TITLE: GCN CIRCULAR NUMBER: 37056 SUBJECT: GRB 240805A: Swift/UVOT Upper Limits DATE: 24/08/06 01:34:23 GMT FROM: Mike Siegel at PSU/Swift MOC mhs18@psu.edu

M. H. Siegel (PSU) and S. Dichiara (PSU) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 240805A 105 s after the BAT trigger (Dichiara et al., GCN Circ. 37032). No optical afterglow consistent with the XRT position (Osborne, GCN Circ. 37045) 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 initial exposures are:

Filter T_start(s) T_stop(s) Exp(s) Mag

white 105 4086 269 >20.4 v 4297 4497 197 >18.7 b 3681 5128 205 >19.5 u 3476 5113 393 >19.5 w1 4708 4908 197 >19.1 m2 4502 4701 197 >19.1 w2 4092 4292 197 >19.1

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.191 in the direction of the burst (Schlegel et al. 1998).

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