[vsnet-grb-info 7457] GRB 090319: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9019
SUBJECT: GRB 090319: Fermi GBM detection
DATE:    09/03/23 15:35:25 GMT
FROM:    Vandiver Chaplin at UAH/Fermi-GBM  <chapliv at email.uah.edu>

V.Chaplin (UAH) reports on behalf of the Fermi GBM Team:

"At 14:55:35.22 UT on 19 MARCH 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090319 (trigger 259167337 / 090319622).

The on-ground calculated location, using the GBM trigger
data, is RA = 274.6, DEC = -11.4 (J2000 degrees,
equivalent to 18h 18m, -11d 24'), with an uncertainty
of 3.0 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 27 degrees.

The GBM light curve consists of two ~6 s peaks at
about T0+13 and T0+30 s on top of a smooth component,
with a duration (T90) of about 67.7 s (8-1000 keV).
The time-averaged spectrum from T0-6.144 to T0+37.889 s is
best fit by a power law function with an exponential
high energy cutoff.  The power law index is 0.90 +/- 0.10 and
the cutoff energy, parameterized as Epeak, is 187.3 +/- 20.4 keV
(chi squared 463.25 for 467 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(7.47 +/- .53)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+13.312 s in the 8-1000 keV band
is 3.85 +/- 0.12 ph/s/cm^2.

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