GCN Circular 45467

Subject

GRB 260829A: Fermi GBM Detection

Event

GRB 260829A

Date

2026-08-29T14:12:23Z (4 days ago)

From

Christian Malacaria at INAF-OAR <cmalacaria.astro@gmail.com>

Via

Web form

C. Malacaria (INAF-OAR) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 06:08:09.39 UT on 29 August 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260829A (trigger 809676494/260829256). The Final real-time localization was reported in GCN 45464

The GBM light curve consists of a prompt emission followed by a bright peak with a duration (T90) of about 26.4 s (50-300 keV). The time-averaged spectrum from T0+18 to T0+34 s is best fit by a Band function with Epeak = 260 +/- 10 keV, alpha = -0.66 +/- 0.04, and beta = -2.17 +/- 0.08.

The event fluence (10-1000 keV) in this time interval is (1.91 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+22 s in the 10-1000 keV band is 19.1 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"