TITLE: GCN CIRCULAR NUMBER: 45470 SUBJECT: GRB 260829A: GECAM-B observation of a long burst DATE: 26/08/30 15:44:43 GMT FROM: xueyuan zao <zaoxueyuan@gmail.com> Xue-Yuan Zao, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered on-ground by GRB 260829A, at 2026-08-29T06:08:10.450 UTC, which is also detected by Fermi/GBM (Fermi GBM team, GCN #45464, GCN #45465 and GCN #45467). 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 47.0 +/-4.0 s. The GECAM-B light curve can be found here: https://www.bursthub.cn/gcn/2026/gecambgrb260829A.png The time-averaged spectrum from T0+16.0 to T0+32.0 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.15 +0.18/-0.15 and the cutoff energy, parameterized as Epeak, is 466 +138/-94 keV. The event fluence (10-1000 keV) in this time interval is (2.31 +0.13/-0.16) E-05 erg/cm^2. The localization of GRB 260829A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn/gcn/2026/gecambgrb260829A_amati.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). View this GCN Circular online at https://gcn.nasa.gov/circulars/45470. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...