TITLE:   GCN CIRCULAR
NUMBER:  14435
SUBJECT: GRB 130420B: Fermi GBM observation
DATE:    13/04/22 11:29:13 GMT
FROM:    Arne Rau at MPE  <arau@mpe.mpg.de>

Arne Rau (MPE) reports on behalf of the Fermi GBM Team:

"At 12:56:32.99 UT on 20 April 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130420B (trigger 388155395 / 130420539),
which was also detected by Swift/BAT (Oates et al., GCN 14411).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is about 50 degrees.

The GBM light curve shows a single pulse with a duration (T90) of
about 16 s (50-300 keV). The time-averaged spectrum from T0-4 s
to T0+4 s is best fit by a power law function with an exponential
high-energy cutoff. The power law index is 0.24 +/- 0.25 and
the cutoff energy, parameterized as Epeak, is 91 +/- 9 keV.

The event fluence (10-1000 keV) in this time interval is
(1.04 +/- 0.08)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band
is 2.6 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."