GRB 260418A
GCN Circular 44374
Subject
GRB 260418A: Insight-HXMT/HE detection
Date
2026-04-21T10:34:05Z (19 days ago)
From
xueyuan zao <zaoxueyuan@gmail.com>
Via
Web form
Xue-Yuan Zao, Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng (IHEP) report on behalf of the Insight-HXMT team:
At 2026-04-18T04:49:35.000 (T0), Insight-HXMT/HE detected a short burst, GRB 260418A, which is also detected by Fermi/GBM (Fermi GBM Team, GCN #44335).
The Insight-HXMT/HE light curve mainly consists of a single pulse with a duration (T90) of 0.30 +0.55/-0.10 s. The 1s peak rate, measured from T0-0.475 s, is 361 cnts/sec. Insight-HXMT/HE detected a total of 292 counts from this burst.
The Insight-HXMT /HE light curve can be found here:
https://www.bursthub.cn//admin/static/hxmtgrb260418A.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 44335
Subject
GRB 260418A: Fermi GBM Final Real-time Localization
Date
2026-04-18T05:00:17Z (22 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely SHORT GRB
At 04:49:35 UT on 18 Apr 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260418A (trigger 798180580.203356 / 260418201).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 140.6, Dec = 29.3 (J2000 degrees, equivalent to J2000 09h 22m, 29d 18'), with a statistical uncertainty of 18.1 degrees.
The angle from the Fermi LAT boresight is 60.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260418201/quicklook/glg_skymap_all_bn260418201.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/bn260418201/quicklook/glg_healpix_all_bn260418201.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260418201/quicklook/glg_lc_medres34_bn260418201.gif