GCN Circular 43106

Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:

GECAM-B was triggered in-flight by GRB 251213A, at 2025-12-13T12:30:05.050 UTC (denoted as T0), which is also detected by SVOM/GRM and GRID. 

According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of a precursor followed by multi-pulses with a duration (T90) of 34.6 +1.0/-1.0 s.

The GECAM-B light curve can be found here:
https://www.bursthub.cn//admin/static/gecambgrb251213A.png

GECAM-B localized this burst to the following position (J2000): 
Ra: 296.5 deg 
Dec: -11.9 deg
Err: 5.6 deg (1-sigma, statistical only)

We note that the non-detection by Fermi/GBM suggests that the error box can be further constrained in the future.

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).