[vsnet-grb-info 19080] GRB 170206A: POLAR observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20624
SUBJECT: GRB 170206A: POLAR observation
DATE:    17/02/07 21:13:46 GMT
FROM:    Yuanhao Wang at IHEP/CAS  <wangyuanhao at ihep.ac.cn>

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

At 2017-02-06T10:51:57.70 UT (T0), during a routine on-ground 
search of data, POLAR detected the GRB 170206A, which was 
also detected by Fermi/GBM
(trigger 508071122/170206453; A. von Kienlin et al. GCN 20616), 
Fermi/LAT(F. Fana Dirirsa et al. GCN 20617) and 
INTEGRAL/SPIACS(trigger_num 7680).

The POLAR light curve consists of multiple peaks,
with a duration (T90) of 1.194 s measured from T0+0.147 s.
The 0.1s peak rate measured from T0+0.4s is 16145.2 cnts/s.
The total counts is about 12918 cnts.
LC_URL:
http://polar.ihep.ac.cn/grb/2017/02/GRB170206A/lc/POLAR_lc_grb170206A.png

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

Using the best location from the Fermi/LAT, which is (J2000):
RA:   212.79 [deg]
Dec:  +14.48 [deg]
Err:  0.85  [deg] (90% containment, statistical error only)

the incident angle in POLAR coordinate at T0 is:
theta: 19.5   [deg]
phi:   148.70 [deg]

The Minimum Detectable Polarization(MDP) for this burst is
estimated to be ~5.7% [1-sigma, statistical only]. 
Follow-up observations are strongly encouraged.

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/ .