TITLE:   GCN CIRCULAR
NUMBER:  46130
SUBJECT: GRB 261102A: Fermi GBM Detection
DATE:    26/11/02 18:29:00 GMT
FROM:    Rushikesh Sonawane  at IISER TVM <rushikesh23@iisertvm.ac.in>

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

"At 06:09:19.31 UT on 02 November 2026, the Fermi Gamma-ray Burst Monitor (GBM) 
triggered and located GRB 261102A (trigger 815292564/261102256).

The on-ground calculated location, using the Fermi GBM trigger data, 
is RA = 102.1, Dec = 53.5 (J2000 degrees, equivalent to 
J2000 6h 48m, +53d 30'), with a statistical uncertainty of 8.3 degrees. 
(radius, 1-sigma containment, statistical only; there is additionally a 
systematic error which we have characterized as a mixture of two Gaussians, 
one with a radius of 1.8 degrees (52% contribution) and one with a radius 
of 4.1 degrees (47% contribution) [A. Goldstein et al. 2020, ApJ, 895, 1]).

The angle from the Fermi LAT boresight is 27 degrees.

The GBM light curve consists of a single emission episode with a duration (T90) 
of about 0.7 s (50-300 keV). The time-averaged spectrum from T0-0.33 to T0+0.77 
s is best fit by a power law function with an exponential high-energy cutoff. 
The power law index is -0.37 +/- 0.04 and the cutoff energy, parameterized as 
Epeak, is 620 +/- 50 keV.

The event fluence (10-1000 keV) in this time interval is (5.1 +/- 0.6)E-07 
erg/cm^2. The 64-ms peak photon flux measured starting from T0-0.06 s in the 
10-1000 keV band is 8 +/- 1 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/"