{
  "bibcode": "2008GCN..7490....1G",
  "body": "Dirk Grupe and Peter Brown (PSU)  report on behalf of the Swift-XRT team:\n\nThe Swift-XRT started observing GRB 080319D (trigger=306793, Brown et \nal. GCN\n7453) at 17:07:37 UT, 148 seconds after the BAT trigger.\n\nThe astrometrically corrected X-ray position (using the XRT-UVOT \nalignment and\nmatching UVOT field sources to the USNO-B1 catalogue) is: RA, Dec = \n99.47254,\n+23.94275 which is equivalent to:\n\nRA (J2000):  06 37 53.41\nDec (J2000): +23 56 33.9\n\nwith an uncertainty of 1.7 arcsec (radius, 90% confidence).\n\nThe 0.3-10 keV X-ray light curve starts with three flares up to 20 \ncounts/s. The\nafterglow decays very fast and started to flatten at about 1000 s after the\nburst. The light curves shows another break at about 5 ks after the \nburst and is\ncurrently decaying with a decay slope of 1.3.\n\nThe spectrum of the PC data can be well fit by an absorbed single\npowerlaw with photon  index 2.12 � 0.27 and column density of\n (3.8 � 1.4)e21 cm-2.  This is in excess of\nthe Galactic column density of 2.17e21 cm-2 in this direction.\nUsing this spectrum we estimated a count rate to flux conversion of\n1 count/s converts to 6.28e-11 ergs/cm2/s.\n\nIf the underlying powerlaw decay continues as is, we predict an XRT \ncount rate\nof 1.6e-3 counts/s at T+24 hours and 6.5e-4 counts/s at T+48 hours\nafter the burst, or 1.0e-13 ergs/s/cm2 and 4.1e-14 ergs/s/cm2, \nrespectively.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 7490,
  "createdOn": 1206043269000,
  "email": "grupe@astro.psu.edu",
  "subject": "GRB 080319D: Swift XRT refined analysis",
  "submitter": "Dirk Grupe at PSU/Swift-XRT  <grupe@astro.psu.edu>",
  "eventId": "GRB 080319D"
}