TITLE:   GCN CIRCULAR
NUMBER:  29788
SUBJECT: GRB 210410A: Fermi GBM detection
DATE:    21/04/11 01:42:52 GMT
FROM:    Joshua Wood at MSFC/Fermi-GBM  <joshua.r.wood@nasa.gov>

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

"At 00:53:16.52 UT on 10 April 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210410A (trigger 639708801 / 210410037).
which was also detected by the Swift/XRT (A. Melandri et al. 2021, GCN 29778),
the Fermi/LAT (M. Arimoto et al. 2021, GCN 29781),
and AGILE (A. Ursi et al. 2021, GCN 29782).

The Fermi GBM Final Real-time Localization (GCN 29777) is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 51.0 degrees.

The GBM light curve consists of a single peak
with a duration (T90) of about 48 s (50-300 keV).
The time-averaged spectrum from T0-0 s to T0+50 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.70 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 1300 +/- 100 keV

The event fluence (10-1000 keV) in this time interval is
(4.5 +/- 0.5)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0 s in the 10-1000 keV band
is 12.6 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well 
with Epeak = 1300 +/- 100 keV, alpha = -0.70 +/- 0.03 and beta = 4.0 +/- 1.6.

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/"