TITLE:   GCN CIRCULAR
NUMBER:  20922
SUBJECT: GRB 170317A: POLAR observation
DATE:    17/03/19 19:12:35 GMT
FROM:    Haulin Xiao at PSI/POLAR  <hualin.xiao@psi.ch>

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

At 2017-03-17 09:45:56.0 UT(T0), during a routine on-ground search of data, POLAR detected GRB 170317A
(Swift BAT (trigger # 742866); LaPorte et al., GCN 20885).


The POLAR light curve consists of one peak with duration (T90) of 6.00 ± 1.00 s measured from T0.
The 1.00 s peak flux at T0 + 5.50 s  is equal to 370 ± 50 counts/sec.
POLAR recorded 1500 events from the burst.
Above measurements are in the energy range of about 15 - 300 keV.

LC_URL: http://polar.psi.ch/triggers/GRB_170317A.png

Using the best location from Swift-BAT, which is (J2000):
RA : 93.087 [deg]
Dec: 50.500 [deg]
the incident angle in the POLAR coordinate at T0 is:
Theta: 81.38 [deg]
Phi: 4.61 [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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