TITLE: GCN CIRCULAR NUMBER: 10421 SUBJECT: GRB 100213B: Swift/UVOT Upper Limits DATE: 10/02/14 12:39:59 GMT FROM: Peter Curran at MSSL P.A. Curran (MSSL-UCL) and L. Vetere (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100213B 158 s after the BAT trigger (Vetere et al., GCN 10412). No optical afterglow consistent with the XRT position (Vetere et al., GCN 10416) or the NOT R-band position (Malesani et al., GCN 10413) is detected in the initial UVOT exposures. 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 158 4654 273 >21.17 v 3430 5065 393 >19.64 b 4250 5722 233 >20.38 u 4044 5679 393 >20.38 w1 3840 5475 393 >20.31 m2 3634 5269 393 >21.10 w2 4660 4860 197 >20.00 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.08 in the direction of the burst (Schlegel et al. 1998).