TITLE: GCN CIRCULAR NUMBER: 20243 SUBJECT: GRB 161203A: POLAR Detection DATE: 16/12/08 15:21:23 GMT FROM: Merlin Kole at U of GenevaPOLAR M. Kole (DPNC/UniGe), N. Produit (ISDC/UniGe), T. Bernasconi (ISDC/UniGe), J. C. Sun (IHEP), Y. H. Wang (IHEP), S. L. Xiong (IHEP), Z. H. Li (IHEP), H. C. Li (IHEP), Y. Zhao (IHEP), T. Batsch(NCBJ), F. Cadoux (DPNC/UniGe), Y. W. Dong (IHEP), M. Z. Feng (IHEP), M. Y. Ge (IHEP), W. Hajdas (PSI), Y. Huang (IHEP), Karol Jedrzejczak (NCBJ), F. J. Lu (IHEP), R. Marcinkowski (PSI), M. Pohl (DPNC/UniGe), A. Rutczynska (NCBJ), D. Rybka (NCBJ), L. M. Song (IHEP), J. Szabelski (NCBJ), X. Wen (IHEP), B. B. Wu (IHEP), X. Wu (DPNC/UniGe), H. L. Xiao (PSI), M. Xu (IHEP), J. Zhang (IHEP), L. Y. Zhang (IHEP), P. Zhang (PSI), S. N. Zhang (IHEP), Y. J. Zhang (IHEP), A. Zwolinska (NCBJ) report for he POLAR team: During a routine on-ground search of data POLAR detected the GRB 161203A, at 2016-12-03T18:41:07.75 UT(T0). This GRB was also observed by Konus-Wind, INTEGRAL SPI/ACS (trigger #7641), CALET (GCN #20240) and Astrosat CZTI (GCN #20241). The POLAR light curve consists two peaks with a total duration (T90) of 4.75 +- 0.25 s measured from T0-0.5 s. The 250-ms peak flux of the first peak, measured at T0+0.5 s is 1509 cnts/sec. The second stronger peak measured at T0+3.0 s has a peak flux of 2821 cnts/sec. The above measurements are in the preliminary calculated energy range of about 80 - 500 keV. LC_URL: http://www.isdc.unige.ch/polar/lc/161203A/lcr.png The analysis results presented above are preliminary as the instrument calibration is still ongoing. Preliminary calculations of the MDP show that a polarimetric measurement of this burst can be attempted. 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://isdc.unige.ch/polar/ This message is quotable in publications.