TITLE: GCN CIRCULAR NUMBER: 15768 SUBJECT: GRB 140129A: Swift/UVOT Observations DATE: 14/01/29 16:52:45 GMT FROM: Craig Swenson at PSU/Swift C. A. Swenson (PSU) and A. Melandri (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 140129A 117 s after the BAT trigger (Melandri et al., GCN Circ. 15760). A source consistent with the XRT position (Evans et al. GCN Circ. 15764) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 02:31:33.78 = 37.89076 (deg.) Dec (J2000) = -01:35:43.4 = -1.59539 (deg.) with an estimated uncertainty of 0.50 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 117 267 147 16.51 ± 0.03 v 605 1250 78 18.69 ± 0.24 b 531 551 20 17.76 ± 0.14 u 275 525 246 16.98 ± 0.04 w1 654 17641 1357 20.77 ± 0.22 m2 5292 13449 1054 >21.2 w2 753 11858 1102 >22.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).