GCN Circular 13983
X.-H. Zhao (YNAO), C. -J. Wang, J.-R. Mao (KASI/YNAO), J.-M. Bai (YNAO) report on behalf of a larger collaboration: We observed the field of GRB 121123A (Helder et al., GCN 13982) with 2.4m Gao-Mei-Gu (GMG) telescope. Observations started at ~1.5 hrs after the burst. The optical afterglow of this burst was detected. The preliminary magnitude was R~19.2. observation is on going. We thank the GMG staff, especially Hong-Yan Gao, and De-Qing Wang for doing these observations.