GCN Circular 34470
M.G. Bernardini (INAF-OAB), J. D. Gropp (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 3.9 ks of XRT data for GRB 230816A, from 97 s to 91.3 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=1.44 (+0.27, -0.43). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.66 (+0.31, -0.14). The best-fitting absorption column is consistent with the Galactic value of 2.9 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.4 x 10^-11 (5.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.9 (+/-1.2) x 10^21 cm^-2 Galactic foreground: 2.9 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.66 (+0.31, -0.14) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01185673. This circular is an official product of the Swift-XRT team.