TITLE: GCN CIRCULAR NUMBER: 36528 SUBJECT: GRB 240521A: GECAM-B detection of a long burst DATE: 24/05/22 03:47:32 GMT FROM: Yue Wang <m18509381757@163.com> Yue Wang, Shao-Lin Xiong, Chen-Wei Wang report on behalf of the GECAM team: GECAM-B was triggered both in-flight and on-ground by a long burst, GRB 240521A, at 2024-05-21T07:32:12.550 UTC (T0). According to the realtime alert data, the GECAM-B light curve shows a long pulse with a duration of ~15 sec (15-1020 keV). The time-averaged spectrum of GECAM-B realtime data from about T0-1 to T0+9 s could be adequately fit by a cut-off power-law with a flux about 3.30E-7 erg/cm^2/s in 20-1000 keV. The GECAM light curve could be found here: https://twikinew.ihep.ac.cn/pubgecam/Sandbox/GRB/GRB240521A_lightcurve.jpg Using the automatic on-ground localization pipeline with the BDS alert data, GECAM-B localized this burst to the following position (J2000): Ra: 199.2 deg Dec: 78.8 deg Err: 2.8 deg (1-sigma, statistical only) The GECAM preliminary location could be found here: https://twikinew.ihep.ac.cn/pubgecam/Sandbox/GRB/GRB240521A_location.jpg We note that these results are based on realtime alert data and thus very preliminary. Refined analysis will be reported later. 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). View this GCN Circular online at https://gcn.nasa.gov/circulars/36528. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...