TITLE: GCN CIRCULAR NUMBER: 23541 SUBJECT: GRB 181212A:Insight-HXMT/HE detection DATE: 18/12/15 11:34:45 GMT FROM: Shuo Xiao at IHEP S. Xiao, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team: At 2018-12-12T16:37:45.500 (T0), the Insight-HXMT/HE detected GRB 181212A (trigger ID: HEB181212692) in a routine search of the data, which was also triggered by Fermi/GBM (Fletcher et al., GCN23524) and Konus-Wind (Frederiks et al., GCN23540). The Insight-HXMT/HE light curve mainly consists of single pulse with a duration (T90) of 5.48 s measured from T0+0.72 s. The 1-s peak rate, measured from T0+2.07 s, is 8019.2 cnts/s. The total counts from this burst is 20371.7 counts. URL_LC: http://www.hxmt.org/images/GRB/HEB181212692_lc.jpg All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 80-800 keV (record 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 fundedjointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information could be found at: http://www.hxmt.org.