TITLE: GCN CIRCULAR NUMBER: 45938 SUBJECT: GRB 261011B: GECAM-B observation DATE: 26/10/13 12:26:52 GMT FROM: Jin-Ye Luo Jin-Ye Luo, Chen-Wei Wang, Yue Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by GRB 261011B at 2026-10-11T17:26:53.000 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #45910). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of a single pulse with a duration (T90) of 9.5 +2.5/-3.5 s. The GECAM-B light curve can be found here: https://www.bursthub.cn/gcn/2026/gecambgrb261011B.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).