TITLE: GCN CIRCULAR NUMBER: 17970 SUBJECT: GRB 150626B: Swift/UVOT Upper Limits DATE: 15/06/27 13:38:34 GMT FROM: Massimiliano de Pasquale at IASF-Palermo M. De Pasquale (UCL-MSSL) and L. M. McCauley (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150626B 131 s after the BAT trigger (McCauley et al., GCN Circ. 17966). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 17968) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 131 281 147 >20.7 u_FC 289 539 246 >20.1 white 131 6476 628 >21.6 v 620 6887 529 >19.5 b 545 7647 469 >20.8 u 289 7502 756 >20.7 w1 669 7298 529 >20.4 m2 644 7092 510 >20.3 w2 595 6682 346 >20.4 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).