[vsnet-grb-info 7880] GRB 090524: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9424
SUBJECT: GRB 090524: Fermi GBM detection
DATE:    09/05/26 15:20:47 GMT
FROM:    Andreas von Kienlin at MPE  <azk at mpe.mpg.de>

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

"At 08:17:56.23 UT on 24 May 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090524 (trigger 264845878 / 090524346).
The on-ground calculated location, using the GBM trigger 
data, is RA = 329.5, DEC = -67.4 (J2000 degrees, 
equivalent to 21h 58m, 67d 24'), with an uncertainty 
of 1.3  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 63 degrees.

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

The GBM light curve consists of two main pulses
with a duration (T90) of about 72 s (8-1000 keV). 
The time-averaged spectrum from T0+0.003 s to T0+71.681 s is 
best fit by a Band function with Epeak = 82.6 +/- 6.3 keV, 
alpha = -1.00 +/- 0.08, and beta = -2.30 +/- 0.09
(chi squared 959 for 840 d.o.f.).

The event fluence (8-1000 keV) in this time interval is 
(1.85 +/- 0.15)E-05 erg/cm^2. The 1-sec peak photon flux measured 
starting from T0+5.120 s in the 8-1000 keV band 
is 14.1 +/- 1.4 ph/s/cm^2.

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