{
  "bibcode": "2009GCN..9599....1M",
  "body": "V. Mangano, B. Sbarufatti (INAF-IASF PA) report on behalf\nthe Swift XRT Team:\n\nWe have analyzed 19 ks of PC data of the candidate X-ray\nafterglow of GRB 090628 (Mangano et al, GCN Circ. 9585)\nspanning the time interval from T+2796 s to T+101.7 ks.\n\nThe best position available for the source is the\nenhanced Swift-XRT position from Goad et al. (GCN Circ. 9590):\nRA, Dec = 237.05272, -15.98489 which is equivalent to\n\nRA (J2000): 15h 48m 12.65s\nDec (J2000): -15d 59' 05.6\"\n\nwith an uncertainty of 1.9 arcsec (radius, 90% confidence).\n\nThe 0.3-10 keV XRT light curve shows an initial flat or rising\nphase followed by a steep decay. The best fit with a broken\npower-law model is insensitive to the initial rise slope,\nof the order of 0.4, possibly consistent with zero,\nand provides a break at 14+/-4 ks after the trigger\nand a post-break decay slope of -1.3+/-0.3.\nThe source is rather faint, and at this rate it will\nreach a level of 8.0e-4 counts/s at T+48 hours.\nAll quoted errors are at the 90% confidence level.\n\nThe average spectrum can be fitted by an absorbed\npower-law model with Cash statistics. Best fit spectral\nparameters are NH < 2.0e21 cm^-2 (consistent with Galactic\nabsorption of 8.7e20 cm^-2, Kalberla et al. 2005)\nand photon index = 1.4 +/- 0.3 (Cstat(dof): 87.6(113)).\nThe 0.3-10 keV observed(unabsorbed) average flux is\n5.0e-13(5.5e-13) erg cm^-2 s^-1.\n\nThe rate to flux conversion factor is 8.0e-11.\n\nThe results of the XRT team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00355942\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 9599,
  "createdOn": 1246376122000,
  "email": "vanessa@ifc.inaf.it",
  "subject": "GRB 090628: Swift XRT refined analysis",
  "submitter": "Vanessa Mangano at INAF-IASFPA  <vanessa@ifc.inaf.it>",
  "eventId": "GRB 090628"
}