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GCN Circular 9390

GRB090513: Fermi GBM detection
2009-05-18T12:06:28Z (15 years ago)
Colleen A. Wilson at NASA/MSFC/NSSTC <>
Colleen A. Wilson-Hodge (NASA/MSFC)
reports on behalf of the Fermi GBM Team:

"At 21:58:47.92 UT on 13 May 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090513 (trigger 263944729 / 090513.916).

The on-ground calculated location, using the GBM trigger
data, is RA = 269.8, DEC = -31.6 (J2000 degrees,
equivalent to 17 h 59 m, -31 d 36'), with an uncertainty
of 4.6 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 89 degrees.

The GBM light curve shows a broad peak
with a duration (T90) of about 23 s (8-1000 keV).
The time-averaged spectrum from T0-1 s to T0+19 s is
adequately fit by a power law function with an exponential
high energy cutoff.  The power law index is -0.9 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 850 +/- 390 keV

The event fluence (8-1000 keV) in this time interval is
(6.8 +/- 0.4)E-06 erg/cm^2. The 1 s peak photon flux measured
starting from T0+5.1 s in the 8-1000 keV band
is 2.7 +/- 0.2 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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