TITLE: GCN CIRCULAR NUMBER: 43291 SUBJECT: GRB 260101A: Swift-XRT refined Analysis DATE: 26/01/01 12:11:45 GMT FROM: Phil Evans at U of Leicester <pae9@star.le.ac.uk> P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), S. Lanava (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi (INAF-IASFPA) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 6.7 ks of XRT data for GRB 260101A, from 100 s to 28.9 ks after the trigger. The data comprise 165 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 late-time light curve (from T0+5.3 ks) can be modelled with a power-law decay with a decay index of alpha=1.65 (+/-0.17). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.02 (+0.16, -0.15). The best-fitting absorption column is 2.1 (+/-0.5) x 10^21 cm^-2, consistent with the Galactic value of 1.6 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.91 (+0.16, -0.15) and a best-fitting absorption column of 2.2 (+0.6, -0.5) 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 (5.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.2 (+0.6, -0.5) x 10^21 cm^-2 Galactic foreground: 1.6 x 10^21 cm^-2 Excess significance: 1.8 sigma Photon index: 1.91 (+0.16, -0.15) If the light curve continues to decay with a power-law decay index of 1.65, the count rate at T+24 hours will be 3.9 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.5 x 10^-13 (2.0 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/01429608. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43291. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...