[vsnet-grb-info 14017] GRB 131011A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15331
SUBJECT: GRB 131011A: Fermi GBM detection
DATE:    13/10/14 00:09:15 GMT
FROM:    Peter Jenke at MSFC  <peter.a.jenke at nasa.gov>

P. Jenke (UAH) reports on behalf of the Fermi GBM Team:

At 17:47:34.99 UT on October 11 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 131011A (trigger 403206457/131011741).
A candidate optical afterglow was found by iPTF (Kasliwal et al. 2013, GCN
15324) using the GBM on-ground location.
Additional follow-ups confirmed that the optical source has faded (Xu et
al. 2013, GCN 15325) and has a redshift of 
z = 1.874 (Rau et al. 2013, GCN 15330).  A weak X-ray
source consistent with the optical afterglow was detected by the 
Swift XRT (Page et al. 2013, GCN 15329).

The angle of the burst direction to the Fermi LAT boresight is 74 degrees.

The GBM light curve consists of one main peak and a small 
post burst with a combined duration (T90) of about 77 s (50-300 keV).
The time-averaged spectrum from T0-3 s to T0+25s is
well fit by a Band function with Epeak of 220 +/- 30 keV.
Alpha = -0.79 +/- 0.08 and Beta = -2.0 +/- 0.1.

The event fluence (10-1000 keV) in this time interval is
(6.60 +/- 0.03)E-05 erg/cm^2. The 1.0-sec peak photon flux measured
starting from T0+4.3 s in the 10-1000 keV band
is 4.3 +/- 0.4 ph/s/cm^2.

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