GCN Circular 7643
A.P. Beardmore (U. Leicester) and H. Ziaeepour (UCL-MSSL) report on behalf of the Swift-XRT team : The Swift-XRT began observing GRB 080426 (trigger=310219, Ziaeepour et al. GCN Circ. 7639) in Photon Counting mode, 230 s after the BAT trigger. The best XRT position for this burst is the UVOT-enhanced position reported by Beardmore et al. (GCN Circ. 7641). Three orbits of data out to T+13 ks, totalling 5.7 ks of exposure, reveal a light curve which follows a simple power-law decay, with an index of -1.07 +/- 0.08. The spectrum from the first three orbits is well fit by an absorbed power-law model, with a photon index of 2.01 +/- 0.25 and column density of (5.3 +/- 1.3)e21 cm^-2, which is slightly in excess of the average Galactic column density in this direction of 3.7e21 cm^-2. The observed (unabsorbed) 0.3-10 keV flux is 5.1e-12 (9.1e-12) erg cm^-2 s^-1. If the burst continues to decay at the same rate, we predict an XRT count rate of 2.0e-3 count/s at T+24 hours, which corresponds to an observed 0.3-10 keV flux of approximately 1.2e-13 erg cm^-2 s^-1. This circular is an official product of the Swift-XRT team.