GCN Circular 43649

Subject

GRB 260208B: Fermi GBM Detection

Event

GRB 260208B

Date

2026-02-08T17:38:17Z (2 days ago)

From

Rushikesh Sonawane at IISER, TVM <rushikesh23@iisertvm.ac.in>

Via

Web form

R. Sonawane (IISER, TVM) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 09:52:44.91 UT on 08 February 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 260208B (trigger 792237169/260208412).
which was also detected by Fermi LAT (A. H. Airasca et al. 2026, GCN 43647Loading...
 
 ).
The Fermi GBM final real-time Localization (GCN 43638Loading...
 
 ) is consistent with the Fermi LAT position.


The angle from the Fermi LAT boresight is 16 degrees.

The GBM light curve consists of two emission episodes with multiple spikes for a duration (T90)
of about 145 s (50-300 keV). The time-averaged spectrum
from T0-8.2 to T0+172.0 s is best fit by
a Band function with Epeak = 855 +/- 61 keV,
alpha = -1.0 +/- 0.02, and beta = -2.12 +/- 0.08.

The event fluence (10-1000 keV) in this time interval is
(9.1 +/- 0.1)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+14 s in the 10-1000 keV band is 23 +/- 0.4 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/"