TITLE: GCN CIRCULAR NUMBER: 29187 SUBJECT: GRB 201227A: Insight-HXMT/HE detection DATE: 20/12/28 15:00:13 GMT FROM: Shuo Xiao at IHEP S. Xiao, C. Cai, Y. F. Du, Y. G. Zheng, Q. Luo, Q. B. Yi, Y. Huang, C. K. Li, G. Li, X. B. Li, J. Y. Liao, S. L. Xiong, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team: At 2020-12-27T15:14:07.400 (T0), Insight-HXMT/HE detected GRB 201227A (trigger ID: HEB201227634) in a routine search of the data, which also triggered Fermi/GBM (trigger 630774852) and AGILE Mini-CALorimeter (GCN#29179). The Insight-HXMT/HE light curve mainly consists of multiple pulses with a duration (T90) of 0.098 s measured from T0-0.03 s. The 1-ms peak rate, measured from T0+0.024 s, is 52740 cnts/sec. The total counts from this burst is 1612 counts. URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB201227634_lc.jpg The HE light curves have not been corrected for data saturation caused by the extreme brightness of this burst in HE. All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 80-800 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org.