{
  "bibcode": "2006GCN..5031....1T",
  "body": "E. Troja (INAF-IASFPA), V. Mangano (INAF-IASFPA),\nP. Romano (INAF-OAB), D. N. Burrows (PSU)\nreport on behalf of the Swift XRT Team:\n\n\nWe have analyzed the XRT data of the first four orbits of\nGRB060428B (Campana et al 2006, GCN 5017).\nThe data set consists of 205 s exposure in Windowed\nTiming (WT) mode followed by  8.4 ks exposure in Photon\nCounting (PC) mode.\n\nThe refined position of the source is\n\n     RA (2000) = 15h 41m 25.57s\n     Dec (2000) = +62d 01' 28.94\"\n\nwith an uncertainty of 3.8 arcsec (90% confinement).\nThis position was evaluated from PC data of the orbits \n2-4,\nthat are not affected by pile-up.\nThis position is 3.35 arcsec from the onboard\ndetected position (Campana et al 2006, GCN 5017) and\n1.4 arcsec from the optical afterglow candidate found by\nPrice et al 2006 (GCN 5019). To evaluete this offset\nwe used the KAIT coordinates from Li et al.(GCN 5027).\n\nThe 0.2-10 keV X-ray light curve shows an initial very\nfast decay with slope -4.4 +/- 0.07, a break at 689 +/- 28 \ns\nfrom the trigger and then a decay slope of -0.89 +/- 0.06.\n\nThe WT spectrum from the first orbit was fitted with an\nabsorbed power law model and showed a photon index of\n2.82 +/- 0.08 (90% confidence level).\nThe WT spectrum covers the 212-418 s time interval.\nThe spectrum shows evidence of an absorption column at the\nlevel of (6.7 +/- 0.7) x 10^20 cm^-2 in excess with \nrespect\nto the Galactic value of 1.7 x 10^20 cm^-2.\nThe 0.2-10 keV unabsorbed flux is 9.8 x 10^-10 ergs cm^-2 \ns^-1.\n\nThe PC spectrum of the orbits 2-4 (time interval 4.4-18.5 \nks) is well\nfit by an absorbed powerlaw model with photon index 2.08 \n+/- 0.16.\nThe 0.2-10 keV unabsorbed flux is 1.6^-12 ergs cm^-2 s^-1.\n\n\nIf decaying at the present rate the source will reach the\nflux level of  2.6^-13 erg cm^-2 s^-1 (corresponding to\na count rate level of 5 x 10^-3 counts s^-1)\nafter one day.\n\nThis Circular is an official product of the Swift XRT \nTeam.",
  "circularId": 5031,
  "createdOn": 1146258194000,
  "email": "nora@ifc.inaf.it",
  "subject": "GRB060428B: Swift XRT Team refined analysis",
  "submitter": "Eleonora Troja at INAF-IASFPA  <nora@ifc.inaf.it>",
  "eventId": "GRB 060428B"
}