{
  "subject": "GRB 261005B: Swift-XRT refined Analysis",
  "createdOn": 1791324861107,
  "circularId": 45822,
  "submittedHow": "email",
  "eventId": "GRB 261005B",
  "body": "J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. D'Ai\n(INAF-IASFPA), S. Campana (INAF-OAB), A. Melandri (INAF-OAR), S. Lanava\n(PSU), S. Dichiara (PSU), D.N. Burrows (PSU), A.P. Beardmore (U.\nLeicester) and P.A. Evans report on behalf of the Swift-XRT team:\n\nWe have analysed 5.1 ks of XRT data for GRB 261005B, from 4.4 ks to\n81.3 ks after the   trigger. The data are entirely in Photon Counting\n(PC) mode. Using 3116 s of PC mode data and 6 UVOT images, we find an\nenhanced XRT position (using the XRT-UVOT alignment and matching UVOT\nfield sources to the USNO-B1 catalogue): RA, Dec = 255.33918, +1.58871\nwhich is equivalent to:\n\nRA (J2000): 17h 01m 21.40s\nDec(J2000): +01d 35' 19.4\"\n\nwith an uncertainty of 2.1 arcsec (radius, 90% confidence).\n\nThe light curve can be modelled with an initial rise, with a power-law\nindex of alpha=-1.5 (+0.0, -1.0), followed by a break at T+8550 s  to\nan alpha of 2.7 (+0.6, -0.5).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.15 (+/-0.13). The\nbest-fitting absorption column is  1.5 (+0.7, -0.6) x 10^21 cm^-2, in\nexcess of the Galactic value of 9.0 x 10^20 cm^-2 (Willingale et al.\n2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 6.1 x 10^-11 (6.5 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.5 (+0.7, -0.6) x 10^21 cm^-2\nGalactic foreground: 9.0 x 10^20 cm^-2\nExcess significance: 1.7 sigma\nPhoton index:\t     1.15 (+/-0.13)\n\nThe results of the XRT-team automatic analysis are available at\nhttps://www.swift.ac.uk/xrt_products/01515414.\n\nThis circular is an official product of the Swift-XRT team.\n",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>"
}