TITLE:   GCN CIRCULAR
NUMBER:  6962
SUBJECT: GRB 071021: Xinglong TNT optical Upper Limit
DATE:    07/10/21 17:17:44 GMT
FROM:    L.P. Xin at NAOC  <xlp@bao.ac.cn>

L.P. Xin, M. Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng,
J. Wang and W.K. Zheng on behalf of EAFON report:
 
We have imaged the field of GRB 071021 (T. Sakamoto, et al.;
GCN 6958) with the TNT 0.8m telescope at Xinglong
Observatory started from  09:55:06.5 UT, 813.8880 after
the burst.  A series of White and R band images were
obtained, no new source was found in our combined
image within the error region of the XRT
(T. Sakamoto, et al.; GCN 6958) and the location reported 
by C. Guidorzi et al (GCN 6959)

The 3-sigma limit derived from
USNO-B1.0 R2 mag were: 
------------------------------------
Band     Mid time     Exp time  Limit Mag
 
White   0.72 hours     40*20s     20.32 
R      1.38 hours      12*300s    20.85
R      3.25 hours      16*600s    21.69
  
This message may be cited.

[GCN OPS NOTE(21oct07): Per author's request, the names for the 3 references
were changed T. Sakamoto, T. Sakamoto, and C. Guidorzi.]