[vsnet-grb-info 14189] GRB 131118A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15503
SUBJECT: GRB 131118A: Fermi GBM detection
DATE:    13/11/19 18:35:12 GMT
FROM:    Andrew Collazzi at NASA/MSFC/ORAU  <andrew.collazzi at nasa.gov>

Andrew C. Collazzi (NASA/ORAU) reports on behalf of the Fermi GBM Team:

"At 22:58:57.47 UT on 18 November 2013, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 131118A (trigger 406508340 / 131118.958). The
on-ground calculated location, using the Fermi GBM trigger data,
is RA = 349.7, Dec = -69.4 (J2000 degrees, equivalent to J2000 23h 18.8m,
-69° 24' ), with a statistical uncertainty of 1.0 degrees (radius, 1-sigma
containment, statistical only; there is additionally a systematic error which
is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT
boresight is 150 degrees.

Due to the high zenith angle of this burst, there may be higher than normal
systematic errors on this location.  This burst was also observed by Swift-BAT
(ground analysis), Suzaku-WAM, and INTEGRAL/SPI-ACS.

The GBM light curve shows a multi-peaked event with a duration (T90)
of about 85 s (50-300 keV). The 1.024-s peak flux during this interval is
12.5 +/- 0.9 erg/s/cm^2 (10-1000 keV). The time-averaged spectrum
from T0-13.8 to T0+99.8 s is equally well fit to a Comptonized model
with Epeak = 370.5 +/- 10.6, alpha = -0.89 +/- 0.03 and a Band model with
Epeak = 366.8 +/- 12.5, alpha = -0.89 +/- 0.03, and beta = -3.4 +/- 0.6.
Both models yield a fluence (10-1000 keV) in this time interval 
of (9.2 +/- 0.1)E-05 erg/cm^2.

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