TITLE: GCN CIRCULAR NUMBER: 40928 SUBJECT: GRB 250702F: Swift-XRT refined Analysis DATE: 25/07/04 00:28:33 GMT FROM: Phil Evans at U of Leicester pae9@star.le.ac.uk
J.P. Osborne (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), D.N. Burrows (PSU), M.A. Williams (PSU), S. Dichiara (PSU), K.L. Page (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 5.2 ks of XRT data for GRB 250702F, from 94 s to 94.1 ks after the trigger. The data comprise 420 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode.
The late-time light curve (from T0+3.9 ks) can be modelled with a power-law decay with a decay index of alpha=1.01 (+/-0.06).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.016 (+/-0.029). The best-fitting absorption column is 3.5 (+/-0.5) x 10^21 cm^-2, at a redshift of 1.52, in addition to the Galactic value of 1.3 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.95 (+/-0.13) and a best-fitting absorption column of 2.1 (+2.1, -1.9) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (3.7 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus: Galactic foreground: 1.3 x 10^20 cm^-2 Intrinsic column: 2.1 (+2.1, -1.9) x 10^21 cm^-2 at z=1.52 Photon index: 1.95 (+/-0.13)
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01329888.
This circular is an official product of the Swift-XRT team.
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