{
  "bibcode": "2006GCN..4959....1P",
  "body": "C. Pagani, D. Morris, J. Racusin, J. Kennea and D. N. Burrows (PSU)  \nreport on behalf of the Swift XRT team:\n\nWe have analysed the first orbit of Swift XRT data on the BAT GRB 060413 \n(Pagani, et al., GCN 4957) with a total exposure of 1700 seconds.\n\nThe refined XRT position is:\n\nRA(J2000):   19 25 07.7\nDec(J2000): +13 45 27.3\n\nThis position is 192 arcseconds from the BAT position \nand 4 arcsec from the XRT position given in GCN 4957. \nWe estimate an uncertainty of 3.6 arcseconds radius (90% containment).\n\nThe 0.2-10 keV light curve starts in Windowed Timing (WT) mode\n119 seconds after the BAT trigger (T0) and then switches into Photon Counting \n(PC) at T0+305. \nThe XRT data show a steep power law decay with slope of -3.5 +/- 0.2\nfollowed by a flare centered at T0+646 seconds with a peak count rate of \n6 counts/s.\n\nThe X-ray spectrum covering the time period from T+119s to T+1840s is\nwell fit by an absorbed power-law with a photon index of 1.9+/-0.1 and a\ncolumn density of 2.30e22 cm-2, which is higher than the Galactic value \nin the direction of the source (1.20e22 cm-2). However, the NH measurement of \nthis galactic plane line of sight is likely to be underestimated.\nThe unabsorbed 0.3-10 keV flux is 4.8e-09 erg/cm**2/s.\n\nDue to the flare in the light curve the predicted XRT count rate is uncertain.  \nExtrapolating the late part of the lightcurve of the first orbit we estimate \nthe XRT count rate to be about 0.0006 cps at T+24 hr, corresponding to an \nunabsorbed 0.3-10 keV flux of about 1.6E-13 erg/cm2/s\n\nThis circular is an official product of the Swift XRT Team.",
  "circularId": 4959,
  "createdOn": 1144973015000,
  "email": "pagani@astro.psu.edu",
  "subject": "GRB 060413: XRT refined analysis",
  "submitter": "Claudio Pagani at PSU/Swift-XRT  <pagani@astro.psu.edu>",
  "eventId": "GRB 060413"
}