[vsnet-grb-info 20224] GRB180111 : Xinglong TNT possible optical detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22320
SUBJECT: GRB180111 : Xinglong TNT possible optical detection
DATE:    18/01/11 23:20:38 GMT
FROM:    L.P. Xin at NAOC  <xlp at nao.cas.cn>

L. P. Xin,   C. Liu,  J. Y. Wei,  Y. L. Qiu, J. S. Deng,  
J. Wang,  X. H. Han, X. M. Meng and C. Wu report:
 
We began to observe GRB 180111A (Lien et a l., GCN22318)  
with Xinglong  0.8-m TNT telescope at 2018-01-11, 14:43:34(UT),
about 93 sec the burst.
 
We obtained several white and R-band images.
In any single white band frame, no any new optical transient 
was detected within UVOT circle and XRT circle 
(Lien et a l., GCN22318, Evens et al., GCN 22319) 
down to 18.5 magnitude at the mid time of 113 sec after the burst  .

However, there is a marginal source in the 20*20sec coadded image 
within the XRT circle  (Evens et al., GCN 22319),  whose position is consistent 
with  the location of the reported optical counterpart (Lien et a l., GCN22318). 
The brightness is about 20.0+/-0.3 calibrated by the local USNO B1.0 R2 mag
at the mid time of 300 sec after the burst. 


We are making further analysis for the possible low S/N detection 
since there is a bright star near the GRB location.
 
The message may be cited.