TITLE:   GCN CIRCULAR
NUMBER:  22186
SUBJECT: GRB 171205A: GMG observation
DATE:    17/12/06 03:54:39 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Mao, X. Ding and J.-M. Bai (YNAO) report:


We observed the field of GRB 171205A (D'Elia et al., GCN 22177) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG) station of Yunnan Observatories. Observations began from 22:45:21 UT, about 15.4 hours after the trigger. We clearlydetected the optical counterpart reported by Izzo et al. (GCN 22180). A very preliminary result was estimated as R~20.4 mag. We note that this source is in the outskirts of the host galaxy and the magnitude that we roughly measured has large uncertainty. Detailed analysis is ongoing.