GCN Circular 10804
L. Vetere (PSU) reports on behalf of the Swift-XRT team: We have analysed 1.6 ks of XRT data for GRB 100526A (Vetere et al. GCN Circ. 10797), from 151 s to 5.0 ks after the BAT trigger. The data comprise 234 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN. Circ 10800). The 0.3-10 keV light curve shows a multiple peak structure, with the main spike at about T+200, followed by a fast decay with of alpha=3.24 (+/-0.08), followed by a break at T+732 s to an alpha of 0.8 (+/-0.4). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.97 (+/-0.08). The best-fitting absorption column is 3.21 (+0.18, -0.17) x 10^21 cm^-2, in excess of the Galactic value of 3.8 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.45 (+0.24, -0.22) and a best-fitting absorption column of 1.8 (+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 3.3 x 10^-11 (5.9 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 0.8, the count rate at T+24 hours will be 0.011 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.7 x 10^-13 (6.7 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/00423181. This circular is an official product of the Swift-XRT team.