TITLE:   GCN CIRCULAR
NUMBER:  22141
SUBJECT: GRB171120A: GWAC-F60A upper limit 
DATE:    17/11/21 11:39:32 GMT
FROM:    L.P. Xin at NAOC  <xlp@nao.cas.cn>

L. P. Xin,   W. L. Dong, P. P. Zhang,  X. H. Han, J. Y. Wei,   E. W. Liang, 
X. G. Wang, Y. J. Xiao,   Y. G. Yang,  X. M. Lu,  L. Huang,    H. B. Cai,   
X. M. Meng,   Y. L. Qiu,  Y. Xu, Y. J. Xiao, Y. T. Zheng, R. S. Zhang,  J. Wang,    
C. Wu,   J. S. Deng, D. W. Xu,  T. Damien and H. L. Li  report:

We  observed  GRB 171120A (Tohuvavohu et al., GCN 22133)   with
GWAC-F60A 60cm optical telescope at 19:06:58 UT,  Nov. 20th 2017, 
about 5.75  hours after the burst. 

No any new source  was  not detected in the XRT error circle 
(Evens et al., GCN 22135) in our 15*300 sec stacked R-band  image  
down to the 3 sigma  limit  of  about 19.5 mag at the mid time  of 6.25 hours 
after the burst. The brightness was calibrated by  USNO B1.0 R2 catalogues.

GWAC-F60A is operated by Guangxi university and NAOC, CAS, 
at Xinglong observatory, China.

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