[vsnet-grb-info 7943] GRB 090602: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9486
SUBJECT: GRB 090602: Fermi GBM detection
DATE:    09/06/03 16:38:59 GMT
FROM:    Elisabetta Bissaldi at MPE  <ebs at mpe.mpg.de>

Elisabetta Bissaldi (MPE) reports on behalf of the Fermi GBM Team:


"At 13:32:22.85 UT on 02 June 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090602 (trigger 265642344 / 090602564).
The on-ground calculated location, using the GBM trigger
data, is RA =  248.9, DEC = -65.0 (J2000 degrees,
equivalent to 16h 36m, -65d 00'), with an uncertainty
of 3.4 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 112 degrees.

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

The GBM light curve consists of a broad single peak
with a duration (T90) of about 16 s (8-1000 keV).
The time-averaged spectrum from T0-1.3s to T0+9s is
best fit by a power law function with an exponential
high energy cutoff. The power law index is -0.56 +/- 0.14 and
the cutoff energy, parameterized as Epeak, is 503 +/- 91 keV
(chi squared 327 for 358 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(5.7 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.8 s in the 8-1000 keV band
is 3.62 +/- 0.17 ph/s/cm^2.


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