GCN Circular 42121

N. P. M. Kuin (MSSL/UCL) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 251005C 123 s
after the BAT trigger (Page et al., GCN Circ. 42113
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 ).
No optical afterglow consistent with the XRT position 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 first finding chart (FC)
exposure and subsequent exposures are:

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

white_FC           123          273          147         >21.6
u_FC               336          586          246         >19.9
white              123         1536          392         >21.3
v                  666         1586          117         >19.4
b                  592         1676          108         >19.8
u                  336         1659          343         >20.0
w1                 715         1461           78         >19.4

The magnitudes in the table are not corrected for the Galactic extinction due
to the reddening of E(B-V) = 0.461 in the direction of the burst (Schlegel
et al. 1998).

Please note that the initial GCN (Page et al., GCN Circ. 42113
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 ) reported
251005A "A-burst", which was corrected to "C" : GRB 251005C.