[vsnet-grb-info 19741] GRB 170826A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21715
SUBJECT: GRB 170826A: Fermi GBM detection
DATE:    17/08/26 19:00:17 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076 at uah.edu>

S. Poolakkil (UAH), E. Bissaldi (Politecnico & INFN Bari) and C. Meegan
(UAH)
report on behalf of the Fermi GBM Team:

"At 08:51:07.51 UT on 26 August 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170826A (trigger 525430272/ 170826369).

The on-ground calculated location, using the GBM trigger
data, is RA = 82.4, DEC = 32.8, with an uncertainty
of 7.2 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The angle from the Fermi LAT boresight at the GBM trigger time is 101
degrees.

The GBM triggered on a single pulse over a
total duration (T90) of about 0.2 s (50-300 keV).
The time-averaged spectrum from T0-0.2 to T0+0.1 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.05 +/- 0.11 and
the cutoff energy, parameterized as Epeak, is 685 +/- 236 keV.

The event fluence (10-1000 keV) in this time interval is
 (8.2 +/- 0.6)E-07 erg/cm^2. The 64 ms peak photon flux measured
starting from T0+0.1 s in the 10-1000 keV band
is 18.6 +/- 2.1 ph/s/cm^2.

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

-- 
Suraj Poolakkil
Fermi GBM Graduate Research Assistant
Dept. of Space Science
University of Alabama in Huntsville