[vsnet-grb-info 25791] GRB 200530A: Fermi-LAT detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27891
SUBJECT: GRB 200530A: Fermi-LAT detection
DATE:    20/06/05 18:03:00 GMT
FROM:    Francesco Longo at U of Trieste,INFN Trieste  <franzlongo1969 at gmail.com>

F. Longo (University and INFN, Trieste), D. Kocevski (NASA/MSFC), N. Di
Lalla (Stanford University),
M. Ohno (Hiroshima Univ.), F. Fana Dirirsa (Univ. of Johannesburg), N.
Omodei (Stanford University)
and J. Racusin (NASA/GSFC) report on behalf of the Fermi-LAT Collaboration:

On May 30, 2020, Fermi-LAT detected high-energy emission from
GRB 200530A, which was also detected by Fermi-GBM at T0 = 00:44:10 UT (GCN
27861).

The GRB is detected at high energy (>100 MeV) by Fermi-LAT at a location of:
RA, Dec = 32.1, 69.2 (degrees, J2000) with an error radius of 0.5 deg
(90% containment, statistical error only).
This was ~40 deg from the LAT boresight when observations started,
and is ~6 deg from the GBM final ground position.
The photon flux above 100 MeV in the time interval 0 - 1000 s
after the GBM trigger is 5.5 e-06 +/- 1.8 e-06 ph/cm2/s.
The estimated photon index above 100 MeV is -2.3 +/- 0.3.
The highest-energy photon is a 1.6 GeV event which is observed
~100 seconds after the GBM trigger.
After ~T0+1000 s, the GRB location moved outside the LAT FoV.
When it re-entered in the LAT FoV at later times (from ~4800  to ~6700 s)
it was not detected.

The late time notification of this detection is due to a delay on the data
processing for the data of May 30.

The Fermi-LAT point of contact for this burst is
Francesco Longo (francesco.longo at ts.infn.it).

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.