TITLE: GCN CIRCULAR NUMBER: 20568 SUBJECT: GRB 170130A: POLAR Observation DATE: 17/02/01 08:43:20 GMT FROM: Radek Marcinkowski at PSI/POLAR R. Marcinkowski (PSI), H.L. Xiao (PSI) and W. Hajdas (PSI) report on behalf of the POLAR collaboration: At 2017-01-30 07:14:45 UT(T0), during a routine on-ground search of data, POLAR detected GRB 170130A, which was also observed by Fermi GBM (trigger # 507453289). Significant detection was recorded in 9 of 25 POLAR modules. The POLAR light curve consists of multi peak structure with duration (T90) of 35.0 +/- 1.0 s measured from T0 and is compatible with Fermi GBM light curve. The 1.0 s peak flux at T0 + 30.5 s is equal to 480 +/- 80 counts/sec. POLAR recorded about 5300 events from the burst. Above measurements are in the energy range of about 20 - 500 keV and bases on data from 9 modules. LC_URL: http://polar.psi.ch/triggers/GRB_170130A_raw_9of25.png or http://polar.psi.ch/pub/lc.php?event=GRB+170130A Using the best location from Fermi GBM, which is (J2000): RA : 271.1 [deg] Dec: -29.1 [deg] Err: 5.5 [deg] the incident angle in the POLAR coordinate at T0 is: Theta: 56.2 [deg] Phi: 230.9 [deg] The analysis results presented above are preliminary. Calibration of the instrument is ongoing. POLAR is a dedicated Gamma-Ray Burst polarimeter which was launched on-board the Chinese space laboratory Tiangong-2 (TG-2) on Sep 15, 2016. The energy detection range of POLAR is ~ 50-500 keV. More information about POLAR can be found at http://polar.psi.ch/pub , http://polar.ihep.ac.cn/en/ and http://isdc.unige.ch/polar/ . This message is quotable in publications.