TITLE:   GCN CIRCULAR
NUMBER:  20888
SUBJECT: GRB 170317A : Xinglong TNT optical observation
DATE:    17/03/17 13:39:57 GMT
FROM:    L.P. Xin at NAOC  <xlp@nao.cas.cn>

L. P. Xin,  T. M. Zhang,  J. Y. Wei,  Y. L. Qiu,  J. S. Deng, 
J. Wang,  X. H. Han，C. Wu and E. W. Liang  reports:
 
We began to observe GRB 170317A (LaPorte et al., GCN 20885)  
with Xinglong  0.8-m TNT telescope at 2017-03-17,11:39:17 (UT), 
about  1.9 hours after the Swift trigger time. 
 
The optical afterglow reported ( LaPorte et al., GCN 20885; 
Mazaeva et al., GCN 20886)  was  clearly detected  in the 
stacked 11*300 sec R-band image.   
Preliminary analysis shows that  the brightness of the optical afterglow
in R band is about 19.8+/-0.1 mag,  calibrated by nearby USNO B1.0 objects
at the mid time of 2.3 hours after the burst.

This message could be cited. 

We thank the excellent support of the Xinglong 80cm TNT staff, particularly S. Liu