TITLE: GCN CIRCULAR NUMBER: 35470 SUBJECT: GRB 240101B: Swift-XRT refined Analysis DATE: 24/01/03 09:51:11 GMT FROM: Phil Evans at U of Leicester <pae9@star.le.ac.uk> J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), S. Dichiara (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 6.9 ks of XRT data for GRB 240101B, from 138 s to 126.6 ks after the BAT trigger. The data comprise 189 s in Windowed Timing (WT) mode (the first 12 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The late-time light curve (from T0+5.0 ks) can be modelled with a power-law decay with a decay index of alpha=0.80 (+0.33, -0.29). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.28 (+0.14, -0.13). The best-fitting absorption column is 6.5 (+/-0.8) x 10^21 cm^-2, in excess of the Galactic value of 2.9 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.39 (+0.29, -0.27) and a best-fitting absorption column of 7.9 (+2.0, -1.8) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (9.4 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 7.9 (+2.0, -1.8) x 10^21 cm^-2 Galactic foreground: 2.9 x 10^21 cm^-2 Excess significance: 4.7 sigma Photon index: 2.39 (+0.29, -0.27) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01205744. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/35470. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...