GRB 260605A

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,

D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia,
and T. Cline on behalf of the Konus-Wind team,

C. Wang (IHEP), S. Xiong (IHEP), S. Zhang (IHEP), J. Wei (NAOC),
and B. Cordier (CEA) on behalf of the SVOM-GRM team,

C. Wang (IHEP), S. Xiong (IHEP), and S. Zhang (IHEP)
on behalf of the Insight-HXMT team,

E. Burns on behalf of the IPN,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:

The long-duration GRB 260605A
(Insight-HXMT/HE detection: Zao et al., GCN 44849
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was detected by Insight (HXMT/HE), SVOM (GRM), Konus-Wind,
and Mars-Odyssey (HEND) at about 3868 s UT (01:04:28).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
 ------------------------------
  RA(2000), deg  Dec(2000), deg
 ------------------------------
 Corners:
  110.4929       +37.9757
  110.4379       +38.1277
  108.8194       +18.8592
  108.8935       +19.0360
 ------------------------------
The error box area is 3003 sq. arcmin, and its maximum
dimension is 20.3 deg (the minimum one is 2.6 arcmin).
The Sun distance was ~27 deg.

This localization may be improved.

A triangulation map and HEALPix FITS files are posted at
http://www.ioffe.ru/LEA/GRBs/GRB260605_T03858/IPN
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density. 

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 2026-06-05T01:04:27.850 (T0), Insight-HXMT/HE detected a long burst, GRB 260605A, which is also detected by SVOM/GRM.

The Insight-HXMT/HE light curve mainly consists of a single pulse with a duration (T90) of 11.0 +2.5/-1.0 s. The 1s peak rate, measured from T0+1.75 s, is 6386 cnts/sec. Insight-HXMT/HE detected a total of 22324 counts from this burst.  

The Insight-HXMT /HE light curve can be found here: 
https://www.bursthub.cn//admin/static/hxmtgrb260605A.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/