[vsnet-grb-info 7310] GRB 090202: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8877
SUBJECT: GRB 090202: Fermi GBM detection
DATE:    09/02/03 10:14:37 GMT
FROM:    Andreas von Kienlin at MPE  <azk at mpe.mpg.de>

A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: 

"At 08:19:30.40 UT on 02 February 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090202 (trigger 255255572 / 090202347).
The on-ground calculated location, using the GBM trigger 
data, is RA = 268.9, DEC = -2.5 (J2000 degrees, 
equivalent to 17h 56m, -02d 30'), 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 55 degrees.

This burst was also independently detected by INTEGRAL SPI-ACS.

The GBM light curve shows a single peak and a tail
with a duration (T90) of about 66 s (8-1000 keV). 
The time-averaged spectrum from T0-1.536 s to T0+15.872 s is
best fit by a power law function with an exponential
high energy cutoff.  The power law index is -1.31 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 570 +/- 170 keV
(chi squared 510.50 for 485 d.o.f.).

The event fluence (8-1000 keV) in this time interval is 
(8.65 +/- 0.31)E-06 erg/cm^2. The 1-sec peak photon flux measured 
starting from T0+8.704 s in the 8-1000 keV band 
is 7.77 +/- 0.41 ph/s/cm^2.

The spectral analysis results presented above are preliminary; 
final results will be published in the GBM GRB Catalog."