GCN Circular 9523

Elisabetta Bissaldi (MPE) reports on behalf of the Fermi GBM Team:


"At 04:59:58.58 UT on 17 June 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090617 (trigger 266907600 / 090617208).
The on-ground calculated location, using the GBM trigger
data, is RA = 78.9, Dec = +15.7 (J2000 degrees,
equivalent to 05h 16m, 15d 42'), with an uncertainty
of 4.2 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 45 degrees.

The GBM light curve consists of a single bright pulse
with a duration (T90) of about 0.45 s (8-1000 keV).
The time-averaged spectrum from T0-0.032 s to T0+0.192 s is
best fit by a Band function with Epeak = 684 (-200/+250) keV,
alpha = -0.45 (-0.27/+0.17) and beta = -2.00 (-0.20/+0.24)
(Castor Stat 626 for 604 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(4.68 +/- 0.20)E-07 erg/cm^2. The 32-msec peak photon flux
measured starting from T0-0.032 s in the 8-1000 keV band
is 10.0 +/- 0.5 ph/s/cm^2.


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