TITLE: GCN CIRCULAR NUMBER: 28379 SUBJECT: GRB 200906A: Swift/UVOT Upper Limits DATE: 20/09/07 16:13:35 GMT FROM: Sam LaPorte at PSU GRB 200906A: Swift/UVOT Upper Limits J. D. Gropp (PSU) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 200906A 76 s after the BAT trigger (Page et al., GCN Circ. 28371). No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 28373) 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 76 226 147 >21.2 u_FC 289 538 246 >20.4 white 76 5054 472 >21.3 v 618 1413 97 >19.4 b 544 4948 274 >20.1 u 289 1487 324 >20.4 w1 668 1462 97 >19.3 m2 643 1438 78 >20.1 w2 594 1389 97 >19.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998).