GCN Circular 17388

V. Pelassa (UAH) reports on behalf of the Fermi GBM Team:

"At 23:59:08.27 UT on 02 Feb 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150202B (trigger 444614351 / 150202999).

The on-ground calculated location, using the GBM trigger data, is
RA = 86.8, Dec = 58.6 (J2000 degrees, equivalent to +05h 47m, +58d 32'),
with an uncertainty of 1.0 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 17 degrees.  This trigger resulted in an Autonomous Repoint
Request (ARR) that was not accepted by the spacecraft.  Following
this observation the Fermi Large Area Telescope also detected
this burst in the ground-based analysis (Axelsson et al. 2015, GCN 17385
Not found
 
 
).

This GRB was also detected by Integral/SPI-ACS.

The GBM light curve consists of a bright peak lasting about 25 s, 
followed at T0+ 100 s by a fainter second episode of emission, 
with a total duration (T90) of about 167 s (50-300 keV). 
The 1.024-sec peak photon flux measured starting from T0+7.808 s 
in the 10-1000 keV band is 23.8 +/- 0.4 ph/s/cm^2.

The time-averaged spectrum of the first episode, from T0-5.120 s to
T0+24.576 s, is best fit by a Band function with Epeak = 253 +/- 12 keV,
alpha = -0.82 +/- 0.02, and beta = -2.36 +/- 0.13. The event fluence 
(10-1000 keV) in this time interval is (3.15 +/- 0.05)E-05 erg/cm^2.

The time-averaged spectrum of the second episode, from T0+103.426 s to
T0+205.827 s, is well fit a power law function with an exponential
high-energy cutoff. The power law index is -1.23 +/- 0.13 and
the cutoff energy, parameterized as Epeak, is 154 +/- 36 keV. 
The event fluence (10-1000 keV) in this time interval 
is (1.37 +/- 0.15)E-06 erg/cm^2.

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

[GCN OPS NOTE(03feb15): The third sentence in the second paragraph
was changed to say the ARR was rejected by the spacecraft.]