TITLE: GCN CIRCULAR NUMBER: 16197 SUBJECT: GRB 140430A: Swift-XRT refined Analysis DATE: 14/05/01 09:48:09 GMT FROM: Phil Evans at U of Leicester M.C. Stroh (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU) and M.H. Siegel report on behalf of the Swift-XRT team: We have analysed 7.0 ks of XRT data for GRB 140430A (Siegel et al. GCN Circ. 16190), from 132 s to 23.5 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 Evans et al. (GCN Circ. 16195). The late-time light curve (from T0+3.8 ks) can be modelled with a power-law decay with a decay index of alpha=0.68 (+0.12, -0.13). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.05 (+/-0.04). The best-fitting absorption column is 3.7 (+1.4, -1.3) x 10^21 cm^-2, at a redshift of 1.6, in addition to the Galactic value of 2.1 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.21 (+0.20, -0.19) and a best-fitting absorption column of 5.3 (+6.5, -5.3) 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 (5.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Galactic foreground: 2.1 x 10^21 cm^-2 Intrinsic column: 5.3 (+6.5, -5.3) x 10^21 cm^-2 at z=1.6 Photon index: 2.21 (+0.20, -0.19) If the light curve continues to decay with a power-law decay index of 0.68, the count rate at T+24 hours will be 0.018 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.0 x 10^-13 (9.6 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/00597722. This circular is an official product of the Swift-XRT team.