{
  "bibcode": "2012GCN.13972....1B",
  "body": "A.P. Beardmore (U. Leicester) and J. R. Cummings (NASA/UMBC) report on\nbehalf of the Swift-XRT team:\n\nWe have analysed 13 ks of XRT data for GRB 121117A (Cummings  et al.\nGCN Circ. 13967), from 41 s to 62.7 ks after the  BAT trigger. The data\ncomprise 204 s in Windowed Timing (WT) mode (the first 5 s were taken\nwhile Swift was slewing) with the remainder in Photon Counting (PC)\nmode. Using 3463 s of PC mode data and 6 UVOT images, we find an\nenhanced XRT position (using the XRT-UVOT alignment and matching UVOT\nfield sources to the USNO-B1 catalogue): RA, Dec = 31.61064, +7.41954\nwhich is equivalent to:\n\nRA (J2000): 02h 06m 26.55s\nDec(J2000): +07d 25' 10.4\"\n\nwith an uncertainty of 1.7 arcsec (radius, 90% confidence).\n\nThe light curve can be modelled with  a power-law decay with a decay\nindex of alpha=1.27 (+/-0.04).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.55 (+0.22, -0.19). The\nbest-fitting absorption column is  8.4 (+7.2, -3.2) x 10^20 cm^-2,\nconsistent with the Galactic value of 5.2 x 10^20 cm^-2 (Kalberla et\nal. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux\nconversion factor deduced from this spectrum  is 4.2 x 10^-11 (4.7 x\n10^-11) erg cm^-2 count^-1. \n\nA summary of the WT-mode spectrum is thus:\nTotal column:\t     8.4 (+7.2, -3.2) x 10^20 cm^-2\nGalactic foreground: 5.2 x 10^20 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.55 (+0.22, -0.19)\n\nIf the light curve continues to decay with a power-law decay index of\n1.27, the count rate at T+24 hours will be 9.9 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.2 x\n10^-14 (4.7 x 10^-14) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00538696.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 13972,
  "createdOn": 1353227866000,
  "email": "apb@star.le.ac.uk",
  "subject": "GRB 121117A: Swift-XRT refined Analysis",
  "submitter": "Andy Beardmore at U Leicester  <apb@star.le.ac.uk>",
  "eventId": "GRB 121117A"
}