TITLE:   GCN CIRCULAR
NUMBER:  17653
SUBJECT: GRB 141220A: GMG observation limit
DATE:    15/03/29 11:09:44 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Mao, B. Lun and J.-M. Bai (YNAO) report:


We observed the field of GRB 141220A (Cummings et al., GCN 17196) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG) 
station of Yunnan Observatory. Observations began from UT 22:28:38.1 20, Dec., 2014 (about 18.4 hours after the trigger). 
We did not detect the optical counterpart down to a limit of r'~21.0. 


We thank Dr. A., de Ugarte Postigo for his kind suggestion and disucssion.  J. Mao apologizes for this very later GCN circular submission.