GCN Circular 9693
Subject
GRB 090717B: Fermi GBM detection
Date
2009-07-20T14:56:58Z (16 years ago)
From
Arne Rau at MPE <arau@mpe.mpg.de>
Arne Rau (MPE) reports on behalf of the Fermi GBM Team:
"At 02:40:31.79 UT on 17 July 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090717B (trigger 269491233 / 090717111).
The on-ground calculated location, using the GBM trigger
data, is RA = 247.0, DEC = 23.0 (J2000 degrees,
equivalent to 16 h 28m m, 23 d 00 '), with an uncertainty
of 3.9 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 35 degrees.
This burst was also independently detected (although not triggered) by
INTEGRAL SPI-ACS.
The GBM light curve consists of a single peak
with a duration (T90) of about 0.9 s (8-1000 keV).
The time-averaged spectrum from T0-0.256s to T0+0.128 s is
adequately fit by a simple power law function with index -1.02 +/- 0.04
(chi squared 604 for 732 d.o.f.).
The event fluence (8-1000 keV) in this time interval is
(4.83 +/- 0.03)E-07 erg/cm^2. The 0.384-sec peak photon flux measured
starting from T0-0.256 s in the 8-1000 keV band
is 3.91 +/- 0.42 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."