TITLE: GCN CIRCULAR NUMBER: 43218 SUBJECT: GRB 251222A / EP251222b: GECAM-B observation DATE: 25/12/23 15:23:20 GMT FROM: guohx@ihep.ac.cn Hao-Xuan Guo, Chen-Wei Wang, Yue Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by a long burst GRB 251222A at 2025-12-22T17:05:52.000 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43186), SVOM (H. Yang et al., GCN #43188, Chen-Wei Wang et al., GCN #43202), Einstein Probe (C.-L. Guo et al., GCN #43201) and Konus-Wind (D. Frederiks et al., GCN #43214). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multiple pulses main emission with a duration (T90) of 55.8 +1.4/-9.6 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb251222A.png Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/43218. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...