TITLE: GCN CIRCULAR NUMBER: 15982 SUBJECT: GRB 140311C: Swift-XRT and UVOT observations DATE: 14/03/13 18:05:25 GMT FROM: Valerio D'Elia at ASDC V. D'Elia (ASDC), L.M.Z. Hagen (PSU), L. Izzo (URoma/ICRA), P. D'Avanzo (INAF-OAB), S. Holland (STScI) report on behalf of the Swift team: We report on Swift observations of the field of the GBM discovered GRB140311C burst (Stanbro, GCN Circ 15977), for which a possible optical counterpart was reported by iPTF (Singer et al., GCN Circ 15971). XRT began observing the field on 2014-03-12 at 23:43:48 UT, i.e.,  118 ks after the trigger, for a total of 2.7ks. No source is detected at the iPTF coordinates, nor in the whole XRT field of view. The 3-sigma upper limit on the count rate is 5E-03 cts/s. The Swift/UVOT began settled observations of the field of GRB 140311C 118480 s after the trigger. No optical afterglow consistent with the iPTF position (Singer et al., GCN Circ. 15971) is detected in the initial UVOT exposure. The preliminary 3-sigma upper limit using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are: Filter         T_start(s)   T_stop(s)      Exp(s)         Mag u               118480       125414         2916        >21.43 The magnitude in the table is not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998).  We note that the photometry may be affected by a nearby bright foreground star. ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.