[vsnet-grb-info 8059] GRB 090630: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9598
SUBJECT: GRB 090630: Fermi GBM detection
DATE:    09/06/30 15:11:20 GMT
FROM:    Arne Rau at MPE  <arau at mpe.mpg.de>

Arne Rau (MPE) reports on behalf of the Fermi GBM Team:

"At 07:27:21.17 UT on 30 June 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090630 (trigger 268039643 / 090630311).

The on-ground calculated location, using the GBM trigger
data, is RA = 146.6, DEC = -46.6 (J2000 degrees,
equivalent to 09 h 24 m, -46 d 36 '), with an uncertainty
of 5.8 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 75 degrees.

This burst was also detected (although not triggered) by INTEGRAL SPI-ACS.

The GBM light curve consists of a single peak
with a duration (T90) of about 5.1 s (8-1000 keV).
The time-averaged spectrum from T0-1.024 s to T0+4.096 s is
best fit by a power law function with an exponential
high energy cutoff.  The power law index is -1.5 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 79 +/- 13 keV
(chi squared 537 for 475 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(5.1 +/- 0.7)E-07 erg/cm^2. The 2.048-sec peak photon flux measured
starting from T0+0.003 s in the 8-1000 keV band
is 2.78 +/- 0.05 ph/s/cm^2.

A Band function fits the spectrum equally well (chi squared 535 for 474 
d.o.f.)
with Epeak= 71 +/- 24 keV, alpha = -1.5 +/- 0.2 and beta = -2.3 +/- 0.4.

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