TITLE:   GCN CIRCULAR
NUMBER:  45700
SUBJECT: GRB 260922A: Swift/UVOT Upper Limits
DATE:    26/09/23 06:26:09 GMT
FROM:    s.shilling@lancaster.ac.uk

S. P. R. Shilling (Lancaster U.) 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 260922A
118.5 s after the BAT trigger (Page et al., GCN Circ. 45690). 
No optical afterglow consistent with the enhanced XRT position
(Beardmore et al., GCN Circ. 45696) 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           118          268          147         >20.2
white              118         4697          530         >20.8
v                  661         1062           58         >18.3
b                  587         1161           58         >19.2
u_FC               331          581          246         >19.7
u                  331         1135          285         >19.8
w1                 710         1111           19         >18.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.035 in the direction of the burst
(Schlegel et al. 1998).