O.J. Roberts (UCD) and C. Meegan (UAH) report on
behalf of the Fermi GBM Team:
"At 10:19:12.43 UT on 06 February 2016, the Fermi
Gamma-Ray Burst Monitor triggered and located GRB
160206B (trigger 476446756 / 160206430). A list of
optical candidates were observed by iPTF within the
2-sigma statistical+systematic region of the final
on-ground calculated location (Singer et al., GCN 18995).
The on-ground calculated location, using the GBM trigger
data, is RA = 184.3, DEC = 52.4 (J2000 degrees,
equivalent to 12h 17m, 52d 24'), with an uncertainty of
4.2 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 is about 83 degrees.
The GBM light curve consists of a FRED-like pulse with a
duration (T90) of about 21.5 s (50-300 keV). The
time-averaged spectrum from T0-4.9 s to T0+16.6 s is best
fit by a power law function with an exponential high-energy
cutoff. The power law index is -0.93 +/- 0.10 and the cutoff
energy, parameterized as Epeak, is 356.0 +/- 69.5 keV.
The event fluence (10-1000 keV) in this time interval is
(4.6 +/- 0.4)E-06 erg/cm^2. The 1.024-sec peak photon flux
measured starting from T0+3.4 s in the 10-1000 keV band is
3.0 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."