TITLE: GCN CIRCULAR NUMBER: 16494 SUBJECT: GRB 140629A: Swift/UVOT Detection DATE: 14/06/30 11:32:49 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (UCL-MSSL) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 140629A 101 s after the BAT trigger (Lien et al., GCN Circ. 16477). A fading source consistent with the XRT position (Evans et al. GCN Circ. 16479) is detected in the initial UVOT exposures. The fact that it is not seen in uvm2 or uvw2 filters is consistent with the redshift given by Moskvitin et al., GCN Circ. 16489 and D’Avanzo et al., GCN Circ. 16493. The preliminary UVOT position is: RA (J2000) = 16:35:54.42 = 248.97676 (deg.) Dec (J2000) = +41:52:36.8 = 41.87690 (deg.) with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 101 251 147 14.78 ± 0.02 v 643 663 20 15.29 ± 0.09 b 569 589 20 15.70 ± 0.06 u 313 563 246 14.89 ± 0.03 w1 692 712 19 17.5 ± 0.3 m2 667 687 19 >17.5 w2 619 639 19 >18.0 The magnitudes in the table are 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).