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GCN Circular 28206

Subject
GRB 200803A: Fermi GBM detection
Date
2020-08-03T22:22:25Z (4 years ago)
From
Rachel Hamburg at UAH <rkh0007@uah.edu>
R. Hamburg (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 03:34:26.00 UT on 03 August 2020, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 200803A (trigger 618118471 / 200803149)
which was also detected by the Fermi/LAT (Cutini et al. 2020,
GCN 28203). The Fermi GBM Final Real-time Localization (GCN 28196) is
consistent with the LAT position. An x-ray afterglow candidate has
been detected by the Swift/XRT (GCN 28205), and a potential optical
counterpart has also been reported by MASTER (GCN 28202).

The angle from the Fermi LAT boresight at the GBM trigger time is ~39
degrees.

The GBM light curve consists of two main pulses
with a duration (T90) of about 119 s (50-300 keV).

The time-averaged spectrum of the first pulse, from T0-4 s to
T0+14 s is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.67 +/- 0.04 and
the cutoff energy, parameterized as Epeak, is 302 +/- 13 keV.
The event fluence (10-1000 keV) in this time interval is
(1.12 +/- 0.03)E-05.

The time-averaged spectrum of the second pulse, from T0+85 s to
T0+118 s is also best fit by a power law function with an
exponential high-energy cutoff. The power law index is
-1.13 +/- 0.02 and the cutoff energy, parameterized as Epeak,
is 223 +/- 8 keV. The event fluence (10-1000 keV) in this time
interval is (1.84 +/- 0.03)E-05.

The 1-sec peak photon flux measured
starting from T0+112 s in the 10-1000 keV band
is 10.8 +/- 0.3 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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