TITLE: GCN CIRCULAR NUMBER: 8004 SUBJECT: GRB 080723A: Swift-XRT refined analysis DATE: 08/07/23 15:35:27 GMT FROM: Andy Beardmore at U Leicester A.P. Beardmore (U. Leicester) and M. Stamatikos (NASA/ORAU) report on behalf of the Swift-XRT team : We have analysed the first two orbits of Swift-XRT data obtained from GRB 080723A (trigger 317662; Stamatikos et al., GCN Circ. 8000). The data were taken in photon counting mode and have an exposure of 2.83 ks, spanning 88 s to 7.44 ks after the trigger. The UVOT-enhanced XRT position was given by Beardmore et al. in GCN Circ. 8001. The light curve can be modelled by a doubly broken power-law, with an inital decay of alpha1 = 1.77 +0.34 -0.25 which flattens to a shallow decay of alpha2 = 0.05 +/- 0.24 at a time tbreak1 = 365 +68 -46 s. This is followed by a further steepening to alpha3 = 1.39 +/- 0.75 at a time tbreak2 = 3.4 +1.2 -1.8 ks. The spectrum of the photon counting mode data from the first two orbits can be fit with an absorbed power-law to give a photon index gamma = 2.39 +0.30 -0.28 and NH = (7.7 +2.5 -2.2)e21 cm^-2, in addition to the Galactic column of 3.9e+21 cm^-2 in the direction of the GRB. The observed 0.3-10 keV flux is (1.14 +0.10 -0.22)e-11 erg cm^-2 s^-1, which corresponds to an unabsorbed flux of 3.57e-11 erg cm^-2 s^-1. If the light curve continues to decay at the same rate we estimate the count rate will be 3.2e-2 count/s one day after the trigger, which corresponds to an observed flux of 1.9e-13 erg cm^-2 s^-1. This circular is an official product of the Swift-XRT team.