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GCN Circular 20616

GRB 170206A: Fermi GBM observation
2017-02-06T18:04:50Z (7 years ago)
Oliver J Roberts at USRA/NASA <>
A. von Kienlin (MPE) and O.J. Roberts (USRA/NASA-MSFC) report 
on behalf of the Fermi GBM Team:

"At 10:51:57.70 UT on February 6th 2017, the Fermi Gamma-Ray
Burst Monitor triggered and located GRB 170206A
(trigger 508071122 /170206453). The on-ground calculated 
location, using the GBM trigger data, 

is RA = 211.80, DEC = +13.06, (J2000 degrees, equivalent to 
J2000 14h 07m, +/- 13d 03')

with an uncertainty of 1.14 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 trigger resulted in an Autonomous Repoint Request (ARR) 
by the GBM Flight Software owing to the high peak flux of the 
GRB. This ARR was accepted and the spacecraft slewed to the 
GBM in-flight location. The initial angle from the Fermi-LAT 
boresight to the GBM ground location is 67 degrees.

The GBM light curve shows a short, bright burst with a duration 
(T90) of about 1.2 s (50-300 keV). The time-averaged spectrum 
from T0+0.1s to T0+1.3 s is best fit by a BAND function, with 
alpha=  -0.28 +/- 0.04, beta= -2.55 +/- 0.12 and Epeak, 
is 341 +/- 13 keV.

The event fluence (10-1000 keV) in this time interval is
(1.34 +/- 0.02) E-05 erg/cm^2. The 64 ms peak photon flux 
measured starting from T0+0.6 s in the 10-1000 keV band is
57.0 +/- 2.1 ph/s/cm^2.

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