GCN Circular 9035

A.J. van der Horst (NASA/MSFC/ORAU) reports on behalf of the
Fermi GBM team:

"We have performed spectral analysis of the GBM data for GRB 090323
(GCN 9021
Not found
 
 
). The analysis was restricted to the first ~70 seconds of
GRB emission, because after that time the Fermi Observatory executed
a maneuver following this bright GRB, which caused rapid, significant
changes in the source angles of the various detectors and in the
background behaviour.

The spectrum from T0-2.0 s to T0+71.7 s is best fit by a power-law
function with a high-energy exponential cutoff. The power-law index
is -0.89 +/- 0.03, and the cutoff energy, parameterized as Epeak, is
697 +/- 51 keV (chi squared 379.4 for 359 d.o.f.). At a redshift of
3.57 (GCN 9028
Not found
 
 
), the Epeak in the GRB rest frame, Epeak_rest, is
3.19 +/- 0.23 MeV.

The event fluence (8-1000 keV) in this time interval is
(1.00 +/- 0.01)E-4 erg/cm^2. The 1-sec peak photon flux
measured starting from T0+65.5 s in the 8-1000 keV band
is 12.3 +/- 0.4 ph/s/cm^2.

This time interval consists of two main emission peaks, from T0-2.0 s
to T0+33.8 s and from T0+33.8 s to T0+71.7 s. Both of these shorter
intervals are also best fit by a power-law function with a high-energy
exponential cutoff. For the first interval the power-law index is
-1.00 +/- 0.03, Epeak is 1173 +/- 175 keV, Epeak_rest is 5.36 +/- 0.80
MeV, and the fluence (8-1000 keV) is (3.68 +/- 0.06)E-5. For the second
interval the power-law index is -0.83 +/- 0.03, Epeak is 574 +/- 34 keV,
Epeak_rest is 2.62 +/- 0.16 MeV, and the fluence (8-1000 keV) is
(6.35 +/- 0.09)E-5.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."