TITLE: GCN CIRCULAR NUMBER: 42190 SUBJECT: GRB 251009A: GECAM-B detection of a short burst DATE: 25/10/10 16:22:21 GMT FROM: Chenwei Wang at IHEP <cwwang@ihep.ac.cn> Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered on-ground by the short burst GRB 251009A at 2025-10-09T15:58:56.300 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN#42179), SVOM/GRM (Wang et al., GCN#42185) and Insight-HXMT (Wang et al., GCN#42189). According to the GECAM-B light curves in about 40-6000 keV, this burst mainly consists of a single pulse with a duration (T90) of 0.14 +0.08/-0.08 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb251009A.png Using the automatic on-ground localization pipeline, GECAM-B localized this burst to the following position (J2000): Ra: 103.2 deg Dec: 34.2 deg Err: 21.4 deg (1-sigma, statistical only) 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/42190. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...