[vsnet-grb-info 9217] GRB 100427A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10702
SUBJECT: GRB 100427A: Fermi GBM detection
DATE:    10/04/29 00:31:46 GMT
FROM:    Adam Goldstein at Fermi-GBM/UAH  <adam.m.goldstein at msfc.nasa.gov>

A. Goldstein (UAH) and D. Gruber (MPE) 
report on behalf of the Fermi GBM Team: 

"At 08:32:08.71 UT on 27 April 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100427A (trigger 294049930 / 100427356),
which was also detected by the Swift-BAT (J.R. Cummings et al. 2010, 
GCN 10699).  The GBM on-ground location is consistent with the Swift-BAT 
position.  The angle from the Fermi LAT boresight is 29 degrees.

The GBM light curve consists of a single pulse with multiple peaks
with a duration (T90) of about 24 s (8-1000 keV). 
The time-averaged spectrum from T0-4.1 s to T0+11.3 s is 
best fit by a power law function with an exponential
high energy cutoff.  The power law index is -1.02 +0.12/-0.11 and
the cutoff energy, parameterized as Epeak, is 121.0 +15.4/-11.8 keV
(Castor C-Stat 519 for 484 d.o.f.).

The event fluence (8-1000 keV) in this time interval is 
(3.01 +/- 0.13)E-06 erg/cm^2. The 1-sec peak photon flux measured 
starting from T0+5.18 s in the 8-1000 keV band 
is 4.79 +/- 0.24 ph/s/cm^2.

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