[AAVSO-HEN] GRB 090206: Fermi GBM detection

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  8916
SUBJECT: GRB 090206: Fermi GBM detection
DATE:    09/02/27 16:00:52 GMT
FROM:    Elisabetta Bissaldi at MPE  <ebs at mpe.mpg.de>

E. Bissaldi (MPE) and A. von Kienlin (MPE)
report on behalf of the Fermi GBM Team:


"At 14:52:42.17 UT on 06 February 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090206 (trigger 255624764 / 090206620).
The on-ground calculated location, using the GBM trigger
data, is RA = 157.2, DEC = +14.5 (J2000 degrees,
equivalent to 10h 29m, 14d 30'), with an uncertainty
of 8.7 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 72 degrees.

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

The GBM light curve consists of a single peak
with a duration (T90) of about 0.8 s (8-1000 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.512 s is
adequately fit by a power law function with an exponential
high energy cutoff.  The power law index is -0.65 +/- 0.14 and
the cutoff energy, parameterized as Epeak, is 710 +/- 170 keV
(chi squared 402 for 456 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(1.04 +/- 0.06)E-06 erg/cm^2. The 64-msec peak photon flux
measured starting from T0 in the 8-1000 keV band is
19.0 +/- 1.0 ph/s/cm^2.


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