[vsnet-grb-info 27534] GRB 210306B: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29637
SUBJECT: GRB 210306B: Fermi GBM detection
DATE:    21/03/09 17:13:46 GMT
FROM:    Stephen Lesage at Fermi-GBM Team  <sjl0014 at uah.edu>

S. Lesage (UAH), A. von Kienlin (MPE), and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 09:32:14.42 UT on 06 March 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210306B (trigger 636715939 / 210306397)
which was also detected by the Swift/BAT (Ambrosi et al. 2021, GCN 29601).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 37
degrees.

The GBM light curve shows a single-peaked structure
with a duration (T90) of about 15 s (50-300 keV).
The time-averaged spectrum from T0-1.3 s to T0+14.1 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.0 +/- 0.2 and
the cutoff energy, parameterized as Epeak, is 73 +/- 8 keV.

The event fluence (10-1000 keV) in this time interval is
(1.3 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.0 s in the 10-1000 keV band
is 2.7 +/- 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/"