TITLE: GCN CIRCULAR NUMBER: 30974 SUBJECT: GRB 211024A: GECAM detection DATE: 21/10/24 14:44:10 GMT FROM: Shuo Xiao at IHEP <xiaoshuo@ihep.ac.cn> S. Xiao, Yi Zhao, S. L. Xiong, C. Cai, J. J. He, Y. Huang, Z. W. Guo, C. Y. Li, X. B. Li, J. C. Liu, X. Y. Song, C. W. Wang, P. Wang, S. L. Xie, W. C. Xue, Q. B. Yi, Y. Q. Zhang, G. Y. Zhao, X. Y. Zhao, C. Zheng, Y. Q. Du, D. Y. Guo, J. Liang, F. J. Lu, Q. Luo, X. Ma, W. X. Peng, R. Qiao, L. M. Song, J. Wang, H. Wu, P. Zhang, S. N. Zhang, X. L. Zhang, Z. Zhang, S. J. Zheng (IHEP), report on behalf of GECAM team: During the commissioning phase, GECAM-B was triggered ground by a short bright burst, GRB 211024A, at 2021-10-24T01:34:11.450 UTC (denoted as T0), which was also detected by Fermi/GBM (GCN 30962). According to the GECAM-B light curves in about 16-3500 keV, this burst mainly consists of a broad pulse with a duration of about 0.1 s. The GECAM light curve could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/tn211024_013411_gb.png GECAM-B localized this burst to the following position (J2000): Ra: 25.7 deg Dec: 1.05 deg Err: 28.73 deg (1-sigma, statistical only) The current systematic error of location is estimated to be several degrees which could be minimized by the ongoing calibration. This location is consistent with Fermi/GBM position within the error. Please note that all GECAM results here are preliminary. The final analysis will be published in journal papers or GECAM online catalog. Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time), which was funded by the Chinese Academy of Sciences (CAS).