TITLE: GCN CIRCULAR NUMBER: 42160 SUBJECT: GRB 251007B: Swift-XRT refined Analysis DATE: 25/10/08 07:17:36 GMT FROM: Phil Evans at U of Leicester pae9@star.le.ac.uk
A.P. Beardmore (U. Leicester), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU), S. Lanava (PSU), J.P. Osborne (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 6.4 ks of XRT data for GRB 251007B, from 134 s to 33.2 ks after the trigger. The data comprise 6 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode.
The light curve can be modelled with a power-law decay with a decay index of alpha=1.68 (+0.24, -0.26).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.79 (+0.39, -0.25). The best-fitting absorption column is 6.5 (+3.1, -0.5) x 10^21 cm^-2, consistent with the Galactic value of 6.0 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 5.0 x 10^-11 (7.5 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus: Total column: 6.5 (+3.1, -0.5) x 10^21 cm^-2 Galactic foreground: 6.0 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.79 (+0.39, -0.25)
If the light curve continues to decay with a power-law decay index of 1.68, the count rate at T+24 hours will be 3.9 x 10^-5 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.9 x 10^-15 (2.9 x 10^-15) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01402467.
This circular is an official product of the Swift-XRT team.
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