{
  "subject": "GRB 261011A: Swift-XRT refined Analysis",
  "format": "text/plain",
  "version": 2,
  "editedOn": 1791896364377,
  "circularId": 45934,
  "editedBy": "Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of K.L. Page at U Leicester <klp5@leicester.ac.uk>",
  "submittedHow": "email",
  "eventType": [],
  "eventId": "GRB 261011A",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "body": "A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB),\nD.N. Burrows (PSU), J.J. DeLaunay (PSU), S. Lanava (PSU), A.P.\nBeardmore (U. Leicester), J.P. Osborne (U. Leicester) and P.A. Evans\nreport on behalf of the Swift-XRT team:\n\nWe have analysed 4.2 ks of XRT data for GRB 261011A, from 301 s to 28.0\nks after the   trigger. The data comprise 1.2 ks in Windowed Timing\n(WT) mode (the first 10 s were taken while Swift was slewing) with the\nremainder in Photon Counting (PC) mode. Using 1938 s of PC mode data\nand 4 UVOT images, we find an enhanced XRT position (using the XRT-UVOT\nalignment and matching UVOT field sources to the USNO-B1 catalogue):\nRA, Dec = 21.89722, -21.56052 which is equivalent to:\n\nRA (J2000): 01h 27m 35.33s\nDec(J2000): -21d 33' 37.9\"\n\nwith an uncertainty of 2.9 arcsec (radius, 90% confidence).\n\nThe light curve can be modelled with a series of power-law decays. The\ninitial decay index is alpha=4.1 (+/-0.6). At T+362 s  the decay\nflattens to an alpha of 1.68 (+0.11, -0.10) before breaking again at\nT+792 s to a final decay with index alpha=1.26 (+0.06, -0.05).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.80 (+/-0.05). The\nbest-fitting absorption column is  7.7 (+1.7, -1.6) x 10^20 cm^-2, in\nexcess of the Galactic value of 0.0 x 10^00 cm^-2 (Willingale et al.\n2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 3.6 x 10^-11 (4.1 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the WT-mode spectrum is thus:\nTotal column:\t     7.7 (+1.7, -1.6) x 10^20 cm^-2\nGalactic foreground: 1.5 x 10^20 cm^-2\nExcess significance: 6.4 sigma\nPhoton index:\t     1.80 (+/-0.05)\n\nThe results of the XRT-team automatic analysis are available at\nhttps://www.swift.ac.uk/xrt_products/01516664.\n\nThis circular is an official product of the Swift-XRT team.\n",
  "createdOn": 1791875685520
}