TITLE:   GCN CIRCULAR
NUMBER:  20645
SUBJECT: GRB 170207A: POLAR Observation
DATE:    17/02/09 14:46:15 GMT
FROM:    Zhao Yi at POLAR  <yizhao@ihep.ac.cn>

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


At 2017-02-07T21:45:04.00 UT (T0), during a routine on-ground 
search of data, POLAR detected the GRB 170207A, 
which was also detected by the 
Fermi/GBM (trigger 508196708/170207906, O.J. Roberts et al,
Circ 20630), IPN Triangulation(D. Svinkin et al, Circ 20628)
and Konus-Wind (D. Svinkin et al, Circ 20629).


The POLAR light curve consists of multiple peaks,
with a duration (T90) of 39.47 s measured from T0+0.82 s.
The 1-s peak rate measured from T0+17.00 s is 6318.2 cnts/s.
The total counts is about 63182 cnts. The above measurements
are in the energy range of about 20-500 keV.


LC_URL:
http://polar.ihep.ac.cn/grb/2017/02/GRB170207A/lc/POLAR_lc_grb170207A.png


Using the best location from the IPN Triangulation, which is (J2000):
RA:     315.704   [deg]
Dec:    +55.690   [deg]
Err:    4.66      [sq. deg]


the incident angle in POLAR coordinate at T0 is:
theta:  70.6      [deg]
phi:    -2.2      [deg]


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/.