TITLE: GCN CIRCULAR NUMBER: 35456 SUBJECT: GRB 240101A: Swift-XRT refined Analysis DATE: 24/01/02 11:11:51 GMT FROM: Phil Evans at U of Leicester pae9@star.le.ac.uk
D.N. Burrows (PSU), J. D. Gropp (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), S. Dichiara (PSU) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 6.8 ks of XRT data for GRB 240101A, from 142 s to 57.6 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode.
The light curve can be modelled with a power-law decay with a decay index of alpha=1.06 (+0.08, -0.07).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.1 (+/-0.3). The best-fitting absorption column is 4.3 (+1.8, -1.5) x 10^21 cm^-2, in excess of the Galactic value of 5.8 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 3.9 x 10^-11 (6.5 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus: Total column: 4.3 (+1.8, -1.5) x 10^21 cm^-2 Galactic foreground: 5.8 x 10^20 cm^-2 Excess significance: 4.1 sigma Photon index: 2.1 (+/-0.3)
If the light curve continues to decay with a power-law decay index of 1.06, the count rate at T+24 hours will be 1.4 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.6 x 10^-14 (9.3 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01205708.
This circular is an official product of the Swift-XRT team.
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