[vsnet-grb-info 27962] GRB 210520A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30065
SUBJECT: GRB 210520A: Fermi GBM detection
DATE:    21/05/21 12:41:47 GMT
FROM:    Peter Veres at UAH  <veresp at gmail.com>

P. Veres, B. Hristov and C. Meegan (all UAH) report on behalf of the
Fermi GBM Team:

"At 19:07:02.00 UT on 20 May 2021, the Fermi Gamma-Ray Burst Monitor
(GBM) triggered and located GRB 210520A (trigger 643230427 /
210520797) which was also detected by the Fermi LAT (Di Lalla et al.,
GCN 30062) and GECAM (Zheng et al GCN 30061). The GBM on-ground
location (reported in GCN 30059) is consistent with the LAT position.

The angle from the Fermi LAT boresight at the GBM trigger time is 21 degrees.

The GBM light curve consists of a large number of pulses
with a duration (T90) of about 56 s (50-300 keV).
The time-averaged spectrum from T0-1.3 s to T0+58 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.18 +/- 0.04 and
the cutoff energy, parameterized as Epeak, is 4.4 +/- 1.8 MeV.

The event fluence (10-1000 keV) in this time interval is
(1.02 +/- 0.04)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.58 s in the 10-1000 keV band
is 2.6 +/- 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/"