[vsnet-grb-info 17757] GRB 160314B: Fermi-LAT detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19197
SUBJECT: GRB 160314B: Fermi-LAT detection
DATE:    16/03/15 22:29:29 GMT
FROM:    Judith Racusin at GSFC  <judith.racusin at nasa.gov>

G. Vianello (Stanford), J. Racusin (NASA/GSFC), D. Kocevski (NASA/GSFC), F. Longo (University of 
Trieste and INFN), and B. Ahlgren (KTH), report on behalf of the Fermi-LAT team:

At 22:17:53.73 on March 14, 2016 Fermi-LAT detected high-energy emission from GRB 160314B, which 
was also detected by Fermi-GBM (trigger 479686676 / 160314929). 

The best LAT on-ground location is found to be:
RA, Dec (J2000) = 167.56, 45.67 
with an error radius of 0.65 deg (90 % containment, statistical error only). 

Unfortunately, the LAT was not taking data at the trigger time T0, because Fermi was just exiting the South 
Atlantic Anomaly (SAA).  Note that LAT and GBM have slightly different SAA definitions in onboard software.  
However, LAT resumed data taking ~30 seconds after T0, and the GRB was 21 deg from the LAT boresight 
at that time. 

The LAT data show a significant increase in the event rate that is spatially and temporally 
correlated with the trigger with high significance. The highest-energy photon is a 900 MeV event which is 
observed ~630 seconds after the GBM trigger.

The Fermi-LAT point of contact for this burst is B. Ahlgren (bjornah at kth.se).

The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater 
than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and 
many scientific institutions across France, Italy, Japan and Sweden.