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GCN Circular 9560

Subject
GRB 090621D: Fermi GBM detection
Date
2009-06-22T19:47:45Z (15 years ago)
From
Arne Rau at MPE <arau@mpe.mpg.de>
Arne Rau (MPE) reports on behalf of the Fermi GBM Team:

"At 10:43:45.14  UT on 21 June 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090621D (267273827 / 090621447).

The on-ground calculated location, using the GBM trigger
data, is RA = 12.3, DEC = -22.6 (J2000 degrees,
equivalent to 00 h 49 m, -22 d 36 '), with an uncertainty
of 4.9 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 79 degrees.

The GBM light curve consists of two peaks
with a duration (T90) of about 39.9 s (8-1000 keV).
The time-averaged spectrum from T0-1.024  s to T0+20.480 s is
adequately fit by a simple power law function with index -1.66 +/- 0.05
(chi squared 752 for 694 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(1.34 +/- 0.03)E-06 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0-1.024 s in the 8-1000 keV band
is 1.74 +/- 0.05 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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