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GCN Circular 9055

Subject
GRB 090330: Fermi GBM detection
Date
2009-03-30T15:59:50Z (15 years ago)
From
Andreas von Kienlin at MPE <azk@mpe.mpg.de>
A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: 

"At 06:42:22.10 UT on 30 March 2009, the Fermi Gamma-Ray Burst Monitor 
triggered and located GRB 090330 (trigger 260088144 / 090330279).
The on-ground calculated location, using the GBM trigger 
data, is RA = 159.2, DEC = -7.7 (J2000 degrees, 
equivalent to 10h 37m, -07d 42'), with an uncertainty 
of 2.1 degrees (radius, 1-sigma containment, 
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
 
The angle from the Fermi LAT boresight is 50 degrees.

The GBM light curve consists of a slowly rising pulse 
with a duration (T90) of about 80 s (8-1000 keV). 
The time-averaged spectrum from T0-2.048 s to T0+24.576 s is 
well fit by a power law function with an exponential
high energy cutoff.  The power law index is -1.01 +/- 0.04 and 
the cutoff energy, parameterized as Epeak, is 261 +/- 18 keV 
(chi squared 606 for 609 d.o.f.).

The event fluence (8-1000 keV) in this time interval is 
(1.14 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured 
starting from T0+12.288 s in the 8-1000 keV band 
is 6.8 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well 
(chi squared 605 for 608 d.o.f.) with Epeak= 246 +/- 25 keV, 
alpha = -0.99 +/- 0.05 and beta = -2.68 +/- 0.55. 

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