[vsnet-grb-info 19057] GRB 170131A: POLAR Observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20600
SUBJECT: GRB 170131A: POLAR Observation
DATE:    17/02/04 03:20:19 GMT
FROM:    Zhao Yi at POLAR  <yizhao at ihep.ac.cn>

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


At 2017-01-31T23:14:59.00 UT (T0), during a routine on-ground 
search of data, POLAR detected the GRB 170131A, 
which was also detected by the 
Fermi/GBM (trigger 507597304/170131969, Circ 20572),
Swift (Circ 20570) and Konus-Wind.


The POLAR light curve consists of multiple peaks,
with a duration (T90) of 21.88 s measured from T0-1.21 s.
The 1-s peak rate measured from T0+16.00 s is 888.4 cnts/s.
The total counts is about 7085 cnts. The above measurements
are in the energy range of about 20-500 keV.


LC_URL:
http://polar.ihep.ac.cn/grb/2017/01/GRB170131A/lc/POLAR_lc_grb170131A.png


Using the best location from the Swift/BAT, which is (J2000):
RA:     341.447  [deg]
Dec:    +64.006  [deg]
Err:    3.00     [arcmin]


the incident angle in POLAR coordinate at T0 is:
theta:  76.5     [deg]
phi:    22.2     [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/.