{
  "bibcode": "2010GCN.10780....1B",
  "body": "A. P. Beardmore, R. L. C. Starling, P. A. Evans (U. Leicester) and\nM. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift-XRT team:\n\nWe have analysed 4.7 ks of XRT data for the INTEGRAL triggered GRB\n100518A (Mereghetti et al. GCN Circ. 10772, Stamatikos et al.  GCN\nCirc. 10775), from 9.6 ks to 17.9 ks after the BAT trigger. The data\nare entirely in Photon Counting (PC) mode.  Using 2.4 ks of PC mode\ndata and 3 UVOT images we find an astrometrically corrected X-ray\nposition (using the XRT-UVOT alignment and matching UVOT field sources\nto the USNO-B1 catalogue): RA, Dec = 304.78931, -24.55436 which is\nequivalent to:\n\nRA (J2000): 20h 19m 9.43s\nDec (J2000): -24d 33' 15.7\"\n\nwith an uncertainty of 2.2 arcsec (radius, 90% confidence). Position\nenhancement is described by Goad et al. (2007, A&A, 476, 1401) and\nEvans et al. (2009, MNRAS, 397, 1177).\n\nThe light curve can be modelled with  a power-law decay with a decay\nindex of alpha=0.68 +1.00 -0.96.\n\nA spectrum formed from the entire PC mode dataset can be fitted with\nan absorbed power-law with a photon spectral index of 3.6 +1.4 -0.7.\nThe best-fitting absorption column is (4.5 +3.5 -3.3) x 10^21 cm^-2,\nin excess of the Galactic value of 6.4 x 10^20 cm^-2 in the direction\nof the burst (Kalberla et al.  2005). The observed (unabsorbed) 0.3-10\nkeV flux for this spectrum is 6.1 x 10^-13 (5.4 x 10^-12) erg cm^-2\ns^-1, resulting in a counts to observed (unabsorbed) 0.3-10 keV flux\nconversion factor of 2.7 x 10^-11 (2.4 x 10^-10) erg cm^-2 count^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00020138.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 10780,
  "createdOn": 1274260414000,
  "email": "apb@star.le.ac.uk",
  "subject": "GRB 100518A: Swift-XRT refined analysis",
  "submitter": "Andy Beardmore at U Leicester  <apb@star.le.ac.uk>",
  "eventId": "GRB 100518A"
}