TITLE: GCN CIRCULAR NUMBER: 9859 SUBJECT: GRB090831C: Swift/UVOT upper limits DATE: 09/09/01 10:42:09 GMT FROM: Patricia Schady at MSSL/Swift P. Schady (MSSL-UCL) reports on behalf of the Swift/UVOT team. The Swift/UVOT began settled observations of the field of GRB 090831C 121s after the BAT trigger (Schady et al., GCN Circ 9854). No new source is detected within the XRT error circle (Evans et al., GCN Circ 9855) in any of the individual or combined UVOT filters. The 3-sigma upper limits of detecting a source at the position of the X-ray afterglow in the first white band finding chart (fc) observation and in consecutive coadded observations for each of the UVOT filters are as follows: Filter T_start(s) T_stop(s) Exp(s) Mag 3-sig UL wh (fc) 121 270 147 > 20.78 wh 561 1183 206 > 20.73 vv 610 1060 58 > 18.47 bb 536 1159 58 > 19.30 uu 279 1134 285 > 19.95 w1 660 1109 58 > 18.74 m2 635 1084 58 > 18.48 w2 586 1209 78 > 18.95 The values quoted above are not corrected for the Galactic extinction due to the large reddening of E(B-V) = 0.38 in the direction of the burst (Schlegel et al., 1998). The photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627).