TITLE: GCN CIRCULAR NUMBER: 15905 SUBJECT: GRB 140301A: Swift-XRT refined Analysis DATE: 14/03/02 12:03:17 GMT FROM: Kim Page at U.of Leicester K. L. Page (U Leicester) reports on behalf of the Swift-XRT team: We have analysed 5.9 ks of XRT data for GRB 140301A (Page et al. GCN Circ. 15896), from 92 s to 51.3 ks after the BAT trigger. The data comprise 382 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 15898). The late-time light curve (from T0+6.4 ks) can be modelled with a power-law decay with a decay index of alpha=0.95 (+0.32, -0.29). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.01 (+/-0.09). The best-fitting absorption column is 3.3 (+/-1.0) x 10^21 cm^-2, at a redshift of 1.416, in addition to the Galactic value of 2.2 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.42 (+0.32, -0.29) and a best-fitting absorption column of 7.2 (+4.1, -3.3) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.0 x 10^-11 (4.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Galactic foreground: 2.2 x 10^20 cm^-2 Intrinsic column: 7.2 (+4.1, -3.3) x 10^21 cm^-2 at z=1.416 Photon index: 2.42 (+0.32, -0.29) If the light curve continues to decay with a power-law decay index of 0.95, the count rate at T+24 hours will be 5.8 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x 10^-13 (2.8 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/00589590. This circular is an official product of the Swift-XRT team.