TITLE: GCN CIRCULAR NUMBER: 42854 SUBJECT: GRB 251125B: GECAM-B detection DATE: 25/11/27 04:41:58 GMT FROM: renyz16607@163.com
Yang-Zhao Ren, Chen-Wei Wang, Chao Zheng, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:
GECAM-B was triggered in-flight by a long burst, GRB 251125B, at 2025-11-25T20:23:45.000 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #42836).
According to the GECAM-B light curves in about 40-6000 keV, this burst mainly consists of a pulse with a duration (T90) of 8.5 +2.0/-3.5 s.
The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb251125B.png
The time-averaged spectrum from T0-0.8 s to T0+9.3 s is best fitted by a power law function. The power law index is -1.36 +0.06/-0.05. The event fluence (10-1000 keV) in this time interval is (2.86 +0.34/-0.31)E-06 erg/cm^2.
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).
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