TITLE: GCN CIRCULAR NUMBER: 29835 SUBJECT: GRB 210419A: Swift-XRT refined Analysis DATE: 21/04/20 02:38:59 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), B. Sbarufatti (PSU), D.N. Burrows (PSU), J. D. Gropp (PSU) and S. Laha report on behalf of the Swift-XRT team: We have analysed 6.8 ks of XRT data for GRB 210419A (Laha et al. GCN Circ. 29828), from 134 s to 64.1 ks after the BAT trigger. The data comprise 143 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 29830). The late-time light curve (from T0+5.5 ks) can be modelled with a power-law decay with a decay index of alpha=1.0 (+/-0.3). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.71 (+0.11, -0.10). The best-fitting absorption column is 1.4 (+0.4, -0.3) x 10^21 cm^-2, in excess of the Galactic value of 7.8 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.60 (+0.29, -0.27) and a best-fitting absorption column of 1.9 (+0.7, -0.6) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 2.6 x 10^-11 (4.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.9 (+0.7, -0.6) x 10^21 cm^-2 Galactic foreground: 7.8 x 10^20 cm^-2 Excess significance: 2.9 sigma Photon index: 2.60 (+0.29, -0.27) If the light curve continues to decay with a power-law decay index of 1.0, the count rate at T+24 hours will be 4.3 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x 10^-13 (2.1 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/01044032. This circular is an official product of the Swift-XRT team.