GRB 260820A
GCN Circular 45413
Subject
GRB 260820A: Insight-HXMT/HE detection
Date
2026-08-21T09:35:34Z (10 days ago)
From
yzh807926@163.com
Via
Web form
Zheng-Hang Yu, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team:
At 2026-08-20T04:24:39.950 (T0), Insight-HXMT/HE detected GRB 260820A, which is also detected by Fermi/GBM (Fermi GBM team, GCN #45409).
The Insight-HXMT/HE light curve mainly consists of a pulse with a T90 of 0.22 +0.19/-0.13 s. The 1 s peak rate, measured from T0-0.15 s, is 707 cnts/sec. Insight-HXMT/HE detected a total of 690 counts from this burst.
The Insight-HXMT/HE light curve can be found here:
https://www.bursthub.cn/gcn/2026/hxmtgrb260820A.png
All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the Normal 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 45409
Subject
GRB260820A: Fermi GBM Final Real-Time Localization
Date
2026-08-20T07:41:32Z (11 days ago)
From
Cuán de Barra at UCD <cuan.debarra@ucdconnect.ie>
Via
Web form
The Fermi GBM team reports the detection of a likely SHORT GRB.
"At 04:24:39.99 UT on 20 August 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260820A (trigger 808892684/260820184).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 118.3, Dec = -6.1 (J2000 degrees, equivalent to J2000 7h 53m, -6d 5'), with a statistical uncertainty of 11.5 degrees.
The angle from the Fermi LAT boresight is 56 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260820184/quicklook/glg_skymap_all_bn260820184.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/bn260820184/quicklook/glg_healpix_all_bn260820184.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260820184/quicklook/glg_lc_medres34_bn260820184.gif"