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GCN Circular 9130

Subject
GRB 090411A: Fermi GBM detection
Date
2009-04-16T14:36:53Z (15 years ago)
From
Rob Preece at UAH <Rob.Preece@nasa.gov>
Rob Preece (UAH)reports on behalf of the Fermi GBM Team:

"At 20:06:36.89 UT on 4 April, 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090411 (trigger 261173198 / 090411838).

The on-ground calculated location, using the GBM trigger
data, is RA = 159.34, DEC = -68.36 (J2000 degrees,
equivalent to 10 h 37 m, 68 d 21'), with an uncertainty
of 2.3 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 59 degrees.

The GBM light curve consists of two main pulses
with a duration (T90) of about 24.6 s (8-1000 keV).
The time-averaged spectrum from T0-2.04 s to T0+18.4 s is
best fit by a Band function with Epeak = 141 +/- 35 keV,
alpha = -0.88 +/- 0.15, and beta = -1.82 +/- 0.08
(chi squared 319.93 for 318 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(8.6 +/- 1.2)E-6 erg/cm^2. The 0.256-sec peak photon flux measured
starting from T0+11.75 s in the 8-1000 keV band
is 3.25 +/- 0.94 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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