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GCN Circular 28874

Subject
GRB 201109A: Fermi GBM detection
Date
2020-11-09T20:47:49Z (4 years ago)
From
Christian Malacaria at NASA-MSFC/USRA <cmalacaria@usra.edu>
C. Malacaria (NASA-MSFC/USRA) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 02:31:05.79  UT on 9 November 2020, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 201109A (trigger 626581870 / 201109105).
The Fermi GBM Final Real-time Localization was reported in GCN 28868.

The angle from the Fermi LAT boresight at the GBM trigger time is 66 degrees.

The GBM light curve consists of a bright peak
with a duration (T90) of about 0.45 s (50-300 keV).
The time-averaged spectrum from T0-0.128 s to T0+0.384 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.61 +/- 0.11 and
the cutoff energy, parameterized as Epeak, is 318 +/- 41 keV.

The event fluence (10-1000 keV) in this time interval is
(9.55 +/- 0.72)E-07 erg/cm^2. The 64-msec peak photon flux measured
starting from T0+64 ms in the 10-1000 keV band
is 18.4 +/- 1.2 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 304 +/- 56 keV, alpha = -0.59 +/- 0.14 and beta = -2.93 +/- 1.42 .


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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