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GCN Circular 9228

Subject
GRB 090422: Fermi GBM observation
Date
2009-04-24T15:57:39Z (15 years ago)
From
Sheila McBreen at MPE <smcbreen@mpe.mpg.de>
Sheila McBreen (UCD/MPE)
reports on behalf of the Fermi GBM Team:

"At 03:35:17.07 UT on 22 April 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090422 (trigger 262064119 / 090422150)
which was also detected by the Swift-BAT (Ukwatta et al. 2009, GCN 9185
& Markwardt et al. 2009, GCN 9195). The GBM on-ground location is
consistent with the Swift position.
The angle from the Fermi LAT boresight is 29 degrees.

The GBM light curve consists of 2 pulses
with a duration (T90) of about 10 s (8-1000 keV).
The time-averaged spectrum from T0-2.4 s to T0+10.8 s is
adequately fit by a simple power law function with
index 1.81 +/- 0.15 (chi squared 358 for 361 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(1.0 +/- 0.1)E-6 erg/cm^2. The 0.128 sec peak photon flux measured
starting from T0-0.256 s in the 8-1000 keV band
is 7.8 +/- 0.5 ph/s/cm^2.
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