TITLE:   GCN CIRCULAR
NUMBER:  20665
SUBJECT: GRB 170210A: POLAR observation
DATE:    17/02/12 02:55:11 GMT
FROM:    Yuanhao Wang at IHEP/CAS  <wangyuanhao@ihep.ac.cn>

Y.H. Wang (IHEP), M.Z. Feng (IHEP), Y. Zhao (IHEP), 
report on behalf of the POLAR collaboration:

At 2017-02-10T02:47:37 UT (T0), during a routine on-ground 
search of data, POLAR detected the long-duration GRB 170210A, 
which was also reported by the 
Fermi/GBM (O.J. Roberts et al, GCN Circ. 20660) and 
IPN Triangulation(K. Hurley et al, GCN Circ. 20661), and also 
detected by Konus-Wind.

The POLAR light curve shows a long burst consists of multiple peaks,
with a duration (T90) of 62.27 s measured from T0+13.12 s.
The 1-s peak rate measured from T0+41.0 s is 6673.75cnts/s.
The total counts is about 106099 cnts.
LC_URL:
http://polar.ihep.ac.cn/grb/2017/02/GRB170210A/lc/POLAR_lc_grb170210A.png

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

Using the best location from the IPN Triangulation, which is (J2000):
RA:     226.055   [deg]
Dec:    -65.101   [deg]
Err:    1731      [sq. arcmin](3 sigma)

the incident angle in POLAR coordinate at T0 is:
theta:  80.6      [deg]
phi:    130.9     [deg]

The Minimum Detectable Polarization(MDP) for this burst is
estimated to be ~7.3% [1-sigma, statistical only]. 

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/.