[vsnet-grb-info 17659] GRB 160225B: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19096
SUBJECT: GRB 160225B: Fermi GBM detection
DATE:    16/02/26 23:54:49 GMT
FROM:    C. Michelle Hui at MSFC/Fermi-GBM  <c.m.hui at nasa.gov>

C. M. Hui (NASA/MSFC), E. Burns (UAH), and C. Meegan (UAH)
reports on behalf of the Fermi GBM Team:

At 19:24:25.39 UT on 25 February 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 160225B (trigger 478121069 / 160225809)
which was also triangulated by IPN (Svinkin et al., GCN 19095)

The on-ground calculated location, using the GBM trigger data, 
is RA = 150.19 , DEC = -34.71  (J2000 degrees, 
equivalent to 10h 00m, -34d 42.0'), with an uncertainty of 1.00 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 100 degrees.

The GBM light curve shows two peaks
with a duration (T90) of about 64 s (50-300 keV).
The time-averaged spectrum from T0+43.009 s to T0+74.753 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.91 +/- 0.03 and
the cutoff energy, parameterized as Epeak, is 124.10 +/- 3.30 keV.

The event fluence (10-1000 keV) in this time interval is
 (1.434 +/- 0.023)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+54.27 s in the 10-1000 keV band is 12.89 +/- 0.37 ph/s/cm^2.

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