GCN Circular 10352
R. Margutti, B. Sbarufatti (INAF-OAB), S. Oates (MSSL/UCL), report on behalf of the Swift-XRT team: The Swift ToO observations of the BATSS burst GRB 100115A (Cummings et al., GCN Circ. 10325) started 40ks after the trigger. The XRT data set consists of 8 ks exposure in PC mode split into two epochs: the first observation was performed at T0+40 ks, while a second epoch of observations was acquired at T0+306 ks. The UVOT-enhanced XRT position was given by Margutti et al. in GCN Circ. 10334. In the second observation the X-ray source reported by Margutti et al., GCN Circ.10326 has faded to a level of (1.4 +/- 0.9)e-3 count/sec corresponding to a decay index of -0.7 +/- 0.4. This source is likely to be the afterglow of GRB 100115A. No further observations are planned. A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.0 (+1.0, -0.5). The best-fitting absorption column is consistent with the Galactic value of 3.1 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.4 x 10^-11 (3.8 x 10^-11) erg cm^-2 count^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020126. This circular is an official product of the Swift-XRT team.