS r'-band frames under cloudy conditions at a mean time of
14:20 UT on 2013-08-24 (i.e., 2.997 days after the burst).

No optical source is detected within the XRT error circle in the
stacked image, down to r'>20.8 mag, calibrated with nearby SDSS field.