GCN Circular 11074
D. Grupe (PSU) reports on behalf of the Swift-XRT team: We have analyzed 9.7 ks of XRT data for GRB 100807A (Grupe et al. GCN Circ. 11067), from 125 s to 24882 s after the BAT trigger. The data comprise 36 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The light curve can be modeled with a broken power-law model. After an initial flare the light curve decays with a slope of 6.4+0.6-1.9. The light curve breaks at 173+/-10s followed by a flatter decay slope of 0.82+/-0.08. A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.12 (+/-0.22). The best-fitting absorption column is consistent with the Galactic value of 3.3 x 10^21 cm^-2 (Kalberla et al. 2005). A fit to the pc mode data is also consistent with the Galactic absorption column density, but the spectrum is slightly flatter with a photon index of 1.79+/-0.37. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from the WT spectrum is 4.38 x 10^-11 (7.54 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+48 hours will be in the order of 1.3 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.7 x 10^-14 (9.8 x 10^-14) erg cm^-2 s^-1. Note that we are currently in the plateau phase which is followed by a steeper decay slope. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00431128. This circular is an official product of the Swift-XRT team.