{
  "bibcode": "2008GCN..7590....1G",
  "body": "O. Godet, A. P. Beardmore, K. Page (U. Leicester) reports on behalf the Swift-XRT team: \n\nThe XRT began observing the field of GRB 080411 (trigger=309010, Marshall et\nal., GCN Circ. 7584) at 21:16:42 UT, 71 seconds after the BAT trigger.  We\nanalysed the first orbit of WT data (0.9 s) at T0+209s and the first 4 orbits\nof PC data (~3.6 ks) from T0+4.2ks to T0+17.4ks.\n\nThe X-ray light-curve shows a broken power-law behaviour. Since there are \nno data between the WT and PC observations, it is difficult to constrain \nthe initial decay and break time. The late decay from the PC data gives a \ndecay slope of 0.98+/-0.05. Using ground data, we confirmed that the initial \nintense flux reported by Marshall et al. (GCN Circ. 7584) from the 0.1s image \ntaken at T0+71s is real and is likely to correspond to the end of the activity \nobserved in the BAT. That implies an initial rapid decay in the XRT light-curve.\n\nThe WT spectrum contains only 20 counts. So, the fitting parameters are not\nwell constrained when the spectrum is fitted by an absorbed power-law (N_H <\n4.6e21 cm^-2 in excess with respect to the Galactic absorption along the burst\nline of sight (5.7e20 cm^-2, Kalberla et al. 2005) and a photon index of 2.85\n+1.54/-1.05).  The PC spectrum from T0+4.2ks to T0_17.4ks is fitted well by \nan absorbed power-law with a photon index of 2.14 +/- 0.09 and an absorption \ncolumn of (1.5 +/- 0.3)e21 cm^-2, in excess with respect to the Galactic one.\n\nThe observed (unabsorbed) flux in the 0.3-10 keV band is 7.1e-10 (1.7e-9) erg\ncm^-2 s^-1 for the WT spectrum and 7.2e-11 (1.1e-10) erg cm^-2 s^-1 for the PC\nspectrum.\n\nThe predicted XRT count rate at T0+1d (T0+3d) is 0.26 (0.07) count s^-1, which\ncorresponds to an observed 0.3-10 keV flux of 2.7e-11 (7.1e-12) erg cm^-2 s^-1.\n\nThis is an official product of the Swift-XRT team.",
  "circularId": 7590,
  "createdOn": 1208006831000,
  "email": "og19@star.le.ac.uk",
  "subject": "GRB 080411: Swift-XRT Refined Analysis",
  "submitter": "Olivier Godet at U.of Leicester  <og19@star.le.ac.uk>",
  "eventId": "GRB 080411"
}