TITLE: GCN CIRCULAR NUMBER: 16243 SUBJECT: GRB 140508A: Swift/UVOT Detection DATE: 14/05/09 19:03:14 GMT FROM: Frank Marshall at GSFC F.E. Marshall (NASA/GSFC) and A. Amarel-Rogers (U. of Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 140508A 68965 s after the GBM trigger (Yu and Goldstein, GCN Circ. 16224). A source consistent with the optical position (Singer et al., GCN Circ. 16226) and the X-ray position (Amarel-Rogers, GCN Circ. 16232) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 17:01:51.95 = 255.46647 (deg.) Dec (J2000) = +46:46:49.5 = 46.78043 (deg.) with an estimated uncertainty of 0.46 arc sec. (radius, 90% confidence). Preliminary detections 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 v 68965 69792 814 19.38 +/- 0.10 b 70632 71427 782 19.59 +/- 0.06 u 69799 70626 814 18.81 +/- 0.05 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.031 in the direction of the burst (Schlegel et al. 1998).