GCN Circular 15288

A. A. Breeveld (UCL-MSSL), D. Grupe (PSU) and J. R. Cummings
(UMBC/GSFC) report on behalf of the Swift team:

The Swift/UVOT began settled observations of the field of GRB 131001A
79990 s after the BAT trigger (Cummings et al., GCN Circ. 15281
Not found
 
 
).
No optical afterglow consistent with the BAT position (Cummings et al.,
GCN Circ. 15281
Not found
 
 
) 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

u                79990        86246          972         >20.94

The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.03 in the direction of
the burst (Schlegel et al. 1998).

The Swift XRT observed the field of GRB 131001A for a total of 972s. 
No source was found in the BAT error circle. The 3 sigma upper limit
at the position of GRB 131001A applying the method described in Kraft
et al. (1991, ApJ, 374, 344) is 0.01 counts/s.

This circular is an official product of the Swift team.