GCN Circular 20845

Yi Zhao (IHEP), Yuanhao Wang (IHEP), Zhengheng Li (IHEP)
report on behalf of the POLAR collaboration:


At 2017-03-09T12:26:42.00 UT (T0), during a routine on-ground 
search of data, POLAR detected the GRB 170309A, 
which was also detected by CALET/CGBM (TRIGGER_NUM:1173097284).


The POLAR light curve consists of multiple peaks,
with a duration (T90) of 2.51 s measured from T0+0.87 s.
The 1-s peak rate measured from T0+2.00 s is 1778.1 cnts/s.
The total counts is about 4523 cnts. 


LC_URL:
http://polar.ihep.ac.cn/grb/2017/03/GRB170309A/lc/POLAR_lc_grb170309A.png


The above results are not dead time corrected. The above
measurements are in the energy range of about 20-500 keV.


All analysis results presented above are preliminary.


POLAR is a dedicated Gamma-Ray Burst polarimeter (50-500 keV)
on-board the Chinese space laboratory Tiangong-2 launched on
Sep 15,2016. More information about POLAR can be found at 
http://polar.ihep.ac.cn/en/ , http://isdc.unige.ch/polar/
and http://polar.psi.ch/pub/.