TITLE:   GCN CIRCULAR
NUMBER:  17339
SUBJECT: GRB150120B: Xinglong TNT optical observation
DATE:    15/01/21 14:07:31 GMT
FROM:    L.P. Xin at NAOC  <xlp@bao.ac.cn>

L. P. Xin,   X. F. Wang,  J. Y. Wei,  Y. L. Qiu, J. S. Deng, 
J. Wang,  X. H. Han and C. Wu on behalf of EAFON report:
 
We began to observe GRB 150120B (D'Elia et al., GCN 17314)  
with Xinglong  0.8-m TNT telescope at 2015-01-20, 10:56:50 (UT),
about 3.58 hours after the burst.
 
In the 15*300sec coadded R-bamd image, the optical counterpart
(D. A. Perley GCN 17315; Guidorzi et al., GCN 17316;  Wiseman et al., 17336; 
Pandey GCN 17337) was detected with a brightness of  
R=21.3+/-0.2 mag at the mid-time of 4.2 hours  after the burst, 
calibrated by the nearby USNO B1.0 R2 mag.
 
The message may be cited.