{
  "submittedHow": "email",
  "circularId": 45697,
  "createdOn": 1790129635554,
  "subject": "GRB 260922A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "eventId": "GRB 260922A",
  "body": "V. D'Elia (SSDC & INAF-OAR), D.N. Burrows (PSU), S. Lanava (PSU), S.\nDichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester),\nB. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB) and P.A. Evans report\non behalf of the Swift-XRT team:\n\nWe have analysed 6.9 ks of XRT data for GRB 260922A, from 97 s to 33.8\nks after the   trigger. The data comprise 192 s in Windowed Timing (WT)\nmode (the first 10 s were taken while Swift was slewing) with the\nremainder in Photon Counting (PC) mode. \n\nThe light curve can be modelled with an initial power-law decay with an\nindex of alpha=2.80 (+0.11, -0.10), followed by a break at T+463 s to\nan alpha of 0.77 (+0.06, -0.07).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 2.18 (+0.11, -0.10). The\nbest-fitting absorption column is  5.1 (+2.0, -1.8) x 10^20 cm^-2, in\nexcess of the Galactic value of 2.9 x 10^20 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 1.70 (+0.15, -0.10)\nand a best-fitting absorption column consistent with the Galactic\nvalue. The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 3.9 x 10^-11 (4.1 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     2.9 (+3.3, -0.0) x 10^20 cm^-2\nGalactic foreground: 2.9 x 10^20 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.70 (+0.15, -0.10)\n\nIf the light curve continues to decay with a power-law decay index of\n0.77, the count rate at T+24 hours will be 0.025 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.6 x\n10^-13 (1.0 x 10^-12) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttps://www.swift.ac.uk/xrt_products/01512686.\n\nThis circular is an official product of the Swift-XRT team.\n"
}