[vsnet-grb-info 7855] GRB 090511: Fermi GBM Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9399
SUBJECT: GRB 090511: Fermi GBM Detection
DATE:    09/05/19 20:48:51 GMT
FROM:    Valerie Connaughton at MSFC  <valerie at nasa.gov>

Valerie Connaughton (UAH) reports on behalf of the Fermi GBM Team:

"At 16:25:16.37 UT on 11 May 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090511 (trigger 263751918 / 090511684).

The on-ground calculated location, using the GBM trigger
data, is RA = 161.9, DEC = 51.3 (J2000 degrees,
equivalent to 10 h 48 m, 51 d 18 '), with an uncertainty
of 7.0 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 67 degrees.

The GBM light curve consists of a single pulse
with a duration (T90) of about 14 s (8-1000 keV).
The time-averaged spectrum from T0-5.1 s to T0+4.1 s is
best fit by a power law function with an exponential
high energy cutoff.  The power law index is -0.95 +/- 0.18 and
the cutoff energy, parameterized as Epeak, is 391 +/- 157 keV.

The event fluence (8-1000 keV) in this time interval is
(1.8 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1 s in the 8-1000 keV band
is 2.5 +/- 0.4 ph/s/cm^2.

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