TITLE:   GCN CIRCULAR
NUMBER:  9077
SUBJECT: GRB 090328: Fermi-LAT refined analysis
DATE:    09/04/01 19:30:09 GMT
FROM:    Sara Cutini at ASDC  <sara.cutini@asdc.asi.it>

Sara Cutini (ASDC), V. Vasileiou (NASA/GSFC, UMBC) and Jim Chiang  
(SLAC/KIPAC) report on behalf of the Fermi LAT team.

We report further analysis with the LAT data on GRB 090328 (McEnery  
et al. GCN Circ. 9044, Kennea et al. GCN Circ. 9045).
The emission in the LAT lasts up around 900s after the trigger, we  
did not find evidence for further high-energy delayed emission beyond  
900s.
Considering the rate of events passing the on board event filters for  
gamma-rays, the light curve shows a single pulse peaking at 25s which  
corresponds to the third spike of GBM light curve (A. Rau at al. GCN  
Circ. 9057).
The highest energy events detected by the LAT  which are  spatially  
coincident with the burst position arrived hundreds of seconds after  
the GRB trigger time.
In a preliminary time resolved spectral analysis we find no evidence  
of a change in spectral index during the whole duration of the burst.
The points of contact for this burst are Julie McEnery (LAT,  
julie.mcenery@nasa.gov) and Arne Rau (GBM, arau@mpe.mpg.de).
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.