TITLE: GCN CIRCULAR NUMBER: 6473 SUBJECT: Swift/UVOT refined analysis of GRB070529 DATE: 07/05/30 14:37:07 GMT FROM: Massimiliano de Pasquale at MSSL-UCL M. De Pasquale (MSSL/UCL) and S. T. Holland (CRESST/USRA/GSFC) report, on the behalf of Swift UVOT team: The Swift Ultraviolet/Optical telescope (UVOT) began its initial V-band finding chart exposure of GRB070529 (Holland et al., GCN circ. 6466) 134 seconds after the trigger and the optical afterglow is clearly detected inside the refined XRT error circle (Mangano et al., GCN circ. 6469). Successively, the optical source appears to fade with a decay slope, based on the V band datapoints, of about -1.8. In the following table, we report the magnitudes and 3 sigma upper limits for this source. Errors are at 1 sigma level. Filter Time (s) Exp(s) Mag V 134-534 393 17.1 +/- 0.1 V 652-1253 420 19.3 +/- 0.4 V 40339-47072 2039 > 20.4 B 613-758 20 > 18.8 U 588-6277 439 > 20.1 UW1 564-7038 459 > 20.5 UM2 540-7038 592 > 20.8 UW2 628-6687 432 > 21.0 No observation was performed in the white filter, due to the crowded field. No correction has been made for the considerable Galactic reddening toward the burst, E(B-V)=0.3 (Schlegel et al. 1998).