[vsnet-grb-info 22461] GRB 190515A: Fermi-LAT detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24560
SUBJECT: GRB 190515A: Fermi-LAT detection 
DATE:    19/05/16 02:05:30 GMT
FROM:    Daniel Kocevski at GSFC  <dankocevski at gmail.com>

D. Kocevski (NASA/MSFC), M. Axelsson (KTH and Stockholm Univ.), L. Scotton (INFN Torino), E. Burns (NASA/GSFC), and M. Arimoto (Kanazawa Univ.) report on behalf of the Fermi-LAT team: 

At 04:33:03 on 2019-05-15, Fermi-LAT triggered on high-energy emission from short GRB 190515A, which was also detected by Fermi-GBM  (trigger 579587588/190515190).

The best LAT on-ground location is found to be

RA, Dec = 137.687 , 29.276 (J2000) 

with an error radius of 0.907 deg (90% containment, statistical error only). This was 44 deg from the LAT boresight at the time of the trigger and 10 deg from the center of the GBM localization (GCN 24550).

The data from the Fermi-LAT show a significant increase in the event rate that is temporally correlated with the GBM emission with high significance. The highest-energy photon is a 874 MeV event which is observed 3 seconds after the GBM trigger.

The photon flux above 100 MeV in the time interval 0-300s after the GBM trigger is 6.5e-06 ph/cm2/s +/- 2.4e-06. The estimated photon index above 100 MeV is -2.6 +/- 0.5.

The Fermi-LAT point of contact for this burst is Magnus Axelsson (magnusa at fysik.su.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.