GCN Circular 20387

R. Marcinkowski (PSI), H. Xiao (PSI) and W. Hajdas (PSI) report on behalf
of the POLAR collaboration:

At 2017-01-05T06:14:07.0 UT(T0), during a routine on-ground search of
data, POLAR detected the GRB 170105A, which was also observed by SPIACS 
at 2017-01-05T06:14:06 and Konus-Wind at 22450.264s UT (06:14:10.264).

The POLAR light curve consists of 1 peak with duration (T90) of 
2.0 +/- 0.5 s measured from T0.
The 0.5 s peak flux at T0 + 0.8 s  is equal to 2490 +/- 90 counts/sec.
POLAR recorded 3600 +/- 160 events from the burst.
Above measurements are in the energy range of about 80 - 500 keV.

LC_URL: http://polar.psi.ch/triggers/GRB_170105A_raw.png
     or http://polar.psi.ch/pub/lc.php?event=GRB+170105A

The analysis results presented above are preliminary. Calibration of the 
instrument is ongoing. POLAR is a dedicated Gamma-Ray Burst polarimeter 
which was launched on-board the Chinese space laboratory Tiangong-2 (TG-2)
on Sep 15, 2016. The energy detection range of POLAR is ~ 50-500 keV.
More information about POLAR can be found at http://polar.psi.ch/pub ,
http://polar.ihep.ac.cn/en/ and http://isdc.unige.ch/polar/ .

This message is quotable in publications.