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GCN Circular 9562

Subject
GRB 090621B: Fermi GBM detection
Date
2009-06-23T00:03:11Z (15 years ago)
From
Adam Goldstein at Fermi-GBM/UAH <adam.m.goldstein@msfc.nasa.gov>
A. Goldstein (UAH) and J.M. Burgess (UAH) 
report on behalf of the Fermi GBM Team: 

"At 22:07:25.70 UT on 21 June 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090621B (trigger 267314847 / 090621922)
which was also detected by the Swift BAT (P.A. Curran et al. 2009, 
GCN 9545). The GBM on-ground location is consistent with the 
Swift position.  The angle from the Fermi LAT boresight 
is 108 degrees.

The GBM light curve consists of one short spike
with a duration (T90) of about 0.128 s (8-1000 keV). 
The time-averaged spectrum from T0-0.064 s to T0+0.064 s is 
best fit by a Band function with Epeak = 321.60 +/- 129.00 keV, 
alpha = -0.13 +/- 0.38, and beta = -1.57 +/- 0.08
(chi squared 401 for 481 d.o.f.).

The event fluence (8-1000 keV) in this time interval is 
(3.71 +/- 0.58)E-07 erg/cm^2. The 0.128-sec peak photon flux measured 
starting from T0-0.064 s in the 8-1000 keV band 
is 6.4 +/- 1.4 ph/s/cm^2.

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