Skip to main content
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 9040

Subject
GRB 090327: Fermi GBM detection
Date
2009-03-27T16:32:30Z (15 years ago)
From
Andreas von Kienlin at MPE <azk@mpe.mpg.de>
A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: 

"At 09:41:41.51 UT on 27 March 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090327 (trigger 259839703 / 090327404).
The on-ground calculated location, using the GBM trigger 
data, is RA = 29.5, DEC = -41.6 (J2000 degrees,
equivalent to 01h 58m, -41d 36'), 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 66 degrees.

The GBM light curve consists of single peak
with a duration (T90) of about 24 s (8-1000 keV). 
The time-averaged spectrum from T0 to T0+16.384 s is  
well fit by a power law function with an exponential
high energy cutoff.  The power law index is -0.50 +/- 0.12 and
the cutoff energy, parameterized as Epeak, is 96.4 +/- 5.1 keV
(chi squared 550 for 475 d.o.f.).

The event fluence (8-1000 keV) in this time interval is 
(3.0 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured 
starting from T0+9.216 s in the 8-1000 keV band 
is 3.5 +/- 0.7  ph/s/cm^2.

A Band function fits the spectrum equally well (chi squared 549 
for 474 d.o.f.) with Epeak= 89.7 +/- 7.0  keV, 
alpha = -0.39 +/- 0.16 and beta = -2.90 +/- 0.45. 

The spectral analysis results presented above are preliminary; 
final results will be published in the GBM GRB Catalog."
Looking for U.S. government information and services? Visit USA.gov