TITLE:   GCN CIRCULAR
NUMBER:  14429
SUBJECT: GRB 130420A: Fermi GBM observation
DATE:    13/04/21 04:44:55 GMT
FROM:    Shaolin Xiong at UAH  <sx0002@uah.edu>

Shaolin Xiong (UAH) and Arne Rau (MPE)
report on behalf of the Fermi GBM Team:

"At 07:30:19.92 UT on 20 April 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130420A (trigger 388135822 / 130420313),
which was also detected by the Swift (Page et al. 2013, GCN 14406).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 134 degrees.

The GBM light curve consists of precursors and a bright peak
with a duration (T90) of about 102 s (50-300 keV).
The time-averaged spectrum from T0-10 s to T0+27 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is 1.00 +/- 0.13 and
the cutoff energy, parameterized as Epeak, is 56 +/- 3 keV.

The event fluence (10-1000 keV) in this time interval is
(1.4 +/- 0.05)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.0 s in the 10-1000 keV band
is 5.2 +/- 0.4 ph/s/cm^2.

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