[AAVSO-HEN] GRB 090717B: Fermi GBM detection

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  9693
SUBJECT: GRB 090717B: Fermi GBM detection
DATE:    09/07/20 14:56:58 GMT
FROM:    Arne Rau at MPE  <arau at 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."