{
  "bibcode": "2011GCN.12673....1Z",
  "body": "B.-B. Zhang (PSU) report on behalf of the Swift Team:\n\nSwift began a target of opportunity observation of GRB 111211A on\nDecember 12, 2011 at 15:53 UT, approximately 0.74 days after the burst\nwas detected by SuperAGILE. Swift data for these observations utilize\nTarget ID 20192.\n\nWe have analysed 2.5 ks of XRT data for the SuperAGILE-detected burst:\nGRB 111211A (Lazzarotto et al. et al. GCN Circ. 12666), from 63.5 ks to\n66.0 ks after the  SuperAGILE trigger. The data are entirely in Photon\nCounting (PC) mode.  An X-ray source is detected within the SuperAGILE\nerror circle. Using 2512 s of PC mode data and 3 UVOT images, we find\nan enhanced XRT position (using the XRT-UVOT alignment and matching\nUVOT field sources to the USNO-B1 catalogue): RA, Dec = 153.09040,\n+11.20789 which is equivalent to:\n\nRA (J2000): 10h 12m 21.70s\nDec(J2000): +11d 12' 28.4\"\n\nwith an uncertainty of 1.8 arcsec (radius, 90% confidence). This\nposition is 93 arcsec from the SuperAGILE position and 1.6 arcsec from\nthe GROND afterglow candidate position (Kann et al. GCN Circ. 12668),\nwhich confirms it is the X-ray afterglow of GRB 111211A. The light\ncurve is consistent with a constant source of mean count rate 1.3e-01\nct/sec. A power-law fit gives an index of -1.309 (+4.183, -0.020).\n\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.02 (+0.18, -0.26). The\nbest-fitting absorption column is  1.3 (+0.7, -0.6) x 10^21 cm^-2, in\nexcess of the Galactic value of 3.4 x 10^20 cm^-2 (Kalberla et al.\n2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 3.7 x 10^-11 (4.9 x 10^-11) erg\ncm^-2 count^-1. \n\n\nA summary of the PC-mode spectrum is thus:\n\nTotal column:\t     1.3 (+0.7, -0.6) x 10^21 cm^-2\nGalactic foreground: 3.4 x 10^20 cm^-2\nExcess significance: 2.5 sigma\nPhoton index:\t     2.02 (+0.18, -0.26)\n\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00020192.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 12673,
  "createdOn": 1323728199000,
  "email": "buz12@psu.edu",
  "subject": "GRB 111211A:  Swift/XRT target of opportunity observation",
  "submitter": "Binbin Zhang at PSU  <buz12@psu.edu>",
  "eventId": "GRB 111211A"
}