{
  "bibcode": "2006GCN..5970....1R",
  "body": "J. L. Racusin, J. Kennea (PSU), J. P. Osborne, and K. L. Page (U \nLeicester) report on behalf of the Swift XRT team:\n\nWe have analyzed the first two orbits of Swift-XRT data on GRB 061222B \n(Racusin et al. GCN 5957), with a total exposure of 119 seconds in Window \nTiming (WT) mode and 906 seconds in Photon Counting (PC) mode.  This \nprovides a refined XRT position at RA, Dec = 105.35321, -25.8594 which is:\n\nRA(J2000) = 7h 01m 24.77s\nDec(J2000) = -25d 51' 33.9\"\n\nwith an estimated error radius of 3.7 arcseconds (90% confidence).  This \nposition is 20 arcseconds from the initial BAT position (Racusin et al. \nGCN 5957), 1.8 arcseconds from the initial XRT position (Racusin et al. \nGCN 5957), and 3.1 arcseconds from the optical candidate discovered by \nBerger et al. (GCN 5956).\n\nThe 0.3-10 keV X-ray light curve between 145s and 4900s after the trigger \ncan be fit with a broken power-law with an initial decay slope of 3.26 +/- \n0.10, a break at 450s, and a post-break slope of 1.24 +/- 0.15.\n\nThe X-ray spectrum from the WT data covering the time period from T+145s \nto T+264s is well fit by an absorbed power-law with a photon index of 2.6 \n+/- 0.2 and column density of (4.0 +/-0.6 )e21 cm**-2. We note the \nGalactic column density in the direction of the source is 2.7e20 cm**-2. \nThe unabsorbed 0.3-10 keV flux for this spectrum is 8.7e-10 erg/cm**2/s.\n\nAssuming the X-ray emission continues to decline at the same rate, we \npredict a 0.3-10 keV XRT count rate of 1e-3 count/s at T+24hr, which \ncorresponds to an observed 0.3-10 keV flux of 3.6e-14 erg/cm**2/s.\n\nAfter the initial first orbit and partial second orbit of automated \nobservations, the automated target was changed back to GRB061222A due to \nXRT thermal constraints.  Observations of GRB061222B will continue at a \nlater time.\n\nThis circular is an official product of the Swift XRT Team.",
  "circularId": 5970,
  "createdOn": 1166796047000,
  "email": "racusin@astro.psu.edu",
  "subject": "GRB061222B: Swift-XRT Refined Analysis",
  "submitter": "Judith Racusin at PSU  <racusin@astro.psu.edu>",
  "eventId": "GRB 061222B"
}