GCN Circular 16034

G. Vianello (Stanford), F. Longo and E. Bissaldi (University and
INFN Trieste) report on behalf of the Fermi-LAT team:

On March 23, 2014, Fermi-LAT detected high-energy emission from
GRB 140323A, initially detected by Swift (Troja et al., GCN 16027
Not found
 
 
)
and also detected by Fermi-GBM (Yu et al., GCN 16032
Not found
 
 
).
We note that the GBM and the Swift trigger times are different.
Here we will use as a reference the GBM trigger time,
i.e. 10:22:53.12 UT.

The data from the Fermi-LAT show a significant increase
in the event rate within 10 degrees of the Swift location.
More than 11 photons above 100 MeV and 3 photons above 1 GeV
are observed within 1000 seconds from the GBM trigger time.
The highest-energy photon is a 2.5 GeV event,
which is observed ~220 seconds after the trigger.

The best LAT on-ground location is found to be

RA, Dec 356.46, -79.87 (J2000)

with an error radius of 0.19 deg (90% containment, statistical
error only). This is 0.09 deg from the Swift/XRT localization
(GCN 16028
Not found
 
 
) and is consistent with it.
The source was 31 deg from the LAT boresight
at the time of the trigger.

The Fermi-LAT point of contact for this burst is
Daniel Kocevski (daniel.kocevski@nasa.gov).

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.