TITLE: GCN CIRCULAR NUMBER: 7882 SUBJECT: GRB 080613A: Swift-XRT detection of the afterglow DATE: 08/06/14 09:15:27 GMT FROM: Cristiano Guidorzi at INAF-OAB C. Guidorzi (INAF-OAB) and C. B. Markwardt (CRESST/GSFC/UMD) report on behalf of the Swift-XRT team: The Swift XRT began observing the INTEGRAL GRB 080613A (Gotz et al., GCN Circ 7871) on June 13, 16:19 UT, 24.2 ks after the INTEGRAL trigger. The data consist of 3.6 ks observed in Photon Counting mode. We detect a single X-ray source within the INTEGRAL error circle at the position RA, Dec = 213.27213, +5.17256 which is equivalent to: RA (J2000): 14 13 05.31 Dec (J2000): +05 10 21.2 with an uncertainty of 5.2 arcsec (radius, 90% confidence). This position lies 4.9" from the optical afterglow found with the Faulkes Telescope North (Guidorzi et al., GCN Circ. 7872) and later confirmed by GROND (Clemens et al. GCN Circ. 7880) and Swift-UVOT (Hoversten and Holland, GCN Circ. 7881), and is therefore consistent with being the X-ray afterglow of GRB 080613A. Presently there is marginal evidence for fading: a power-law fit of the light curve gives a decay index of 1.2 ± 1.5, so still compatible with a constant rate of of (2.8 ± 0.3)e-2 counts/s. Forced by the small number of counts, we extracted the 0.3-10 keV spectrum from a 10-pixel radius circular region and adopted the Cash statistics. The spectrum can be fit with a power law with an absorbing column density fixed to the Galactic value (2.0e20 cm-2) and a photon index of 1.3 ± 0.3. The observed (unabsorbed) 0.3-10 keV flux is 1.50 (1.53)e-12 erg cm-2 s-1. This circular is an official product of the Swift-XRT team.