TITLE:   GCN CIRCULAR
NUMBER:  29393
SUBJECT: GRB 210204: Fermi GBM observation
DATE:    21/02/04 16:16:59 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi@ba.infn.it>

E. Bissaldi (Politecnico and INFN Bari)
reports on behalf of the Fermi GBM Team:


"At 06:29:25.66 UT on 4 February 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210204A (trigger 634112970 / 210204270).
The Fermi GBM Final Real-time Localization was reported in GCN 29390.

The angle from the Fermi LAT boresight at the GBM trigger time is 57 degrees.

The GBM light curve consists of multiple emission episodes
with a duration (T90) of about 210 s (50-300 keV).
The time-averaged spectrum encompassing the first two emission
episodes from T0-8 s to T0+45 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.51 +/- 0.07 and
the cutoff energy, parameterized as Epeak, is 162 +/- 33 keV.

The event fluence (10-1000 keV) in this time interval is
(5.76 +/- 0.04)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+201.5 s in the 10-1000 keV band
is 29.3 +/- 0.4 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak = 140 +/- 50 keV, alpha = -1.5 +/- 0.1,
and beta = -2.3 +/- 0.5.


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/"