TITLE: GCN CIRCULAR NUMBER: 32495 SUBJECT: GRB 220826A: Fermi GBM observation DATE: 22/08/27 11:13:39 GMT FROM: Andreas von Kienlin at MPE azk@mpe.mpg.de
P. Veres and C. Meegan (both UAH) report on behalf of the Fermi GBM Team:
"At 11:55:22.98 UT on 26 August 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220826A (trigger 220826497 / 683207727) which was also detected by the Swift/BAT (Caputo et al., GCN 32484) The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 54 degrees.
The GBM light curve shows two pulses with a duration (T90) of about 16.6 s (50-300 keV). The time-averaged spectrum from T0-0.5 s to T0+10.8 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.66 +/- 0.20 and the cutoff energy, parameterized as Epeak, is 113 +/- 14 keV
The event fluence (10-1000 keV) in this time interval is (1.50 +/- 0.14)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from T0 + 5.2 s in the 10-1000 keV band is 4.3 +/- 0.3 ph/s/cm^2.
A Band function fits the spectrum equally well with Epeak= 66 +/- 13 keV, alpha = 0.28 +/- 0.58 and beta = -2.14 +/- 0.18.
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/"