GRB 200806A: Swift/UVOT Possible Detection

The Swift/UVOT began settled observations of the field of GRB 200806A 86 s after the BAT trigger (Ambrosi et al., GCN Circ. 28211). A source consistent with the enhanced XRT position (Beardmore et al. GCN Circ. 28214) is marginally detected in the initial UVOT exposures. The preliminary detection and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 86 236 147 20.26 +/- 0.28 v 629 821 39 >17.9 b 555 747 39 >19.3 u 300 722 265 >19.5 w1 678 870 39 >18.8 m2 653 845 39 >19.4 w2 604 1052 58 >19.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.42 in the direction of the burst (Schlegel et al. 1998).