TITLE: GCN CIRCULAR NUMBER: 16388 SUBJECT: GRB 140610A: Swift-XRT refined Analysis DATE: 14/06/12 08:33:01 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U Leicester) reports on behalf of the Swift-XRT team: We have analysed 11 ks of XRT data for GRB 140610A (Evans et al. GCN Circ. 16375), from 3.1 ks to 115.0 ks after the BAT trigger. The data comprise 586 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. Using 463 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 286.26899, +3.90822 which is equivalent to: RA (J2000): 19h 05m 04.56s Dec(J2000): +03d 54' 29.6" with an uncertainty of 3.1 arcsec (radius, 90% confidence). The light curve from T0+3.1-10.6 ks can be modelled with a power-law decay with a decay index of alpha=0.66 (+0.26, -0.25). At T0+10.6 ks the count rate is 0.04 +/- 0.01 ct/sec. In subsequent observations, spanning T0+61-115 ks and containing 7.5 ks of exposure, the source is undetected with a 3-sigma upper limit of 0.002 ct/sec. This is substantially below the extrapolated decay detailed above, and suggests a decay index of alpha > 1.71. A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.3 (+0.9, -0.8). The best-fitting absorption column is 3.1 (+2.0, -1.4) x 10^22 cm^-2, in excess of the Galactic value of 1.2 x 10^22 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 6.0 x 10^-11 (2.0 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.1 (+2.0, -1.4) x 10^22 cm^-2 Galactic foreground: 1.2 x 10^22 cm^-2 Excess significance: 2.2 sigma Photon index: 2.3 (+0.9, -0.8) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00601259. This circular is an official product of the Swift-XRT team.