[vsnet-grb-info 14214] GRB 131127B: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15528
SUBJECT: GRB 131127B: Fermi GBM detection
DATE:    13/11/28 12:53:49 GMT
FROM:    Andreas von Kienlin at MPE  <azk at mpe.mpg.de>

A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team:

"At 14:12:18.36 UT on 27 November 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 131127B (trigger 407254341 / 131127592).
The on-ground calculated location, using the GBM trigger
data, is RA = 306.1, DEC = -0.8 (J2000 degrees,
equivalent to 20h 24m, -00d 48'), with an 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 88 degrees.

This burst was also independently detected by INTEGRAL SPI-ACS.

Three candidates for an optical afterglow were found by iPTF 
(Singer et al, GCN 15524) using the GBM on-ground location.

The GBM light curve is multi-peaked with a duration (T90) 
of about 18 s (50-300 keV).
The time-averaged spectrum from T0-0.003 s to T0+20.480 s is
best fit by a Band function with Epeak = 181.7 (+7.9/-7.2) keV,
alpha = -1.05 +/- 0.02 , and beta = -2.24 (+0.05/-0.06)

The event fluence (10-1000 keV) in this time interval 
is (3.85 +/- 0.03)E-05  erg/cm^2. The 1.024-sec peak photon 
flux measured starting from T0+5.824 s in the 10-1000 keV band
is 37.6 +/- 0.5  ph/s/cm^2.

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