GRB 261019A
GCN Circular 46013
Hao-Xuan Guo, Zheng-Hang Yu, Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng (IHEP) report on behalf of the Insight-HXMT team:
At 2026-10-19T09:14:11.500 (T0), Insight-HXMT/HE detected a long burst, GRB 261019A, which is also detected by Fermi/GBM (Fermi GBM team, GCN #45989).
The Insight-HXMT/HE light curve mainly consists of a pulse with a T90 of 100 +/-12 s. The 1s peak rate, measured from T0+1.5 s, is 895 cnts/sec. Insight-HXMT/HE detected a total of 24784 counts from this burst.
The HXMT/HE light curve can be found here:
https://www.bursthub.cn/gcn/2026/hxmtgrb261019A.png
All measurements above are made with the CsI detectors of Insight-HXMT/HE 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://hxmten.ihep.ac.cn/
GCN Circular 45989
The Fermi GBM team reports the detection of a likely LONG GRB.
"At 09:14:05.59 UT on 19 October 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261017A (trigger 814094050/261019385).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 321.9, Dec = -72.4 (J2000 degrees, equivalent to J2000 21h 27m, -72d 24'), with a statistical uncertainty of 2.6 degrees.
The angle from the Fermi LAT boresight is 118 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261019385/quicklook/glg_skymap_all_bn261019385.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261019385/quicklook/glg_healpix_all_bn261019385.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261019385/quicklook/glg_lc_medres34_bn261019385.gif"
