[vsnet-grb-info 7497] GRB 090328B: Fermi GBM Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9056
SUBJECT: GRB 090328B: Fermi GBM Detection
DATE:    09/03/30 18:06:00 GMT
FROM:    Adam Goldstein at Fermi-GBM/UAH  <adam.m.goldstein at msfc.nasa.gov>

A. Goldstein (UAH) reports on behalf of the Fermi GBM Team: 

"At 17:07:04.94 UT on 28 March 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090328B (trigger 259952826 / 090328713).
The Fermi Observatory executed a maneuver following this trigger and 
tracked the burst location for the next 5 hours, subject to 
Earth-angle constraints.

The on-ground calculated location, using the GBM trigger 
data, is RA = 155.72, DEC = +33.40 (J2000 degrees, 
equivalent to 10h 23m, 33d 24'), with an uncertainty 
of 7.94 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 74 degrees.

The GBM light curve consists of a single bright peak
with a duration (T90) of about 0.32 s (8-1000 keV). 
The time-averaged spectrum from T0-0.13 s to T0+0.13 s is 
well fit by a Band function with Epeak = 1967.0 +/- 701.0 keV, 
alpha = -0.92 +/- 0.06, and beta = -2.48 +/- 0.66
(chi squared 452.6 for 482 d.o.f.).

The event fluence (8-1000 keV) in this time interval is 
(9.61 +/- 0.31)E-07 erg/cm^2. The 0.064-sec peak photon flux measured 
starting from T0+0.0 s in the 8-1000 keV band 
is 29.83 +/- 2.38 ph/s/cm^2. 

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