{
  "bibcode": "2014GCN.15968....1I",
  "body": "L. Izzo (URoma/ICRA), V. D'Elia (ASDC) and J. L. Racusin (NASA/GSFC)\nreport on behalf of the Swift-XRT team:\n\nWe have analysed 6.2 ks of XRT data for GRB 140311A (Racusin  et al.\nGCN Circ. 15944),  from 9.5 ks to 57.1 ks after the  BAT trigger. The\ndata are entirely in Photon Counting (PC) mode. Using 2850 s of PC mode\ndata and 7 UVOT images, we find an enhanced XRT position (using the\nXRT-UVOT alignment and matching UVOT field sources to the USNO-B1\ncatalogue): RA, Dec = 209.30521, +0.64191 which is equivalent to:\n\nRA (J2000): 13h 57m 13.25s\nDec(J2000): +00d 38' 30.9\"\n\nwith an uncertainty of 1.5 arcsec (radius, 90% confidence).\n\nThe light curve can be modelled with  a power-law decay with a decay\nindex of alpha=1.13 (+0.16, -0.14).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.61 (+0.17, -0.12). The\nbest-fitting absorption column is  consistent with the Galactic value\nof 2.8 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed\n(unabsorbed) 0.3-10 keV flux conversion factor deduced from this\nspectrum  is 3.9 x 10^-11 (4.1 x 10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nGalactic foreground: 2.8 x 10^20 cm^-2\nIntrinsic column:    0 (+2.2, -0) x 10^22 cm^-2 at z=4.95\nPhoton index:\t     1.61 (+0.17, -0.12)\n\nIf the light curve continues to decay with a power-law decay index of\n1.13, the count rate at T+24 hours will be 0.013 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.1 x\n10^-13 (5.3 x 10^-13) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00591390\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 15968,
  "createdOn": 1394643748000,
  "email": "Luca.Izzo@ICRA.it",
  "subject": "GRB 140311A: Swift-XRT refined Analysis",
  "submitter": "Luca Izzo at ICRA  <Luca.Izzo@ICRA.it>",
  "eventId": "GRB 140311A"
}