TITLE: GCN CIRCULAR NUMBER: 25023 SUBJECT: GRB 190706B: Swift/UVOT Detection DATE: 19/07/07 19:29:34 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and A. Tohuvavohu (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 190706B 100 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 24993). No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 24995) 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 100 250 147 20.35 +/- 0.27 u_FC 312 562 246 >19.86 white 100 5778 519 >20.9 v 642 17542 561 >19.9 b 568 5644 292 >20.6 u 312 13071 647 >19.9 w1 691 11551 1204 >20.0 m2 666 7285 490 >19.6 w2 618 17284 1199 >20.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.15 in the direction of the burst (Schlegel et al. 1998).