[vsnet-grb-info 27475] GRB 210226A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29578
SUBJECT: GRB 210226A: Fermi GBM detection
DATE:    21/02/27 03:20:46 GMT
FROM:    Joshua Wood at MSFC/Fermi-GBM  <joshua.r.wood at nasa.gov>

J. Wood (NASA/MSFC) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 04:43:56.56 UT on 26 February 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210226A (trigger 636007441 / 210226197)
which was also detected by the Swift/BAT and Swift/XRT (A.P. Beardmore et al. 2019, GCN 29568).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 58.6 degrees.

The GBM light curve consists of a single peak
with a duration (T90) of about 26 s (50-300 keV).
The time-averaged spectrum from T0-6 s to T0+18 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.2 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 170 +/- 29 keV

The event fluence (10-1000 keV) in this time interval is
(2.7 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.2 s in the 10-1000 keV band
is 4.1 +/- 0.2 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/"