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GCN Circular 20837

Subject
GRB 170305A: POLAR observation
Date
2017-03-08T09:24:45Z (7 years ago)
From
Radek Marcinkowski at PSI/POLAR <radoslaw.marcinkowski@psi.ch>
R. Marcinkowski (PSI), H.L. Xiao (PSI) and W. Hajdas (PSI) report on behalf
of the POLAR collaboration:

At 2017-03-05 06:09:06.8 UT(T0), during a routine on-ground search of data, 
POLAR detected GRB 170305A, which was also observed by Fermi GBM (trigger 
# 510386951; GCN 20818, M. Stanbro) and Konus-Wind, INTEGRAL (SPI-ACS),
Mars-Odyssey (HEND), and Swift (BAT) (GCN 20824, K. Hurley et al.).

The POLAR light curve consists of 1 peak with duration (T90) of 
0.3 +/- 0.05 s measured from T0. The 64ms peak flux at T0 + 0.1 s  
is equal to   9630 +/- 120 counts/sec. POLAR recorded 2400 events from 
the burst. Above measurements are in the energy range of about 20 - 500 keV.

LC_URL: http://polar.psi.ch/triggers/GRB_170305A_raw.png
     or http://polar.psi.ch/pub/lc.php?event=GRB+170305A

Using the best location from IPN Triangulation (GCN 20824, K. Hurley et al.), 
which is (J2000):
RA : 39.66 deg
Dec:  9.90 deg
the incident angle in the POLAR coordinate at T0 is:
Theta: 31.4 deg
Phi:  239.1 deg

The analysis results presented above are preliminary. 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/ .

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