GRB 260921B
GCN Circular 45805
Subject
GRB 260921B: GECAM-B observation
Date
2026-10-03T13:36:38Z (4 days ago)
From
guohx@ihep.ac.cn
Via
Web form
Hao-Xuan Guo, Jin-Ye Luo, Chen-Wei Wang, Chao Zheng, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:
GECAM-B was triggered on-ground by GRB 260921B, at 2026-09-21T21:44:41.950 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #45685).
According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 46 +4/-7 s.
The GECAM-B light curve can be found here:
https://www.bursthub.cn/gcn/2026/gecambgrb260921B.png
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
GCN Circular 45685
Subject
GRB 260921B: Fermi GBM Final Localization
Date
2026-09-21T23:19:25Z (15 days ago)
From
Matt Godwin <msg0028@uah.edu>
Via
Web form
The Fermi GBM team reports the detection of a likely LONG GRB
"At 21:44:37.15 UT on 21 September 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 260921B (trigger 811719882/260921906).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 62.12, Dec = 31.21 (J2000 degrees, equivalent to J2000 4h 8m, +31d 12'),
with a statistical uncertainty of 2.22 degrees.
The angle from the Fermi LAT boresight is 107 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260921906/quicklook/glg_skymap_all_bn260921906.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/bn260921906/quicklook/glg_healpix_all_bn260921906.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260921906/quicklook/glg_lc_medres34_bn260921906.gif"