[vsnet-grb-info 19101] GRB 170208B: Fermi GBM Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20646
SUBJECT: GRB 170208B: Fermi GBM Detection   
DATE:    17/02/09 15:19:35 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts at nasa.gov>

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

"At 22:33:36.53 UT on the 8th of February 2017, 
the Fermi Gamma-Ray Burst Monitor triggered and 
located GRB 170208B (trigger 508286021 / 170208940), 
which was also detected by Konus-Wind 
(Svinkin et al. 2017, GCN 20643) and Swift 
(Siegel et al. 2017, GCN 20632). The GBM on-ground 
location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM 
trigger time using the Swift-XRT position is 54 degrees.

The GBM light curve consists of a long GRB with 
overlapping episodes of bright emission over a 
duration (T90) of about 22 s (50-300 keV). The 
time-averaged spectrum from T0-8.0 s to T0+14.0 s is 
adequately fit by a Band function with 
Epeak = 104.1 +/- 5.5 keV, alpha = -0.83 +/- 0.05, and 
beta = -2.33 +/- 0.09

The event fluence (10-1000 keV) in this time interval is 
(1.13 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux
measured starting from T0-7.9 s in the 10-1000 keV band
is 12.1 +/- 0.3 ph/s/cm^2.

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