Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 16847

GRB 140928A: Fermi-LAT detection
2014-09-28T21:32:01Z (10 years ago)
Judith Racusin at GSFC <>
R. Desiante (Udine University & INFN Trieste), E. Bissaldi (University & INFN Trieste), D. Kocevski (NASA/GSFC), J.  L. Racusin (NASA/GSFC),
F. Longo (University & INFN Trieste) and M. Arimoto (Tokyo Tech) report on behalf of the Fermi-LAT team:

At 10:29:53.55 on September 28, 2014, Fermi-GBM (trigger 433592996/140928437) triggered on GRB 140928A, which entered the Fermi-LAT 
field of view at T0+1550 s, and was observed until T0+3200 s, during which the LAT detected high-energy emission.

The best LAT on-ground location is found to be:

RA, Dec = 43.81 , -56.08 (J2000)

with an error radius of 0.16 deg (90% containment, statistical error only). This was 110 deg from the LAT boresight at the time of the trigger.

The data from the Fermi-LAT show a significant increase in the event rate at a position consistent with the GBM localization.

More than 20 photons above 100 MeV are observed from 1550 s (when the GRB entered the LAT FOV) to 3200s (when the spacecraft entered 
the SAA) after the GBM trigger. 

The highest-energy photon is a 35 GeV event which is observed 3100 seconds after the GBM trigger.

A Swift ToO has been approved for this burst.

The Fermi-LAT point of contact for this burst is Makoto Arimoto (

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.
Looking for U.S. government information and services? Visit