[vsnet-grb-info 15453] GRB 140821A: Fermi GBM Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16742
SUBJECT: GRB 140821A: Fermi GBM Detection
DATE:    14/08/25 16:44:54 GMT
FROM:    Binbin Zhang at UAH  <binbin.zhang at uah.edu>

Bin-Bin Zhang (UAH) reports on behalf of the Fermi GBM Team:

"At 23:56:02.84  UT on the 21st of August 2014, the Fermi Gamma-Ray Burst 
Monitor triggered and located GRB 140821A (trigger 430358165 / 140821997). 
The trigger resulted in an Autonomous Repoint Request (ARR) that was 
accepted. The GBM on-ground location is consistent with the Fermi flight 
software position.

The angle from the Fermi LAT boresight is 93 degrees.

The GBM light curve consists of single peak with a duration (T90) of about
32 s (50-300 keV). The time-averaged spectrum from T0+11 s to T0+43 s is
well fit by Band function parameterized as Ep=483+/-22 keV, 
alpha=-0.82+/-0.03 and beta=-2.4+/-0.1. 

The event fluence (10-1000 keV) in this time interval is
(6.314+/-0.067)E-05 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+29 s in the 10-1000 keV band is  19.5+/-0.6 ph/s/cm^2.

The burst spectrum may be contaminated by solar flare activity that is 
detected at energies below ~20 keV in many of the same GBM detectors. 
Although the solar emission has several peaks, the first of which is  
around T0+130 s, it may have significant overlap with the time of the
burst.

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