TITLE: GCN CIRCULAR NUMBER: 41049 SUBJECT: GRB 250706B/C: Insight-HXMT detection DATE: 25/07/09 09:05:53 GMT FROM: Chenwei Wang at IHEP cwwang@ihep.ac.cn

Chen-Wei Wang, Shao-Lin Xiong, Cheng-Kui Li, Chao Zheng, Wen-Jun Tan, Jia-Cong Liu, Hao-Xuan Guo, Xiao-Bo Li and Wang-Chen Xue report on behalf of the Insight-HXMT team:

At 2025-07-06T16:45:26.900 (T0), Insight-HXMT/HE was triggered on-ground by the long bright burst GRB 250706B/C, which is also detected by Konus-Wind (D. Frederiks, GCN #41013, GCN #41027) , SVOM (Jesse Palmerio et al., GCN #40989, GCN #41026) and Fermi/LAT (F. Longo, GCN #41019). The Insight-HXMT/HE light curve mainly consists of numerous pulses with a T90 of 36.6 +/- 0.1s. The 1s peak rate, measured from T0+36.150 s, is 18784 cnts/sec. The total counts from this burst is 293497 counts.

The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb250706C.png

All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 60-900 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope.

Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org.

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