TITLE:   GCN CIRCULAR
NUMBER:  20706
SUBJECT: GRB 170219A: Fermi GBM observation
DATE:    17/02/19 21:08:46 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

O.J. Roberts (USRA/NASA), M. Stanbro and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 00:03:07.12 UT on February 19th 2017, the Fermi
Gamma-Ray Burst Monitor triggered and located
GRB 170219A (trigger 509155392 / 170219002), which
was also detected by Konus-Wind
(Frederiks et al. 2017, GCN 20703) and for which a
triangulated position was reported by IPN
(Svinkin et al. 2017, GCN 20702). The GBM localisation 
is within about 2.5-sigma of the triangulated IPN position.

The initial angle from the Fermi-LAT boresight to the GBM
ground-location using the centre of the IPN triangulated
position is 133 degrees.

The GBM light curve shows a bright, short burst a duration
(T90) of about 0.08 s (50-300 keV). The time-averaged spectrum
from T0-0.03 s to T0+0.05 s is best fit by a power law function
with an exponential high-energy cutoff.  The power law index is
-0.59 +/- 0.10 and the cutoff energy, parameterized as Epeak
is 1165 +/- 182 keV

A Band function fits the spectrum equally well with
alpha= -0.56 +/- 0.11, beta= -3.25 +/- 1.19 and Epeak
is 1093 +/- 202 keV.

The event fluence (10-1000 keV) in this time interval is
(9.52 +/- 0.49)E-07 erg/cm^2. The 64 ms peak photon flux
measured starting from T0+0 s in the 10-1000 keV band is
29.4 +/- 1.9 ph/s/cm^2.

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