[vsnet-grb-info 16135] GRB 150206B: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17417
SUBJECT: GRB 150206B: Fermi GBM detection
DATE:    15/02/06 22:30:53 GMT
FROM:    Eric Burns at U of Alabama  <eb0016 at uah.edu>

E. Burns (UAH) and H.-F Yu (MPE)
report on behalf of the Fermi GBM Team:

"At 09:46:27.48 UT on 06 February 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150206B (trigger 444908790 / 150206407).

The on-ground calculated location, using the GBM trigger
data, is RA = 220.6, DEC = +57.5 (J2000 degrees,
equivalent to 14 h 42 m, 57 d 30 '), with an uncertainty
of 6.8 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
The angle from the Fermi LAT boresight is 76 degrees.

Early follow-up observations of the GBM location error box by the
intermediate Palomar Transient Factory yielded three possible optical
counterparts (Singer et al. 2015, GCN 17415).

The GBM light curve consists of a single main peak
with a duration (T90) of about 5 s (50-300 keV).
The time-averaged spectrum from T0-1.024 s to T0+4.096 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.50 +/- 0.15 and
the cutoff energy, parameterized as Epeak, is 72 +/- 4 keV.

The event fluence (10-1000 keV) in this time interval is
(1.1 +/- 0.05)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.576 s in the 10-1000 keV band
is 5.2 +/- 0.3 ph/s/cm^2.

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