TITLE: GCN CIRCULAR NUMBER: 16338 SUBJECT: Chandra late-time observations of GRB140515A DATE: 14/05/28 19:03:45 GMT FROM: Raffaella Margutti at Harvard R. Margutti, E. Berger, R. Chornock, W. Fong, T. Laskar and A. Zauderer (Harvard U.) report: "We observed the location of GRB 140515A (D'Avanzo et al., GCN 16267) at z=6.32 (Chornock et al., GCN 16269) with the Chandra X-ray Observatory (Program 15508477, PI Margutti). Our observations started on May 25th, 07:38:38 UT, 858.6 ks after the BAT trigger. No X-ray source is detected at the position of the optical and radio afterglow (Fong et al., GCN 16274, Laskar et al., GCN 16283), with a 3-sigma count-rate limit of 1.5E-4 c/s (0.3-10 keV energy range, total exposure time of 19.8 ks). Adopting the best fitting parameters from the total PC-mode spectrum (photon index Gamma=1.8, intrinsic neutral hydrogen column density NHint=2.3E+22 cm-2 at z=6.32), we compute an observed flux limit of 1.5E-15 erg/s/cm2 (0.3-10 keV). The Galactic hydrogen column density in the direction of the burst is NHgal=2.5E+20 cm-2 (Kalberla et al., 2005). Our observations constrain the late-time (t> 100 ks) X-ray afterglow decay to be steeper than t^-2.6. We thank Belinda Wilkes and the entire Chandra team for making these observations possible."