[AAVSO-HEN] GRB 091126: Fermi GBM detection

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  10223
SUBJECT: GRB 091126: Fermi GBM detection
DATE:    09/12/01 10:18:21 GMT
FROM:    Sheila McBreen at MPE  <smcbreen at mpe.mpg.de>

D. Tierney (UCD) and S. McBreen (UCD/MPE)
report on behalf of the Fermi GBM Team:

"At 07:59:24.76 UT on 26 November 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 091126 (trigger 280915166 / 091126333).
The on-ground calculated location, using the GBM trigger
data, is RA = 83.3, DEC = -19.3 (J2000 degrees,
equivalent to 05 h 33 m, -19 d 18 '), with an uncertainty
of 5.4 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 93 degrees.
This burst was also independently detected by INTEGRAL SPI-ACS.

The GBM light curve consists of one pulse
with a duration of about 0.3 s (8-1000 keV).
The time-averaged spectrum from T0-0.256 s to T0+0.256 s is
adequately a power law function with an exponential
high energy cutoff.  The power law index is -0.60 (+0.24/-0.21) and
the cutoff energy, parameterized as Epeak, is 458 (+215/-107) keV
(CSTAT  478 for 476 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(5.9 +/- 0.5)E-7 erg/cm^2. The 0.128 sec peak photon flux measured
starting from T0+0 s in the 8-1000 keV band
is 8.3 +/- 0.7 ph/s/cm^2.

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