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GCN Circular 29387

Subject
GRB 210202A: Fermi GBM detection
Date
2021-02-03T16:34:35Z (3 years ago)
From
Rachel Hamburg at UAH <rkh0007@uah.edu>
C. Fletcher (USRA), B. Hristov (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

At 20:10:31.30 UT on 02 February 2021, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 210202A (trigger 633989436 / 210202841). There
was also
a Fermi/LAT ground detection (R. Hamburg et al., GCN 29386).
The Fermi GBM Final Real-time Localization was reported in GCN 29380.
It is consistent with the Fermi/LAT human-generated position.

The angle from the Fermi LAT boresight at the GBM trigger time is 45
degrees.

The GBM light curve consists of multiple peaks
with a duration (T90) of about 18 s (50-300 keV).
The time-averaged spectrum from T0+0.003 s to T0+18.7 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.71 +/- 0.03 and
the cutoff energy, parameterized as Epeak, is 297 +/- 12 keV.
The spectrum is also well fit by a Band function
with Epeak = 265 +/- 16 keV, alpha = -0.66 +/- 0.04,
and beta = -2.5 +/- 0.2.

The event fluence (10-1000 keV) in this time interval is
(1.670 +/- 0.036)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.5 s in the 10-1000 keV band
is 16 +/- 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/"
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