[vsnet-grb-info 18910] GRB 170101A: POLAR observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20361
SUBJECT: GRB 170101A: POLAR observation
DATE:    17/01/03 15:05:07 GMT
FROM:    Yuanhao Wang at IHEP/CAS  <wangyuanhao at ihep.ac.cn>

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

At 2017-01-01T02:47:18.27 UT (T0), during a routine on-ground
search of data, POLAR detected the GRB 170101B, which was also
detected by the Fermi/GBM (trigger 504953918/170101374).

The POLAR light curve consists of multiple peaks,
with a duration (T90) of 11.2 s measured from T0+0.3 s.
The 0.2-s peak rate measured from T0+8.1 s is 968 cnts/s,
the total counts is about 5217 cnts. The above measurements
are in the energy range of approximately 80-500 keV.

LC_URL:
http://polar.ihep.ac.cn/grb/2017/01/GRB170101B/lc/GRB170101B.JPG

Using the best location from the Fermi/GBM, which is (J2000):
RA:    70.640[deg]
Dec:    -1.580[deg]
Err:     1.2[deg]

the incident angle in POLAR coordinate at T0 is:
theta:    63.43[deg]
phi:   -110.01[deg]

The Minimum Detectable Polarization(MDP) for this burst is
estimated to be ~23.5% [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/html/.