TITLE: GCN CIRCULAR NUMBER: 39830 SUBJECT: GRB 250225B: GECAM-A detection DATE: 25/03/22 05:45:38 GMT FROM: zhengchao_astro@foxmail.com Jia-Cong Liu, Shao-Lin Xiong, Peng Zhang, Yan-Qiu Zhang, Chen-Wei Wang (IHEP) report on behalf of the GECAM team: GECAM-A detected a long burst, GRB 250225B, at 2025-02-25T19:39:13 UTC (denoted as T0), which was also observed by Swift/BAT (H. A. Krimm et al. 2025, GCN 39473), SVOM/GRM (Yan-Qiu Zhang et al. 2025, GCN 39493), Fermi/GBM (M. Godwin et al. 2025, GCN 39502), and Konus-Wind (A. Tsvetkova et al. 2025, GCN 39498). According to the GECAM-A light curves in about 50-200 keV, this burst mainly consists of multiple pulses with a T90 of about 63.2 ± 2.5 s. The GECAM light curve can be found here: https://www.bursthub.cn//admin/static/gecamgrb250225B.png We note that these results are preliminary. Refined analysis will be reported.  Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two microsatellites (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).