TITLE: GCN CIRCULAR NUMBER: 10468 SUBJECT: GRB 100302A: Swift/UVOT Upper Limits DATE: 10/03/03 19:04:52 GMT FROM: Michele Stark at PSU/Swift M. A. Stark (PSU) and J. R. Cummings (NASA/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100302A 132 s after the BAT trigger (Cummings et al., GCN 10458). No optical afterglow consistent with the XRT position (Cummings et al., GCN 10458) is detected in the initial UVOT exposures. We do not see any source within the XRT error circle that might correspond to the R and I-band source reported by Huang et al. (GCN 10461) from the Lulin 1-meter telescope or the i' source reported by Cucchiara and Fox (GCN 10465) from Gemini-N. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the initial exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag --------------------------------------------------- white_FC 133 282 147 >21.06 white 133 2044 431 >21.24 v 621 1933 156 >18.82 b 547 2032 136 >19.58 u 291 2007 382 >20.10 w1 670 1982 155 >19.49 m2 645 1957 136 >19.26 w2 596 1908 156 >19.61 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).