////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  20347
SUBJECT: GRB 161228A: POLAR Observation
DATE:    16/12/30 11:51:57 GMT
FROM:    Haulin Xiao at PSI/POLAR  <hualin.xiao@psi.ch>

Hualin Xiao (PSI), Wojtek Hajdas (PSI) and Radoslaw Marcinkowski (PSI) report on behalf of the POLAR collaboration:

At 2016-12-28T09:43:24.0 UT(T0), during a routine on-ground search of data, POLAR detected the GRB 161228A,
which was also observed by Fermi GBM (trigger #504611009).

The POLAR light curve consists of one peak with duration (T90) of 3.5 +- 0.5 s measured from T0.
The  0.5 s peak flux at T0+1.75 s  is equal to 330 +-43 cnts/sec.
Above measurements are in the energy range of about 80 - 500 keV.

LC_URL: http://polar.psi.ch/triggers/GRB_161228A_raw.png
and http://polar.psi.ch/pub/lc.php?event=GRB+161228A
 

Using the best location from the Fermi-GBM, which is (J2000):

RA: 358.42  [deg]
	
Dec: -24.6  [deg]

Err:  5.63  [deg]

the incident angle in the POLAR coordinate at T0 is:

Theta: 70.47  [deg]

Phi:  171.332 [deg]

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.