{
  "bibcode": "2021GCN.30728....1K",
  "body": "G. Koziol (UniGE), H. C. Li (UniGE), M. Kole (UniGE), Y. H. Wang (IHEP),\n\nN. Produit (UniGE), J. C. Sun (IHEP) and Y. Zhao (IHEP/BNU)\n\nreport on behalf of the POLAR collaboration:\n\n \n\nDuring on-ground blind search of archive POLAR data, we found a SGR-like\n\nburst whick took place on 2017-01-18 16:16:25.5 UT (T0). The burst has a\n\nduration (T90) of 0.32 +/- 0.02 seconds, the light curve and data files\n\n(both in ROOT and FITS formats) can be found at:\n\nhttps://www.astro.unige.ch/polar/content/sgr-candidate-170118\n\n \n\nUsing the localization method of POLAR (Y. H. Wang et al, 2021),\n\nthe location of this event is best fitted as (in J2000):\n\n \n\nRA :   33.5   [deg] (l = 136.04)\n\nDec:  +50.7   [deg] (b = -10.06)\n\nErr:    8.1   [deg] (radius, 1 sigma containment, statistical only)\n\n \n\nThe incident angle in the POLAR local coordinate at T0 is:\n\nTheta: 60.0   [deg]\n\nPhi:   50.0   [deg]\n\n \n\nThe spectra is better fitted with \"bbody+powerlaw\" model than Band function\n\nor single powerlaw. The temperature (kT) is 13.85 +/- 0.79 keV with a\n\nnormalization of 99.34 +/- 7.93, and the power law index is 1.73 +/- 0.43\n\nwith a normalization of 74.21 +/- 182.29. The fluence (50-500 keV) from\n\nT0 to T0 + 1.0 s is (5.09 +/- 1.33) E-06 erg/cm^2, and the average photon\n\nflux (50-500 keV) over this time period is 40 +/- 1 ph/s/cm^2.\n\n \n\nThe results presented above are preliminary. Refined analyses are ongoing.\n\nAdditionally, more burst events are expected to be found in the blind\n\nsearch of data which was recently started, and to be circulated by GCN.\n\n \n\nPOLAR was a dedicated Gamma-Ray Burst polarimeter which was launched\n\non-board the Chinese space laboratory Tiangong-2 (TG-2) on Sep 15, 2016,\n\nand ended operation in April 2017. More information about POLAR can be\n\nfound at https://www.astro.unige.ch/polar/ , http://polar.ihep.ac.cn/en/ ,\n\nand http://polar.psi.ch/html/ .",
  "circularId": 30728,
  "createdOn": 1630071275000,
  "email": "lihc@ihep.ac.cn",
  "subject": "POLAR detection of a SGR-like burst",
  "submitter": "Hancheng Li at IHEP/POLAR  <lihc@ihep.ac.cn>"
}