TITLE:   GCN CIRCULAR
NUMBER:  20889
SUBJECT: GRB 170317A: GMG observation
DATE:    17/03/17 14:58:21 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Mao, Y. Xin and J.-M. Bai (YNAO) report:


We observed the field of GRB 170317A (LaPorte et al., GCN 20885) with the 2.4-meter
optical telescope at Gao-Mei-Gu (GMG) station of Yunnan Observatories. Observations began
from 13:58:18 UT, about 4.2 hours after the trigger. We detected the afterglow with
R~19.96+/-0.10 mag, calibrated by a nearby USNO-B1.0 star.