{
  "bibcode": "2008GCN..7608....1T",
  "body": "E. Troja (U. Leicester/INAF-IASFPa) and M. Stamatikos (NASA/ORAU)\nreport on behalf of the Swift-XRT team:\n\nWe have analysed 9.9 ks of Swift XRT data for GRB 080413B (Stamatikos et\nal. GCN Circ. 7598), from T0+134 s to T0+20.1 ks. \nThe data set consists of 376 s exposure in Windowed Timing (WT) mode \nfollowed by 9.5 ks exposure in Photon Counting (PC) mode.\n\nBy using orbits 2-4 of PC data [from T0+6.0 ks to T0+20.1 ks]\nin order to avoid pile-up effects, we derive an XRT refined position \n\n     RA (2000) = 21h 44m 34.43s  = 326.1435 d\n     Dec (2000) = -19d 58' 52.9\" = -19.9814 d\n\nwith an uncertainty of 3.7 arcsec (90% containment). This position\nis 3.6 arcsec from the UVOT candidate afterglow (GCN Circ. 7598), \nand 3.4 arcsec from the source reported in Kruehler et al. (GCN Circ.\n7599).\n\nThe X-ray light curve is well fitted by a simple power-law, with a \ndecay slope of 0.88 +/- 0.06.\n\nA spectrum obtained from the WT mode data, from T0+135 s to T0+511 s,\ncan be modelled with an absorbed power-law with a photon index of \n2.05 +/- 0.10 , and a redshifted absorbing column of (0.32 +/- 0.13) \nx 10^22 cm^-2 at a redshift of z=1.1 (Vreeswijk et al. GCN Circ 7601) \nin addition to the Galactic column of 3.06 x 10^20 cm^-2 (Kalberla et \nal. 2005). The observed (unabsorbed) 0.3-10 keV flux in this spectrum is\n1.79 x 10^-10 (2.13 x 10^-10) erg/cm^2/s. \nThe PC spectrum of the first four orbits, from T0+512 s to T0+20.1 ks, \ncan be fit by an absorbed power-law model with photon index 1.93 +/-\n0.08 and a column density consistent with the WT spectrum. \nAll the reported errors are at the 90% confidence level.\n\nIf the source continues to decay at the present rate, we predict a count\nrate of 0.035 count/sec at T0+24 hours, which corresponds to a 0.3-10 keV \nobserved (unabsorbed) flux of 1.6 x 10^-12 (1.8 x 10^-12) erg/cm^2/s.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 7608,
  "createdOn": 1208112901000,
  "email": "nora@ifc.inaf.it",
  "subject": "GRB 080413B: Swift XRT refined analysis",
  "submitter": "Eleonora Troja at INAF-IASFPA  <nora@ifc.inaf.it>",
  "eventId": "GRB 080413B"
}