[AAVSO-HEN] GRB 070520: Xinglong EST optical Upper Limit

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  6424
SUBJECT: GRB 070520: Xinglong EST optical Upper Limit
DATE:    07/05/20 15:06:24 GMT
FROM:    L.P. Xin at NAOC  <xlp at bao.ac.cn>

L.P. Xin, M.Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng,
Y. Urata, and W.K. Zheng on behalf of EAFON report:
 
We have imaged the field of GRB 070520 (P. Romano et al., GCN 6423)
with the EST 1m telescope at Xinglong Observatory?  
Observation started from 13:14:54 UT, 579s after the burst
with R band filter, 
we derieved 3 sigam limit is ~20.6 in our 20*60s co-added images 
withmean time ~20minutes.

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