TITLE: GCN CIRCULAR NUMBER: 38209 SUBJECT: GRB 241113A: Swift-XRT refined Analysis DATE: 24/11/14 00:29:13 GMT FROM: Phil Evans at U of Leicester pae9@star.le.ac.uk
A.P. Beardmore (U. Leicester), M. Ferro (INAF-OAB), R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), D.N. Burrows (PSU), M. A. Williams (PSU), J.P. Osborne (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 7.7 ks of XRT data for GRB 241113A, from 60 s to 34.4 ks after the BAT trigger. The data comprise 75 s in Windowed Timing (WT) mode (the first 10 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode.
The light curve can be modelled with an initial power-law decay with an index of alpha=1.90 (+/-0.24), followed by a break at T+165 s to an alpha of 0.92 (+0.04, -0.05).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.32 (+0.33, -0.30). The best-fitting absorption column is 2.2 (+1.1, -0.9) x 10^21 cm^-2, in excess of the Galactic value of 2.0 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.2 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus: Total column: 2.2 (+1.1, -0.9) x 10^21 cm^-2 Galactic foreground: 2.0 x 10^20 cm^-2 Excess significance: 3.7 sigma Photon index: 2.32 (+0.33, -0.30)
If the light curve continues to decay with a power-law decay index of 0.92, the count rate at T+24 hours will be 8.0 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.5 x 10^-13 (4.1 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01267501.
This circular is an official product of the Swift-XRT team.
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