TITLE: GCN CIRCULAR NUMBER: 14540 SUBJECT: GRB 130502B Swift-XRT observations DATE: 13/05/03 13:17:58 GMT FROM: Stefan Immler at NASA/GSFC A. Melandri (INAF-OAB) and S. Immler (NASA/CRESST/GSFC) report on behalf of the Swift-XRT team: We have analysed 3.4 ks of XRT data for the Fermi/LAT-detected burst: GRB 130502B, from 55.1 ks to 67.9 ks after the Fermi/LAT trigger. The data are entirely in Photon Counting (PC) mode. An X-ray source is detected within the Fermi/LAT error circle. Using 3614 s of PC mode data and 6 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 66.76207, +71.06071 which is equivalent to: RA (J2000): 04h 27m 02.90s Dec(J2000): +71d 03' 38.5" with an uncertainty of 1.5 arcsec (radius, 90% confidence). This position is 157 arcsec from the Fermi/LAT position. The light curve is consistent with a constant source of mean count rate 1.1e-01 ct/sec. A power-law fit gives an index of 0.8 (+/-1.3). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.88 (+0.28, -0.26). The best-fitting absorption column is 2.8 (+1.0, -0.9) x 10^21 cm^-2, in excess of the Galactic value of 1.1 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.3 x 10^-11 (6.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.8 (+1.0, -0.9) x 10^21 cm^-2 Galactic foreground: 1.1 x 10^21 cm^-2 Excess significance: 3.1 sigma Photon index: 1.88 (+0.28, -0.26) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020266. This circular is an official product of the Swift-XRT team.